Further Reading

Fig. 1.91 A clinical photogram showing dermoid cyst of the clitoris which can be confused with cliteromegaly

–Clinically, a round doughnut-shaped mucosa is seen protruding from the urethral opening.

–Management of urethral prolapse ranges from medical therapy that consists of topical estrogen use to conservative surgical excision when medical therapies fail.

Congenital Abnormalities of the Female

External Genitalia and Urethra

•Distal urethral stenosis

•Labial fusion

•Clitoral hypertrophy

•Urethral prolapse

Further Reading

1. Bertram JF, Douglas-Denton RN, et al. Human nephron number: implications for health and disease. Pediatr Nephrol. 2011;26:1529–33.

2. Caiulo VA, Caiulo S, Gargasole C, et al. Ultrasound mass screening for congenital anomalies of the kidney and urinary tract. Pediatr Nephrol. 2012;27:949.

3.Chowdhary SK, Lander A, Parashar K, Corkery JJ. Single-system ectopic ureter: a 15-year review. Pediatr Surg Int. 2001;17(8):638–41.

4.Daneman A, Alton DJ. Radiographic manifestations

of renal anomalies. Radiol Clin North Am. 1991;29(2):351–63.

5. Decter RM. Renal duplication and fusion anomalies. Pediatr Clin North Am. 1997;44:1323.

6. Glassberg KI. Normal and abnormal development of the kidney: a clinician’s interpretation of current knowledge. J Urol. 2002;167:2339.

7. Gribouval O, Gonzales M, Neuhaus T, et al. Mutations in genes in the renin-angiotensin system are associated with autosomal recessive renal tubular dysgenesis. Nat Genet. 2005;37:964.

8.Gubler MC. Renal tubular dysgenesis. Pediatr Nephrol. 2014;29:51.

9. Harris J, Robert E, Källén B. Epidemiologic characteristics of kidney malformations. Eur J Epidemiol. 2000;16:985.

10. Kluth D, Fiegel HC, Geyer C, et al. Embryology of the distal urethra and external genitals. Semin Pediatr Surg. 2011;20:176–87.

11. Krishnan A, de Souza A, Konijeti R, et al. The anatomy and embryology of posterior urethral valves. J Urol. 2006;175:1214–20.

12.Nakai H, Asanuma H, Shishido S, Kitahara S, Yasuda K. Changing concepts in urological management of the congenital anomalies of kidney and urinary tract, CAKUT. Pediatr Int. 2003;45(5):634–41.

13.Piscione TD, Rosenblum ND. The malformed kidney: disruption of glomerular and tubular development.

Clin Genet. 1999;56:341.

14. Sanna-Cherchi S, Caridi G, Weng PL, et al. Genetic approaches to human renal agenesis/hypoplasia and dysplasia. Pediatr Nephrol. 2007;22:1675.

15. Sanna-Cherchi S, Ravani P, Corbani V, et al. Renal outcome in patients with congenital anomalies of the kidney and urinary tract. Kidney Int. 2009;76:528.

16.Schedl A. Renal abnormalities and their developmental origin. Nat Rev Genet. 2007;8(10):791–802.

17. Seikaly MG, Ho PL, Emmett L, et al. Chronic renal insufficiency in children: the 2001 annual report of the NAPRTCS. Pediatr Nephrol. 2003;18:796.

18.Shnorhavorian M, Bittner R, Wright JL, Schwartz SM. Maternal risk factors for congenital urinary anomalies: results of a population-based case-control study. Urology. 2011;78:1156.

19.Song R, Yosypiv IV. Genetics of congenital anomalies of the kidney and urinary tract. Pediatr Nephrol. 2011;26(3):353–64.

20. Viana R, Batourina E, Huang H, et al. The development of the bladder trigone, the center of the antireflux mechanism. Development. 2007;134:3763–9.

21.Weizer AZ, Silverstein AD, Auge BK, et al. Determining the incidence of horseshoe kidney from radiographic data at a single institution. J Urol.

2003;170(5):1722–6.

22. Westland R, Schreuder MF, Ket JC, van Wijk JA. Unilateral renal agenesis: a systematic review on associated anomalies and renal injury. Nephrol Dial Transplant. 2013;28:1844.

23.Wiesel A, Queisser-Luft A, Clementi M, et al. Prenatal detection of congenital renal malformations by fetal ultrasonographic examination: an analysis of 709,030 births in 12 European countries. Eur J Med Genet. 2005;48(2):131–44.

24.Yavuz S, Kıyak A, Sander S. Renal outcome of children with horseshoe kidney: a single-center experi-

ence. Urology. 2015;85:463.

25. Yiee JH, Baskin LS. Penile embryology and anatomy. Scientific World Journal. 2010;10:1174–9.

26.Zalel Y, Pinhas-Hamiel O, Lipitz S, et al. The development of the fetal penis – an in utero sonographic evaluation. Ultrasound Obstet Gynecol. 2001;17:129–31.

2.1Introduction

•The word “hydro” represents “water” and “nephro” represents “kidney”.

•Hydronephrosis means “water inside the kidney”.

•Hydronephrosis is defined as distension and dilation of the renal pelvis and calyces (Figs. 2.1 and 2.2).

•Hydroureteronephrosis refers to distention of both the ureter and the renal pelvis and calices.

•Hydronephrosis is usually caused by obstruction of the free flow of urine from the kidney.

•Hydroureteronephrosis is usually caused by obstruction at the uretrovesical junction or below.

•The signs and symptoms of hydronephrosis depend upon:

–Whether the obstruction is acute or chronic

–Whether the obstruction is partial or complete

–Whether the obstruction is unilateral or bilateral

–Hydronephrosis that occurs acutely with sudden onset can cause intense pain in the flanks (Dietl’s crisis).

