Obturator hernia is a very rare form of hernia. It has a high rate of morbidity and mortality and the early diagnosis is considered a challenge because of the non-specific symptoms and signs.
Obturator hernia has an incidence of 0.07–1% of all forms of hernias and accounts for 0.2–1.6% of all cases with mechanical obstruction of the small bowel. With the highest rate of mortality among hernias of the abdominal wall (13-40%), it also has a predilection for female patients and a female-to-male ratio of 6:1. Obturator hernia is sometimes referred to as "little old lady’s hernia" because it mostly affects elderly females due to atrophy of preperitoneal fat surrounding obturator vessels in the obturator canal. In 6% of cases, bilateral hernias can be detected. Obturator hernia generally presents as acute intestinal obstruction. In the majority of cases, the contents are small bowel. However, it may also contain omentum, appendix, or Meckel's diverticulum. The hernia sac follows the path of obturator nerves and muscles by passing through the foramen obturatum [1] [2].
Conditions causing a raised intra-abdominal pressure such as multiparity, ascites, chronic obstructive pulmonary disease (COPD) and constipation are other risk factors [3].
The clinical diagnosis is challenging because of rarity, deep location, and infrequent signs and symptoms. The physical examination is usually not contributory resulting in diagnostic delay. The hernial sac compresses and irritates the obturator nerve in the canal leading to medial thigh pain radiating down to the medial aspect of the knee and less frequently to the hip due to compression of the anterior division, a sign known as the Howship-Romberg sign. It is pathognomic of obturator hernia and is observed in 15–50% of cases. A palpable mass is identified in 20% of the patients in the medial proximal aspect of the thigh at the origin of the adductor muscles [2] [4]. When a patient presents with obstruction of the small bowel and intermittent symptoms with medial thigh pain, obturator hernia must be suspected.
The further symptoms are that of bowel obstruction, dull and crampy abdominal pain, nausea, and emesis. These symptoms are present in more than 80% of patients. Obstruction may be acute or intermittent [5].
Several imaging methods have been used to diagnose the disorder including ultrasonography, plain radiography of the abdomen, and barium enema. Computed tomography (CT) of the abdomen and pelvis is the most relevant diagnostic tool. Recent reports have shown that a definite and early diagnosis of obturator hernia s possible by CT of the abdomen and pelvis [6] [7]. It is readily available, requires a short time, and is minimally invasive. CT scan can be especially helpful in the initial presentation when nonspecific signs and symptoms are identified [5].
The abdominal radiography often shows a nonspecific pattern of small bowel obstruction. Occasionally, gas shadows in the foramen obturatum or intraluminal air bubbles proximal to the superior ramus of the pubic bone will be diagnostic [8] [9]. On upper gastrointestinal tract series and barium enema, a loop of small bowel may be seen in the obturator canal [10].