Spontaneous calyceal rupture caused by urolithiasis

Clinical History

A 64-year-old man was admitted to the emergency department with acute left-sided iliac fossa pain for the last 7 days. Two days before, the patient was medicated empirically for spontaneous passage of suspected ureteral stone. He presented with increased pain and tenderness in the previous 6 hours.

Imaging Findings

The abdominal X-ray was unremarkable, except for pelvic phleboliths (Fig. 1 and 2).
Due to progressive worsening of the symptoms, CT was performed revealing hydronephrosis and a retro-peritoneal fluid collection. An obstructive stone with sharp edges, intermediate density (400 UH) and measuring 13 mm, was shown in the proximal left ureter (Fig. 3 and 4). In the urographic phase, a clear extravasation of iodinated contrast material was noted surrounding the proximal ureter with the stone, and continuing as a retro-peritoneal fluid collection; the rupture was noted at the middle calyceal level of the left kidney. The retro-peritoneal fluid collection extended distally to the level of the internal inguinal orifice following the psoas muscle and crossed the midline at the level of the aortic bifurcation extending into the contralateral perirenal space (Fig. 5 and 6).

Discussion

Urine extravasation is a rare condition resulting from leakage of the urinary collecting system at any level from the calyx to the urethra. Frequently it is caused by external trauma or iatrogenic manipulations [1]. More rarely, a spontaneous rupture can occur, generally due to an obstructed collecting system with transmitted back pressure (e.g. calculi, surgical ligature, abdominal or pelvic mass, pregnancy, retro-peritoneal fibrosis or bladder outlet obstruction) [2]. Most cases have been detected at the fornix level, the weakest point of the collecting system [3].

Clinically, the patient presents with nonspecific findings similar to renal colic (flank pain, haematuria, nausea, vomiting, fever, peritoneal irritation, and/or sepsis) [3]. Renal colic is a common urologic emergency, with an estimated incidence of 3–5% [4], the majority of them resolving with spontaneous passage of the stone. Persistent renal colic leads to complications such as acute infection, hydronephrosis, renal insufficiency, and rarely to collecting system rupture [4, 5]. Spontaneous urinary rupture must be considered when flank pain is unresponsive or recurs with treatment.

Imaging plays a key role in diagnosis. Plain abdominal radiography is often non-contributing. US represents the first line of investigation for renal colic and can identify hydronephrosis, calculi within the renal pelvis, and perinephric urinoma [1, 6]. Intravenous pyelogram can be a useful tool, showing contrast media extravasation [3]. CT is the technique of choice, because of higher sensibility and the possibility of demonstration of the rupture site by showing the leakage of contrast media [1, 3]. Typical findings of calyceal rupture include irregularity of a calyx, hazy margins of the pelvis, perinephric stranding and a perinephric fluid collection. Delayed acquisitions are mandatory to identify the attenuation increase of the urinoma [6]. Most urinomas leak into a subcapsular location or into the perirenal space. If extensive, a urine leak may cross the midline or extend inferiorly [6].

Distinguishing ureter rupture from forniceal tear is important because they have different therapeutic approaches [3]. Ureteral rupture often requires drainage or surgical intervention, while forniceal rupture implies supportive management (usually double-J ureteric stent being the method of choice). Some authors prefer open surgery even for forniceal rupture, but commonly it is reserved for failure of the previous treatments [1, 4].

In our patient, a double-J ureteric stent was placed without technical problems. Control CT performed 2 weeks later showed a well-positioned stent, no contrast extravasation and almost complete resolution of the fluid collection.

Differential Diagnosis List

Final Diagnosis

Spontaneous calyceal rupture

URL:	https://www.eurorad.org/case/12567
DOI:	10.1594/EURORAD/CASE.12567
ISSN:	1563-4086