Computed tomography in the investigation and management of obturator hernia

Background

Obturator hernias are a rare groin hernia. They are most commonly found incidentally during laparoscopic inguinal hernia repair. They may also present acutely with strangulation, most commonly of the small bowel. ¹ This may be life threatening, particularly in elderly patients. Low body mass and wide pubic bones are thought to increase the likelihood of obturator hernias. We investigated our experience with obturator hernias in the elective and emergency setting.

Methods

Cases of obturator hernia presenting as either elective or emergency cases to Northumbria NHS Trust were identified from a hospital database. Cases were included from 2004 to 2014. There were no exclusions. There were a number of surgeons involved with an interest in groin hernia surgery.

Results

Twenty-one patients were included. The mean age was 66 years old (range 53 to 87 years). Eleven were male. There were four emergency presentations with a mean age of 77 years old (range 69 to 84 years). One emergency case presented with small bowel obstruction, while the other three cases presented with acute groin pain. Two patients had a preoperative computed tomography (CT), which showed an obturator hernia confirmed at surgery (Figures 1, 2 and 3). The patient with small bowel obstruction had an open bowel resection alone with no hernia repair. They were discharged with no complications or recurrence on follow-up. The other three cases had a mesh repair (one laparoscopic, one plug repair at laparotomy, one pre-peritoneal). One patient who underwent a laparotomy died of a postoperative pneumonia. The others were discharged uneventfully. OPEN IN VIEWER

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Figure 2.

CT images of obturator hernia.

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Figure 3.

CT images of obturator hernia.

In the elective group of 17 patients, 8 patients were taken for an elective laparoscopic inguinal hernia repair but found to actually have an obturator hernia alone. An obturator hernia was found incidentally with an inguinal hernia in three patients. Five patients were expected to have an obturator hernia on clinical examination alone. At surgery, an obturator hernia was found in three cases. In the other two cases, no hernia was found. One patient had a pre-operative CT, which showed an obturator hernia confirmed at surgery.

All the elective cases underwent a laparoscopic TAPP repair with polypropylene mesh. All were performed as day cases with no recurrence on postoperative follow-up to one year.

Discussion

Obturator hernia is a rare abdominal hernia. An obturator hernia occurs at the obturator canal, which is a defect in the pubic fascia of the obturator membrane between the ischium and pubic bones. Risk factors for developing a hernia include age, female sex, multi-parity, wide pubic bones and low body mass. A paper by Nasir et al. ² reported the most common presenting signs and symptoms were bowel obstruction, abdominal/groin pain, and a palpable lump. Patients may also present with the Howship-Romberg sign, which involves inner thigh pain on internal rotation of the hip.

A number of case reports and case series have advocated the use of CT scan in the diagnosis of obturator hernia.^3–5 We corroborate this recommendation. Indeed, we would develop this point further by emphasising the point that clinical examination alone is not reliable in the diagnosis of obturator hernia. In our study, two patients had surgery, which could have been avoided with preoperative imaging. In our emergency group, one patient died following a laparotomy. This approach with the concurrent risks may have been avoided for a pre-peritoneal approach if a pre-operative CT had been performed showing no bowel contents. This is supported by the findings of Seewoo et al. ⁷ in the importance of timely surgery in elderly patients.

A number of patients in our study were found to have an obturator hernia when they were expected to have an inguinal hernia clinically. This supports a laparoscopic approach to groin hernia repair in that this approach affords easier repair than the dilemma, which may have ensued from a conventional groin incision for an open inguinal hernia repair. There are a variety of operative methods described in obturator hernia repair. ⁶ We would advocate a laparoscopic approach when feasible, recognizing the need for laparotomy and bowel resection when necessary. Our study has shown excellent results for laparoscopic repair in both the elective and emergency settings.

A recent paper by Rath et al. ⁸ described the incidence of occult obturator hernias as around 4% during laparoscopic groin hernia repair. They showed good results for mesh repair over the myopectineal orifice. We have also shown good results for repair of occult obturator hernias.

Conclusions

CT would be recommended in cases of diagnostic uncertainty. It may avoid unnecessary surgery in the elective setting and allow a focused procedure in the emergency setting. Laparoscopic repair is feasible in the emergency and elective setting with excellent results.