16 Paediatric urology

Following fertilization, a blastocyte (sphere of cells) is created, which implants into the uterine endometrium on day 6. The early embryonic disc of tissue develops a yolk sac and amniotic cavity, from which are derived the ectoderm, endoderm, and mesoderm. Organ formation occurs between 3 and 10 weeks’ gestation. Most of the genitourinary tract is derived from the mesoderm.

The pronephros (precursor of the kidney; pro = (Gk) before) is derived from an intermediate plate of mesoderm, which functions between weeks 1–4. It then regresses. The mesonephros (meso = (Gk) middle) functions from weeks 4–8 and is also associated with two duct systems—the mesonephric duct and adjacent to this, the paramesonephric duct (para = (Gk) beside) (Fig. 16.1a). The mesonephric (Wolffian) ducts develop laterally and advance downwards to fuse with the cloaca (Latin = sewer), a part of the primitive hindgut. By week 5, ureteric buds grow from the distal part of the mesonephric ducts and by a process of reciprocal induction, they stimulate the formation of the metanephros (permanent kidney; meta = (Gk) after) when they reach the renal tissue. Branching of the ureteric bud forms the ureter, renal pelvis, calyces, and collecting ducts. Glomeruli and nephrons (distal convoluted tubules, proximal convoluted tubules, and loop of Henle) are derived from metanephric mesenchyme (metanephros). During weeks 6–10, the caudal end of the fetus grows rapidly and the fetal kidney effectively moves up the posterior abdominal wall to the lumbar region. Urine production starts at week 10.

Thus, in both males and females, the mesonephric duct forms the ureters and renal collecting system. The paramesonephric duct essentially forms the female genital system (Fallopian tubes, uterus, upper vagina); in males, it regresses. The mesonephric ducts also form the male genital duct system (epididymis, vas deferens, seminal vesicles) and central zone of the prostate; in females, it regresses (see  p. 648).

The mesonephric ducts and ureters drain into the cloaca. During weeks 4–6, the cloaca is subdivided into the urogenital canal or sinus (anteriorly) and the anorectal canal (posteriorly) by a process of growth, differentiation, and remodelling (Fig. 16.1b).¹ The bladder is formed by the upper part of the urogenital canal. Bladder smooth muscle (detrusor) is developed from adjacent pelvic mesenchyme. The trigone develops separately, arising from a segment of the mesonephric duct. The bladder dome is initially connected to the allantois, but this connection later regresses to become a fibrous cord (urachus).

The inferior portion of the urogenital canal forms the entire urethra in females and the posterior urethra in males. Closure of the urogenital groove creates the male anterior urethra. The mesonephric ducts separate from the ureters (Fig. 16.1c) and travel caudally to join the posterior urethra in males (where they differentiate into the male genital duct system at 8–12 weeks).

Sexual differentiation and gonadal development is determined by the sex chromosomes (XY, male; XX, female). The gonads produce hormones which influence the subsequent differentiation of internal and external genitalia.

Gonads develop from the genital ridges (formed by cells of the mesonephros and coelomic epithelium). At 5–6 weeks, primordial germ cells migrate from the yolk sac to populate the genital ridges. Primitive sex cords are formed, which support germ cell (sperm and ova) development.

From 4 weeks, the mesonephric (Wolffian) ducts are incorporated into the genital system when renal function is taken over by the definitive kidney. At 6 weeks, coelomic epithelium creates the paramesonephric (Müllerian) ducts which develop laterally and are fused to the urogenital sinus at their bases.

Embryos are genetically programmed to be female unless the testis- determining gene (SRY) is present, in which case the embryo will differentiate into a male. The SRY gene is located on the Y chromosome. It stimulates medullary sex cords in the primitive testis to differentiate into Sertoli cells which produce Müllerian inhibiting substance (MIS) at 7–8 weeks. The sex cords differentiate into seminiferous cords, which later form the seminiferous tubules of the testis within which the primordial germ cells differentiate into spermatogonia. MIS triggers regression of the paramesonephric ducts, testosterone secretion from Leydig cells of the testis, and the initial phase of testicular (abdominal) descent. The androgens testosterone and dihydrotestosterone (DHT) are responsible for masculinization of the fetus.

During weeks 8–12, the mesonephric ducts differentiate into the epididymis, vas deferens, seminal vesicles, and ejaculatory ducts. Under the influence of DHT, proliferation and budding of the urethral endoderm gives rise to prostatic acini and glands and by a process of reciprocal induction, forms the prostatic capsule and smooth muscle from the surrounding mesenchyme (completed by week 15).

After week 23, the second androgen-dependent phase of testicular descent occurs. The testes rapidly descend from the abdomen (via the inguinal canal during weeks 24–28) and into the scrotal sac, aided by calcitonin gene-related polypeptide acting on the gubernaculum. The testis is enclosed in a diverticulum of peritoneum called the processus vaginalis. The distal part persists as the tunica vaginalis around the testis, the remainder usually regresses.

External genitalia develop from week 7. Urogenital folds form around the opening of the urogenital sinus and labioscrotal swellings develop on either side. The penile shaft and glans are formed by elongation of the genital tubercle and fusion of urogenital folds. The scrotum is created by fusion of labioscrotal folds.

The genital ridge forms secondary sex cords (primitive sex cords degenerate) which surround the germ cells to create ovarian follicles (week 15). These undergo meiotic division to become primary oocytes which are later activated to complete gametogenesis at puberty. Oestrogen is produced from week 8 under the influence of the aromatase enzyme. In the absence of MIS, the mesonephric ducts regress and the paramesonephric ducts become the Fallopian tubes, uterus, and upper two-thirds of the vagina. The sinovaginal sinus is developed at the junction of the paramesonephric ducts and the urogenital sinus. This forms the lower third of the vagina.

