Expansion
Through the obturator canal, causing the Howship-Romberg sign
Expansion
The hernia passes through the obturator canal, the gap in the upper obturator membrane transmitting the obturator vessels and nerve from pelvis to thigh.
- Rare, but with high mortality because diagnosis is usually late
- Classically in thin elderly women - a wider pelvis, and loss of the protective preperitoneal fat that normally plugs the canal
- Presents as small bowel obstruction with no visible or palpable lump
The distinguishing feature is the Howship-Romberg sign: pain along the medial thigh and knee, worsened by extension, abduction or internal rotation of the hip, caused by compression of the obturator nerve. It is present in about half of cases and is easily mistaken for arthritis.
Diagnosis is usually made on computed tomography, or at laparotomy for unexplained obstruction.