Technique
Ultrasonography
Ultrasonography (US) has become the modality of choice for scrotal imaging. It can differentiate intra- from extratesticular tumors with a sensi- tivity of over 95%. The specificity, however, is considerably lower. Transducers using 10-MHz provide detailed resolution, although with scrotal swelling a lower frequency is necessary for full coverage.
Seminal vesicles and surrounding structures are readily studied with endorectal US. Three- dimensional (3D) endorectal US outlines the prostate in three planes and aids the study of transition zone hyperplasia; the central zone and enlarged transition zones are best identified using a coronal plane.
Transabdominal gray-scale US has a limited role in evaluating the prostate; the gland is located too far posteriorly and is too small for detailed study. An endorectal US approach is preferred.
Variability in interpreting endorectal US prostate images is a concern. Even well-trained physicians differ both in describing findings of random videotaped images of the prostate and in deciding whether to biopsy.
Transperineal US during contrast enhanced voiding urosonography has been proposed in children (1). Posterior urethral valves can be detected with this technique but further work is necessary to establish its clinical relevance.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) of the scrotum is still evolving. Especially in children, with an equivocal US study MRI may obviate the need for exploratory surgery. In addition, new applications being reported suggest that MRI will evolve into the primary imaging modality of the testes.
Endorectal surface coils allow prostate zonal study. The prostatic capsule, neurovascular bundles, vas deferens, and seminal vesicles are readily studied.
T1-weighted magnetic resonance (MR) images outline the prostatic margin with sur- rounding fat, although the internal prostate zonal architecture is not defined. T2-weighted images show a hyperintense peripheral zone and a heterogeneous more hypointense central and transition zones. An endorectal coil im- proves spatial resolution. Postgadolinium T1- weighted images reveal less peripheral zone enhancement than central zone.
Magnetic resonance voiding cystourethrog- raphy is feasible after gadolinium-enhanced excretory MR urography. Magnetic resonance fluoroscopy using a T1-weighted gradient echo sequence provides real-time urethral imaging during voiding. Both sonourethrography and MR imaging of the anterior urethra are feasible, with the urethral lumen distended with saline.
Both modalities provide information about periurethral tissues.
Male Reproductive Organs
801
Urethrography
At times urethral catheterization is difficult or even impossible. In such a setting, advancing a urethral catheter over a hydrophilic guidewire is helpful. Ultrasonography has been used instead of a retrograde urethrogram to visualize the urethra; US can provide a 3D view of the urethra.
Urethrography is performed using an iodi- nated contrast agent. Occasionally reported is use of undiluted gadolinium diethylene- triamine-pentaacetate (Gd-DTPA) in someone with a severe reaction to iodine-containing con- trast, achieving good radiographic contrast, but such use should be balanced against the greater toxicity of gadolinium contrast compared to iodinated contrast.
Cavernosography
Cavernosography, performed by direct contrast injection into the corpora cavernosa, provides cavernous arterial systolic occlusion pressure.
Vasodilators aid in interpreting these studies.
This study currently is rarely performed, having been supplanted by US and clinical evaluation using erection-enhancing pharma- cologic agents.
Color duplex Doppler US is considerably simpler than cavernosography and measures peak velocity flow, which correlates with cav- ernous arterial systolic occlusion pressure;
peak velocity flow measurement represents a noninvasive evaluation of corporeal artery function.
Vesiculography (Vasography)
Seminal vesicle, vas deferens, and ejaculatory duct patency is established by vesiculography, performed by cannulating and injecting con- trast into the vas deferens. Surgical cannulation is often employed, although endorectal US- guided seminal vesiculography is feasible. If endorectal US identifies dilated seminal vesicles or midline cysts, US-guided seminal tract punc- ture and contrast injection allows radiographic visualization of these structures. Injecting a mixture of contrast agent and indigo-carmine dye is useful if identification of these structures is desired during subsequent surgery.
Scintigraphy
Monoclonal antibody radioimmunoscintigra- phy with indium-111–capromab pendetide is promising in men with prostate cancer, both to detect initial lymph node involvement and in those with suspected recurrent or residual disease after prostatectomy. This murine- derived antibody is believed to act against the intracellular domain of prostate-specific mem- brane antigen, a glycoprotein expressed by prostate epithelial cells.
Testicular scanning is performed with technetium-99m (Tc-99m)-pertechnetate. This radiotracer establishes a blood flow pattern.
Biopsy
Traditional prostate biopsy is performed using a digital rectal examination for guidance, with a needle being inserted either transperineally or transrectally. Currently an endorectal US- guided approach is commonly employed, using a needle up to 18-gauge for core biopsies. If a tumor can be palpated or localized by US, a direct biopsy is obtained, but, as will be dis- cussed later, US-guided multisextant biopsies are often preferred. Endorectal US-guided pro- static nerve blockade increases patient comfort prior to systematic needle biopsy of the prostate.
A transrectal US-guided prostate biopsy is quite safe. Of necessity, a transrectal biopsy approach is through a nonsterile field, but post- procedure infections are surprisingly few.
An MRI-guided prostate biopsy is also fea- sible, mostly using an open magnet.
Congenital Abnormalities
Prostate
Two types of prostatic ectopia are possible, developing from either urogenital sinus or mesonephric structures. Ectopic prostatic tissue has been found along the lateral rectal wall.
Müllerian remnants, including utricular cysts, coexist with hypospadias.
Wolffian Duct Structures
Failure of seminal vesicle buds to develop results in absent seminal vesicles. Some individ-
uals also have ureteric bud failure, leading to an absent ipsilateral ureter and kidney. Thus detec- tion of a seminal vesicle cyst or similar anomaly should lead to a renal study to exclude associ- ated renal agenesis. Most seminal vesicle cysts are congenital; they are discussed later (see Wolffian duct structures).