The genital tubercle forms the clitoris; the urogenital folds become the labia minora and the labioscrotal swellings form the labia majora.

The first phase of testicular descent from the genital ridge to internal inguinal ring occurs under the influence of MIS acting on the gubernaculum (around 7–8 weeks’ gestation). The second phase of testicular descent through the inguinal canal into the scrotum occurs at 24–28 weeks’ gestation under the influence of testosterone. Failure of descent results in cryptorchidism or congenital UDT.

Four percent at birth for a full-term neonate, however, many will spontaneously descend after birth and the incidence at 1y is 1.3–1.8%. The incidence of unilateral UDT is greater than bilateral UDT.

UDT demonstrate the degeneration of Sertoli cells, loss of Leydig cells, atrophy, and abnormal spermatogenesis. Male fertility depends on the transformation of gonocytes to dark adult spermatocytes within the first 3 months of post-natal life. This appears to be defective in UDT.²

Examine the scrotum and inguinal region to elucidate if a testis is palpable and to identify its location. Retractile testes may be brought back down into the bottom of the scrotum without tension. Assess for associated congenital defects. If neither testis is palpable, consider chromosome analysis (to exclude an androgenized female) and endocrine analysis (high LH and FSH with a low testosterone indicates anorchia, confirmed with serum inhibin B). For the impalpable testis, USS is of limited use. Most proceed directly to examination under anaesthetic ± diagnostic laparoscopy and treatment.

Overall success rates of orchidopexy vary according to position of the UDT: 92% for inguinal testes, 87% for canalicular testes, and 74% for abdominal testes.³

UTI is a bacterial infection of the urine, which may involve the lower urinary tract/bladder (cystitis) or upper urinary tract/kidney (pyelonephritis) (see  p. 176).

children may be asymptomatic or symptomatic.

Simple UTI: presents with mild dehydration and pyrexia.

Severe UTI: presents as fever ≥38°C, unwell, vomiting, with moderate to severe dehydration.

Atypical UTI: includes features of serious illness/septicaemia, poor urinary flow, abnormal renal function, failure to respond to treatment in <48h, and non-E. coli infection.

Recurrent UTI: in children, describes either one episode of cystitis with one episode of pyelonephritis, ≥2 episodes of pyelonephritis, or ≥3 episodes of cystitis. It may be due to bacterial persistence, unresolved infection, or re-infection.

up to age 1, the incidence in boys is higher than girls (male: female ratio is 3:1), but thereafter, the incidence in girls becomes greater (school age males 1%; females 3%).

common bacterial pathogens are E. coli, Enterococcus, Pseudomonas, Klebsiella, Proteus, and S. epidermidis. Bacteria enter via the urethra to cause cystitis and ascending infection causes pyelonephritis. Alternatively, there can be haematogenous spread from other systemic infections.

Urine analysis and culture: advised with unexplained fever ≥38°C or if symptomatic of UTI. Clean catch specimen where possible. In toilet-trained children, an MSU specimen is considered diagnostic with ≥10⁵ colony-forming units (CFU)/mL in asymptomatic children and ≥10⁴CFU/mL if symptomatic. In young children, a catheterized urine specimen with ≥10CFU/mL) of one pathogen or a suprapubic aspirate with ≥10²CFU/mL are diagnostic of UTI. Collection bag specimens are less reliable due to skin flora contamination.

Imaging: refer to NICE recommendations (Tables 16.1–16.3).¹

Infants <3 months (and children at risk of serious illness): are managed according to the ‘feverish illness in children’ guidelines.² For children aged 3 months to 3y, antibiotics are recommended (before urine culture results are available) for specific symptoms of UTI and for non-specific symptoms where the risk of intermediate to serious infection is high (i.e. associated anatomical or functional abnormality).² In children older than 3y, antibiotics are indicated if urine dipstick analysis is positive for nitrites ± leukocyte esterase or if there is good clinical evidence of UTI.

Infants <3 months: paediatric referral and treat with IV antibiotic such as third-generation cephalosporin (cefotaxime or ceftriaxone).²

Infants and children >3 months with pyelonephritis: paediatric referral; 7–10 days of oral cephalosporin or co-amoxiclav or IV cefotaxime or cefriaxone for 2–4 days followed by oral antibiotics for a total of 10 days.

Infants and children >3 months with cystitis: oral antibiotics for 3 days (trimethoprim, nitrofurantoin, cephalosporin, or amoxicillin), and reassess. The choice of antibiotics should be directed by local hospital guidelines.

Asymptomatic bacteriuria does not require antibiotics or routine follow-up. Antibiotic prophylaxis is not recommended following a first-time simple UTI, but can be considered after recurrent symptomatic UTI.³ Advice on preventing UTI should be given, including good intake of fluids, regular voiding, and treatment of constipation.

Follow-up: recurrent UTI or abnormal imaging requires paediatric assessment. Long-term follow-up is needed for bilateral renal anomalies, impaired renal function, hypertension, and/or proteinuria. Follow-up should include recordings of growth (height, weight), BP, and urine dipstick testing.

Generally defined as a maximal anteroposterior renal pelvis diameter (RPD) of ≥5mm on antenatal USS.

