Female Reproductive Organs 12

Technique

Hysterosalpingography

Conventional

The gold standard in evaluating tubal patency is laparoscopy, although in many institutions hysterosalpingography is commonly used. In developed countries hysterosalpingography is performed with fluoroscopic visualization; in others, where fluoroscopic equipment often does not exist, a delayed anteroposterior image after contrast instillation is an alternative.

The primary application of hysterosalpingog- raphy is in evaluating infertility. This examina- tion is readily performed by most radiologists, does not require anesthesia, and side effects and complications are uncommon, with the major complication being pelvic infection. The indica- tions for this examination have decreased con- siderably, and the current major indication is to determine whether fallopian tubes are patent or not. It has been supplanted by magnetic reso- nance (MR) in evaluating most müllerian duct anomalies. This examination does not evaluate well the fimbriated fallopian tube ends and external structures. A lack of intraperitoneal contrast spill does not establish tubal obstruc- tion; spasm, mucous plugs, and technical factors in performing the study also result in non- spillage. Thus in one study only 84% of the nonpatent tubes at hysterosalpingography were obstructed at perioperative salpingoscopy (1).

A number of studies have commented on an increased pregnancy rate after hysterosalpin- gography. The choice of a water-soluble versus an oil-soluble contrast agent in performing hysterosalpingography does not affect the subsequent rate of term pregnancy (2).

Other Imaging Techniques

Selective catheterization of the fallopian tubes (selective salpingography) is useful if hystero- salpingography reveals a blocked tube and further intervention is contemplated. If needed, a guide wire is inserted through the tube and a catheter is advanced into the tube. At times a fal- lopian tube believed to be obstructed will be shown to be patent with this technique.

Endovaginal ultrasonography (US) during air and saline instillation into the uterus also evaluates tubal patency (variously called sonos-

similar names). The use of B-mode US and Doppler US to assess tubal flow of a contrast agent and thus establish tubal patency have been proposed, but with limited success.

A liquid containing air bubbles, such as agi- tated saline or one containing human serum albumen, can be used as a contrast agent during sonographic hysterosalpingography. Fluid and air bubbles are seen in the cul-de-sac if the fallopian tubes are patent. These procedures are similar to hysterosalpingography except that endovaginal US is used.

Female Reproductive Organs

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In a woman with a contraindication to iodine-based contrast, tubal patency can be established by magnetic resonance imaging (MRI) after infusing gadolinium–diethylenetri- amine pentaacetic acid (Gd-DTPA); the pres- ence of contrast material in the peritoneal cavity implies tubal patency.

Anecdotal hysterosalpingoscintigraphy using technetium-99m (Tc-99m)–macroaggregated albumin (MAA) has been reported.

Computed Tomography

Pelvic CT is commonly used to evaluate gyne- cologic disease. Computed tomography is especially useful in staging malignancies. An occasional false-positive diagnosis of malig- nancy does occur, and among other entities it includes pelvic actinomycosis, chronic appen- dicitis, and even an ectopic pregnancy.

Ultrasonography

A number of terms describe US of the female pelvic structures: sonography, sonohysterogra-

terms are used. Saline may or may not be instilled into the uterine cavity prior to scan- ning. The examination is performed either using a transabdominal approach or the probe is positioned in the vagina, uterus, or rectum.

Ultrasonography during surgery uses a sterile intraabdominal probe.

For consistency, the terms transabdominal,

Whenever intrauterine saline is instilled it is specifically mentioned. Unless Doppler is men- tioned, the examination involves conventional US.

Intraoperative US is useful in guiding difficult dilation and curettage (D&C). Endovaginal sonohysterography aids some operative intra- uterine biopsies and resections, although its effectiveness compared to hysteroscopy is not known.

Transabdominal US provides a general over- view of the pelvis. It is limited in obese patients.

Endovaginal US allows the use of higher fre- quency transducers and thus has better resolu- tion than a transabdominal approach, but it has a limited field of view, especially of large tumors.

The two studies are therefore complementary and at times both need to be performed.

Endovaginal US is generally considered more specific in detecting adnexal and ovarian dis- orders than transabdominal US. In women with postmenopausal bleeding, endovaginal US improves clinical diagnostic accuracy and the certainty of diagnosis. Both conventional and Doppler US are feasible. No definite contra- indication to endovaginal US exists. A three- dimensional (3D) endovaginal US technique is employed in some centers; whether it provides any advantage over the current 2D techniques remains to be established.

The terms sonohysterography and hys-

that the uterine cavity has been distended with fluid, usually sterile saline. It then should be qualified whether the examination is performed transabdominally or endovaginally. Sterile saline injected into the uterine cavity acts as a sonographic window for endovaginal US. Such scanning achieves higher resolution than is obtainable with conventional endovaginal US. A number of publications have reported sensitiv- ities and specificities of over 95% for this tech- nique in detecting intracavitary lesions, and this technique has gained wide acceptance. Yet a word of caution is in order about this procedure:

A risk of intraperitoneal malignant cell dissem- ination exists in a setting of endometrial cancer.

In an elegant study of infusion sonohysterogra- phy using 10 to 20 mL of saline performed when the abdomen was open but prior to the start of a surgical procedure, fluid spilled from the fal- lopian tubes was shown to contain malignant cells (3). Whether the use of sterile water rather than saline to lyse free tumor cells is helpful remains to be established.

Intrauterine US has a higher sensitivity and specificity than an endovaginal approach in detecting uterine abnormalities. Some authors have suggested that intrauterine US might replace hysterosalpingography for uterine study. This may be so, although part of the reason may be the poor study quality of much of hysterosalpingography, especially with digital filming—gross contrast-filled uterine images provide no intrauterine details.

The indications for intrauterine US are

not yet settled, but it appears to have a role

between that of hysterosalpingography and

hysteroscopy.

Endovaginal Doppler US measures blood flow velocity in uterine arteries and both a resis- tive index (RI) and pulsatility index (PI) are readily calculated. From a simplistic viewpoint, flow with a high PI is common with a benign tumor, while a low PI value suggests a malig- nancy. These indices are used together with other imaging findings.

The uterine arteries are assessed using a transperineal approach. No significant differ- ences in PI should be detected between the transperineal and endovaginal routes. Likewise, no differences should be evident between endovaginal color Doppler imaging and color Doppler energy in assessing ovarian blood flow or detecting tumors.

Few studies have evaluated the role of laparoscopic US. In women undergoing both endovaginal US and laparoscopic US, the latter revealed additional morphologic detail, better defined the adnexal masses, and detected more adnexal lesions than endovaginal US (4).

Magnetic Resonance Imaging

Magnetic resonance has evolved into the imaging modality of choice for the study of the female pelvis. The relatively high cost of MRI is generally cited as the reason it is currently not used more often as a screening examination.

Nevertheless, a number of studies have con- cluded that MRI is superior to CT and US in evaluating neoplasms and other gynecologic conditions, and future MR application in gyne- cologic disorders will undoubtedly increase.

Magnetic resonance imaging is useful in women with primary amenorrhea both to detect congenital anomalies and as an aid for surgical planning. It provides the best results if the protocol is tailored to a specific question to be answered. Aside from possible screening, the trend is away from set generalized protocols.

Endovaginal and endorectal coils are used only if advantageous for a specific question.

Coronal T2-weighted images are very useful, especially in uterine evaluation. In particular for cystic lesions, fluid signal intensity is often expressed relative to the signal intensity of urine.

Magnetic resonance hysterography using saline injection has been proposed, but similar

to US, a possibility of intraperitoneal malignant cell dissemination exists in a setting of endo- metrial cancer.