Congenital bilateral vas deferens absence is a cause of azoospermia. This condition is detected with rectal US.
An ectopic ejaculatory duct insertion is rare.
Persistent Müllerian Duct Syndrome
Normally in a male fetus antimüllerian hormone causes müllerian duct regression.
Absence or lack of function of this hormone results in a uterus and fallopian tubes being present in a phenotypically normal male, a con- dition called persistent müllerian duct syn- drome. Two types exist: in the male type, one testis descends normally but the uterus and fallopian tubes are in or close to the inguinal canal, while in the female type bilateral cryp- torchidism is evident and testes are located in the broad ligament and the uterus is in the pelvis. Simple cryptorchidism is generally sus- pected preoperatively because male external genitalia are otherwise normal.
Imaging findings are confusing if the diagno- sis is not suspected. Computed tomography (CT) and MR identify a uterus and fallopian tubes as tubular structures posterior to the bladder, and testes located close to where ovaries are normally found in a phenotypically normal male. Testicular atrophy develops in older individuals, making further identification difficult. Similar to other males with cryptor- chidism, these individuals are prone to develop- ing testicular cancer.
Urethra
Duplication
Urethral duplication is rare. Most are located in the midline and lie in a dorsal-to-ventral direc- tion. Duplications range from complete to incomplete, and the duplicated urethra origi- nates either from the bladder or a normal urethra. An accessory urethral termination ranges from an epispadial to a hypospadial loca- tion. Some duplications are associated with
renal and multisystem abnormalities. Pubic bones tend to be abnormally separated with epispadial duplications.
A congenital urethroperineal fistula is a sep- arate entity distinct from a duplication. Boys with a congenital urethroperineal fistula have normal micturition. An extreme hypospadial urethral duplication mimics a congenital ure- throperineal fistula. In general, in a duplication the ventral urethra is the more functional channel, while with a fistula the dorsal channel is usually the primary one.
Cystography defines the underlying anatomy prior to surgical correction. For complete eval- uation of a duplicated system, both a voiding cystourethrogram and a retrograde urethro- gram are obtained.
Valves
Posterior valves
The most common cause of urethral obstruc- tion in male infants is the presence of congeni- tal posterior urethral valves. Obstruction varies in gradation. At times mild obstruction is not discovered until adolescence or even later. Some of these infants develop marked hydronephrosis and renal failure before the condition is de- tected. These valves are usually classified into three type:
Type I valves are folds extending from the verumontanum to the anterolateral ure- thral wall. These are most common.
Type II valves also arise from the verumon- tanum but extend proximally into the bladder neck. These valves tend to be of limited significance and probably are acquired rather than congenital in origin.
Type III valves consist of a prominent uro- genital membrane with a central opening distal to the verumontanum. They are rare.
A syndrome exists of posterior urethral valves, persistent unilateral reflux, and unilat- eral renal dysplasia even to the point of non- function. A majority of infants and children with posterior urethral valves have vesico- ureteral reflux, which often does not resolve after valve ablation. Long-term follow-up is thus required. Some of these infants also have impaired bladder compliance and detrusor instability, and these findings persist after valve
ablation; in addition to voiding cystourethrog- raphy, postoperative urodynamic studies are often helpful.
After birth, a voiding cystourethrogram should be diagnostic for posterior urethral valves (Fig. 13.1). Catheterization is easy in those with type 1 valves, but may not be possi- ble with type 3 valves, depending on the central opening. The prostatic and membranous urethra are dilated, with an abrupt transition in caliber at the valve site. At times the valves are identified.
In many infants US detects a dilated posterior urethra during voiding and bilateral hydro- nephrosis (Fig. 13.2). Vesicoureteral reflux and hydronephrosis is associated with a dysplastic kidney in some. A thick, trabeculated bladder wall and diverticula develop eventually. Severe obstruction in a neonate can result in calyceal perforation and urinary ascites.
A retrograde urethrogram is not appropriate for detecting these valves; they tend to be effaced against the urethral wall, and obstruc- tion is not detected. A voiding cystourethro- gram is the examination of choice. In a search for posterior urethral valves, some radiologists remove the catheter while others leave it in place. Some believe that a catheter can obscure the valves.
Voiding cystourethrography in boys with severe posterior urethral valves identifies a tra- beculated bladder body and smooth bladder
base; bladder base trabeculations do not develop. A trabeculated bladder body evolves as a result of contractions due to parasympathetic (cholinergic) stimulation during voiding, while the bladder base relaxes due to sympathetic (adrenergic) stimulation and thus remains smooth.
Indications for percutaneous nephrostomy in neonates with posterior urethral valves include renal failure, severe infection, and, at times, evaluation of a dilated collecting system. Such diversion, however, is not without its own prob- lems. Even if a proximal urinary tract diversion is performed, many neonafes tend to continue losing renal function. Diversion also results in a defunctionalized bladder and loss of bladder compliance. In general, primary valve ablation performed in infants prior to age 1 year results in better recovery of bladder function than those treated with urinary diversion, realizing that in some of these infants neither procedure halts progression of renal insufficiency.
Results of renal transplantation in children with end stage renal disease due to posterior urethral valves are similar to those obtained in children with nonobstructive renal disease. In either case, probably all children with contem- plated renal transplantation should be studied for the presence of congenital posterior urethral valves; the presence of these valves has a role in graft function deterioration.