The incidence of antenatal hydronephrosis (RPD ≥5mm) is approximately 0.6% on second trimester (20 weeks’ gestation) USS. The incidence of antenatal USS-detected congenital anomalies of the urinary tract is 0.1–4%. An increasing degree of hydronephrosis is related to increased risk of urinary tract pathology and requirement for surgery.^1,2 However, in around 65%, antenatal hydronephrosis will resolve and overall, <5% will require nephrological or surgical intervention.³

Causes include transient hydronephrosis (48%), physiological hydronephrosis (15%), PUJO, VUR, megaureter, multicystic dysplastic kidney (MCDK), renal cysts, posterior urethral valves (PUV), ectopic ureter, and ureterocele (also see Table 16.4).³

Specific post-natal investigation and management will depend on the underlying diagnosis and severity of hydronephrosis and are described individually later in this chapter. The important principles of post-natal management include:

Consider urgent referral to paediatric urology for:

Consider referral to paediatric nephrology or urology for:

(Please refer to local hospital guidelines as these will differ between different hospitals and tertiary centres.)

VUR results from abnormal retrograde flow of urine from the bladder into the upper urinary tract.

overall incidence in children is 1–2%; younger > older; girls > boys (female : male ratio = 5:1); Caucasian > Afro-Caribbean. The offspring of an affected parent has up to 70% incidence of VUR; siblings of an affected child have 30% risk of reflux. Screening of offsprings and siblings is controversial and many would only recommend it if there is significant renal scarring in the index case.

the ureter passes obliquely through the bladder wall (1–2cm) where it is supported by muscular attachments which prevent urine reflux during bladder filling and voiding. The normal ratio of intramural ureteric length to ureteric diameter is 5:1. Reflux occurs when the intramural length of ureter is too short (ratio <5:1) (Paquin’s law). The degree of reflux is graded I–V (see  p. 408; Fig. 8.3). The appearance of the ureteric orifice changes with increasing severity of reflux, classically described as stadium, horseshoe, golf hole, or patulous.

VUR (associated with UTI) can result in reflux nephropathy and renal scarring, causing hypertension (10–20%) and rarely, progressive renal failure.

Symptoms of UTI (fever, dysuria, suprapubic and abdominal pain), failure to thrive, vomiting, diarrhoea. It is important to elicit associated symptoms and signs of bladder and/or bowel dysfunction: urinary frequency, urgency, prolonged voiding intervals, daytime wetting, holding manoeuvres to prevent wetting, and constipation.

The majority of primary VUR grades I–II will resolve spontaneously (80%),¹ with overall 50% resolution in grades III–V.² Reflux tends to improve with age as the length of the intramural ureter increases with growth (Table 16.5). General advice includes good fluid intake, regular voiding, perineal hygiene, treatment of constipation, and use of probiotics. Provide parents with UTI advice and emphasize the need to seek medical attention early if the child has an unexplained febrile illness or suspected UTI. It is important to treat any coexisting bladder or bowel dysfunction.

The need for antibiotic prophylaxis in VUR remains controversial. A NIH randomized placebo-controlled study of children with VUR (RIVUR Study) aims to further investigate this. The Swedish reflux trial in children has reported that prophylactic antibiotics and endoscopic surgery decreases (febrile) infection rates in girls, but not in boys, as compared to surveillance alone.³

Currently, low-dose antibiotic prophylaxis is given to keep the urine sterile and lower the risk of renal damage in young children (≤1y old) with a history of febrile UTI⁴ and until reflux resolves in higher grades of VUR (III–V). Whilst on treatment, growth, BP, and urine should be monitored (for proteinuria and bacteriuria), with an annual renal tract USS. If the child remains well, antibiotics may be discontinued when they are toilet-trained (dry day and night). If febrile UTI recurs after conservative or surgical resolution of VUR, reinvestigate for bladder dysfunction and recurrence of VUR.⁴ Longer term follow-up into adolescence is recommended if there is any renal abnormality on USS or DMSA, even if VUR has resolved.⁴

Indications for surgery include: high-grade VUR (girls benefit more than boys), breakthrough febrile UTI despite antibiotic prophylaxis, and non-compliance with medical therapy. Circumcision reduces the risk of UTI in boys with VUR⁵ and is used for those with anatomical anomalies and recurrent or breakthrough UTI.

Surgical techniques include endoscopic injection, ureteric re-implantation performed by open surgery (98% success) or laparoscopically. Endoscopic injection of Deflux^® is the first-line surgical treatment. Indications for ureteric re-implantation include failure of Deflux^®, duplex renal system, and renal ectopia.

Deflux^® is a hyaluronic acid/dextranomer bulking agent which is injected intramurally within the distal ureter and also at the ureteric orifice (‘HIT’ technique) with 80–90% success rates, although recent studies have suggested that repeat treatments may be required.⁶ Deflux^® is most effective for VUR grades I–III. It has replaced the traditional subtrigonal injection (‘STING’) of bulking agent (collagen) into the ureteric orifice.

Megaureter is the term for a dilated ureter, usually larger than 7mm in diameter, which may be a primary condition or secondary to another underlying problem. It can be classified into four different groups:

Primary megaureter can be refluxing or obstructed and is associated with either a simplex renal system or a duplex. Obstruction is due to either a stenotic or aperistaltic distal ureter, which results in a dilated and tortuous ureter proximally.

Secondary megaureter may be:

Megaureter affects approximately 1 in 2000 children. Males are more commonly affected than females; the left ureter is more commonly affected than the right side.

Megaureter is the underlying cause for prenatal ultrasound-detected fetal hydronephrosis in around 4% of cases,¹ associated with a dilated ureter (>7mm) (see  p. 658). After birth, UTI is the most common presentation. When associated with an undetected obstructed megaureter, this may present as urosepsis with an infected, obstructed system, which is a urological emergency and requires urgent decompression and antibiotics.