One limitation of pelvic MRI is the lack of contrast differentiation between bowel and adjacent soft tissue structures. Prior adminis- tration of an oral contrast agent is helpful. Pos- itive oral contrast agents are commonly used, although a negative agent tends to identify bowel wall and adjacent structures better. A sus- pension of superparamagnetic iron oxide par- ticles (a negative oral contrast agent) shows promise in differentiating bowel loops from adjacent structures. Intravenous contrast- enhanced MRI visualizes normal ovarian and uterine anatomy. The uterus normally enhances several seconds before the cervix. Some studies suggest that T2-weighted images are superior to postcontrast T1-weighted images in evaluating both normal and abnormal pelvic structures, although most investigators believe that con- trast-enhanced MRI is superior to precontrast MR in characterizing and differentiating pelvic tumors.

Magnetically labeled water perfusion imag- ing is a possible noncontrast technique for evaluating uterine blood flow. The use of short inversion delay times reveals the uterine artery dividing into its branches (5); longer inversion delay times reveal intracervical branching, fol- lowed by tissue enhancement.

Proton MR spectroscopy, although in clini- cal use in evaluating brain tumors, is rarely employed in gynecologic practice. This spectro- scopic technique detects tumor metabolites, provided that a tumor is sufficiently large to be imaged. Single-voxel proton MR spectroscopy of pelvic tumors identifies a characteristic lactate signal in both malignant and some benign tumors (6); a signal from choline- containing compounds was detected only in solid tumors. The presence of lactate signifies anaerobic glycolysis. A high lipid peak is evident in tumors containing a high fat content, such as dermoid cysts.

Scintigraphy

Pelvic scintigraphy occasionally detects a

hypervascular uterus. In general, such a blush

represents increased uterine vascularity during

the secretory and menstrual phases; a similar

blush during earlier phases should be consid- ered abnormal.

Carbon-11-methionine is used as a positron emission tomography (PET) tracer. Preliminary studies suggest that benign or borderline malig- nant ovarian neoplasms do not accumulate C-11-methionine while carcinomas evidence significant uptake; in some patients this study thus appears useful in differentiating benign from malignant ovarian neoplasms.

Malignant ovarian tumors show 2-[18F]- fluoro-deoxy-D-glucose (FDG)-PET uptake.

The limitations are that inflammatory processes and endometrial and follicular cysts also have an affinity for FDG, while borderline car- cinomas tend to be false negative. Intrauterine accumulation of this agent occurs during men- struation. In general, FDG-PET is more helpful in detecting recurrent ovarian carcinoma.

Radioimmunoscintigraphy has a role in detecting the spread of ovarian cancer. A common agent used is indium-111–satumomab pendetide (OncoScint)-labeled antibody to tumor-associated antigen.

Biopsy

Endovaginal US-guided biopsy and drainage are established diagnostic and therapeutic pro- cedures. Most complications are self-limiting and consist of infection and hemorrhage.

Congenital Abnormalities

Müllerian Duct Anomalies

Bilateral fallopian tubes develop from Müllerian (paramesonephric) ducts, with the fused caudal ductal segments forming the uterus, cervix, and upper part of vagina. The lack of development or a müllerian duct fusion defect results in a specific developmental abnormality. Several müllerian duct anomaly classifications have been proposed; the one used here is a classification proposed by Buttram and Gibbons in 1979, and adopted by others since then (Table 12.1).

Congenital uterine malformations include agenesis, unicornuate, bicornuate, and septate uterus. The prevalence of these malformations

is <5%. Most affected women are not at an increased risk for sterility; however, they have a higher rate of spontaneous abortion and pre- mature births compared to those with a normal uterus. Also, these women are at an increased risk for urinary tract abnormalities, including renal agenesis.

Imaging

Congenital uterine malformations are com- monly studied with hysterosalpingography, although US is often the first imaging modality employed and is believed by some to be more sensitive. Three-dimensional US is useful in the study of müllerian duct abnormalities, achiev- ing a sensitivity and specificity of close to 100%

in defining these abnormalities. Nevertheless, MRI has evolved as the preferred imaging modality in evaluating suspected müllerian duct abnormalities. In particular, MRI is useful in differentiating a bicornuate uterus from a septate uterus. It aids in locating gonadal tissue

I. Segmental müllerian agenesis or hypoplasia A. Vaginal

B. Cervical C. Fundal D. Tubal E. Combined II. Unicornuate

A. With rudimentary horn With endometrial cavity

Communicating Noncommunicating Without endometrial cavity B. Without rudimentary horn III. Didelphys

IV. Bicornuate A. Complete B. Partial C. Arcuate V. Septate

A. Complete B. Incomplete VI. DES related

Source: Adapted from Buttram and Gibbons (7).

not visualized by US and is useful in identifying ambiguous genitalia.

Coronal T2-weighted MR images of the uterus are easier to interpret if their oblique axis is placed parallel to the endometrial canal. The degree of obliquity can be estimated from sagit- tal images.

Prior surgery makes interpretation of imag- ing findings more difficult; this is especially true with MRI.

Agenesis/Hypoplasia

The Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome consists of congenital absence of the vagina and uterus and represents complete cessation of müllerian duct development; this syndrome is believed to be due to a deficiency of estrogen and other receptors. Ovarian neo- plasms develop in young girls in association with this syndrome.

Some authors divide this syndrome into a typical or isolated form, consisting of symmet- rical nonfunctioning muscular buds (müllerian duct remnants) and normal fallopian tubes, and an atypical, more generalized form consisting of aplasia of one or both buds and with or without fallopian tube dysplasia. Some duct remnants are cystic. Differentiation between the two forms is made on the basis of laparoscopic findings, although MRI can often suggests a diagnosis. The atypical form is associated with skeletal, renal, and ovarian abnormalities.

Lack of adequate müllerian duct development leads to vaginal agenesis; with a functioning uterine anlage, MRKH syndrome results in hematometra. With a laparoscopic finding of an atypical MRKH syndrome, appropriate imaging is reasonable, often beginning with MR (Fig. 12.1).

A complex of renal dysgenesis, Gartner’s duct cyst, and ipsilateral müllerian duct obstruction in 10 girls resulted in a dilated Gartner’s duct protruding into the bladder and presenting as a ureterocele in some and extending posterior to the bladder in others (8); all had unilateral müllerian duct obstruction.

Agenesis of a portion of the müllerian ducts and congenital absence of the uterus and vagina is also found in male pseudohermaphrodites.

Occasionally genitography is helpful in defining the underlying anatomy.

The appearance of a hypoplastic uterus is that of a normal uterus except for a smaller size. This condition is not common. A small uterus is also seen in such conditions as prior diethylstil- bestrol (DES) exposure.

Isolated fallopian tube agenesis is rare and is associated with maldevelopment of mesonep- hric and paramesonephric ducts, possibly on an ischemic basis. Hysterosalpingography simply reveals fallopian tube nonfilling. Tubal obstruc- tion due to other causes, including prior fallo- pian tube torsion causing hemorrhage and eventual reabsorption, must be excluded.

Unicornuate Uterus

Abnormal unilateral development of one of the Müllerian ducts results in an unicornuate uterus. These women have a high prevalence of associated urinary tract abnormalities, includ- ing an ectopic kidney, renal agenesis, double renal pelvis, horseshoe kidney, and medullary sponge kidney. They also suffer from a high spontaneous abortion rate and a high rate of ovum implantation in a rudimentary horn and subsequent rupture during pregnancy.

