Stone obstruction of a circumcaval ureter

A 49-year-old patient with no significant medical history presents with chronic low back pain. The pain increased within three days, accompanied by febrile sensations, but there was no deterioration in the general condition.

An abdominal ultrasound was conducted, revealing moderate right ureterohydronephrosis with no clearly visible obstruction.

Following this, a CT urogram (refer to Figures 1a, 1b, 1c, and 2) was performed. The results indicated an aberrant course of the right ureter, which bends in a kinking manner and passes medially behind the inferior vena cava at the level of L3. This led to the identification of calcic lithiasis responsible for ureteropyelocalicial dilation upstream. Subsequently, the ureter continues its course to the right of the aorta, circles the inferior vena cava, and then positions itself in its normal location in front of the iliac vessels.

Retrocaval or circumcaval ureter is defined as a spiral path of the ureter around the inferior vena cava. It is very rare and usually becomes symptomatic in the third or fourth decade of life due to hydronephrosis from compression of the ureteral segment by the IVC against the psoas muscle, ureteral kinking or from an adynamic retrocaval ureteral segment [1].

The precocity of the symptoms depends on the degree of obstruction. The anomaly can be asymptomatic and only discovered incidentally or during autopsies. The majority of retrocaval ureters, 80%, these clinical manifestations are related to obstruction of the upper urinary tract and its complications. In 70% of cases, it is pain on the right side of variable intensity, which can go up to renal colic [2].

Retrocaval ureter is classified into two types based on radiological appearance and the site of narrowing of ureter. There are two variants reported. Type I is a low-loop fish hook appearance with lower ureter curving medially towards the vertebrae. This is the commoner of the two variants seen. Type II is a high-loop variant where the looping ureter turns medially at the level of pelviuretric junction [3].

Obstruction of the ureter has been described in association with an anomalous course, that is, posterior, medial, anterior and finally lateral to the inferior vena cava [4], which is the same case of our patient.

Imaging holds the key to the diagnosis, and ultrasound is generally the imaging modality that first shows the dilated collecting system but poorly delineates the ureter. Computed tomography (CT), which can delineate both the ureter and IVC, is considered the investigation of choice [5].

The management of a patient with renal calculi along with a retrocaval ureter is hence laden with a dilemma of treating for renal calculus alone or repairing the ureteral anomaly also [6].

Retrocaval ureter is a rare congenital anomaly that should be noted in the radiological report, especially when lithiasis is present, due to its significance in management.