Empirical treatment is to start antibiotic prophylaxis at birth whilst the diagnosis is being established (trimethoprim 2mg/kg daily). If the differential renal function is >40%, patients can be managed with expectant or conservative treatment and follow-up renal tract USS. If the ureteric dilatation resolves or improves and the child remains well, they may discharged at the age of 5 with UTI advice. Prophylactic antibiotics can be continued if infection is a feature, however, recurrent, breakthrough, or severe UTI would be an indication for surgical intervention.

Endoscopic or open cystotomy and insertion of a ureteric stent is the procedure of choice in this young age group. Definitive surgical correction with ureteric re-implantation is deferred until after 6 to 12 months old if possible as this is associated with less morbidity and better outcomes.

The aims of surgery are to excise the stenotic or aperistaltic distal ureteric segment and perform an intravesical ureteric re-implantation with a Cohen repair, bringing the ureter across the trigone in a submucosal tunnel.

For more severely dilated and capacious ureters, it is often necessary to taper the ureter before re-implantation. This can be achieved by placation of the ureter (Starr technique), folding of the ureter (Kalicinski technique), or by ureteric excision. The choice of re-implantation surgery is then a Leadbitter–Politano repair which has the advantage of creating a longer anti-refluxing submucosal tunnel. This is often coupled with a psoas hitch to help prevent kinking and further obstruction of the ureter. For bilateral cases of megaureter, a transureteroureterostomy can be performed. Here, one ureter is excised distally and attached to drain into the contralateral ureter so only one ureter drains urine from both kidneys into the bladder. This ureter can then be plicated and re-implanted as before. Nephroureterectomy is indicated if the megaureter is associated with a non-functioning or poorly functioning kidney.

Renal tract USS and MAG3 renogram should be performed after 1y to reassess the degree of ureteric dilatation and for pelvicalyceal dilatation. Prophylactic antibiotics may be continued in children with persistent reflux, but can be stopped once the child is fully toilet-trained if they remain well.

An ectopic ureter is caused by the ureteric bud which arises from an abnormal (high or low) position on the mesonephric duct during embryological development. There is a direct correlation between the location of the ectopic ureter and the degree of ipsilateral renal hypoplasia or dysplasia.¹ Eighty percent is associated with a duplicated collecting system. A duplex kidney has an upper and a lower moiety, each with its own renal pelvis and ureter. The two ureters may join to form a single ureter or they may pass down individually to the bladder (complete duplication). In this case, the upper renal moiety ureter always opens onto the bladder below and medial to the lower moiety ureter (Weigert–Meyer rule), predisposing to ectopic placement of the ureters and ureteric orifices (see  p. 423; Fig. 8.10).

Incidence: about 1 in 2000. Female to male ratio is ≥3:1. Most ectopic ureters in females are associated with a duplex kidney whereas most ectopic ureters in males are associated with a single renal system.

May present with an antenatal diagnosis of hydronephrosis and dilated ureter to the bladder. Later presentations include acute or recurrent UTI. Obstruction of the ectopic ureter can lead to hydroureteronephrosis which may present post-natally as an abdominal mass or pain.

Commence prophylactic trimethoprim (2mg/kg daily) whilst conducting post-natal investigation. An ectopic ureter without an ureterocele, but associated with upper renal moiety dilatation, requires urgent treatment to decompress the system and avoid the, complication of an infected, obstructed system (pyoureteronephrosis).

Management is mainly expectant if there are no symptoms and no evidence of acute obstruction or dilatation. Where an ectopic ureter is associated with a poorly functioning renal upper pole moiety or single-system kidney, surgery is an option. This includes open or laparoscopic upper moiety heminephrectomy or total nephrectomy with excision of the associated ureter. Ureteropyelostomy and uretero-ureterostomy can be considered in duplex systems where the upper renal pole has reasonable function. Where some useful function is retained in a single-system kidney, the distal ureter can be resected and re-implanted into the bladder.

an ureterocele is a cystic dilatation of the distal ureter as it drains into the bladder.

1 in 5000–12,000 clinical paediatric admissions¹ (although 1 in 500 are found at autopsy).² Female to male ratio is 4:1, predominantly affecting Caucasians. Ten percent of ureteroceles are bilateral.

Ureteroceles may be associated with a single or duplex renal system. Eighty percent are associated with the upper moiety of a duplex kidney.

They are further classified into intravesical or extravesical ureteroceles.

Intravesical (20%): the ureterocele is completely confined within the bladder. These tend to be associated with single systems and are more common in males. Subtypes include:

Extravesical (or ectopic) (80%): when the ureterocele extends to the bladder neck or urethra and tend to occur with duplex systems; most commonly in females. Subtypes include:

Presentation: most present with antenatal hydronephrosis. Later presentation in infants may be with symptoms of UTI, an abdominal mass, or pain. Association with ureteric duplication increases the risk of reflux and reflux nephropathy. Extravesical ureteroceles can also cause BOO and bilateral hydroureteronephrosis (urological emergency) or ureteric obstruction and unilateral hydroureteronephrosis, which require urgent assessment and intervention. A prolapsing ureterocele can present as a vaginal mass in girls.

Commence prophylactic antibiotics at birth (trimethoprim 2mg/kg daily). Urgent surgical intervention is required for obstruction.

a blockage of the ureter at the junction with the renal pelvis, resulting in a restriction of urine flow.^*

childhood incidence is estimated at 1 in 1000. Boys are affected more than girls (ratio 2:1 in newborns). The left side is more often affected than the right side (ratio 2:1). They are bilateral in 10–40%.

