MALIGNANT URETERIC OBSTRUCTION

Malignant ureteric obstruction
Locally advanced prostate cancer, bladder or ureteric cancer may cause unilateral or bilateral ureteric obstruction. Locally advanced non-urological malignancies can also obstruct the ureters (e.g. cervical cancer, rectal cancer, lymphoma).

Unilateral obstruction
is often asymptomatic; an incidental ultrasound finding that requires no specific treatment in the presence of a normal contralateral kidney. Occasionally, loin pain and systemic symptoms may develop due to infection of the obstructed upper urinary tract. In this circumstance, drainage by nephrostomy or stenting is required.

Bilateral ureteric obstruction
is a urological emergency. The patient presents either with symptoms and signs of renal failure, or anuric without a palpable bladder. A mass will probably be palpable on rectal examination. Investigations: renal ultrasound will demonstrate bilateral hydronephrosis and an empty bladder; CT urography will confirm the presence of dilated ureters down to a mass at the bladder base.

Immediate treatment of bilateral ureteric obstruction
After treating any life-threatening hyperkalaemia, options include bilateral percutaneous nephrostomy or ureteric stenting. A clotting screen is required prior to nephrostomy insertion. Insertion of retrograde ureteric stents in this setting is usually unsuccessful because tumour involving the trigone obscures the location of the ureteric orifices. More successful is antegrade ureteric stenting following nephrostomy insertion, both of which are performed under sedoanalgesia. The full-length double-J silicone or polyurethane ureteric stents require periodic (4 6 monthly) changes to prevent calcification or blockage. In the case of prostate cancer, hormone therapy should be commenced if not previously used; even in patients with androgen-independent disease, high-dose parenteral oestrogens may relieve ureteric obstruction.

Long-term treatment of bilateral ureteric obstruction
Longer-term treatment options include urinary diversion by formation of ileal conduit, ureteric re-implantation, insertion of short  permanent  metallic ureteric stents, or ureteric replacement with isolated ileal segments or prosthetic graft material. Such procedures are often complicated and inappropriate in these poor-prognosis patients.