•If symptoms occur they can include:

–Back, flank or lower abdominal pain

–Nausea and vomiting

–Dysuria

–Burning during micturition

–Urinary incontinence

–Hematuria

–Febrile urinary tract infections

•Hydronephrosis should be graded accurately in order to make good clinical decisions concerning the management and follow-up.

•There are currently two methods to grade the degree of hydronephrosis:

–The simple classification system of “mild, moderate, and severe” is less accurate.

–The Society for Fetal Urology (SFU) has developed a more accurate numerical grading system for hydronephrosis.

•The causes of hydronephrosis can be congenital or acquired.

•It is important to understand that hydronephrosis does not always mean there is obstruction to the flow of urine from the kidney and hydronephrosis is a secondary effect of some other disease. Thus, the terms hydronephrosis and obstruction should not be used interchangeably.

•With the widespread use of prenatal ultrasounds, antenatal hydronephrosis is currently the most common diagnosed prenatal condition.

•Hydronephrosis can be caused by obstruction anywhere along the upper or lower urinary tract.

–Obstruction that occurs anywhere along the upper urinary tract will lead to increased pressure within the kidney.

–Obstruction occurring in the lower urinary tract can also cause this increased pressure through efflux of urine into the kidney.

–Grades II resolves in approximately 36 % of patients

–Grade III resolves in approximately 16 % of patients

–Grade IV resolves in approximately 3 % of patients

•The initial severity of the hydronephrosis at the time of antenatal diagnosis and the presence of the hydronephrosis at birth were the only two factors that predicted hydronephrosis failure to resolve.

•Hydronephrosis that was mild to mild-to- moderate in severity resolved in 71 % of patients, compared to 28 % of children with moderate to severe hydronephrosis. This supports the claim that the severity of hydronephrosis predicts failure of the lesion to resolve.

2.2Pathophysiology

•Hydronephrosis can result from anatomic or functional causes that interrupt the flow of urine (Figs. 2.10 and 2.11).

•This interruption can occur anywhere along the urinary tract from the kidneys to the urethral meatus.

•Gross changes within the urinary tract depend on:

–The duration of obstruction

–The degree of obstruction

–The level of obstruction

•Within the intrarenal collecting system, the degree of dilation is limited by surrounding renal parenchyma.

•This is in contrast to the extrarenal components which can dilate to the point of tortuosity.

•Hydronephrosis can reasonably be viewed as a beneficial compensatory mechanism that actually protects the kidney against high intrapelvic pressures and further renal damage.

•The extent and persistence of these functional insults are directly related to the duration and severity of the obstruction.

–Brief disruptions lead to reversible functional disturbances with little associated anatomic changes.

Figs. 2.5 and 2.6 A micturating cystourethrogrma showing severe vesicoureteric reflux in a patient with a duplex system. An intravenous urogram showing a negaureter with hydroureteronephrosis is seen in the second picture.

In patients with megaureter, there is no anatomical obstruction at the uretrovesical junction and micturating cystourethrogram doe not show vesico ureteric reflux

–More chronic disruptions lead to profound tubular atrophy and permanent nephron loss.

•The rise in ureteral or renal pelvic pressure leads to marked changes in glomerular filtration, tubular function, and renal blood flow.

•The glomerular filtration rate (GFR) declines significantly within hours following acute obstruction. This significant decline of GFR can persist for weeks after relief of obstruction.

•In addition, renal tubular ability to transport sodium, potassium, to concentrate and to dilute the urine is severely impaired.

•Increased ureteral pressure also results in pyelovenous and pyelolymphatic backflow.

•Acute hydronephrosis:

–Acute hydronephrosis when corrected, usually allows full recovery of renal function.

–It can be associated with little anatomic disturbance to renal parenchyma.

•Chronic hydronephrosis:

–In chronic hydronephrosis, the loss of function is usually irreversible even with correction of the obstruction.

–It may be associated with compression of the papillae, thinning of the renal parenchyma around the calyces, and coalescence of the septa between calyces.

–Eventually, cortical atrophy progresses to the point at which only a thin rim of parenchyma is present (Figs. 2.12, 2.13, and 2.14).

–Microscopic changes consist of dilation of the tubular lumen and flattening of the tubular epithelium. Fibrotic changes and increased collagen deposition are observed in the peritubular interstitial tissue.

Figs. 2.7, 2.8, and 2.9 An intravenous urogram showing hydrouretronephrosis secondary to obstruction at the uretrovesical junction. Note the ureter tappering at the lower part. This was confirmed intraoperatively in the second

two intraoperative picrures. Note the dilated ureter above the site of obstruction. This was treated by resection of the stenotic part and reimplantation of the ureter

DUPLEX URETER

Fig. 2.12 Intraoperative photograph showing an atrophic kidney with dilated refluxing duplex system. Note the markedly dilated duplex ureter

–Acute, unilateral obstruction can cause hypertension via activation of the reninangiotensin system.

–The elevation in blood pressure is probably volume mediated as renin secretion is usually normal in patients with bilateral

urinary tract obstruction or obstruction of a solitary functioning kidney. The elevation in blood pressure resolves with the diuresis following correction of the obstruction.

–The plasma renin activity is also typically normal in chronic unilateral obstruction, and the elevation in blood pressure is unrelated to the renal disease.

•The pathophysiological changes of hydronephrosis depends on several factors which can be summarized as follows:

–Persistent hydronephrosis will lead to the following changes:

•Dilatation of the renal pelvis and the intrarenal collecting system.

•The degree of dilatation is limited by surrounding renal parenchyma.