In children, most PUJ obstruction is congenital. Intrinsic obstruction may be due to aberrant development of ureteric/renal pelvis muscle, aberrant insertion of the ureter into the renal pelvis, abnormal collagen, or ureteric folds or polyps. Extrinsic causes include compression of the PUJ by aberrant crossing vessels. Coexisting VUR is found in up to 25%.

PUJ obstruction is the most common cause of hydronephrosis (without ureteric dilatation) found on antenatal USS. Infants may also present with an abdominal mass, UTI, and haematuria. Older children present with flank or abdominal pain (exacerbated by diuresis), UTI, nausea and vomiting, and haematuria following minor trauma.

If prenatal USS has shown a large or bilateral hydronephrosis, a follow-up renal tract USS should be performed soon after birth. If there is a prenatal unilateral hydronephrosis (and the bladder is normal), the scan is deferred until day 3–7 (to allow normal physiological diuresis to occur, which may spontaneously improve or resolve the hydronephrosis). MAG3 renogram is performed at 6–12 weeks for diagnosis and to assess split renal function. Significant obstruction is unlikely if the anteroposterior renal pelvis diameter is <15mm.

Conservative: infants are placed on prophylactic trimethoprim (2mg/kg daily) until the diagnosis is established. Children may be observed with USS and MAG3 renogram if they remain stable, with good renal function and no other complications (such as infection or stones).

Surgery: pyeloplasty is indicated if children are symptomatic, have a significant hydronephrosis (>30mm AP renal pelvis diameter) or impaired split renal function (<40%).Techniques include open or laparoscopic Anderson–Hynes dismembered pyeloplasty. Success rates are around 90–95%. Post-operative follow-up is with USS (± MAG3 renogram). Where renal function is poor (<10–15%) on the side of the PUJ obstruction, options include temporary percutaneous drainage or ureteric stent to assess the potential for recovery (i.e. suggesting a pyeloplasty could improve function) or nephrectomy where the impairment is severe or irreversible.

PUV are derived from an abnormal congenital membrane arising from the verumontanum and attaching obliquely to the anterior urethra (beyond the external urethral sphincter), resulting in lower urinary tract obstruction. An alternative term is COPUM or congenital obstructive posterior urethral membrane. Urethral instrumentation or spontaneous partial rupture of the membrane is thought to cause the classical appearance of two valve-like folds in the prostatic urethra.

1 in >5000 males.

PUV may arise through an abnormal insertion of the Wolffian ducts into the urogenital sinus during fetal development.

Prenatal USS: the majority are diagnosed prenatally, with 60% identified on USS at 20 weeks. They account for 1% of cases of antenatal hydronephrosis. Features include: bilateral hydroureteronephrosis, dilated and thick-walled bladder, dilated posterior urethra (keyhole sign), thick-walled bladder, oligohydramnios (reduced amniotic fluid), and renal dysplasia. Early diagnosis is associated with poor prognosis.

Newborn and infants: respiratory distress secondary to pulmonary hypoplasia, palpable abdominal mass (hydronephrotic kidneys or distended bladder), ascites, UTI sepsis, electrolyte abnormalities (renal impairment), failure to thrive.

Older children: milder cases may present later with recurrent UTI, poor urinary stream, incomplete bladder emptying, poor growth and incontinence. There is a risk of renal failure, VUR, and voiding dysfunction (over- or underactive bladder), also described as ‘valve bladder syndrome’.

Associated features: ‘pop-off valve syndrome’ is seen in 20%. It describes mechanisms by which high urinary tract pressure is dissipated to allow normal renal development. It includes leaking of urine from a small bladder or renal pelvis rupture (urinary ascites), unilateral reflux into a non-functioning kidney (VUR with renal dysplasia or VURD), and formation of bladder diverticuli.

Commence prophylactic antibiotics immediately (trimethoprim 2mg/kg daily) and drain the bladder with a paediatric feeding tube or suprapubic catheter if this proves difficult. Check serum electrolyes and arrange for urgent post-natal renal tract USS and MCUG.

Definitive treatment is with cystoscopy and transurethral ablation of the valve. The most important incision is made at the 12 o’clock position with either cold knife or electrocautery. Complications of surgery include urethral strictures. A temporary cutaneous vesicostomy is indicated (communicating stoma between the bladder dome and suprapubic abdominal wall, allowing free drainage of urine) when the urethra is too small for the resectoscope. Alternatives are ureterostomy drainage with valve ablation performed at a later stage. Any underlying bladder dysfunction should be diagnosed and treated.

Monitor children for linear growth (height, weight, and head circumference), renal function, BP, urine analysis (for proteinuria, osmolality), USS, and formal GFR with chromium EDTA. Renography (MAG3 and DMSA) are also performed to assess split renal function and look for evidence of obstruction or reflux. Videourodynamic studies are used to assess and aid in the management of any associated voiding dysfunction.

Thirty-five percent have long-term poor renal function; 20% develop end-stage renal failure. Bladder dysfunction is common despite treatment of outflow obstruction. This includes bladder overactivity, incontinence, and bladder underactivity associated with chronic urinary residuals and poor concentration of urine (with polyuria). From age 16y, care should be transferred to an adult urologist or nephrologist. Problems may arise with retrograde ejaculation, impotence and reduced libido (related to renal impairment), and abnormal prostatic or seminal vesicle secretions, contributing to reduced fertility.

Congenital cystic kidney disease can be is classified into non-genetic and genetic types.

The cysts of a ‘multicystic’ kidney are not due to dilatation of renal collecting ducts (as in polycystic disease), but instead, the entire kidney is dysplastic and non-functioning, with immature dysplastic stroma and non-communicating cysts of various sizes. The proximal ureter is atretic in about 66%.

