The normal pattern of the kidney and bladder is described in Chap. 4 (Figs. 4.8 and 4.9, pp 21–22).
Renal Parenchyma
The diagnosis of acute renal failure is biological, and the main advantage of ultrasound is first to rule out the possibility of an obstacle [1].
Arguments suggestive of acute renal failure will be normal or increased volume (Fig. 9.1). Chronic renal failure would give small kidneys with thin- ning of the parenchyma and irregular borders (Fig. 9.2). Kidneys can show global dedifferentia- tion. The parenchyma can resemble the sinus (parenchymocentral dedifferentiation), or, within the parenchyma, medullary pyramids and cortex can be hard to detect (corticomedullary dediffer- entiation). However, these patterns do not seem useful in emergency situations.
Acute pyelonephritis is usually barely or not accessible to two-dimensional ultrasound, but severe forms can sometimes be diagnosed. Fig- ure 9.3 shows the routine ultrasound of a 52-year- old female, admitted for severe sepsis, with mas- sive bilateral enlargement of the kidneys, with no differentiation. Diagnosis was hemorrhagic pyonephritis with diffuse purulent areas.
Parenchymatous candidiasis can sometimes be diagnosed (Fig. 9.4). Emphysematous pyelonephri- tis, a rare finding, gives gas bubbles within the parenchyma. In the case of severe rhabdomyolysis with acute renal failure, we can observe enlarged kidneys with complete dedifferentiation. Renal trauma is presented in Chap. 24.
A renal cyst is a benign finding. In view of its great frequency, we insert a characteristic example (Fig. 9.5) and a case of renal polycystic disease (Fig. 9.6).
Fig. 9.1. Acute renal failure. The kidney has a homoge- neous echoic pattern, i.e., complete dedifferentiation.
Kidney and liver (L) have the same echogenicity, and the kidney is barely outlined (arrows). This scan, as nearly all that follow, is longitudinal
Fig. 9.2. Chronic renal failure. Small size (arrows), thin- ned parenchyma and irregular borders
Renal Pelvis
Septic shock, increased creatinemia, and a drop in diuresis are daily situations. The possibility of a urinary obstacle will be ruled out in a few seconds if a small ultrasound unit is readily available.
Dilatation of the renal pelvis is rarely but regu- larly encountered in our experience. Of 400 con- secutive critically ill patients, we have had eight cases, 2%. This rate was increased if only sepsis or acute renal failure are considered. Interestingly, the pain is nearly always absent in septic, encephalo-
pathic patients. Causes encountered in the ICU were pelvic hematoma, obstruction of the urinary probe (see Fig. 9.12), bladder distension with over- flow, blocked calculi or hydronephrosis (Fig. 9.7) with superimposed pyonephrosis (Fig. 9.8). Detec- tion of dependent echoic patterns within dilated cavities of hydronephrosis is characteristic of pyonephrosis [2]. Pelvic cancer is a classic cause. In trauma, a blood clot can again cause obstructive anuria.
Dilated calices and renal pelvis yield a well- known pattern. The three calices and the pelvis, 56 Chapter 9 Urinary Tract
Fig. 9.3. This kidney is frankly enlarged (long axis, 14 cm) and the peripheral area is extremely thickened (arrowheads), without differentiation. It was an acute pyonephritis responsible for severe septic shock. Each kidney weighed 500 g and contained multiple areas with pus, necrosis and hemorrhage
Fig. 9.4. Hyperechoic pattern of the pyramids (arrows) in a patient with patent urinary candidosis
Fig. 9.5. Inferior renal cyst (asterisk). The kidney seems to be interrupted, with a ragged edge. This cyst is regu- lar, anechoic. This pattern, here caricatured, should not disconcert since it is regularly observed
Fig. 9.6. Renal polycystic disease. Cysts have peripheral topography and do not communicate with each other, two features that distinguish it from dilatation of the urinary cavities
normally virtual or barely visible, are clearly depicted here, anechoic and communicating with each other (Fig. 9.9). In polycystic disease, the numerous cysts do not communicate with each other (see Fig. 9.6). It should be noted that a mod- erate dilatation, with persistence of the concavity of the calyces, indicates acute obstruction. Con- versely, massive dilatation evokes chronic obstruc- tion, with the end of the calices rather bulged and thinned parenchyma (Fig. 9.7).
A dilated ureter is rarely accessible, since intra- abdominal structures are usually in the way (Fig. 9.10).
Dilatations of calices and pelvis without obstruction are possible, and attributable to chronic infectious episodes, rare causes and the ampullary pelvis, a variant of the normal pelvis, which should affect 8% of the population [3].
For some authors, however, this pattern means occult obstruction [4], which should be recog- nized and treated. In our observations, recogni- tion of a unilateral and moderate dilatation in a septic patient should not be considered fortu- itous.