Hysterosalpingography reveals a fusiform- shaped uterus tapering to its connection with the single fallopian tube. The uterus is displaced toward the side of the functioning tube. When performing this study, one must be careful not to confuse a bicornuate or septate uterus with a unicornuate one. Even if hysterosalpingography does demonstrate what appears to be a unicor- nuate uterus, a contralateral noncommunicating uterine horn may still be present but simply not communicate with the main uterine cavity, a finding not detected with hysterosalpingogra- phy. Such a rudimentary noncommunicating horn is detected by CT, US, or MRI, although US may be nonspecific, defining only a single cavity but without providing sufficient detail. Mag- netic resonance imaging is the procedure of choice to provide both uterine and adnexal region anatomic details.

A pregnancy in a noncommunicating rudi-

mentary horn is associated with a high rate of

perforation and thus, if detected, resection of

this cavity is generally performed. Such a cavity

also predisposes to endometriosis, presumably

due to retrograde expulsion of menstrual

products.

Didelphys

A didelphic uterus results from fusion failure of müllerian duct caudal segments (Fig. 12.2). In complete didelphys each uterine cavity has a separate cervix and a variable septum is present in the vagina (Figs. 12.3 and 12.4). Some women also have associated renal agenesis, dysplasia, or hypoplasia, and an ectopic ureter to Gartner’s duct cysts. A duplicated uterus can be occluded unilaterally. Girls with unilateral occlusion of a duplicated uterus develop hydrocolpos, hydrometrocolpos, hematometrocolpos, and hematosalpinx.

During hysterosalpingography uterus didel- phys is confused with a unicornuate uterus if only one of the uterine cavities is injected with contrast. Magnetic resonance imaging is the examination of choice in defining these abnormalities and providing preoperative guidance (Figs. 12.5 and 12.6). It should be noted that a congenital anomaly of cloacal exstrophy is also associated with two vaginas and hemiuteri.

Bicornuate

It is necessary to differentiate between a bicor- nuate and a septate uterus because of the dif- ferences in pregnancy outcome and because therapeutic approaches for these two conditions are different. A bicornuate uterus tends to be associated with a normal pregnancy while abor- tion rates with a septate uterus are about double that of a bicornuate uterus.

Obstruction of one uterine horn leads to a unilateral hematometra. A variant is a partial vaginal septum and resultant hematometro- colpos. Complicating the diagnosis is that an occasional bicornuate uterus reveals unilateral intermittent occlusion.

During hysterosalpingography a bicornuate uterus resembles a septate uterus. It is also similar to uterus didelphys, except that a bicor- nuate uterus has only one cervical os. Measure- ment of the angle of divergence between the two uterine cavities during hysterosalpingography has been used in an attempt to differentiate between a bicornuate and a septate uterus. A

MR imaging of disorders associated with female infertility: use in diagnosis, treatment, and management. RadioGraphics 2003;23:1401–1421, with permission from the Radiological Society of North America.)

B A

Figure 12.2. Classification of common uterine anomalies. A:

Uterus didelphys. B: Bicornuate uterus. C: Septate uterus. The septum consists mostly of fibrotic tissue.

A

B

C

detected by hysterosalpingography. The inter- cornual distance (maximal lateral extent between the high signal endometrium) is normal in a septate uterus and is increased in a bicornuate uterus.

An arcuate uterus should be considered to represent either a mild form of bicornuate uterus or a normal variant. It is usually associ- ated with normal term gestation.

Septate

A septate uterus occurs when the septum of the fused müllerian ducts fails to absorb. The resid- ual septum ranges from complete to partial and consists of fibrous tissue, myometrium, or both.

Because the müllerian ducts have already fused, the external uterine surface is normal, distin- septate uterus is suggested with an angle less

than 75 degrees, while with an increased angle a bicornuate uterus is more likely. Nevertheless, considerable overlap exists between these two conditions; MR provides better differentiation.

Magnetic resonance imaging has a sensitivity and specificity similar to those of laparoscopy in this differential and is currently the preferred procedure (Fig. 12.7).

Magnetic resonance imaging defines both the outer and inner uterine contours, and it is the external contour that is most useful in differen- tiating a bicornuate from a septate uterus.

The external fundal outline is convex outward

in the normal uterus, or it is flat, or it has a

short indentation in a septate uterus, and it

is deeply indented (fundal notch) in a bicornu-

ate uterus, an abnormality that cannot be

Figure 12.4. Duplicated uterus with an obstructed hemivagina in a 12-year-old girl. A: Transverse ultrasonography (US) scan identifies a dilated right uterus (u) and a normal left uterus (curved arrow).

B: A dilated uterine cavity (u) and distended vagina (v) are identified by longitudinal US of the obstructed right side. C: An endometrial cyst (c) is also present adjacent to the right ovary. (Source: Garel L, Dubois J, Grignon A, Filiatrault D, Vliet GV. Ultrasonography of the pediatric female pelvis: a clinical perspective. Radiographics 2001;21:

1393–1407, with permission from the Radiological Society of North America.)

A B

C

Figure 12.3. Uterus didelphys. Two uterine cavities are evident.

The patient had a previous vaginal septum resected.

Figure 12.5. Uterus didelphys with obstructed hemivagina. A: Transverse T2-weighted MRI identifies two uteri (arrows), two cer- vices, and both ovaries (arrowheads.] B: Coronal T2-weighted image shows a hematocele (arrows) due to an obstructed right hemi- vagina. (Source: Imaoka I, Kitagaki H, Sugimura K. MR imaging associated with female infertility. Nichi-Doku Iho 2000;45:440–450, with permission from Nihon Schering K. K.)

A B

Figure 12.6. Didelphys in a 13-year-old. Right uterus (arrow) is hypointense due to blood and left uterus (arrowhead) hyperin- tense due to fluid and secretions. (Source: Burgener FA, Meyers SP, Tan RK, Zaunbauer W. Differential Diagnosis in Magnetic Resonance Imaging. Stuttgart: Thieme, 2002, with permission.)

Figure 12.7. Endometrial carcinoma in a bicornate uterus. A transverse oblique MR image identifies an intrauterine tumor (arrow). (Source: Burgener FA, Meyers SP, Tan RK, Zaunbauer W.

Differential Diagnosis in Magnetic Resonance Imaging.

Stuttgart: Thieme, 2002, with permission.)

guishing this abnormality from a bicornuate

uterus.

Magnetic resonance imaging is helpful in identifying this condition (Figs. 12.8 and 12.9).

Nevertheless, both US and MRI most often mis- diagnose a septate uterus as either a normal or bicornuate uterus. The MR septal signal inten- sity varies depending on its composition and often is not a reliable indicator in differentiat-

ing a septate from a bicornuate uterus; on T2- weighted images a fibrous septum is seen as a hypointense region, while a myometrial septum has a signal intensity similar to myometrium.

Generally hysteroscopic metroplasty is per- formed for a septate uterus, with preservation of future vaginal delivery.

Diethylstilbestrol-Related Abnormalities

Patients who have been exposed in utero to DES

develop a number of gynecologic abnormali-

ties, including cervical stenosis, various uterine

development abnormalities, and distorted fallopian tubes. Clinically, DES exposure is as- sociated with subsequent infertility and ectopic pregnancies.

Hysterosalpingography in these patients shows a narrow irregular cervix and a small irregular uterine cavity. The uterus may have a T-shape. Currently hysterosalpingography is the preferred imaging modality in evaluating DES- related abnormalities.

Sex Differentiation Abnormalities

These abnormalities are usually subdivided into genetic disorders, gonadal disorders, and phe- notypic sex differentiation disorders. Unless testicular tissue is present, a fetus develops into a female or a variant of a female. Genetic and hormonal evaluations are needed to define the underlying abnormalities in many of these infants and imaging has a limited role. Ultra- sonography is helpful in outlining internal genital anatomy, although MRI provides better resolution.

Gonadal Disorders

Gonadal disorders include true hermaphro- ditism and gonadal dysgenesis (Turner’s syn-

present in true hermaphrodites. For instance, an ovotestis can contain spermatogenesis in testic- ular tissue.

