A hernia through the anatomical structure known as the obturator canal (within the floor of the pelvis) is known as an obturator hernia. A recent report reviewed the presentation and management of these hernias (Stamatiou, et al., The American Surgeon, Sept 2011, p1147).
OBTURATOR HERNIA FACTS:
The obturator region lies in the medial portion of the upper thigh, between the flexor muscles of the thigh in front, and the extensor muscles behind. Obturator hernias are quite rare, with an incidence of 0.073 to 1 percent of all hernias. In 6 percent of cases, obturator hernias are found on both the right and left sides simultaneously. Patients who have obturator hernias, commonly have either inguinal or femoral hernias 25% of the time.
OBTURATOR HERNIA PRESENTATION:
Patients who develop obturator hernias are commonly elderly, often debilitated women, with very thin frames. Many of these patients have undergone multiple pregnancies, which may have stretched out the structures in the pelvis floor. However, emaciation, malnourishment and a thin body habitus that all result in loss of connective and fatty tissues which normally support the obturator canal are likely the biggest culprits. Conditions that increase intra-abdominal pressure (such as constipation, chronic airway obstruction, and ascites) are also known risk factors.
The obturator canal is a small tunnel that is about two to three cm long and one cm wide. In patients that lose the integrity of the surrounding tissues, the space opens up and can allow intra-abdominal organs to enter the space. Since there is a small sensory nerve that lives in the obturator canal, herniating contents can contact that nerve causing sharp, shooting pain in the region of the inner thigh. This is known as obturator neuralgia. On examination (either using a rectal or vaginal examination), when the examiner pushes on the contents of an obturator hernia the patient may experience pain sensation in the medial thigh which is known as the Howship-Romberg sign. Further, motor symptoms can occur such as weakness of the adductor muscles. This may cause the affected thigh to sit in an abnormally abducted position. When small intestines get stuck in the obturator canal, it can lead to a small bowel obstruction. For this reason, when a patient is suspected of having an obturator hernia that is causing bowel obstruction, prompt laparoscopic exploration and repair is indicated.
TREATMENT OF OBTURATOR HERNIAS:
Surgical exploration and repair is the only effective treatment for obturator hernias. If an obturator hernia is identified and repaired, exploration of the uninvolved side should also be performed.
1) Transabdominal Approach: Open abdominal surgery for exploration and repair is indicated for patients who may be very ill as a result of bowel compromise. This approach also helps to evaluate and possibly remove compromised intestines.
2) Extra-abdominal Approach: Pre-peritoneal, obturator and inguinal approaches may be used for repair of obturator hernias that have been diagnosed radiographically. These approaches are only viable for stable patients who clearly have no serious involvement of the intestines. With the obturator approach, an incision is made just overlying the palpable mass (hernia sac with contents) in the thigh. In the case of a pre-peritoneal approach, either a low transverse suprapubic incision or a lower midline incision may be used to approach the hernia defect. This approach will allow evaluation of both the left and right sides through the same incision.
3) Laparoscopic Approach: Laparoscopy is a very effective means of both diagnosing and treating obturator hernias. This approach allows excellent visualization of the entire pelvic floor as well as inspection of both the right and left obturator canals. Not only can bilateral defects be seen and repaired, but the entirety of the small intestines can also be readily evaluated with the laparoscopic approach. If necessary, bowel resection may also be performed using this minimally invasive approach. Laparoscopic repair can be performed using a TAP of TEPP technique.