Obturator hernias are a rare type of abdominal hernia, and can be clinically very difficult to diagnose.
Typically obturator hernias occur in elderly women 3,4 or patients with chronically raised intra-abdominal pressure (e.g. ascites, COPD, chronic cough) 4. It has been suggested that the female predominance of these hernias is the result of pregnancy, which leads to relaxation of the pelvic peritoneum and a wider and more horizontal obturator canal 4.
In general obturator hernias are asymptomatic unless 2
- they compress the obturator nerve: Howship-Romberg sign (only present in approximately half of cases) 4
- contain bowel which incarcerates/obstructs/strangulates
The obturator foramen is occluded by the obturator membrane which is pierced anterosuperiorly by the obturator artery, vein and nerve. This neurovascular bundle then travels along a 2-3 cm oblique tunnel, the obturator canal. It is through this deficiency that an obturator hernia occurs. Presumably, due to the sigmoid colon on the left, these hernias are more common on the right 4.
The layers that the hernial neck passes through include:
The hernia will then lie superficial to obturator externus and deep and inferior to pectineus muscle.
The hernia may contain:
- no more than peritoneum filled with fluid, as seen in patients with ascites
- small bowel (most common)
- colon 4
- Meckel diverticulum
- ovary/fallopian tube
- and even uterus 4
The diagnosis is readily made on CT/MRI with either fluid or bowel able to be traced along the aforementioned course to lie in the medial upper thigh.
Signs of complication including:
- bowel obstruction
- perforation secondary to strangulation
Treatment involves surgery and repair of the hernial orifice.
If the hernia contains bowel, or can be clearly traced through the obturator foramen, then there are very few alternative diagnoses.
If seen with ultrasound, it may be mistaken for a bursa or acetabular labral cyst.
- 1. Aguirre DA, Santosa AC, Casola G et-al. Abdominal wall hernias: imaging features, complications, and diagnostic pitfalls at multi-detector row CT. Radiographics. 25 (6): 1501-20. doi:10.1148/rg.256055018 - Pubmed citation
- 2. Cubillo E. Obturator hernia diagnosed by computed tomography. AJR Am J Roentgenol. 1983;140 (4): 735-6. AJR Am J Roentgenol (citation) - Pubmed citation
- 3. Howship's syndrome from whonamedit.com, the dictionary of medical eponyms. Howship's syndrome
- 4. Glicklich M, Eliasoph J. Incarcerated obturator hernia: case diagnosed at barium enema fluoroscopy. Radiology. 1989;172 (1): 51-2. Radiology (abstract) - Pubmed citation