Patients with Turner’s syndrome have their gonads replaced by connective tissue. The inci- dence of malignancy is increased in this tissue.

Phenotypic Differentiation Disorders

Phenotypic abnormalities develop in a setting of several endocrine disturbances. Female pseudohermaphrodites have a normal fem- ale XX karyotype and normal internal female genitalia, but have virilizing external genitalia due to excess androgen from a number of sources. The most common etiology is congen- ital adrenal hyperplasia. Ultrasonography or MRI should confirm normal internal genitalia.

Male pseudohermaphrodites have a normal male XY karyotype, and testicular tissue is present, but the internal or external genitalia is ambiguous. Imaging should exclude the pres- ence of ovaries and uterus.

Testicular feminization is a rare sex-linked disorder caused by androgen receptor gene mutations. Peripheral insensitivity to androgen leads to female external genitalia, undeveloped müllerian duct structures, androgen-producing testes, and a male genotype. As a result, the prox- imal third of the vagina, cervix, uterus, and fal- lopian tubes are either absent or rudimentary.

The sexual orientation is female. Testes are undescended. Ultrasonography identifies a blind-ending vagina and no uterus or adnexal

transverse oblique MR image. (Source: Burgener FA, Meyers SP, Tan RK, Zaunbauer W. Differential Diagnosis in Magnetic Reso- nance Imaging. Stuttgart: Thieme, 2002, with permission.) Figure 12.8. Septate uterus. Transverse T2–weighted image identifies a septum in the uterine cavity (arrow). The external uterine outline is normal. (Source: Imaoka I,Kitagaki H,Sugimura K. MR imaging associated with female infertility. Nichi-Doku Iho 2000;45:440–450, with permission from Nihon Schering K. K.)

structures; MRI also diagnoses uterine agenesis and detects undescended testes, often within or just below the inguinal canal; the testes are smaller and more hypointense than normal on T1-weighted images and isointense on T2- weighted images.

Testicular feminization should be suspected in girls having ambiguous genitalia and an inguinal hernia. Later these patients have primary amenorrhea. In distinction to male cryptorchidism, the incidence of testicular neo- plasms in patients with testicular feminization begins to increase only after the age of 30 years.

Thus in the complete form of testicular femi- nization gonadectomy can be delayed.

Cloacal Malformation

In a cloacal malformation the rectal, urinary, and genital tracts communicate and exit through a common perineal opening, or cloaca.

This rare anomaly occurs only in girls, develops early in the embryo, and varies in appearance depending on how the connecting tracts join.

A diverting colostomy is generally performed initially. A contrast study of the cloaca helps define the underlying anatomy. Using this study as a guide, a catheter can be advanced into the bladder and a cystogram performed. Injection into the distal limb of the colostomy should define the rectal communication.

Diastasis of the symphysis pubis is common in these girls. Sacral and spinal chord abnor- malities are common.

McCune-Albright Syndrome

A combination of café-au-lait spots, fibrous dysplasia, and precocious puberty is found in McCune-Albright syndrome. Ovarian follicular cysts are a common finding.

Vagina and Urethra

Gartner’s duct cysts originate from meson- ephric (wolffian) duct remnants that fail to reabsorb. Most occur parallel and anterolateral to the vagina and are small and asymptomatic, although occasionally a large cyst is encoun- tered. An occasional one visualizes during hys- terosalpingography if it communicates with the uterus.

Vaginal obstruction results in hemato (metro)colpos or hydrocolpos. At times the obstruction evolves into a large pelvic soft tissue tumor, evident both clinically and with imaging.

Obstructions range from imperforate hymen to a vaginal septum. With hematometra, cervical dysgenesis is also in the differential. Both US and MR are useful in detecting these abnor- malities (Fig. 12.10). Endorectal US is a viable alternate for suspected vaginal abnormalities if endovaginal US is not feasible. Transperineal US should detect a vaginal septum.

Magnetic resonance imaging of hematocol- pos reveals a high signal intensity blood collec- tion on both T1- and T2-weighted images and helps establish whether the distention extends into the fallopian tubes.

Congenital urethral valves are rare in female infants, with most distal urethral obstructions being secondary to a mucous membrane. Ure- thral duplication is also rare.

Trauma

Blunt abdominal trauma results in uterine rupture, especially during pregnancy. Most are seat-belt injuries; traumatic rupture involves the

Sagittal T2-weighted MR image reveals a greatly distended uterus (arrows). Blood and debris account for the slightly hyper- intense appearance. (Source: Burgener FA, Meyers SP, Tan RK, Zaunbauer W. Differential Diagnosis in Magnetic Resonance Imaging. Stuttgart: Thieme, 2002, with permission.)

fundus, and fetus and placenta extrude into the maternal abdomen. Uterine rupture during the second or third trimester of pregnancy should be diagnostic with US; an empty uterus is identified. Computed tomography can also detect uterine rupture and an intraabdominal fetus.

Uterine rupture during labor is associated with prior hysteroscopy, prior repeated curet- tage, and perforation. Spontaneous uterine rupture during pregnancy is a complication of Ehlers-Danlos syndrome type IV.

Urethral rupture due to pelvic fracture is rare in women (9). If present, an associated vaginal tear is often also found.

Ultrasonography can detect vaginal foreign bodies in young girls. The echogenicity and acoustic shadowing of a foreign body varies. At times US detects an indentation of the posterior bladder wall.

Acute Gynecologic Conditions

Imaging of acute gynecologic conditions are discussed in more detail in their respective sec- tions in this chapter. Not uncommonly these conditions are in a differential diagnosis of an acute abdomen (discussed in Chapter 14).

Computed tomography in 100 consecutive nonpregnant women suspected of having appendicitis or an acute gynecologic condition achieved a 100% sensitivity and 97% specificity in diagnosing appendicitis and 87% sensitivity and 100% specificity for acute gynecologic condition (10).

Torsion

Ovary

Clinical

Torsion, or a twist of the ovary around its pedicle, leads to venous stasis, edema, and even- tual ischemia. Although isolated ovarian torsion does occur, usually it is associated with fallop- ian tube torsion. It can occur during pregnancy.

An ovarian cyst or other tumor, regardless of etiology, predisposes to torsion (gynecologists and urologists prefer the terms severe torsion or even simply torsion to what gastroenterologists

would label as volvulus for an equivalent condi- tion in the gut).

Ovarian torsion occurs most often in girls and young women but has developed in neonates. Depending on the degree of twist, the onset of pain ranges from gradual to sudden.

Severe pain is a common presentation of com- plete torsion. Clinically, acute right ovarian torsion mimics appendicitis. A not uncommon scenario consists of acute appendicitis being suspected in a young girl, but subsequent laparotomy detects a torsed and necrotic ovary.

Chronic partial ovarian torsion is rare. Inter- mittent venous obstruction and edema result in massive ovarian enlargement.

Neglected amputated ovaries secondary to ovarian torsion can evolve into calcified cystic tumors which became attached to adjacent structures by a pedicle containing vessels.

Salpingo-oophorectomy is often performed for ovarian torsion. Occasionally prophylactic oophoropexy or even laparoscopic shortening of the uteroovarian ligament is feasible for intermittent torsion.

Imaging

Imaging shows a large, irregular adnexal tumor ranging from solid to thick-walled and cystic (Figs. 12.11 and 12.12). Any cystic component,

Figure 12.11. Ovarian torsion in an 11-year-old girl with pelvic pain. Computed tomography reveals a retrovesical tumor.

Normal gynecological structures were not identified. An appen- diceal abscess was initially suspected. (Courtesy of Luann Teschmacher, M.D., University of Rochester.)

when present, represents engorged follicles.