The incidence of unilateral MCKD is 1 in 4000, with a male to female ratio of 2:1. Bilateral disease occurs in 10% of cases and is incompatible with life.

MCDK is detected on antenatal USS (20 weeks’ gestation). A 34-week antenatal USS is performed to assess for contralateral anomalies.

MCKD may be simple (contralateral kidney is normal on USS) or complicated (contralateral side is abnormal). Unilateral disease is associated with VUR or PUJ obstruction in the contralateral kidney in ∼30%. An ureterocele will be associated with MCKD in 10% of cases.

Post-natal renal tract USS is performed at 1 week after birth.

This does not require prophylactic antibiotics. Repeat USS and DMSA renogram are performed at 6 weeks to confirm there is no renal function in the MCDK. Affected kidneys (especially those <6cm) tend to involute. Most can be treated conservatively with surveillance of growth, BP, urine analysis, and USS follow-up. Consider surgical removal for MCDK >6cm (which tend to grow), any solid component, hypertension, symptoms, or parental preference

Prophylactic antibiotics are started at birth. Post-natal USS and MAG3 renogram are performed to investigate obstruction (i.e. contralateral PUJ obstruction). MCUG and DMSA renogram are performed to exclude reflux.

The risk of developing hypertension or Wilms’ tumour (see  p. 238) with MCDK is rare and routine nephrectomy to prevent the development of these conditions is no longer recommended. Follow-up of BP, growth, proteinuria, and renal tract USS is recommended.

Presents in young children with a flank mass, loin pain, or haematuria. Diagnosis is on USS or CT, demonstrating multilocular cysts in the renal parenchyma, which may extend into the collecting system. It is included in a spectrum of disease that is closely associated with Wilms’ tumour and so the recommended treatment used to be partial or full nephrectomy, but many specialists will monitor these now rather than proceed directly to surgery.

A disease of infancy and childhood where renal collecting tubules and ducts become cystically dilated and numerous small cysts form in the renal cortex and medulla bilaterally. Incidence of 1 in 10 000–40 000. Severe forms present early and have a poor prognosis. Prenatal USS demonstrates oligohydramnios (amniotic fluid <200mL) and large, ‘bright’ homogeneously hyperechogenic kidneys which can cause obstructed labour and respiratory problems (secondary to pulmonary hypoplasia). Neonates have large flank masses, limb and facial anomalies. All cases are associated with congenital hepatic fibrosis. Infants may develop fatal uraemia and respiratory failure; older children present with renal failure, hypertension, and portal hypertension. Most develop end-stage renal failure by adulthood, requiring haemodialysis, nephrectomy (to control hypertension), and subsequent renal transplantation.

Typically presents in adulthood, although older children can present with complications of haematuria, flank pain, flank mass, UTI, proteinuria, hypertension, and intracerebral bleeds (secondary to berry aneurysm rupture). ADPKD is the most commonly inherited renal disease with an incidence of ∼1 in 1000. It is characterized by multiple expanding cysts of both kidneys that ultimately destroys the intervening parenchyma and accounts for 10% of all chronic renal failure. Ninety percent of cases are due to a defective PKD1 gene located on chromosome 16; the remainder is due to a defective PKD2 gene on chromosome 4.

An autosomal recessive disorder which develops in early childhood and accounts for up to 20% of paediatric renal failure. Medullary cystic disease is a similar (autosomal dominant) condition which develops in later childhood. Histology in both conditions shows interstitial nephritis associated with corticomedullary cysts. Disease progression causes a reduction in kidney size. Features include polyuria and polydipsia (due to a salt-losing nephropathy), anaemia, growth retardation, hypertension, and chronic renal failure. Initial treatment includes salt replacement. Dialysis and renal transplantation are later options.

Renal cysts are also a feature of autosomal dominant conditions, including von Hippel–Lindau syndrome (cerebellar and retinal haemangioblastomas, phaeochromocytoma, pancreatic cysts, renal cell carcinoma (RCC)) and tuberous sclerosis (adenoma sebaceum, epilepsy, learning difficulties associated with renal angiomyolipoma, and RCC).

Hypospadias is a congenital deformity where the opening of the urethra (the meatus) is sited on the underside (ventral) part of the penis, anywhere from the glans to the perineum. It is often associated with a ‘hooded’ foreskin (prepuce) and chordee (ventral curvature of the penile shaft). It occurs in 1 in 250 live male births. There is an 8% incidence in offsprings of an affected male and a 14% risk in male siblings.

Hypospadias can be classified according to the anatomical location of the urethral meatus (Fig. 16.6). Most common are anterior hypospadias accounting for 50–80% of cases.

Hypospadias results from incomplete closure of urethral folds on the undersurface of the penis during embryological development. This is related to a defect in the production or metabolism of fetal androgens or the number and sensitivity of androgen receptors in the tissues. Chordee is caused by abnormal urethral plate development or an intrinsic abnormality of the corpora cavernosa and the ‘hooded’ foreskin is due to failed fusion of the preputial folds (resulting in a lack of ventral foreskin).

A full clinical examination to establish the diagnosis, assess the penis and urethral plate, and detect associated abnormalities needing treatment. Patients with unilateral or bilateral absent or impalpable testes and hypospadias should undergo chromosomal and endocrine investigation to exclude disorders of sex development. Posterior hypospadias can be associated with other urinary tract malformations and requires USS investigation.