A parapyelitic cyst or hypoechoic fat may, in a hasty examination, simulate renal dilatation.
pelvis. Note the rounded end, which indicates chronic obstruction. This single scan does not show patent signs of acute infection (see Fig. 9.8). Septic shock, transverse scan of the right kidney
Fig. 9.8. Sequel of Fig. 9.7. The ultrasound scan of the kidney now shows heterogeneous echoic masses within the dilated cavities (arrows). These images had a undu- lating motion in real-time. The diagnosis of superim- posed infection (pyonephrosis over hydronephrosis) can now be put forward
slightly more dilated. The end of the calyces is concave (arrows), usually a sign of acute obstruction. Longitudi- nal scan, making it possible to visualize the three calyx groups
Fig. 9.10. In this rarely obtained longitudinal scan of the right flank, one can observe a dilated ureter (U), inferi- or vena cava (V) and abdominal aorta (A). The ureter is usually masked by bowel gas
An acute obstruction may not yield dilatation of the calices if they have lost their compliance (fibro- sis, retroperitoneal malignancy), or sometimes because of major hypovolemia [5–7]. Only iodine explorations would make the diagnosis of obstruc- tion, but we have not yet encountered this situa- tion.
Bladder
This organ is easy to explore and can provide high- ly contributive information in daily practice. As a rule, a catheterized bladder is empty. A careful examination should, if necessary, identify the bal- loon of the probe, which seems lost in the pelvis, but always medial (Fig. 9.11).
A bladder that is probed but not empty is not a normal finding (Fig. 9.12). In this case, the bladder should be repeatedly examined in order to check that the trapped volume does not increase. Rarely but regularly, we observe a genuine distended bladder. If this occurs in a sedated patient with cir- culatory support, the physician can make a wrong diagnosis of anuria and increase drugs or fluid therapy, before the distension becomes clinically obvious. Therefore, if anuria occurs in such patients, the first reflex should be to check if there is no occult bladder retention.
Similarly, in an obese patient, the clinical diag- nosis of distended bladder can be difficult. It will always be immediate with ultrasound. Distended
bladder is maybe one of the most obvious diag- noses for the beginner in ultrasound (see Fig. 9.12).
The ultrasound probe, applied just over the pubis, detects a huge liquid mass which is medial, round, and near the anterior wall. The pitfalls are easily avoidable. The most frequent is the peritoneal effusion that mimics a distended bladder. If a sin- gle transversal scan is performed at the pelvis, peritoneal effusion can have a roughly square sec- tion and look like a moderately distended bladder (Fig. 9.13). However, peritoneal effusion appears to open when the probe scans more cranially, where- as a bladder appears to close.
In the female, the association of peritoneal effu- sion and a full bladder will yield a complex but characteristic pattern, the Thai dragoon head sign (Fig. 9.14).
In a recently anuric patient, a daily ultrasound can detect recovery of diuresis. This procedure does not last more than 10 s and should prevent a prolonged and useless insertion of a urinary probe.
The bladder content can be informative.A blood clot yields an echoic dependent pattern. A calculus gives a dependent image with a frank posterior shadow. A purulent retention can have a very char- acteristic pattern (Fig. 9.15). Last, an enlarged prostate can be detected (Fig. 9.16).
58 Chapter 9 Urinary Tract
Fig. 9.11. In this suprapubic transversal scan, probe pointing toward the rear and the bottom of the patient, one can see a regular round and medial structure, the in- flated balloon of the urinary probe. The bladder is here correctly drained, thus virtual (compare with Fig. 9.12)
Fig. 9.12. Major bladder distension in spite of a urinary probe. The balloon and the end of the probe are visible.
The probe was obstructed here. Longitudinal suprapu- bic scan
Fig. 9.13. Suprapubic transversal scan. This medial fluid image with square section and a tissular image (M) lif- ting the floor is highly suggestive of a moderately distended bladder. It is in fact peritoneal effusion in the Douglas pouch. The image at M is probably a bowel loop. A dynamic scan of the ultrasound probe upward and downward will prevent the error: the bladder will be identified below, and this fluid image will have an opened shape above
Fig. 9.14. This complex transverse suprapubic scan may intrigue the operator. One can imagine the head of a Thai dragon. This is, in fact, a full bladder associated with peritoneal effusion in a young woman. The bladder is the round shape at the top of the screen. The eyes and the mouth of the dragoon reflect the peritoneal effusion.
The nose is formed by the uterus and the large liga- ments. The teeth are generated by solid structures float- ing in the effusion – a hemoperitoneum here
Fig. 9.15. a Two elements can be distinguished in this bladder, separated by an artifactual line: a dependent echoic sediment and a nondependent anechoic area.