Anterior Valves
True anterior urethral valves are rare, with most believed to represent a fold that is part of a ure- thral diverticulum. Some of these valves are detected investigating prenatal hydronephrosis, while others manifest by voiding dysfunction later in life. Bladder rupture can develop in a neonate with anterior urethral valves.
A voiding cystourethrogram should detect these valves, although their imaging appearance is very similar to that of an anterior urethral diverticulum.
Stricture
Urethral strictures are distinct from posterior or anterior urethral valves. Identical congenital urethral strictures occasionally develop in relatives.
Figure 13.1. Posterior urethral valves in an 11-year-old.
The prostatic urethra is dilated and has a “spinning-top”
configuration.
Diverticulum
A congenital urethral diverticulum originates from the anterior urethra and is associated with urethral obstruction. These diverticula have either a saccular appearance (and originate from the ventral urethral wall) or are diffuse (megalourethra).
A saccular diverticulum is a ventral out- pouching in the midurethra; it is rare in the bulbous urethra, in which case cystic dilation of Cowper’s gland duct should be suspected. It contains a valve-like deformity in its distal end;
as the diverticulum fills with urine, the distal end is elevated into the urethra and limits flow.
Clinically, a saccular diverticulum should be suspected with intermittent urinary obstruction swelling of the penis.
A voiding cystourethrogram should detect an abnormality but may not differentiate a diverticulum from anterior urethral valves.
Hypospadias
Hypospadias consists of an abnormal ventral urethral termination due to failure of urogeni- tal fold fusion. Varying degrees of malposition are possible; at times a urethra even terminates in the perineum. The utricle tends to be Figure 13.2. Posterior urethral valves in a 4-week-old infant with failure to thrive. A: A voiding cystourethrogram reveals a dilated proximal urethra. B: A cystogram identifies marked bladder trabeculations. C: Ultrasonography (US) confirms bladder wall thicken- ing. D: Renal US reveals a shrunken, hyperechoic, dysplastic kidney (arrows) containing several cysts. (Courtesy of Luann Teschmacher, M.D., University of Rochester.)
A B
C D
enlarged, with its size having a direct relation- ship to severity of hypospadias.
About 10% of boys with hypospadias have a familial history and have associated cryp- torchidism; renal abnormalities are uncommon.
A distal urethral malignancy occasionally devel- ops in men with congenital hypospadias.
A voiding cystourethrogram aids in defining underlying anatomy.
Epispadias
Epispadias is part of the spectrum of pelvic abdominal wall failure-to-fuse anomalies.
Failure of dorsal urethral closure results in epispadias. Various gradations occur ranging from failure of bladder neck closure to a defect in the distal urethra. The urethral sphinc- ter is underdeveloped, and these boys have incontinence.
A blind epispadial sinus, or congenital pre- pubic sinus, is a congenital accessory urethra that does not communicate with the bladder.
The underlying anatomy can be outlined with a fistulogram.
Megalourethra
Urethrography in a male infant with a mega- lourethra revealed crescent-shaped anterior urethral dilatation (2); associated abnormalities included prune-belly syndrome, absent corpus spongiosum, and bilateral undescended testes.
Testes
Anorchia/Cryptorchidism Clinical
Scrotal agenesis is very rare. Among boys with a clinically impalpable testis, about one-fifth have an absent testis (anorchia) and the rest cryp- torchidism. A minority of boys with anorchia have complete testicular agenesis along with epididymis and vas deferens, but a majority have blind-ending cord structures—also called a vanishing testis. The blind-ending cord in these boys with a vanishing testis terminates mostly in the inguinal canal, with a minority intraabdominally, in the superficial inguinal ring, or, least common, in the scrotum. Yet the diagnosis of agenesis is imprecise; some indi-
viduals who have negative inguinal canal, and scrotal exploration have later developed an intraabdominal seminoma, presumably from an overlooked intraabdominal testis.
Cryptorchidism is more common than anorchia. Pathogenesis of cryptorchidism is unclear; it is probably part of an embryoge- netic defect. These infants are also prone to develop renal agenesis, ureteral duplication and seminal vessel abnormalities. Normally at birth the testes are already descended into the scrotum. With clinical suspicion of an unde- scended testes, the primary question is: What is the location of the testis? Clinically, these infants can be subdivided into those with a nonpalpa- ble testis and those with a palpable testis in an abnormal location. About 25% have a nonpal- pable testis located in the abdomen or inguinal canal (and occasionally even distal to the exter- nal inguinal ring), while a palpable testis ranges in location from the inguinal canal, inguinal pouch, and high scrotal position, to even an unusual ectopic position. In most babies with cryptorchidism the testis descends shortly after birth, but an undescended testis persisting beyond the age of 1 year generally will not change position. By puberty, an undescended testis degenerates and has a low spermatogenesis rate.
A high scrotal testis is one located below the external inguinal canal; it can be manipulated to the upper scrotum, but then ascends. Some con- sider it to represent the mildest form of an undescended testis. A high scrotal testis tends to be smaller than the contralateral one. These boys have a higher prevalence of testicular torsion.
A nonpalpable testis is more common on the left side.
Bilateral cryptorchidism is found in about half of adults with Noonan’s syndrome. A high prevalence of undescended testis is found in Down syndrome. Premature infants are some- what prone to having cryptorchidism. An asso- ciation exists between cryptorchidism and epididymal abnormalities.
