Clinical History
An 88-year-old woman with a history of bladder carcinoma and ovariectomy for ovarian cysts presented to the emergency department with left lower quadrant abdominal pain, along with absence of intestinal transit, nausea and vomiting during the past 5 days.
Imaging Findings
The abdominal radiograph showed distended small bowel loops and air-fluid levels, indicating an intestinal occlusion.
A non-enhanced abdominal CT was performed because the patient presented with acute renal failure. It showed distended small bowel loops measuring up to 3.5 cm in diameter. The last dilated loop was located in the left pelvic fossa and tapered into the obturator foramen. The distal, non-distended bowel passed through the obturator foramen, protruded between the left external obturator and pectineus muscles where there was stranding of the surrounding fat, then looped back into the abdominal cavity. Distal bowel loops were not dilated.
These findings suggested an incarcerated left obturator hernia with a mechanical ileus of the afferent small bowel.
Although parietal enhancement could not be evaluated because of the absence of intravenous contrast, there were no indirect signs of bowel ischaemia such as mesenteric fat stranding or intraperitoneal free fluid.
Discussion
Obturator hernias are rare, accounting for 0.05 - 1.4 % of all hernias [1, 2]. They occur predominantly in women (up to 9:1 female:male ratio) and in patients with increased abdominal pressure. Pelvic floor weakness secondary to childbirth may play a role and explain the female predominance. The characteristic patient is described as an ‘elderly, emaciated, multiparous women’. Obturator hernias occur mostly on the right, possibly because of the protection by the sigmoid on the left.
They consist of the herniation of abdominal content - usually fat, ascites or bowel, but sometimes ureter, bladder, annexes or uterus - through the supero-lateral aspect of the obturator foramen into the obturator canal, along the path of the obturator neurovascular bundle. The hernia sac most often lies between the external obturator and pectineus muscles, but can also lie between the fasciculi of the external obturator or, least commonly, between the internal and external obturator muscles. Three stages were defined [2]: herniation of preperitoneal fat (stage 1), of the peritoneum (stage 2), and of an abdominal organ (stage 3).
Clinical diagnosis is difficult. A suggestive sign is obturator nerve neuropathy due to compression by the herniated content (Howship-Romberg sign). They can otherwise present when complications arise. These are frequent and include bowel obstruction, incarceration and strangulation. Also, abdominal inflammatory processes may extend into the hernia causing atypical signs and symptoms. Delayed diagnosis explains the frequent bowel necrosis, seen in up to 50% of surgical hernia repairs [1], as well as their high mortality (up to 70 %) [2].
Imaging of obturator hernias is mainly performed in the context of suspected complications. CT is the modality of choice, with intravenous contrast injection and positive or water oral contrast for better visualisation of bowel loops. It allows evaluation of the hernial content and path and readily demonstrates complications such as strangulation, incarceration and intestinal occlusion or perforation. Accessory postural manoeuvres and Valsalva may aid in the detection of smaller, inconspicuous hernias [3].
Treatment is surgical both in the presence and absence of complications, due to the high rate of incarceration [1].
In the present patient, the absence of intravenous contrast impeded the evaluation of the bowel wall’s vascular integrity. The patient underwent laparoscopic repair of the hernia, which did not show signs of vascular compromise of the bowel. Pathological examination of the resected hernial pouch revealed inflammatory changes with no sign of malignancy.
Differential Diagnosis List
Mechanical ileus secondary to incarcerated obturator hernia.
Mechanical ileus secondary to postoperative adhesions or extrinsic compression
Femoral hernia
Mass in the adductor space: tumour
haematoma
abscess
Final Diagnosis
Mechanical ileus secondary to incarcerated obturator hernia.
