Obturator hernias (alternative plural: herniae) are characterized by bowel herniating between the obturator and the pectineus muscles. They are a rare type of abdominal hernia and can be a challenge to diagnose clinically.
Typically obturator hernias occur in older women or patients with chronically raised intra-abdominal pressure (e.g. ascites, COPD, chronic cough) . They can occur in pregnancy, due to relaxation of the pelvic peritoneum and a wider and more horizontal obturator canal . It has been suggested that there is a female predominance with this type of hernia, and they occur in less than 0.04% of all hernias .
In general, obturator hernias are asymptomatic unless they :
- compress the obturator nerve: Howship-Romberg sign (only present in approximately half of cases)
- 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 .
The layers that the hernial neck passes through include:
The hernia may contain any of the following:
- no more than peritoneum filled with fluid, as seen in patients with ascites
- small bowel (most common)
- Meckel diverticulum
- ovary/fallopian tube
- and even uterus
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:
Treatment and prognosis
Treatment involves surgery and repair of the hernial orifice.
History and etymology
Howship-Romberg sign is named for the German neurologist, Moritz Heinrich Romberg (1795-1873) , and British surgeon John Howship (1781-1841) .
If a 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.