Some hemorrhage is common and, if untreated, eventual necrosis ensues.

Echogenicity of a torsed ovary varies consid- erably.A US finding of a twisted vascular pedicle is suggestive of ovarian torsion but this is not always present. Doppler US suggests the degree of viability of a torsed ovary. With a nonviable ovary, Doppler US shows absent arterial and venous flow centrally, low-velocity arterial flow in the periphery, or absent or even reversed diastolic arterial flow. The lack of blood flow within a twisted vascular pedicle implies a non- viable ovary. The presence of internal arterial flow has prognostic implications because some of these can be treated successfully with laparo- scopic untwisting.

Occasionally US detects an engorged fallo- pian tube. Cul-de-sac fluid is a common but nonspecific finding. Ultrasonography is not foolproof, however. Transabdominal US in two girls with abdominal cysts revealed a “double wall” sign, and duplication cysts were diagnosed (11); surgery revealed ovarian cysts, torsion, and hemorrhage within the cyst wall.

In addition to detecting engorged blood vessels in ovarian torsion, MR often also detects uterine deviation to the twisted side. The lack of CT or MRI contrast enhancement of the involved ovary signifies arterial compromise.

The wall of any associated cystic tumor is ede- matous and thickened. Any superimposed hem- orrhage modifies the imaging appearance.

A rare finding with torsion involving an ovarian tumor is presence of intravascular gas within the tumor. This gas probably represents oxygen released from trapped oxyhemoglobin.

Fallopian Tube

Isolated fallopian tube torsion can develop in the absence of prior surgery or infection, but it is rare. Prior adhesions, inflammation, or ovarian disease predisposes to torsion. Possible congenital associations include a long meso- salpinx or mesovarium. Clinically, these patients have severe lower abdominal pain and signs of peritoneal inflammation.

Ultrasonography reveals an adnexal tumor and also a hydrosalpinx.

Uterus

Uterine torsion consists of the long uterine axis being rotated more than 45 degrees. Some of these torsions involve a uterine myoma.

Torsed uterine leiomyomas tend to be hyper- intense on T2-weighted MRI once ischemia develops.

Figure 12.12. Ovarian torsion. A: US in a young girl with suspected appendicitis identified a normal appendix (cursors). B: Further pelvic US detected a tumor in the pouch of Douglas and cul-de-sac. Surgery revealed a left fallopian tube and ovary torsed 720 degrees. (Courtesy of Luann Teschmacher, M.D., University of Rochester.)

A

B

Infection/Inflammation

Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) is most often bacterial in origin and most often bilateral.

Clinically, it mimics an acute abdomen and sug- gests appendicitis or bowel perforation. Acute salpingitis typically manifests as a pyosalpinx or hydrosalpinx. The infection spreads and evolves into either peritonitis or a tubo-ovarian abscess.

Peritonitis ranges from diffuse to focal, occa- sionally localizing around the liver (Fitz-Hugh Curtis syndrome is discussed in Chapter 14).

Gonococcal ovarian infection is rare. The clini- cal presentation is nonspecific.

Hysterosalpingography is contraindicated during suspected acute salpingitis. Endovaginal US often identifies free fluid in the cul-de-sac but endovaginal US has a low sensitivity in identifying fallopian tube intraluminal fluid or even a developing tuboovarian abscessees.

Either CT, US, or MRI should detect a tuboovar- ian abscess or hydrosalpinx once it is estab- lished. A hydrosalpinx is common, usually bilaterally. Superficially, the imaging appearance of a pyosalpinx or hydrosalpinx mimics a dilated loop of bowel. The wall of a pyosalpinx tends to enhance considerably with contrast.

Endovaginal Doppler US reveals a low resistive index in presence of severe infection.

Magnetic resonance imaging is not often performed for suspected PID but it has con- siderable potential. MRI findings include a fluid-filled tube, pyosalpinx, tubo-ovarian abscess, polycystic-appearing ovaries, and pelvic fluid. In one study, MRI sensitivity in detecting PID was 95% and specificity 89% and, for comparison, endovaginal US sensitivity was 81% and specificity 78% (12).

One sequela of scarring during healing is tubal obstruction and resultant hydrosalpinx formation.

Abscess

Among less common causes of a tubo-ovarian abscess is endovaginal oocyte retrieval for in vitro fertilization. Clinically, these patients present with pain and often a palpable tumor.

The CT and US findings of a tubo-ovarian abscess, regardless of cause, are similar to those

of other intraabdominal abscesses. Often an abscess consists of a complex, thick-walled, cystic adnexal tumor having no specific charac- teristics. Some abscesses are associated with a hydrosalpinx. The presence of gas, although uncommon, is almost pathognomonic of an abscess. Most of these abscesses form discrete tumors, with an occasional one being diffuse and having an appearance similar to focal peritonitis.

Ovarian abscesses range from hypointense to hyperintense on T1-weighted images. A thin hyperintense rim is common. Most abscesses are hyperintense on T2-weighted images. Many contain linear stranding.

Some of these abscesses obstruct an adjacent ureter, and imaging should thus also evaluate for any hydroureter. The presence of adenopathy is variable.

The imaging appearances of a tubo-ovarian abscess and a necrotic tumor overlap. The dif- ferential often also includes an appendiceal or Crohn’s abscess.

Pelvic abscesses are drainable using an endovaginal US-guided trocar and catheters (13).

Tuberculosis

Adnexal involvement with tuberculosis is uncommon. A typical pattern of spread in affected individuals is from fallopian tubes to the uterus, with resultant infertility.

Tubal calcifications develop with tuberculous involvement. These are seen as linear or some- what nodular calcifications along the fallopian tubes. Generally both tubes are involved.

The presence of such calcifications, regardless of how they are detected, should suggest tuberculosis.

Hysterosalpingography identifies fallopian tube occlusion or narrowing, with the tube lumen having an irregular, beaded appearance.

Outpouchings tend to mimic salpingitis isth- mica nodosa. Any contrast spilled from the fimbriated tubal ends is loculated. A hydro- salpinx develops in some. Extensive fistulas are not common. Endovaginal US reveals fallopian tube wall thickening. Any hydrosalpinx is readily detected.

Uterine involvement leads to synechiae

varying in size and extent; these synechiae can

be identified if intrauterine fluid is instilled. An eventual decrease or even obliteration of the uterine cavity ensues. Endovaginal US reveals a thickened and inhomogeneous endometrium.

Occasionally endometrial aspiration biopsy in a woman with bleeding yields necrotic debris with focal granulomas and even acid-fast bacilli.

Cervical tuberculosis can mimic a carcinoma;

a biopsy should be diagnostic.

Actinomycosis

Pelvic actinomycosis is a chronic infection with the anaerobic gram-positive bacteria Actino-

normal body cavities; its growth is promoted by the presence of an intrauterine device. When invasive, it causes a chronic, indolent infection consisting of a soft tissue tumor mimicking a neoplasm. Histology identifies characteristic actinomyces granules.

The imaging findings are often more exten- sive than the symptoms suggest. A charac- teristic of this infection is extensive fistuliza- tion extending into surrounding structures.

Occasionally one of the ureters becomes obstructed.

Two examples serve to illustrate the great mimicry of this infection: Pelvic actinomycosis with secondary liver involvement in a 50-year- old woman initially suggested a pelvic neoplasm with liver metastases (14). Computed tomo- graphy and US in a 37-year-old nulliparous woman with an intrauterine device revealed a large right adnexal mass adherent to the uterus and compressing the bladder, a preoperative diagnosis of ovarian cancer was made, and she underwent bilateral salpingo-oophorectomy and total abdominal hysterectomy (15); the resected specimen revealed actinomycosis.