An undescended testis is prone to developing a malignancy, with the most common tumors being a seminoma and embryonal cell carci- noma. Metachronous tumors occur with bilat- eral cryptorchidism. The risk of malignancy increases even after orchiopexy, to the point that some surgeons advocate orchidectomy
for postpubertal cryptorchid males. As an example of the risk for cancer, a 26-year-old man with Noonan’s syndrome had had bilateral orchiopexy for undescended testicles at 12 years of age, and now US confirmed a right testicular solid tumor and CT identified retroperitoneal adenopathy (3); orchiectomy revealed findings consistent with a seminoma.
Postpubertal males with cryptorchidism rarely have normal spermatogenesis; matura- tion arrest and seminiferous tubular atrophy are common. Bilateral dysgenesis is evident even with unilateral cryptorchidism because the risk of malignancy is also increased in the con- tralateral normally located testis and some investigators suggest a post-pubertal biopsy for carcinoma-in-situ.
Transverse testicular ectopia, consisting of an abnormal testicular descent resulting in a uni- lateral location of both testes, is extremely rare.
It is usually associated with an inguinal hernia.
The spermatic cord of the ectopic testis origi- nates from its correct site. In such a situation, one testis is in the inguinal region and another in the ipsilateral scrotum.
An undescended testis can develop torsion later in life; an underlying neoplasm is associ- ated with such torsion.
Imaging
Individuals operated on previously for cryp- torchidism tend to develop microlithiasis (4);
annual US surveillance is recommended for these patients with microlithiases.
Because of ease and ready availability, US is the current primary imaging modality in evalu- ating cryptorchidism. Ultrasonography cor- rectly identifies over 90% of inguinal testes but only a minority of atrophic inguinal testes.
Ultrasonography has a low yield if no testis is palpable or is intraabdominal in location or in those with an associated inguinal hernia. MRI should be considered for these infants.
Ultrasonography identifies an undescended testis as a smooth oval structure that is usually smaller than a normal testis. An enlarged lymph node has a similar appearance, and visualiza- tion of a linear echogenic mediastinum testis is helpful in differentiating between these two structures.
Computed tomography is limited in this condition. Especially in children, the lack of
surrounding fat makes testis detection difficult.
Magnetic resonance imaging is evolving as the preferred imaging modality for an unde- scended testis and its role will undoubtedly increase in the future. It localizes most unde- scended testes, including those in the abdomen.
A current reasonable approach is to add either MR or US if the first study is inconclusive. A testis is hypointense on T1- and hyperintense on T2-weighted signal intensity, although the T2- weighted signal intensity is lower than usual with an atrophic or fibrotic testis. Most unde- scended testes are perivesical in location, with an occasional one outside the pelvis.
One promising technique is MR venography;
imaging at various delayed venous phases after gadolinium infusion detects the contrast- enhanced pampiniform venous plexus. This technique detected testes not identified with more conventional MRI (5).
Spermatic arteriography has been supplanted by noninvasive imaging.
Thermography has been suggested as an aid in detecting an undescended testis but is of limited use with an abdominal testis. It appears to have a role if a high undescended testis is sus- pected but is not palpable and not detected by US.
Therapy
In the past, therapy for an undescended testis included surgical exploration, supplanted later by subumbilical laparoscopy, and, more recently, transinguinal laparoscopy. One approach for a nonpalpable testis is initial abdominal laparoscopy; if vas deferens or sper- matic vessels enter the internal inguinal ring, surgical exploration of the inguinal canal is performed, but if both vas deferens and spermatic vessels are absent or end blindly intraabdominally, a diagnosis of anorchia or vanishing testis is presumed.
Residual testicular and epididymal abnor- malities persist in adults who are treated for an undescended testis in childhood. The cryp- torchid testis is smaller in adults treated surgi- cally when they were children. The fertility rate of adult men who underwent surgical correc- tion of bilateral cryptorchidism as children is markedly reduced compared to those who had unilateral cryptorchidism; the resultant fertility
is independent of surgical timing. These adults tend to have an abnormal US echo pattern in the involved testes.
Polyorchidism
Polyorchidism is uncommon. It is a result of transverse division of the embryonic genital ridge. Bilateral polyorchidism is extremely rare.
These boys are at an increased risk for cryp- torchidism, inguinal hernia, and testicular malignancy, at times uncommon ones such as a rete testis adenoma and an embryonal carcinoma.
An occasional polyorchid testis is detected by US.
Dysplasia
Cystic dysplasia is a rare congenital nonneo- plastic condition resulting in multiple cysts in the mediastinum testes. The defect probably represents a lack of connection between rete testis tubules and efferent ductules.
Rete testis cystic dysplasia presents as a scrotal or abdominal tumor. Ipsilateral renal agenesis is found in some individuals, and whenever cystic dysplasia is detected, ipsilateral renal agenesis should be excluded. Other asso- ciated lesions include multicystic dysplastic kidney, duplication anomalies, and cryptor- chidism. Multicystic epididymides and seminal vesicles have developed in association with polycystic renal disease.
Ultrasonography reveals multiple small cysts.
The appearance is similar to that seen with a ter- atoma or even testicular microlithiasis.
Vas Deferens
Wolffian duct structures include the epi- didymis, vas deferens, seminal vesicles, and ejaculatory ducts. Malformations of these struc- tures consist of cysts, agenesis, and partial atresia; an occasional one is associated with renal agenesis. Congenital absence of the vas deferens can be either bilateral or unilateral. In some, unilateral vas deferens agenesis is associ- ated with unilateral renal agenesis (bilateral renal agenesis is incompatible with life), and a finding of vas deferens agenesis should lead to a renal study. Those with congenital unilateral
vas deferens absence and infertility often have anomalies in the contralateral testes. An asso- ciation exists between the absence of a vas deferens and cystic fibrosis; in fact, congenital bilateral vas deferens absence probably is a mild form of cystic fibrosis.