Surgery is indicated where deformity is severe, interferes with voiding, or is predicted to interfere with sexual function. Repair is performed between 6–18 months of age. Androgens have been used preoperatively to help increase tissue size. Surgery aims to correct penile curvature (orthoplasty), reconstruct a new urethra, and bring the new meatus to the tip of the glans using urethroplasty, glansplasty, and meatoplasty techniques.

Distal (and selected cases of middle and proximal hypospadias) can be treated by a Snodgrass procedure (tubularized incised plate (TIP) urethroplasty). The penis is degloved and an artificial erection created to assess for chordee which may be corrected with dorsal plication. The glans wings are incised to separate them from the urethral plate which is incised in the midline to widen it and allow tubularization and a layered suture closure over a catheter. A dartos pedicle is used to cover the repair. Reconstruction of the glans is with layered suture repair (glansplasty).The catheter is removed 7 days later.

Many proximal and some middle hypospadias may require a two-stage procedure which consists of initial preparation of the urethral plate and insertion of a free graft (prepuce or buccal mucosa). A fine catheter is placed into the bladder and an occlusive dressing applied. The dressing is removed under general anaesthesia around 7 days later, the graft examined for viability, and the catheter removed. The second stage of tubularization of the neo-urethra and closure is performed around 6 months later.

Overall complication rate of 4–7% in the short to medium term. Complications increase with time and severity of hypospadias. They include urethrocutaneous fistula, urethral stricture, meatal stenosis, spraying of urine, voiding dysfunction, urethral diverticulum, recurrent chordee, sexual dysfunction, poor cosmesis, and failure of repair or graft requiring re-operation.

See Tables 16.6 and 16.7.

Disorders of sex development (DSD) are defined as congenital conditions in which the development of chromosomal, gonadal, or anatomical sex is atypical. They are estimated to affect 1 in 4500 births. DSD is divided into:

Complete androgen insensitivity syndrome (CAIS), caused by androgen resistance, is the most common cause of 46XY DSD. Where the family history is positive, karyotyping can be performed at birth. Sporadic cases are difficult to detect. In CAIS, the phenotype and external genitalia are female, however, internal genitals are usually absent (or rudimentary). At puberty, there is breast development, scanty pubic and axillary hair, a short blind-ending vagina, and patients are often tall. They may present at this time for investigation of primary amenorrhoea, with raised LH and testosterone. Undescended testes may be palpable in the inguinal canal and will require removal after puberty due to malignancy risk. Oestrogen replacement is then given.

In comparison, incomplete or partial androgen insensitivity syndrome (PAIS) presents with a wide spectrum of phenotypes, most commonly with a degree of ambiguous genitalia.

The most common type is congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (in 95%), an autosomal recessive disorder. CAH accounts for around 85% of all infants with ambiguous genitalia. Formation of hydrocortisone is impaired, resulting in a compensatory increase in adrenocorticotrophin hormone (ACTH) and testosterone production. Some forms have a ‘salt-wasting’ aldosterone deficiency which can present in the first few weeks of life with adrenal crisis (severe vomiting and dehydration), requiring rehydration and steroid replacement therapy with mineralocorticoids and glucocorticoids. Rarer causes of CAH are 11β-hydroxylase deficiency and 3β-hydroxysteroid dehydrogenase deficiency (see Fig. 16.7).

Disorders of ovarian development (i.e. 46XX gonadal dysgenesis, 46XX testicular DSD) can also be included in this category.

A multidisciplinary approach is required with full parental input. In cases of ambiguous genitalia, advise parents to delay registering the birth until a diagnosis is established and gender has been assigned. The Registry Office has special provision for this situation. Gender assignment of ambiguous genitalia is guided by the functional potential of gonadal tissue, reproductive tracts, and genitalia, with the aim of optimizing psychosocial well-being and producing a stable gender identity. This is ultimately decided by a full multidisciplinary team (paediatric urologists, endocrinologist, geneticists, and psychologists) in tertiary specialist centres. Patients have a higher risk of gonadal malignancy, which requires surveillance and/or removal of gonadal tissues and hormone replacement. Patients with hypogonadism will require hormone replacement and artificial induction of puberty.

Exstrophy–epispadias complex describes a spectrum of congenital malformations affecting the abdominal wall, pelvis, genitourinary tract, and sometimes also the spine and anus. It includes bladder exstrophy, epispadias, and cloacal exstrophy.

This is the most common manifestation and results from defective development of the anterior bladder and lower abdominal walls, resulting in the posterior bladder wall lying exposed on the abdomen. Virtually all cases are associated with epispadias (see  p. 690).

incidence is ~1 in 30 000 live births. Male to female ratio is 5:1. Increased risk in offspring of affected patients and with younger maternal age and increased parity.

classically described as an embryological malformation causing abnormal overdevelopment of the cloacal membrane, which prevents in-growth of lower abdominal (mesenchymal) tissues. The cloacal membrane normally perforates to form the urogenital and anal openings, but in exstrophy, premature rupture results in a triangular defect below the umbilicus. The timing of rupture determines the type of resulting defect (bladder exstrophy, cloacal exstrophy, or epispadias). Other theories challenge this and suggest abnormal development of the bony pelvis or maldevelopment of the genital hillocks below their normal position, with midline fusion below rather than above the cloacal membrane (resulting in premature cloacal rupture prior to mesenchymal in-growth).

Typical features seen on prenatal USS include a lower abdominal wall mass, absent bladder filling, low-set umbilicus, small genitalia, abnormal iliac crest widening. Diagnosis can help planning of delivery in a centre with facilities to perform early surgical correction.