Endometritis/Cervicitis

Among rarer causes of endometritis is infection with Trichinella spiralis, at times resulting in small calcifications with trichinella infiltrating the basal endometrium. A rare endometritis evolves into pyometra, perforation, and an acute abdomen.

Most syphilitic cervicitis is evident both clinically and pathologically. Rarely, syphilis presents with a cervical tumor mimicking a carcinoma.

Rarer Infections

Especially in the tropics, colorectal amebiasis can evolve into an amebic rectovaginal fistula.

These fistulas heal after definitive therapy.

In endemic areas fallopian tube involvement with Schistosoma haematobium infection should be considered. Infected patients have an increased incidence of ectopic pregnancies and eventually develop infertility. Schistosoma eggs are found in the fallopian tubes, resulting in hydrosalpinx and PID.

Ovarian echinococcal infection is rare even in endemic regions, although adnexal involvement is not. Imaging reveals a pelvic cyst, with some cysts containing internal septa or even having an onion skin appearance. With active disease, color Doppler reveals increased peripheral vas- cularity. In endemic regions a check for hydatid serology appears reasonable.

Salpingitis Isthmica Nodosa

Salpingitis isthmica nodosa is an inflammatory disorder affecting the fallopian tubes and asso- ciated with infertility and an increased risk of ectopic pregnancy.

Hysterosalpingography reveals multiple diverticulum-like outpouchings adjacent to the tubal lumen, most often in the proximal isthmic portion of the tube, with the distal isthmus and tubal segments adjacent to uterine cornua less often involved. Fallopian tubes tend to be more convoluted than usual, a difficult subjec- tive finding. Associated hydrosalpinx and tubal occlusion are common. Selective salpingogra- phy establishes whether fallopian tubes are patent.

Uterine Synechiae

Intrauterine adhesions, or synechiae, range

from focal to diffuse involvement of the uterine

cavity. Synechiae are associated with infertility

(Asherman’s syndrome). Most common causes

of Asherman’s syndrome are postpartum uterine surgery and termination of pregnancy.

Rare causes include infections such as tubercu- losis and even schistosomiasis.

Hysterosalpingography identifies synechiae as irregular fixed filling defects within the uterine cavity. A severity grading system is reported (Table 12.2), although the hystero- graphic findings do not always reflect the hys- teroscopic appearance. Most synechiae can be differentiated from polyps because the latter have a smooth round or oval configuration and synechiae are irregular in outline. Occasionally extensive adhesions obliterate the endometrial cavity to the point of preventing filling during hysterosalpingography.

Synechiae are identified with endovaginal US.

Sonohysterography reveals synechiae as bridg- ing bands in the fluid-distended uterine cavity.

The fibrous synechiae have a low signal inten- sity on T2-weighted MRI and are not visualized directly, but MRI is useful in evaluating the uterine cavity above adhesions for the presence of endometrial tissue. A normal endometrium and endometrium-to-myometrium junctional zone are absent on T2-weighted MRI in women with severe Asherman’s syndrome.

Operative hysteroscopy consisting of the surgical division of synechiae is the therapy of choice. Video-enhanced endoscopic hys- teroscopy is further aided by intraoperative US;

such US allows hysteroscopic lysis of adhesions at equivalent distances from the uterine wall, especially in the uterine cornua.

An endometrial carcinoma can develop in a setting of intrauterine synechiae.

Pregnancy Related

Normal Pregnancy

Hysterosalpingography is contraindicated dur- ing pregnancy. If performed, it reveals an early intrauterine pregnancy as a small sessile tumor.

Ultrasonography

The ability of US to visualize normal ovaries decreases from the first trimester to the second and from the second trimester to the third.

Early US signs of an intrauterine pregnancy include a chorionic rim sign, consisting of a hyperechoic rim around an intrauterine fluid collection, and the presence of a double decid- ual sac. Sensitivities of these two signs for an intrauterine pregnancy are about 60–80%, and specificity approaches 100%.

Endovaginal US can assess the corpus luteum during early pregnancy. Corpus luteum ranges from macrocystic, to microcystic, to noncystic.

No correlation exists between corpus luteum size and pregnancy failure, although a decrease in volume between two examinations is associated with a greater risk of nonviable outcome.

A hyperechoic, thick-walled sac within a thickened endometrium suggests an intrauter- ine pregnancy, although it is insensitive in detecting an early pregnancy. With a positive pregnancy test and endovaginal US evidence of intrauterine fluid but without an embryo or yolk sac, follow-up US is necessary.

Doppler US of the uterine arteries can be obtained by either endovaginal and transab- dominal techniques. During early pregnancy, the intrauterine arterial peak systolic velocity and resistive index values recorded transab- dominally are lower than the endovaginal ones, but after 28 weeks of gestation the differences narrow.

An abnormal uteroplacental circulation, detected by Doppler US, suggests a spontaneous preterm delivery. An abnormal color Doppler

syndrome

Grade Description

1 Single uterine defect less than one tenth of uterus in size

2 One or more defects occupying less than one fifth of uterus

No gross uterine cavity deformity 3 About one third of uterus involved

Uterine cavity deformed by adhesions 4 All or most of uterus involved

Severe deformity

Source: Adapted from Dykes et al. (16).

study of a viable early pregnancy is associated with an increased risk of miscarriage. A uterine artery systolic/diastolic ratio significantly higher than normal later in pregnancy is often found with preterm delivery.

Transperineal US is often used to monitor cervical effacement at the start of labor. Ultra- sonography reveals progressive cervical canal shortening and the opening of a funnel-shaped internal os, which gradually extends to the lower cervix and leads to effacement.

Magnetic Resonance Imaging

Magnetic resonance imaging offers a number of advantages in the pregnant patient and fetus. It is used for pelvimetry, because aside from the lack of ionizing radiation, MRI readily outlines the maternal bony pelvis and related soft tis- sues together with the fetus. A number of MR pelvimetry techniques have been described, most having the goal of decreasing image acqui- sition time.

Magnetic resonance is a viable alternative for differentiating hydronephrosis of pregnancy from hydronephrosis due to an obstructing stone. Only limited studies are available on the use of gadolinium in pregnancy. Current evi- dence points to no obvious harm.

Ectopic Pregnancy

An ectopic pregnancy implants either within the fallopian tube or in other locations in the pelvis or abdomen. Intraabdominal pregnancy is dis- cussed in Chapter 14.

Etiology for ectopic implantation is un- known. Previous infection appears to play a role. Women on progestin-only pills are more prone to extrauterine pregnancies than those on combined oral therapy.

A human chorionic gonadotropin (hCG) of

>2000 mIU/mL and no US evidence of an intrauterine pregnancy is suggestive of an ectopic pregnancy, although some of these women do have a normal pregnancy. In early pregnancy small amounts of intrauterine fluid detected by US should be interpreted with caution; it is found with both an intrauterine and an ectopic pregnancy.

Some ectopic pregnancies resolve sponta- neously. A longer time from the last menstrual

period, decreasing b-hCG levels, the absence of gestational sac, and a high ectopic pregnancy resistive index are predictors of spontaneous resolution (17).

Tubal Clinical

Tubal rupture due to an ectopic tubal pregnancy is treated by salpingectomy. On the other hand, an ectopic tubal pregnancy detected prior to tubal rupture is amenable to laparoscopic microsurgery or other therapy.

An ectopic pregnancy manifests as pain, vaginal bleeding, and an adnexal mass. These findings are nonspecific and are found in a number of other conditions both in the preg- nant and nonpregnant woman. A pregnancy test differentiates between these two groups. A tubal pregnancy results in hemosalpinx, bloody ascites, and a complex adnexal mass, findings identified by imaging with varying success rates. A bilateral tubal ectopic pregnancy is extremely rare.

