546 CHAPTER 15 Pediatric urology

Ectopic ureter

Definition

The ureteric orifice is situated below the normal anatomical insertion on the trigone of the bladder.

Pathogenesis

The ureteric bud arises from an abnormal position on the mesonephric duct during embryological development. Females are affected more than males (female–male ratio is 3:1). 80% of cases are associated with a duplicated collecting system (which predominantly affects females).

A duplex kidney has an upper pole and a lower pole, 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 pole ureter always opens onto the bladder below and medial to the lower pole ureter (Weigert–Meyer rule), predisposing to ectopic placement of the ureteric orifice.

Sites of ectopic ureters

•Females: bladder neck, urethra, vagina

•Males: posterior urethra, seminal vesicles, ejaculatory duct, vas deferens, epididymis, bladder neck

Presentation

Acute or recurrent UTI is common in both sexes. Obstruction of the ectopic ureter can lead to hydronephrosis and hydroureter, which may present as an abdominal mass.

•Females: When the ureteric opening is below the urethral sphincter, girls present with persistent vaginal discharge or incontinence, despite successful toilet training.

•Males: The ureter is always sited above the external urethral sphincter, so boys do not develop incontinence. UTIs may trigger epididymitis.

Investigation of urinary tract

•US demonstrates ureteric duplication, dilatation, and hydronephrosis.

•VCUG is used to assess reflux in lower pole ureters (Fig. 15.3).

•Cystourethroscopy can directly identify a ureteric opening in the urethra.

•Isotope renogram (99mTc-DMSA) is used to assess renal function to help plan surgery.

Treatment

An ectopic ureter is often associated with a poorly functioning renal upper pole or single-system kidney. In such cases, open or laparoscopic heminephrectomy or total nephrectomy with excision of the associated ureter is indicated.

When some function is retained in a single-system kidney, the distal ureter can be resected and reimplanted into the bladder.

548 CHAPTER 15 Pediatric urology

Ureterocele

Definition

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

Incidence

Females are affected more than males (female–male ratio is 4:1). They predominantly affect Caucasians. 80% of cases are associated with the upper pole of a duplex system, although they can be found in single systems (more commonly in adults); 10% are bilateral.

Classification

•Intravesical: confined within the bladder

•Ectopic: if any part extends to the bladder neck or urethra

•Stenotic: intravesical ureterocele with a narrow opening

•Sphincteric: ectopic ureterocele with an orifice distal to the bladder neck

•Sphincterostenotic: orifice is both stenostic and distal to the bladder neck

•Cecoureterocele: ectopic ureterocele that extends into the urethra, but the orifice is in the bladder

Presentation

Infants commonly present with symptoms of UTI. Association with duplicated ureters increases the risk of reflux and reflux nephropathy.

Ureteroceles can also cause obstruction and hydronephrosis, which may be identified on antenatal ultrasound (US) scan or present in children with an abdominal mass or pain.

A prolapsing ureterocele can present as a vaginal mass in girls.

Investigation

•US shows a thin-walled cyst in the bladder often associated with a duplex system.

•Intravenous pyelogram (IVP) may demonstrate deviation of upperpole duplex kidney and delayed excretion of contrast signifying altered renal function. In single systems, contrast in the ureterocele gives the appearance of a cobra head.

•Voiding cystourethrogram can identify location, size, and associated reflux.

•Cystoscopy may reveal a defect near the trigone.

•99mTc-DMSA assesses renal segment function.

Treatment

Single-system ureterocele: Initial management is usually endoscopic incision of the ureterocele, which can be followed by surgical ureteric reimplantation to preserve renal function and prevent reflux.

Duplex-system ureterocele: Treatment options vary with the individual and include endoscopic incision, upper pole nephrectomy for a poorly functioning unit with ureterectomy (heminephroureterectomy), or, when there is useful renal function, ureteropyelostomy can be performed.

URETEROPELVIC JUNCTION (UPJ) OBSTRUCTION 549

Ureteropelvic junction (UPJ) obstruction

Definition

UPJ obstruction is a blockage of the ureter at the junction with the renal pelvis resulting in a restriction of urine flow.

Boys are affected more than girls. The left side is affected more often than the right side. Obstruction is bilateral in up to 40% of patients.

Etiology

In children, most UPJ obstruction is congenital, due to either an intrinsic narrowing (secondary to aberrant development of ureteric/renal pelvis muscle, abnormal collagen, or ureteral polyps) or extrinsic causes (compression of the UPJ by aberrant vessels).

Coexisting vesicoureteric reflux (VUR) is found in 40% of patients.

Presentation

UPJ obstruction is the most common cause of hydronephrosis found on prenatal and early postnatal US (differential diagnoses include UVJ obstruction, VUR, renal abnormalities, and posterior urethral valves). Infants may also present with an abdominal mass, UTI, and hematuria.

Older children present with flank or abdominal pain (exacerbated by diuresis), UTI, nausea and vomiting, and hematuria following minor trauma.

Investigation

If prenatal US has shown a large or bilateral hydronephrosis, a follow-up renal tract ultrasound scan should be performed soon after birth. If there is a prenatal unilateral hydronephrosis (and the bladder is normal), the scan is deferred until days 3–7 (to allow normal physiological diuresis to occur, which may spontaneously improve or resolve hydronephrosis).

If upper tract obstruction persists, a voiding cystourethrogram (VCUG) is indicated (to rule out VUR and examine for posterior urethral valves), and a renogram can assess individual renal function and drainage (DTPA, MAG-3).

Treatment

Children may be observed with US and renogram if they remain stable and have good renal function and no other complications (such as persistent infection or stones).

If children are symptomatic or have a significant hydronephrosis with impaired renal function (<40%), pyeloplasty is recommended.