Four patterns were identified among men with vas deferens agenesis (6): bilateral agene- sis (64%), bilateral agenesis associated with uni- lateral renal agenesis (3%), unilateral agenesis (15%), and unilateral agenesis with unilateral renal agenesis (18%). A cystic fibrosis mutation was detected in 64% of men with bilateral age- nesis but in none with unilateral agenesis, and the latter condition thus presumably is due to a different pathogenetic pathway.
The absence of vas deferens is identified by endorectal US.
Other anomalies include an ectopic vas def- erens and vas deferens duplications.
Abnormal wolffian duct development can result in an ectopic vas deferens insertion into the posterior bladder wall.
Splenogonadal Fusion
An unusual cause of a scrotal mass in boys is splenogonadal fusion. In this congenital entity, splenic tissue is located in the epididymis, tunica albuginea, or along the spermatic cord, almost always on the left side. Although usually found as a discrete tumor, occasionally varying amounts of splenic tissue extend from the splenic hilum inferiorly. Such continuous splenic tissue is associated with other systemic anomalies.
Many of these discrete splenic tumors are ini- tially thought to represent a neoplasm. Consid- eration of splenogonadal fusion is important because at times a surgeon is able to dissect splenic tissue off the tunica albuginea.
Adrenal Rests
Testicular epididymal and adjacent structure adrenal rests derive from aberrant adrenal cortical tissue migrating into these structures during fetal development. Incidental adrenal rests are most common in newborns but gener- ally involute with age. Hyperplasia of these adrenal rests leads to either focal tumors or diffuse testicular enlargement. In fact, a testicu-
lar tumor in a male with congenital adrenal hyperplasia most often represents testicular adrenal rests. These testicular rests can change in size, at times rapidly. Most symptomatic ones are discovered in the pediatric age group, at times associated with precocious puberty. These solid, multiple, and usually bilateral tumors are believed to develop secondary to elevated adrenocorticotropic hormone (ACTH) levels and are also found in Addison’s disease and Cushing’s syndrome. A rare such adrenal rest develops a malignancy.
Most are located adjacent to the mediastinum testis. US reveals these predominantly intrates- ticular, often multiple, bilateral tumors to be mostly hypoechoic when small but often contain hyperechoic regions with growth (7);
with color Doppler US they range from hyper- vascular, isovascular, to hypovascular relative to normal testis. Some contain a spoke-wheel pattern of converging vessels. They are isoin- tense on T1- and hypointense on T2-weighted MR images, tumor margins are well-defined and most show contrast enhancement (7). Their appearance suggests a neoplasm. With the pres- ence of adrenal hyperplasia, whether these tumors should be investigated for a possible underlying malignancy remains an individual clinical decision.
Ultrasonography and MRI appear similar in detecting intratesticular adrenal rest tissue (8); MR showed 71% of testicular adrenal rests to be isointense and 29% slightly hyper- intense to normal testicular tissue on T1- weighted images; all were hypointense on T2-weighted images, and 85% enhanced dif- fusely postcontrast.
At times testicular vein sampling reveals ele- vated cortisol levels (compared with peripheral blood).
These tumors regress with glucocorticoid therapy.
Trauma
Urethra
Anterior pelvic arch fractures are usually associated with membranous urethral injury, while straddle injuries tend to involve the bulbous urethra. Associated bladder injury should also be suspected. A retrograde urethro-
gram should be obtained with any suspected urethral injury.
Urethral trauma ranges from incomplete to complete rupture. Blind bladder catheterization should be discouraged in such a setting to avoid converting a partial tear into complete rupture.
A classification of injury to the anterior and posterior urethra is outlined in Table 13.1. Type IV injury is least common. A retrograde ure- throgram should be diagnostic for a tear.
Although CT is not directly employed for ure- thral trauma, it is often obtained to evaluate pelvic structures, and it does provide indirect evidence of urethral injury. With type I injury the prostate is elevated, type II is associated with contrast extravasation above the urogenital diaphragm, and type III is associated with extravasation below the urogenital diaphragm.
An MRI can establish the length of urethral injury and any prostatic displacement. The sequelae of urethral injury are stricture, impo- tence, and incontinence, the latter due to prior sphincter injury. Future impotence is suggested if MRI detects avulsion of the corpus caver- nosum, separation of the corporeal body, and superior or lateral prostatic displacement. With both corpus cavernosum avulsion and prostatic displacement, the probability of permanent impotence is over 90%.
Strictures in boys with posttraumatic ure- thral disruption are almost always inferior to the verumontanum; stricture length tends to be overestimated during urethrography due to incomplete filling.
Smaller, less fibrous posttraumatic recto- urethral fistulas tend to heal spontaneously after a double diversion; others require recon- Table 13.1. Classification of blunt urethral trauma
Type I: Posterior urethra intact but stretched Type II: Partial or complete posterior injury with tear
of membranous urethra above urogenital diaphragm
Type III: Partial or complete combined anterior/
posterior urethral injury with urogenital diaphragm disruption
Type IV: Bladder neck injury with extension into urethra
IVA: Injury to base of bladder with periurethral extravasation simulating a true type IV injury
Type V: Partial or complete anterior urethral injury Source: Adapted from Goldman et al. (9).
struction. A urethral stricture is a potential postreconstruction complication.
Penis
The most common conditions resulting in pri- apism due to trauma are an intracavernosal arteriovenous fistula, a pseudoaneurysm, or asymmetric cavernosal arterial blood flow.
These fistulas can be detected by selective angiography, and subsequent embolization can be therapeutic. The embolic materials used are autologous blood clots, N-butyl-cyanoacrylate, and others.