At birth, cover the bladder with plastic film and irrigate regularly with sterile saline. Trauma to the bladder mucosa can result in squamous metaplasia, cystitis cystica or adenocarcinoma, and squamous cell carcinoma after chronic exposure.

aims to provide a continent reservoir for urine storage, preserve renal function, and create functional and cosmetically acceptable external genitalia. Selected cases are suitable for a one-stage complete primary repair of bladder exstrophy (CPRE), involving closure of the bladder plate and epispadias repair. However, many require staged procedures.

Surgical complications: increased risk of malignancy in urinary or orthotopic bladder, fistula, hypospadias, bladder stones, infection (UTI, epididymitis), incontinence.

This is the most severe form of exstrophy–epispadias complex. Characterized by an exomphalos (midline abdominal defect with bowel covered in a thin sac of amnion and peritoneum), below which are two halves of an exstrophied bladder separated by an exstrophied bowel segment. It is associated with a bifid or micro-penis and the absence of one or both testes. The incidence is between 1 in 200 000 and 1 in 400 000; male to female ratio is 6:1. There is a high risk of associated congenital anomalies. Surgical reconstruction may require terminal colostomy, pelvic osteotomy, anterior bladder reconstruction ± augmentation cystoplasty. Gender assignment may need to be considered in males.

In epispadias, the urethra opens onto the dorsal surface of the penis, anywhere from the glans, penile shaft, or most commonly, the penopubic region. An incomplete urethral sphincter mechanism (seen with posterior urethral epispadias) results in a high risk of incontinence. Epispadias is also associated with dorsal chordee (causing an upward curvature of the penis) and with incomplete foreskin dorsally. Epispadias is part of the exstrophy–epispadias complex (see  p. 688). Primary epispadias (without exstrophy) is rare.

Diastasis of the symphysis pubis results in splaying and rotation of the corpora cavernosa, laterally placed neurovascular bundles, and shortening of the penile shaft. There is reduced male fertility, with paternity rates of ∼36%. Females have a bifid clitoris, poorly developed labia, and demonstrate a spectrum of urethral deformities, ranging from a patulous urethral orifice to a urethral cleft affecting the entire length of the urethra and sphincter. There is >40% risk of VUR which commonly requires ureteric re-implantation.

affects 1 in 117 000 males; rarely seen in females (1 in 400 000).

Males: urethroplasty with functional and cosmetic reconstruction of the external genitalia (penile lengthening and correction of chordee) at 6–18 months. The modified Cantwell–Ransley technique is commonly used in males. It describes mobilizing the urethra to the ventral aspect of the penis, with advancement of the urethral meatus onto the glans with a reverse meatal advancement glanuloplasty. The corporal bodies are separated and rotated medially above the urethra and re-approximated. From age 4–5y, when children can be toilet-trained, bladder neck reconstruction can be performed (Youngs–Dees–Leadbetter procedure). This achieves continence and any bladder residuals may then be emptied by urethral catheterization. If this surgery fails, insertion of artificial urinary sphincters may be tried. Some patients may require bladder augmentation and Mitrofanoff reconstruction to achieve continence.

Females: surgery involves urethral repair reinforced with pubic fat, along with clitoral reconstruction ± bladder neck repair.

Urinary incontinence can be divided into primary types (never been dry) or secondary (re-emergence of incontinence after being dry for 6 months).

Education of the family and child are essential. Children may need bladder retraining, timed voiding, change of voiding posture, and avoidance of bladder irritants. Diet should be modified to avoid constipation, and use laxatives if it does occur. Psychological counseling and support should be available. Many conditions respond and improve with these measures alone.

Specific management

Nocturnal enuresis (NE) is defined as intermittent incontinence whilst sleeping.¹  Monosymptomatic nocturnal enuresis (MNE) is defined as (nocturnal) enuresis in children without any other LUTS and without a history of bladder dysfunction.¹ MNE accounts for <50% of children with bedwetting. Non-monosymptomatic nocturnal enuresis (NMNE) includes children with associated voiding dysfunction. Primary NE refers to children that have never been dry for more than a 6-month period; Secondary NE refers to the re-emergence of bedwetting after a period of being dry for at least 6 months.

Nocturnal enuresis is estimated to affect up to 15% of 5y olds² and 10% of 7y old children (Table 16.8).³ There is 15% spontaneous resolution of symptoms per year.¹ The prevalence in adults is ∼0.5%.

Three main factors that interact to produce nocturnal enuresis are:

Familial predisposition, psychological factors, UTI, and constipation are also considered to contribute to nocturnal enuresis.

The aim is to establish the underlying pathophysiological factors to guide treatment. Enquire about the frequency of episodes and whether it is a new or recurrent problem. Specifically ask about daytime urinary symptoms, urgency, holding manoeuvres, symptoms of UTI, and daytime incontinence. Enquire about bowel habit (constipation, incontinence). Establish any underlying contributory medical conditions, a family history, and psychosocial history.

Physical examination in a child with MNE is usually normal. Examination of the abdomen and genitals, neurological exam, lower limb sensation, and examination of the spine in children with associated voiding dysfunction (NMNE) is recommended.

General advice should be given to children and their parents. Active treatment is usually deferred until age 6y. First-line treatments are enuresis alarm and desmopressin.^4,5

A full response to treatment is 14 consecutive dry nights or an 90% improvement in the number of wet pads.⁴ Patients with nocturnal polyuria (and normal bladder function) tend to have a good response to desmopressin. Patients with functionally reduced bladder capacity (which may be associated with occult bladder dysfunction) benefit most from a combination of enuresis alarm, bladder training, and anticholinergic drugs (i.e. oxybutynin) ± desmopressin.