Teaching Case

A 79-year-old man presented with intense cramp-like abdominal pain, initially periumbilical but subsequently diffuse, without worsening factors and partially relieved after analgesic medications. He denied relevant medical history. Physical examination revealed generalized abdominal tenderness, with guarding over the left iliac fossa. Blood tests revealed elevated inflammatory markers and creatinine.

Chest and abdominal radiographs were unremarkable. Subsequent abdominal CT revealed a 3-mm calculus located in the proximal left ureter and a significant amount of hypodense peri-renal fluid extending to para-renal spaces along the ureter (Figures 1,2).

On excretory phase (Figures 3,4) there was extravasation of iodinated urine from the upper urinary tract to the peri-renal space, anterior para-renal space, and inferiorly along the posterior para-renal fascia. It collected anteriorly to the left psoas muscle. Distally to the obstructive stone, the ureter was not filled.

These findings are consistent with upper urinary tract rupture secondary to proximal left ureteric obstruction by a calculus.

A left double-J ureteral stent was placed and antibiotic therapy was initiated. He was discharged within two days. Follow-up CT 28 days later showed no signs of urinary extravasation nor calculus along the ureter (Figures 5,6).

The stent was removed 4 weeks after discharge with good clinical outcomes.

Background

Urinary obstruction by stones is the most frequent cause of spontaneous rupture of the urinary collecting system, although uncommon (5-17%). Obstruction occurs more commonly at the vesicoureteral junction. Rupture usually occurs in the upper tract, although perforation at the site of ureteric impaction has been described.[1,2-4] Most stones less than 5 mm pass spontaneously within 4 weeks (98%).[4] In this case, the obstructive calculus measured 3 mm. Its location immediately proximal to the crossing of gonadal vessels may suggest a role of extrinsic compression by those. The proximal location may have contributed to the rupture, given the higher pressure in the collecting system.

Urinary tract rupture may also be secondary to other causes of elevated urinary tract pressure such as obstruction by ureteric strictures or tumours, urethral valves or prostatic hyperplasia, infections, extrinsic ureteral compression by neoplasms, gravid uterus, aortic aneurism or retroperitoneal fibrosis. It can also be iatrogenic or traumatic.[1,3,4]

Clinical Perspective

Patients may present with flank pain, more generalized pain, nausea, vomiting, and sometimes signs of peritonitis. High temperature and leucocytosis usually accompany the clinical symptoms. Hematuria may also be present. Such clinical presentation may resemble other painful processes such as pyelonephritis, appendicitis, duodenal ulcer, biliary colic, and cholecystitis.[1,2,5]

Imaging Perspective

Plain abdominal radiographs are not usually helpful, although in some cases stones and signs of paralytic ileus may be present. Ultrasound may detect fluid collections near the collecting system but it has low specificity for distinguishing urinoma from hematoma or abscess. Hydronephrosis is not always present. Doppler evaluation may reveal increased resistance and pulsatility indices in the interlobular arteries. The most sensitive and specific non-invasive imaging modality to detect ureteral stone obstruction and rupture is contrast-enhanced CT. Excretory images reveal iodinated urine extravasation in the peripelvic, perinephric, or retroperitoneal spaces. CT may also detect other causes of acute abdomen. Retrograde pyelography may be useful in cases of uncertain diagnosis. [1,2,5]

Outcome

Endoscopic or percutaneous urinary diversion is immediately performed and definite stone treatment should be deferred until the rupture is completely healed. Added to antibiotic therapy, this approach has shown excellent results. Open surgery is mostly reserved for cases of rupture secondary to neoplastic conditions requiring removal.[1,2] Although stenting alone may be successful, shock wave lithotripsy may be required. Follow-up imaging is mandatory to ensure total resorption of fluid collections.[5]

Take-Home Message / Teaching Points

Spontaneous rupture is an uncommon complication of urinary obstruction that should be suspected in patients with refractory renal colic. Contrast-enhanced CT is the preferred imaging modality to detect and quantify urinary extravasation. Urinary diversion is the first therapeutic approach to allow complete healing of the rupture and only then stone treatment should be performed.