Pyuria. Transverse scan of the bladder. b Another pat- tern of pyuria. Multiple hyperechoic elements as in weightlessness, indicating microbial gas
Fig. 9.16. Medial regular tissular mass protruding in the bladder lumen, typical from a prostatic adenoma. This finding is sometimes useful in cases of acute obstructive renal failure
b
Uterus and Adnexa
We like to take a look at the uterus before any emergency radiological examination, in order to check its vacuity (Fig. 9.17). If a pregnancy is detected (Fig. 9.18), the reader should see Chap. 28, where all details about management are detailed.
Occurrence of an acute respiratory disease in a pregnant woman usually raises problems [8]. For this emergency application, we do not need to await full repletion of the bladder. In some postop- erative cases where the suprapubic approach is impossible, using a perineal approach is autho-
rized, as is an endovaginal investigation with the small probe covered with a glove. This approach, although not very academic, is perfectly valuable when a distended bladder is sought.
The aim of this book is not to describe gyneco- logical problems such as uterine apoplexy, ectopic pregnancy or others. It suffices to note that pyometritis gives a liquid endouterine image.
Hyperechoic punctiform images (gas) are a strong argument if there is severe pelvic sepsis [9].
Endometritis produces diffuse swallowing of the parenchyma [9]. Ectopic pregnancy shows a subtle direct image for the specialist, and a rough indirect image for the nonspecialist, the hemoperitoneum.
Note that this hemoperitoneum can be echoic at the first examination, thus particularly misleading (Fig. 9.19). The syndromes of defibrination can provide information on a rapid ultrasound confir- mation, although history and physical data are generally sufficient for the decision of a lifesaving hysterectomy.
Renal Transplantation
A grafted kidney usually lies in the fossa iliaca.
Surgical complications are more accessible to ultrasound than medical complications. Post- operative collection can be caused by abscess, hematoma, lymphocele or urinoma. They can be 60 Chapter 9 Urinary Tract
Fig. 9.17. Empty uterus in a long-axis scan, behind the bladder. The vacuity line, which indicates absence of pregnancy, is frankly outlined within the uterine muscle
Fig. 9.18. An embryo is visible in the uterus, seemingly observing the viewer. It is like a cat turned on its back, head at the right of the image. This should incite the physician not to overindulge in ionizing radiation pro- cedures
Fig. 9.19. Transverse view of the pelvis in a young female in shock. A motionless echoic mass indicates a massive blood clot in a highly probable ectopic pregnancy. The intensivist should not be asked the precise site of the pregnancy, since the recognition alone of a peritoneal effusion indicates, here, immediate lifesaving surgery
treat a urinary obstruction and to drain infected urine at the bedside if ultrasound-guided. The kid- ney is punctured by the posterior or posterolateral approach. The colon and the pleura are thus avoid- ed. A needle is inserted in the dilated cavities.
Urine is collected for analysis. A guide is then introduced through the needle.A drainage catheter is inserted, sometimes after several dilatations.
We have had the opportunity to use this tech- nique to treat a patient who could not be moved as she had severe septic shock. Later, procedures were performed in the radiology department for local- izing the obstruction level and in the operating room for removing the calculus, at this time in a stabilized patient.
Percutaneous nephrostomy is a procedure whose mortality rate (0.2%) is said to be lower than that of surgery [3]. Complications include hemorrhage or infection and should be balanced with the advantages.
If suprapubic catheterization is indicated, ultra- sound guidance provides visual monitoring. A penetration site more cranial than classically done
aiguë. In: Goulon M (ed) Réanimation et Médecine d’Urgence. Expansion Scientifique Française, Paris, pp 153–174
4. Laval-Jeantet M (1991) La détection de maladies graves par échographie systématique chez le généra- liste. Presse Med 20:979–980
5. Goldfarb CR, Onseng F, Chokshi V (1987) Nondila- ted obstructive uropathy. Radiology 162:879 6. Maillet PJ, Pelle-Francoz D, Laville M, Gay F, Pinet A
(1986) Nondilated obstructive acute renal failure:
diagnostic procedures and therapeutic manage- ment. Radiology 160:659–662
7. Charasse C, Camus C, Darnault P, Guille F, Le Tulzo Y, Zimbacca F, Thomas R (1991) Acute nondilated anuric obstructive nephropathy on echography: dif- ficult diagnosis in the intensive care unit. Intensive Care Med 17:387–391
8. Felten ML, Mercier FJ, Benhamou D (1999) Develop- ment of acute and chronic respiratory diseases during pregnancy. Rev Pneumol Clin 55:325–334 9. Ardaens Y, Guérin B, Coquel Ph (1990) Echographie
pelvienne en gynécologie. Masson, Paris
10. Cauquil P, Hiesse C, Say C, Vardier JP, Cauquil M, Brunet AM, Galindo R, Tessier JP (1989) Imagerie de la transplantation rénale. Feuillets de Radiologie 29:469–480
