Ureteric sciatic hernia: a rare cause of hydronephrosis and renal colic

Clinical History

An 83-year-old woman with 5-day history of left renal colic radiating to iliac fossa, refractory to analgesic treatment and associated with increased serum creatinine levels.
Previous history of right lumbar pain with vomiting and normal renal ultrasound study was reported 6 months before.

Imaging Findings

Ultrasound revealed an enlarged left kidney with moderate dilatation of the collecting system (grade 3 hydronephrosis) and with no evidence of lithiasis. Ureteral dilatation could be followed down the pelvis, with a normal ureterovesical junction (UVJ).
Unenhanced CT was performed, showing a marked left hydronephrosis with a dilated ureter until the pelvic inlet, where there was a small fatty hernia located behind the left hip and anterior to the piriformis muscle, and including the ureter. There was an abrupt calibre change of the ureter at this. These findings are consistent with a sciatic hernia harbouring part of the pelvic ureter.
There is no evidence of inflammatory changes, compressive tumours, or herniation of any other abdominal organ. Right kidney and ureter were normal.

Discussion

Ureterosciatic hernia is very rare, with less than 30 cases reported. [1] The herniation usually occurs through the suprapiriformis compartment of the greater sciatic foramen. [2, 3] It was hypothesised that the left lower part of the ureter was serpentine in shape and shifted to the outside of the pelvis, with herniation into the greater sciatic foramen. [4]
Predisposing factors could be piriformis muscle atrophy (related to hip joint disease), neuromuscular disorders, locomotor disturbances of the lower extremities, defects in the parietal pelvic fascia, adhesions, or congenital deformities. [1–5]
Clinical presentation of ureteric sciatic hernias is variable, more common in women and left ureter [6], with either acute or chronic symptoms, and patients may have non-urologic complaints (including vague abdominal pain or symptoms more typical of small-bowel obstruction) [2], or urologic clinical symptoms of renal colic due to ureteral obstruction.
Unilateral hydroureteronephrosis with a normal UVJ on the ultrasound examination and no lithiasis on the abdominal plain X-ray could indicate a sciatic ureteral hernia.
As many of these patients have limited renal function, unenhanced abdominal CT usually has to be performed to establish level and cause of obstruction. Unilateral dilated ureter is seen proximal to the level of the pelvic inlet where the ureter courses posterior and lateral to the ischial spine [1] and through the greater sciatic foramen, anterior to the piriformis muscle [2]. The distal part of the ureter has a normal size, including the UVJ.
If intravenous pyelography is performed, a curling ureter, also referred as “curlicue ureter” sign, in the frontal projection is considered pathognomonic, wherein the knuckle of the herniated ureter passes laterally to the medial wall of the bony pelvis. [2, 7]

Ureteric sciatic hernias are extremely rare, and no literature is available on long-term outcome. [7] Treatment options include observation in asymptomatic patients (incidental finding), surgical repair (ureterolysis, reimplantation, and hernioplasty), and ureteral stent placement. [8, 9]
In this case the decompression of the renal collecting system with a percutaneous nephrostomy improved the symptoms. However, 3 weeks after closing the nephrostomy, pain reoccurred, and surgical ureterolysis and ureter reimplantation was performed.

Sciatic ureteral hernia is a very rare cause of hydronephrosis, and the diagnosis must be obtained with abdominal CT, or intravenous or percutaneous pyelography. A “curlicue ureter” and ectopic location of the ureteral obstruction point, anterior to the piriformis muscle, are the key features for the diagnosis.

Differential Diagnosis List

Final Diagnosis

Left ureteric sciatic hernia with hydronephrosis

URL:	https://eurorad.org/case/15588
DOI:	10.1594/EURORAD/CASE.15588
ISSN:	1563-4086