A ruptured ovarian neoplasm in a pregnant woman mimics a ruptured ectopic pregnancy.

Imaging

Transabdominal US is generally performed as an initial examination for a suspected ectopic pregnancy. With a positive pregnancy test, the primary role of US is to detect an intra- uterine pregnancy. The significance of not de- tecting an intrauterine pregnancy is limited, although an ectopic pregnancy is then consid- ered. A definite diagnosis of an ectopic preg- nancy is sonographic detection of a live embryo in an extrauterine location, a finding not often made.

Endovaginal US provides additional informa-

tion in a setting of both an ectopic pregnancy

and an intrauterine pregnancy. It is possible to

detect an intrauterine pregnancy within several

weeks after conception. The intradecidual sign

consists of a hyperechoic endometrial region in

the thickened decidua. This sign, in those

with a b-hCG level >2000 mIU/ml, achieved a

sensitivity of 88% for diagnosing an intrauter-

ine pregnancy (18). In a typical clinical setting

sonographic evidence of an intrauterine

pregnancy essentially excludes an ectopic pregnancy (see Heterotopic Pregnancy, below).

An ectopic pregnancy can be missed with endovaginal US, and some practices perform both transabdominal US for an overview and endovaginal US for its higher resolution;

occasionally an ectopic pregnancy is detected with transabdominal US but not endovagi- nal US.

The ovary is a useful landmark when search- ing for an ectopic pregnancy. With endovaginal US an ectopic tubal pregnancy appears as a ring-like tumor having an anechoic center and a hyperechoic periphery—an adnexal ring sign.

Although often sought, this sign is not pathog- nomonic for an ectopic pregnancy. In some patients with a subsequently proven ectopic pregnancy, US will not detect any adnexal tumor or tubal ring. The reverse is also true, namely, the sonographic findings of an ectopic pregnancy can be mimicked by other condi- tions, for instance, a ruptured ovarian hemor- rhagic cyst (19). The presence of intrauterine fluid does not exclude an ectopic pregnancy because such a pregnancy may be associated with a pseudosac.

Published sensitivities and specificities of US in detecting an ectopic pregnancy vary depend- ing on specific criteria used. In general, with a positive pregnancy test and no detectable intrauterine pregnancy, the presence of fallo- pian tube rings or extraovarian complex tumors has a high specificity and sensitivity for a tubal pregnancy.

In symptomatic pregnant women, an US three-layer endometrial appearance has been described in some women with ectopic preg- nancy, but this sign is also seen in other condi- tions. Small endometrial decidual cysts are also identified in some ectopic pregnancies, but their significance is questionable.

Color Doppler US is believed to add little to a diagnosis of an ectopic pregnancy. Nevertheless, only an occasional ectopic pregnancy has arte- rial endometrial blood flow, and the presence of endometrial arterial blood flow aids in exclud- ing an ectopic pregnancy.

In general, the presence of an adnexal tumor or intraperitoneal fluid should not be used as a criterion for diagnosing tubal rupture. With a distended tube, blood and an amniotic sac of a tubal pregnancy have different MR signal inten- sities; bloody ascitic fluid has varying hyperin-

tensity on T1-weighted MR images. An adnexal tumor has a complex signal intensity on both T1- and T2-weighted images.

The therapy of an ectopic pregnancy gener- ally is surgical. As alternate therapy, tubal pregnancies can be managed with local methotrexate injection using abdominal or endovaginal US for guidance. Nevertheless, methotrexate therapy has its own complica- tions, including an acute abdomen and bleed- ing. Of interest is that hysterosalpingography after methotrexate therapy shows bilateral tubal patency in some of these women.

Cornual

A cornual ectopic pregnancy is rare, occurring in about 2% to 4% of all ectopic pregnancies.

Rupture at the implantation site occurs at an advanced gestational age, and resultant severe bleeding is associated with increased maternal morbidity and mortality.

A cornual pregnancy has been successfully treated with methotrexate injection; US and laparoscopy are used for guidance.

Ovarian

An intraovarian ectopic pregnancy is rare. Sur- gical findings range from a hematoma, to an ovum, to placenta and fetus. Most often implan- tation is superficial and the ovary can be preserved.

Ultrasonography usually shows a complex nonspecific tumor. Some of these consist of a double hyperechoic structure surrounding a hypoechoic region. Endovaginal US aids in localization.

In the rare combined intrauterine and ovarian pregnancy, the ovarian pregnancy consists of a rapidly growing adnexal tumor and intraperitoneal hemorrhage, and it is not surprising that US cannot distinguish between an intraovarian pregnancy and an ovarian cancer.

Cervical

It has been said (20):

The majority of obstetricians will never see a cervi- cal pregnancy; the minority who has to treat this pathology wishes to have never seen one.

In one pregnant woman with painless bleed- ing, US identified no embryonal structures, a retained miscarriage was presumed, and during cervical dilation uncontrollable hemor- rhage ensued (20); a total hysterectomy was performed.

Ultrasonography can suggest a cervical preg- nancy. However, cervical abortion and even ges- tational trophoblastic disease occasionally has similar US findings.

Magnetic resonance imaging in women with a cervical pregnancy revealed a poorly mar- ginated heterogeneous tumor that was hyperin- tense on T1-weighted images (21); it contains markedly enhancing solid components and is surrounded by peripheral enhancement. Post- contrast MR can evaluate the trophoblast blood supply prior to therapy.

Heterotopic Pregnancy

A heterotopic pregnancy consists of both an intrauterine and extrauterine pregnancy. It is a rare entity. The incidence of a heterotopic preg- nancy increases in women who have undergone assisted reproduction. The condition can be sus- pected with endovaginal US by detecting both pregnancies. At times a salpingectomy is fea- sible on the extrauterine pregnancy, and the intrauterine pregnancy continued to term.

Uterine Rupture

Uterine rupture during labor is not common in the West. It is associated with prior uterine scar- ring and carries a high fetal death rate. The rare spontaneous rupture of an unscarred uterus occurs mostly in older, multiparous women.

Uterine Dehiscence

Complete uterine dehiscence after cesarean section consists of transmural disruption, while partial dehiscence involves disruption only of the endometrial or serosal layer. Occasionally an anteriorly placed placenta beneath the uterine scar masks dehiscence. In general, CT is unreli- able in detecting dehiscence, but preliminary studies suggest that MRI is useful.

Ultrasonography appears useful in assessing the risk of rupture during subsequent pregnan- cies in women with previous cesarean section.

The risk of rupture or dehiscence is related to the thickness of the lower uterine segment and in pregnant women with a previous cesarean section, preoperative US can measure this lower uterine segments. Resultant sensitivity and specificity in predicting dehiscence will vary depending on the assumed lower uterine segment cut-off thickness.

Preliminary study suggests that MRI is useful in detecting uterine dehiscence.

Preeclampsia and Related Conditions

Preeclampsia is characterized by hypertension and proteinuria. Edema develops in some of these women. Preeclampsia leads to multiorgan damage, including placenta, liver, kidneys, and brain; it can lead to eclampsia, and is the primary cause of maternal death in a number of countries.

In women with pregnancy-induced hyperten- sion the HELLP syndrome (consisting of hemol- ysis, elevated liver enzymes, and low platelets) is a life-threatening, severe complication asso- ciated with preeclampsia and eclampsia, but it has also developed after delivery. Pathogenesis appears multifactorial and probably involves genetic and immunologic factors. The coagula- tion system is activated, and endothelial dysfunction becomes evident, with fibrin deposition in vessels and liver sinusoids.

