Ureterovesical Junction Obstruction

Ureterovesical junction obstruction is obstruction of urine flow where the ureter enters the bladder. It can be primary (an aperistaltic segment present from birth) or secondary (stone, stricture, tumour, ureterocele, infection or injury).

It causes hydroureteronephrosis, infection and loss of renal function.

It is a common site of ureteric stone impaction, and the commonest site of ureteric stricture after pelvic surgery and radiotherapy.

Pathophysiology. Primary obstruction results from a short abnormal distal ureter that fails to propagate peristalsis. Secondary causes:

• Stones at the intramural ureter.
• Ischaemic or post-surgical stricture (stone surgery, ureteric reimplant, gynaecological and pelvic surgery).
• Radiation fibrosis.
• Schistosomiasis and tuberculosis.
• Bladder or prostate tumour, and endometriosis.
• Ureterocele and bladder outlet obstruction.

Flank pain, recurrent urinary infection and pyelonephritis, haematuria, and renal impairment, which may be silent with unilateral disease. Children present with antenatal dilatation or infection, and adults with colic or incidental hydronephrosis. Fever with obstruction, or bilateral obstruction, is urgent.

• Ultrasound for hydroureteronephrosis. Urinalysis, culture, creatinine and eGFR.
• CT urography with delayed phase for site, stone, tumour or stricture.
• Diuretic renography (mercaptoacetyltriglycine) with furosemide 40 mg intravenously in adults: half time over 20 minutes indicates obstruction, and under 10 minutes excludes it.
• Voiding cystourethrogram to exclude reflux. Retrograde pyelography for the stricture.
• Cystoscopy and ureteroscopy with biopsy of any lesion at the orifice, and cytology. Tuberculosis and schistosomiasis testing in endemic areas.

Differential diagnosis.

• Primary obstructive megaureter
• Refluxing megaureter
• Ureteric stone
• Bladder tumour at the orifice
• Ureterocele
• Bladder outlet obstruction with secondary dilatation
• Pelviureteric junction obstruction

• Infected obstruction: urgent stent or nephrostomy with ceftriaxone 2 g intravenously once daily, adjusted to cultures.
• Stone: ureteroscopy with laser lithotripsy. Tamsulosin 400 micrograms orally once daily after a meal for up to 4 weeks may help passage of distal stones of 5 to 10 mm.
• Short stricture (under 1 to 2 cm): balloon dilation or endoscopic incision with a stent for 4 to 6 weeks, with success of about 50 to 70%.
• Definitive repair for recurrent or longer strictures, and primary obstruction needing surgery: ureteroneocystostomy (extravesical or intravesical) with tapering for a megaureter, and a psoas hitch or Boari flap when there is limited length. Success is about 90 to 95%.
• Children: prophylaxis with amoxicillin 10 mg/kg orally once daily at night (under 3 months) or trimethoprim 2 mg/kg (maximum 100 mg) once daily at night, and surgery for infection, falling function or worsening dilatation.
• Tumour: treat the cancer, with drainage by stent or nephrostomy as needed. Schistosomiasis: praziquantel 40 mg/kg orally in a single day. Tuberculosis: antituberculous drugs, with reconstruction after 4 to 6 weeks of treatment.
• Non-functioning kidney: nephrectomy if infected or symptomatic.
• Perioperative cefazolin 2 g intravenously (3 g if over 120 kg) as a single dose.

Monitoring. Ultrasound and creatinine at 6 weeks and 3 months, diuretic renography at 3 to 6 months, then yearly for 2 years. Stents changed every 3 to 6 months where long term drainage is used.

Referral and escalation. Refer to urology, and to paediatric urology for children. Urgent referral for infection with obstruction, bilateral obstruction, solitary kidney or acute kidney injury.