With suspected penile fracture some sur- geons operate without any diagnostic imaging being performed, with imaging requested pri- marily for equivocal clinical findings. In this setting, however, traumatic rupture of the corpus cavernosum is not uncommon and some investigators believe that preoperative caver- nosography should be performed and therapy modified accordingly. A corpus cavernosum tear is identified as contrast extravasation during cavernosography. Most corpora caver- nosa ruptures are proximal, the vast majority being unilateral; associated complete urethral rupture is rare.
Mostly anecdotal reports suggest that MRI is superior to US in identifying corpus caver- nosum rupture; the role of MR will undoubtedly expand. MRI detects corpus cavernosum rupture as a discontinuity in the hypointense tunica albuginea (10); associated subcutaneous haematoma were identified both on T1- and T2- weighted images, but corpus cavernosum haematomas were better seen on contrast enhanced T1-weighted images.
Follow-up MRI after surgical repair reveals a hyperintense signal at the tunical suture site on precontrast T1-weighted images, enhancing with contrast (10); the tear site gradually recov- ered its hypointensity on spin echo sequences.
Scrotum and Testes
A painful, ecchymotic scrotum is common after scrotal trauma. Preoperative US is useful in suspected testicular rupture. Still, both false- positive and false-negative findings occur. For instance, fracture of the tunica albuginea can
be missed with US. Ultrasonography cannot provide an accurate diagnosis of rupture. On the other hand, if US is abnormal, even if the findings are nonspecific, testicular rupture should be suspected. Ultrasonography reveals testicular rupture as regions of heterogeneous echogenicity and loss of normal contour. Only occasional fracture planes are identified by US.
An intratesticular pseudoaneurysm devel- oped after blunt trauma (11).
Traumatic dislocation of the testis is rare and most are inguinal in location. Associated sper- matic cord injury is also often present. Imaging is helpful in guiding surgical correction.
Among mountain bikers (with less than half being symptomatic), 94% had abnormal scrotal US, consisting of scrotal calculi (81%), epidi- dymal cysts (46%), epididymal calcifications (40%), testicular calcifications (32%), hydro- celes (28%), varicoceles (11%), and testicular microlithiasis (1%) (12).
Prostate and Adjacent Structures
Hyperplasia/Hypertrophy
Clinical
Benign prostatic hyperplasia (BPH), also called benign hypertrophy, adenomatous hypertrophy, or simply adenoma, increases with age. Some physicians use this term to describe a symptom complex rather than use it as an anatomic entity.
The term lower urinary tract symptoms is used by some for this broad clinical entity.
The prevalence varies among racial and ethnic groups; it is considerably less common among Japanese men than among Caucasians.
Estrogen has a role in its development. Serum beta-carotene and smoking appear to be risk factors for BPH. Familial BPH does exist.
Most benign hyperplasia occurs in the tran- sition zone and only occasionally in the peri- urethral glandular zone. Some enlarged glands contain cysts, calcifications, or even regions of hemorrhage. Little correlation is apparent between prostatic calcifications and the extent of hyperplasia. Likewise, endorectal US meas- urements of prostate size or transition zone volume do not relate to the degree of bladder outlet obstruction. Also, the volume of residual
urine correlates poorly with prostate size and flow rate. Prostatic capsule rigidity may play a role in benign hyperplasia. Prostatic innerva- tion also appears to be a factor, because a- adrenergic receptor blocking agents lower resistance to flow in those with an enlarged prostate. On the other hand, in a setting of benign hyperplasia ischemia does not appear to be a factor in bladder outlet obstruction.
Occasionally a prostatic biopsy suggests a low-grade adenocarcinoma, which actually rep- resents hyperplasia of verumontanum mucosal glands.
At times voiding cystourethrography shows a smooth posterior impression at the bladder neck. If this impression is only several millime- ters in length, it probably should be considered within the normal range. When enlarged, it is called median lobe hyperplasia and is produced by periurethral gland hyperplasia. Such hyper- plasia occurs in men with spinal cord injury and in those who have undergone numerous catheterizations.
Occasionally an inguinal cystocele mimics clinical findings of prostatic enlargement but without actual evidence of bladder outlet obstruction. Also, not all prostatic enlargement is secondary to hyperplasia or neoplasm; in some parts of the world bladder schistosomia- sis is a cause of prostatic enlargement.
Imaging
Does intravenous (IV) urography have a con- tinued role in men with prostatism? In a large minority of patients with prostatism, IV urog- raphy reveals excretory system dilation, calculi, an unexpected congenital anomaly, or other abnormality. Voiding cystourethrography adds little to the diagnosis, except perhaps in younger men in a search for alternate diagnoses for ure- thral obstruction. Prostate size cannot be evalu- ated with this examination.
Computed tomography reveals prostatic hypertrophy as a smooth homogeneous, but CT is not indicated for simple benign prostatism.
Computed tomography attenuation values are similar for benign disease and a malignancy.
Bladder wall thickening is common with bladder outlet obstruction. To obtain repro- ducible US results, bladder wall thickness should be measured after bladder filling with a standardized amount of fluid—about 150 mL.
Not all bladder wall thickening is due to bladder outlet obstruction.
The sonographic appearance varies from a fine to a rough pattern or a combination, and hypoechoic to hyperechoic. Echogenicity in any one patient is due to a mix of complex hyper- plastic glands and a cystic atrophic component.
Nodules are detected in some glands. Any calcifications present appear hyperechoic. At times the central and peripheral gland portions appear to be separated.
