Am Fam Physician. 1998;57(2):352-356
Obturator hernia is a rare condition, accounting for approximately 1.5 percent of all hernias and up to 2 percent of all cases of mechanical intestinal obstruction. However, this condition is associated with high rates of morbidity and mortality. The poor prognosis is attributed to a delay in diagnosis and complications of surgery in patients of advanced age and debilitated condition. Two recent articles emphasize the importance of early diagnosis of obturator hernia.
Both articles report small case series of patients with symptomatic obturator hernia. In one of the series (six cases), the patients were all elderly women (average age: 78 years) of low body weight (average weight: 88 lb). In all patients, a delay of several days occurred between the onset of symptoms and hospital admission, and a further delay occurred in some of the patients between hospital admission and definitive diagnosis and surgery. Conditions such as deafness, dementia and other medical or communication disorders made diagnosis more difficult in a significant proportion of patients.
All of the patients presented with symptoms of intestinal obstruction. The classic tests for obturator hernia—the Howship-Romberg and Hannington-Kiff signs—were not consistently helpful, and hernial sacs could not be palpated in all cases. The authors of one of the articles report that ultrasound of the inguinal region and inner thigh reliably confirmed the diagnosis.
The obturator canal in the pelvis is 1 to 2 cm long and 1 cm wide. With significant weight loss, the normal fat padding of the canal disappears, and increased intra-abdominal pressure can produce herniation. The hernia compresses the obturator nerve, producing pain and paresthesia of the anterior thigh. Abdominal contents may traverse the obturator canal and may be located behind the pectineus muscle in the thigh, where the hernia may be difficult to see or feel. A mass may be felt on vaginal or rectal examination.
With the Howship-Romberg test, extension and abduction of the thigh produce pain along the medial thigh to the knee. The more specific Hannington-Kiff sign is characterized by loss of the adductor reflex with retention of the patellar reflex on the side of the herniation. The hernia is usually small and located on the right side but is frequently complicated by strangulated and gangrenous bowel. Although barium studies, computed tomography and other investigations may be helpful in the diagnosis of this condition, it appears that a high index of suspicion and early use of appropriate ultrasonography may reduce delay in diagnosis and definitive treatment.