Duplicated Ureter

Duplicated ureter is a congenital anomaly in which a kidney has two collecting systems. It is incomplete (bifid, the ureters joining before reaching the bladder) or complete (two ureters with separate bladder orifices).

It occurs in about 0.8% of people, more often in women (about 2 to 1), and is bilateral in about 20 to 40%.

Most are asymptomatic. Problems arise from reflux, obstruction, ectopic insertion and ureterocele.

Pathophysiology. Two ureteric buds arise from the mesonephric duct. In a complete duplex, the Weigert-Meyer rule applies:

• The upper pole ureter inserts inferomedially, often ectopically, and tends to be obstructed, with ureterocele or ectopic insertion.
• The lower pole ureter inserts superolaterally, with a short intramural tunnel, and tends to reflux.

Ectopic upper pole ureters open at the bladder neck, urethra or vestibule in girls, and at the prostatic urethra, seminal vesicle or vas deferens in boys.

Incidental finding in many patients. Urinary infection, flank pain, haematuria and stones. Girls with an ectopic upper pole ureter have continuous dribbling with normal voiding. Boys with ectopic insertion may have epididymitis. A ureterocele can cause bladder outlet obstruction, retention and urinary infection in infants.

• Ultrasound: two pelvicalyceal systems, a hydronephrotic and thin upper pole, dilated ureter, and a ureterocele as a cystic bladder structure.
• Voiding cystourethrogram: lower pole reflux gives the "drooping lily" appearance.
• Diuretic renography (mercaptoacetyltriglycine) or dimercaptosuccinic acid scan for the function of each moiety.
• Magnetic resonance or CT urography for anatomy, especially in girls with ectopic ureters.
• Cystoscopy and vaginoscopy for ectopic orifices.
• Urinalysis, culture, creatinine.

Differential diagnosis.

• Ureterocele without duplication
• Ectopic ureter in a single system
• Vesicoureteric reflux
• Pelviureteric junction obstruction
• Megaureter
• Renal cyst
• Urinary incontinence from other causes

• Asymptomatic, incidental duplication without dilatation or reflux: no treatment.
• Reflux into the lower moiety: antibiotic prophylaxis in infants, with amoxicillin 10 mg/kg orally once daily at night under 3 months, and trimethoprim 2 mg/kg (maximum 100 mg) orally once daily at night after that. Surgery for breakthrough infection or persistent high grade reflux: endoscopic injection or ureteric reimplantation of both ureters in a common sheath.
• Obstructed upper moiety or ectopic ureter:
  • Functioning moiety: ureteroureterostomy or ureteropyelostomy to the lower system, or reimplantation.
  • Non-functioning moiety (function under about 10%): upper pole heminephrectomy with removal of as much ureter as possible.
• Ureterocele: endoscopic incision or puncture in infants with obstruction or infection, with later reimplantation if reflux or obstruction persists.
• Perioperative cefazolin 25 to 30 mg/kg intravenously (maximum 2 g) as a single dose in children, or 2 g in adults (3 g if over 120 kg).
• Adults: stones in duplex systems need ureteroscopy with identification of both ureteric orifices.

Monitoring. Ultrasound at 3 months after treatment, and yearly in those with reflux or reduced function. Renography at 6 to 12 months. Blood pressure and creatinine yearly. Review for urinary infection.

Referral and escalation. Refer to paediatric urology for children with infection, dilatation, incontinence or ureterocele. Urgent referral for febrile infection with obstruction, retention from ureterocele, or sepsis.