Prostatic size estimates are of less importance in BPH than with a suspected cancer. In addi- tion, a “gold standard” is more difficult to estab- lish than with a radical prostatectomy for cancer. Studies suggest that endorectal US and MRI measurements of prostatic hyperplasia are similar, although endorectal US may underesti- mate prostatic weight. Gross prostate size esti- mates, however, are useful; transurethral resection is more difficult with a very large gland.
Magnetic resonance imaging reveals BPH to be hypointense on T1- and heterogeneous and mildly hyperintense on T2-weighted images (Fig. 13.3).
Figure 13.3. Benign prostatic hypertrophy, bladder outlet obstruction, and thick bladder wall (arrows), detected on T2- weighted magnetic resonance (MR) image. (Source: Burgener FA, Meyers SP, Tan RK, Zaunbauer W. Differential Diagnosis in Magnetic Resonance Imaging. Stuttgart: Thieme, 2002, with permission.)
Therapy Resection
Currently surgical resection is the gold standard in treating BPH, most often using a trans- urethral approach. Post-resection MRI reveals degenerative changes near the prostate surface and shrinkage of the prostatic capsule. A dilated prostatic urethra is readily identified.
A complication of a radical retropubic prosta- tectomy is an inguinal hernia. Most of these hernias are indirect. Fistulas are uncommon;
with surgery being close to the symphysis pubis, an occasional fistula leads to osteitis pubis.
Bladder hypertrophy due to obstruction by BPH is to a large extent reversible after surgical relief, except in those with irreversible degener- ative changes.
Nonsurgical
The natural progression of BPH suggests that in many men an initial decision to prescribe no therapy is a viable option; symptoms in most men do not progress. In some, a-adrenergic- blocker therapy and 5a-reductase inhibitor therapy are helpful.
Although a number of nonsurgical tech- niques, such as laser therapy, microwave ther- motherapy, and others have been tried, thermal ablation is currently the only viable alternative to surgery, achieving similar results. Balloon dilation has been disappointing.
Laser Therapy
Laser ablation thermotherapy leads to coagula- tion necrosis, with eventual reepithelialization.
In theory, laser coagulation shrinks the prostate by inducing prostatic necrosis without injury to the urethra or surrounding tissues. Currently, results from US-guided laser-induced trans- urethral thermal therapy appear inferior to those obtained with transurethral resection.
One disadvantage of laser therapy is that no tissue is obtained and it takes longer to attain symptomatic improvement compared to trans- urethral resection. Prostatic volume initially is not reduced, and postprocedure urinary reten- tion is common. Laser therapy, however, is still a new technique, and further advances are to be expected.
Few complications are encountered and symptoms eventually improve in most. Rarely, the loss of ejaculation, epididymitis, or an abscess develops. Urethral stricture is a late complication.
Magnetic resonance imaging detects prostate changes during and after laser-induced ther- motherapy. Repetitive T2-weighted fast spin echo (FSE) MRI during coagulative laser ther- motherapy revealed persistent hypointense regions, presumably representing coagulation necrosis. These regions increase in size during therapy. The prostate remains enlarged shortly after treatment, and contains poorly defined hypointense regions surrounding the urethra;
with time, the prostate gland returns to its pre- operative size.
Central coagulation necrosis is seen as a hypointense region surrounded by a hyper- intense rim. The prostate increases in size, presumably due to edema; edema is evident in the surrounding tissues and the presacral space thickens. Subtracting postprocedure laser- induced lesion volume (obtained via MR planimetry) from preprocedure volume pre- dicts prostatic volumes at late follow-up (13), although transitional zone volume was under- estimated and peripheral zone volume was overestimated.
Microwave Ablation
Transurethral microwave thermotherapy is a potential outpatient procedure requiring little or no anesthesia. A temperature ≥60°C results in coagulation and tissue necrosis. Tissue vapor- ization ensues if the temperature is >100°C. Use of higher energy levels improves results but at the expense of increased morbidity.
Symptomatic improvement is achieved in about half of men treated with microwave thermotherapy. Imaging findings are in- constant. Magnetic resonance imaging detects prostatic urethral widening. Necrosis is an inconstant finding. Findings on voiding cys- tourethrography and retrograde urethrography before and after transurethral microwave therapy do not correlate with subjective improvement. The transition zone volume, obtained from pretreatment endorectal US, appears to relate to long-term microwave ther- motherapy efficacy.
Other Therapy
Self-expanding endourethral stents have been used to treat bladder outlet obstruction due to prostatic hyperplasia; still, urethral stents have had limited success, with some stents dislodge or become encrusted.
Preliminary results using an electrosurgical generator for transurethral prostatic electrova- porization are encouraging. Postoperative urine incontinence is a potential complication.
High-intensity focused ultrasound therapy is still experimental.
Infection/Inflammation
Prostatitis
Prostatitis can be either acute or chronic. At times a specific pathogen is detected; if not, the clinical symptoms are often ascribed to prosta- todynia, a previously poorly defined condition.
In this work prostatodynia is used to designate pelvic venous congestion and is discussed later (see Vascular Abnormalities).
Granulomatous prostatitis is a histologic diagnosis. Common causes are prior prostatic surgery and prostatic needle biopsy. Occasion- ally prostatic granulomas develop in a setting of prior bacillus Calmette-Guérin therapy.
Ultrasonography reveals a complex pattern in prostatitis. At times prostatic nodules are present. In a normal gland Doppler US using a coronal plane reveals capsular and parenchymal arteries radiating symmetrically. These arteries become more prominent in acute prostatitis.
Ejaculatory duct calcifications develop in chronic prostatitis.
Early prostatic cancer and prostatitis are difficult to differentiate with current imaging.
