Describe Obturator Hernia in detail.

The Concept

An obturator hernia is a rare hernia in which abdominal contents protrude through the obturator canal (the opening in the obturator foramen of the pelvis, transmitting the obturator nerve and vessels). It has a very characteristic epidemiology: it occurs almost exclusively in elderly, thin, emaciated women ('the little old lady's hernia'), in whom loss of the protective extraperitoneal fat allows the bowel to enter the canal.

Clinical Features — the Howship-romberg Sign

Because the hernia is deep within the pelvis and thigh, it produces no visible external swelling, and typically presents as unexplained intestinal obstruction in an elderly woman. The classic clue is the Howship-Romberg sign — pain referred along the inner aspect of the thigh to the knee, caused by pressure of the hernia on the obturator nerve, often worsened by extension, abduction or internal rotation of the hip.

Diagnosis, Management & Prognosis

The lack of an external lump means the diagnosis is often made late — on CT or at laparotomy for obstruction. Treatment is surgical reduction and repair of the defect, with resection of any non-viable bowel. Because of the delayed diagnosis and the frail, elderly patients affected, the mortality is relatively high — which is why the Howship-Romberg sign is emphasised as an early clue.

WHY Mortality Is High

The relatively high mortality of obturator hernia results from a combination of factors: the frail, elderly, comorbid patients affected, the absence of an external sign leading to delayed diagnosis, and the frequent presence of strangulated bowel by the time of surgery. This is precisely why the Howship-Romberg sign is stressed — recognising inner-thigh pain as a clue to an obturator hernia in an elderly woman with obstruction can bring the diagnosis forward and save a life.

The Bottom Line

An obturator hernia is a rare hernia of thin elderly women presenting as obstruction with the Howship-Romberg sign, diagnosed late and carrying a high mortality, treated surgically.

A Note on Bilaterality & Recurrence

Obturator hernias may be bilateral, and because the affected patients are frail with weak pelvic tissues, the defect can be difficult to close durably. At operation the obstruction is relieved, non-viable bowel resected, and the canal repaired (with mesh where feasible). The combination of late presentation, frail patients and technically awkward repair is what keeps its mortality among the highest of the abdominal hernias.

Medial thigh pain relieved by hip flexion is the clue.

• Obturator hernia = protrusion through the obturator canal; rare; classically elderly, thin, emaciated women.
• No external swelling → presents as unexplained intestinal obstruction.
• Howship-Romberg sign: pain along the inner thigh to the knee (obturator nerve compression) — the key clue.
• Often diagnosed late (CT/laparotomy); treat by surgical reduction and repair (± bowel resection); relatively high mortality.