Thrombocytopenia and fibrinolysis ensue with vascular thromboses and emboli. The HELLP syndrome has led to intracerebral hemorrhage and death. Cardiopulmonary and renal compli- cations develop, and these women are at risk of acute renal failure and spontaneous liver rupture with its associated high maternal and fetal mortality. This syndrome is usually treated by prompt delivery.

Ophthalmic artery pulsatility and resistivity indices, measured with Doppler US, decrease in preeclamptic women (compared to normoten- sive gravid women) (22); these indices increase with progression to severe preeclampsia, suggesting that early vasodilation and late vasospasm are part of the spectrum of preeclampsia.

Doppler US of the umbilical and uterine

arteries is useful in preeclamptic women and

those with HELLP syndrome. Impaired placen-

tal hemodynamics is common, with one study finding blood flow restriction in at least one uterine artery in a majority of women (23).

Women with an abnormal Doppler study before delivery have significantly higher blood pres- sures than those with a normal predelivery study; likewise, abnormal Doppler US is associ- ated with an increased number of perinatal deaths and significantly higher fetal distress as compared to a normal Doppler study.

Placenta

Dynamic MR reveals early placental enhance- ment; it has heterogeneous enhancement during the second trimester and evolving into enhanced lobules during the third trimester;

normal placental enhancement precedes myometrial en-hancement and it can be differ- entiated from myometrium.

A placental maturity classification was devel- oped in 1979, based on US findings of placental texture (24); this classification, using a grad- ing scale from 0 to 3, correlates with fetal pulmonic maturity as determined by the lecithin-sphingomyelin ratio. Those with pre- mature placental aging are at increased risk of perinatal complications such as hypertension, oligohydramnios, and delayed intrauterine growth.

A relationship exists between smoking and placental calcifications.

Transabdominal US should detect most pla- centa previa, with only occasional transperineal or endovaginal US necessary. An MRI can provide substantially similar information, but at the expense of substituting a more complex study for a simpler one.

Placenta membranacea or placenta diffusa results when chorion fails to differentiate. It is associated with bleeding, abortion, and fetal death. Ultrasonography in placenta membran- acea reveals total placenta previa covering the uterine wall and containing numerous lacuna.

With placenta increta, chorionic villi invade the myometrium while placenta percreta signifies that the villi penetrated through the myometrium. Both evolve in a setting of uterine scarring such as prior cesarean section, D&C, and other causes. An association exists with placenta previa. Placenta percreta can lead to uterine rupture and an acute abdomen.

Ultrasonography suggests placenta accreta by detecting the absence of the typically visualized retroplacental sonolucent space. Doppler US in placenta percreta reveals placental extension into the myometrium and increased blood flow through the myometrium. Gadolinium- enhanced MRI also differentiates placenta accreta from placenta percreta.

The resultant bleeding with abnormal placentation can be massive and a total hysterectomy required for bleeding control.

Hypogastric artery balloon occlusion in several women with abnormal placentation, performed after cesarean delivery but prior to hysterec- tomy and hypogastric artery ligation, was effec- tive in decreasing blood loss (25).

Placental nontrophoblastic tumors include chorioangioma and teratoma. These tumors are benign and often overlooked, but multiple placental chorioangiomas lead to fetal cardiac failure or anemia. Their presence can be sug- gested by US.

Antepartum Bleeding

Discussed here are only some of the more unusual causes of pregnancy-related bleeding.

Premature delivery and various placental abnormalities, discussed above, are common causes. Most first trimester bleeding is associ- ated with either an ectopic pregnancy or par- tial placental separation from its myometrial implantation (separation occurring before the 20th week of pregnancy is called abortion and separation after the 20th week abruptio placen-

last half of pregnancy are placenta previa (low placental implantation) and abruptio placentae.

Transabdominal US may not detect a cause

for first trimester bleeding, and in these women

endovaginal US, with its better resolution,

is more helpful. If detected, a subchorionic

hematoma has a crescent appearance elevat-

ing the chorionic membrane. Ultrasonography

establishes whether a normal-appearing

gestational sac is visible. A clot secondary to

abruptio placentae often has a similar transab-

dominal US appearance to normal placenta and

thus normal US does not exclude abruptio. At

times only an abnormally thick placenta is

detected.

Most intraamniotic bleeding is secondary to trauma. It is common after amniocentesis. A rare cause of third trimester bleeding is cervical varices.

Postpartum Bleeding

Retained intrauterine placental tissue post- partum or postabortion is termed a placental polyp. It is associated with massive bleeding, at times months or even years after delivery.

Ultrasonography after delivery has low sensi- tivity in detecting retained trophoblastic tissue;

if detected, this tissue appears as a hetero- genous, hyperechoic tumor. At times retained fluid is evident. Sonohysterography detects free- floating endometrial tissue, yet the role of endovaginal sonohysterography is not clear in this setting, although it is more sensitive than endovaginal US; it should decrease the number of curettages in women with bleeding.

Magnetic resonance imaging reveals most placental polyps as pedunculated intrauterine tumors. They are hyperintense on T2-weighted images, with blood often surrounding them.

Postcontrast, these polyps enhance more than myometrium and appear as a high signal inten- sity uterine cavity tumor.

Bleeding postpartum is generally managed medically. At times hysterectomy is necessary for unresponsive major bleeding, but arterial embolization should be considered in intra- ctable postpartum bleeding not controlled with vaginal packing and uterotonic drugs. In these patients angiography is useful not only to iden- tify a bleeding site but also to act as a guide for selective embolization of the vessel involved.

Embolization controls both immediate and delayed bleeding. Generally multiple arteries are embolized, including uterine, vaginal, ovarian arteries or even a division of the inter- nal iliac arteries. Few complications are encoun- tered with uterine artery embolization, and normal menses resumes in almost all women with obstetric hemorrhage who undergo selec- tive uterine artery embolization (26).

It takes about 7 weeks for the postpartum uterus to involute to its baseline.

The differential diagnosis of a placental polyp includes a choriocarcinoma, although the latter is associated with elevated serum b-hCG levels.

A leiomyoma has variable signal intensities.

Gestational trophoblastic disease and a uterine arteriovenous malformation are also in the differential.

A rare cause of late postpartum hemorrhage after cesarean section is an aneurysm bleed- ing into the uterus; angiography not only is diagnostic but also permits therapeutic embolization.

Gestational Trophoblastic Disease

Gestational trophoblastic diseases include a spectrum of disorders ranging from hydatidi- form mole (molar pregnancy) to a choriocarci- noma and the rare placental site trophoblastic tumor. They originate from trophoblastic tissue and are believed to be due to abnormal fertil- ization. Most are located in the uterus, although an ectopic one originates in the ovary and other sites of an ectopic pregnancy.

Hydatidiform Mole

A hydatidiform mole is not a neoplasm, although an occasional one progresses to a per- sistent trophoblastic neoplasm (see below). A mole can be complete or partial.

A complete molar pregnancy develops when a normal sperm fertilizes an aberrant ovum containing abnormal maternal chromosomes.

No viable fetus develops. The placenta contains abnormal chorionic villi and excessive tro- phoblastic proliferation, with the latter leading to elevated serum b-hCG levels. Following evac- uation of a mole, b-hCG levels should gradually return to normal; otherwise continued tro- phoblastic disease should be suspected.

A partial mole contains a fetus, although usually an abnormal one. A hydatidiform mole can coexist with viable multiple pregnancies.

The risk of molar pregnancy is increased at the extremes of reproductive life and in those with a prior mole.

Bleeding and a uterus larger than expected are the most common presentation. Pre- eclampsia is not uncommon. With current management nearly all of these patients can be cured.

A hydatidiform mole distends the uterine cavity but does not invade the myometrium.

Computed tomography reveals a hypervascular

tumor, at times containing cystic regions. Either