Of interest is that in some patients with prosta- titis MR spectroscopy detects an elevated choline peak and reduced or no citrate, findings mimicking those of cancer (14).
Abscess
Predisposing factors for periprostatic or pro- static abscesses are diabetes mellitus, ure- thral catheterization or manipulation, and an immunocompromised status. Most abscesses are infected, with only an occasional sterile abscess encountered. Any portion of the
prostate can be involved, and an abscess may or may not communicate with the urethra. Some prostatic abscesses result in bladder outlet obstruction.
A prostatic abscess is detected either by CT or endorectal US. Typically US reveals hypoechoic or anechoic regions with internal echoes, sug- gesting fluid-filled structures containing septa- tions. Some mimic loculated cystic prostatic tumor.
Once diagnosed, a prostatic abscess can be drained using endorectal US guidance, and a perineal or transurethral drainage approach can be used.
Tuberculosis
Tuberculosis either is primarily genital in origin and involves the seminal vesicles, prostate, and adjacent structures, or these structures are involved by extension from the kidneys. An occasional tuberculous prostatitis is associated with intravesical carcinoma therapy with bacillus Calmette-Guérin.
Tuberculosis results in prostatic inflamma- tion, enlargement, necrosis, or abscess. Cystog- raphy reveals prostatic enlargement simply as bladder base elevation. Urethrography identifies any urethral stricture or fistula to adjacent structures. Endorectal US reveals prostatic enlargement with multiple hypoechoic foci within the gland, usually anteriorly in the tran- sition zone, representing necrotizing granulo- mas. Eventually these granulomas calcify.
In some men seminal vesicle and vas de- ferens calcifications are the only imaging abnormality. Vas deferens calcifications are either intramural or intraluminal in location, and the appearance mimics findings seen with diabetes mellitus.
Computed tomography reveals inflammation of the surrounding structures, including peri- vesical fat stranding.
Other infections
The seminal vesicles dilate and calcify sec- ondary to schistosomal involvement. At times the ejaculatory ducts also dilate. Schistoso- miasis induces prostatic retention cyst forma- tion and eventual prostatic enlargement and calcifications.
Ultrasonography detects hyperechoic pro- static foci. Seminal vesiculography outlines the dilated lumen and irregular border. After therapy the prostate decreases in size and the hyperechoic foci become less evident. Some investigators believe that calcifications also diminish.
In endemic regions the presence of typical calcifications is presumptive evidence for schis- tosomiasis.
Prostatic aspergillosis is rare in a immuno- competent patient. It is associated with recur- rent urinary tract infections.
Brucellar prostatitis is rare even in brucel- losis-endemic regions, such as certain provinces of Spain. Ultrasonography is useful to follow therapy.
Malacoplakia
Prostatic malacoplakia is a granulomatous inflammatory disorder, presumably being a variant of chronic granulomatous prostatitis.
Prostatic malacoplakia can form fistulas to adja- cent structures. It often mimics a malignancy and some affected men have undergone a radical prostatectomy for suspected carcinoma.
Past urinary tract infections are a common precedent.
Ultrasonography revealed a hypoechoic peripheral zone tumor in three men with pro- static malacoplakia (15).
A biopsy should provide the diagnosis by detecting Michaelis-Gutmann bodies, although even a biopsy can be misdiagnosed as a carcinoma.
Tumors
Sclerosing Adenosis
Sclerosing adenosis usually develops in a setting of prostatic gland hyperplasia. Even histologi- cally, this entity is difficult to differentiate from a well-differentiated adenocarcinoma.
Prostatic and Müllerian Cysts
Prostatic cysts are uncommon. Embryologically, many of these cysts represent either an enlarged prostatic utricle or a cystic müllerian duct; both tend to be located close to the midline, which helps differentiate them from the more laterally located seminal vesicle and ejaculatory duct
cysts. Müllerian duct cysts tend to project some- what lateral to the midline, while utricle cysts are midline structures; müllerian duct cysts tend to be larger and extend further superiorly, while utricle cysts tend to be small. However, considerable overlap exists and these cysts cannot be readily differentiated from each other. A rare müllerian duct cyst is associated with prostatitis.
A dilated utricle is associated with hypospa- dias and testicular abnormalities. Some utricle cysts lead to dysuria. They vary in size. Urogra- phy and US simply detect a retrovesical cyst.
An occasional midline prostatic cyst is a cys- tadenoma or a simple cyst, but not all prostatic cysts are benign. A rare one is a prostatic cystic adenocarcinoma, often in a young man.
Clinically most prostatic cysts are asympto- matic, although an occasional larger one leads to bladder outlet obstruction or becomes infected.
Magnetic resonance reveals prostatic cysts similar to other fluid-filled structures; namely, they are hypointense on T1- and hyperintense on T2-weighted images. Blood and other fluid modify these findings.
Prostatic cysts are amenable to transrectal puncture and drainage under US guidance. A müllerian duct cyst causing ejaculatory duct obstruction was drained transurethrally using US guidance (16).
Benign Neoplasm
Benign prostatic neoplasms are almost non- existent, and most reported ones are anecdotal.
No imaging features differentiate them from malignancies.
A schwannoma within the prostate ranges from a focal tumor to an enlarged prostate.
Transrectal US identified one as a hypoechoic nodule in the periphery (17); specific diagnosis could be established only by biopsy.
Prostate involvement in neurofibromatosis is rare. Endorectal coil MR localizes and provides guidance for biopsy of suspicious tumors.
Prostate Carcinoma Primary
Clinical Aspects
General: In the West, prostatic cancer is the most commonly diagnosed cancer in men. For
