Overview
Definition:
An obturator hernia is a rare type of abdominal wall hernia where abdominal contents protrude through the obturator canal, typically in the medial thigh region
It is characterized by a narrow neck and a long, tortuous path through the pelvis.
Epidemiology:
Obturator hernias account for less than 1% of all abdominal wall hernias
They are predominantly seen in elderly, emaciated women, often multiparous, due to lax abdominal walls and increased intra-abdominal pressure
Bilateral occurrence is uncommon but reported.
Clinical Significance:
Obturator hernias are notorious for their high rate of strangulation and incarceration, leading to bowel obstruction and ischemic complications
Early diagnosis and surgical intervention are crucial due to the potential for severe morbidity and mortality
The close proximity to the obturator nerve can lead to characteristic pain syndromes.
Clinical Presentation
Symptoms:
Dull, constant, or intermittent pain in the medial thigh, groin, or hip area, often radiating to the knee (Howship's Rome sign)
Nausea and vomiting
Abdominal distension
Constipation or obstipation due to bowel obstruction
Signs of intestinal ischemia if strangulated.
Signs:
A palpable but often small or impalpable mass in the medial thigh
Tenderness in the affected area
Signs of peritonitis if perforation has occurred
Positive obturator sign (pain on passive internal rotation and adduction of the hip).
Diagnostic Criteria:
There are no formal diagnostic criteria for obturator hernia
Diagnosis relies on a high index of suspicion based on characteristic symptoms, physical findings, and imaging confirmation, especially in the context of unexplained bowel obstruction or thigh pain in at-risk populations.
Diagnostic Approach
History Taking:
Detailed history of pain character, location, radiation, and associated symptoms
Prior abdominal surgeries, pregnancy history, significant weight loss, and bowel habit changes are important
Rule out other causes of thigh pain or bowel obstruction.
Physical Examination:
Careful palpation of the medial thigh for any masses, especially in the femoral triangle and obturator canal region
Assess for tenderness
Perform hip examination, including passive internal rotation and adduction to elicit pain
Abdominal examination to assess for distension, tenderness, and bowel sounds
Rectal examination may reveal a mass in some cases.
Investigations:
Computed tomography (CT) scan of the abdomen and pelvis with oral and IV contrast is the investigation of choice, demonstrating the hernia sac contents and its passage through the obturator canal
Ultrasound may be helpful for superficial masses
Plain X-rays of the abdomen may show signs of bowel obstruction.
Differential Diagnosis:
Femoral hernia, inguinal hernia, adductor muscle strain, hip osteoarthritis, psoas abscess, gynecological pathology (e.g., ovarian cysts), lymphadenopathy, tumors of the adductor compartment.
Management
Initial Management:
Fluid resuscitation
Nasogastric tube decompression
Analgesia
Correction of electrolyte imbalances
Broad-spectrum antibiotics if strangulation or perforation is suspected.
Medical Management:
Medical management is generally not indicated for diagnosed obturator hernias due to the high risk of complications
Conservative management is reserved for extremely frail patients where surgery is absolutely contraindicated, with the understanding of significant risks.
Surgical Management:
Surgical repair is indicated for all confirmed obturator hernias, especially if incarcerated or strangulated
Options include: Transabdominal preperitoneal (TAPP) repair, Totally extraperitoneal (TEP) repair, and open approaches (e.g., inguinal or femoral approach to access the sac)
Transinguinal approach is common for accessing the sac and ligating the neck
Mesh repair is often preferred for definitive closure
Division of the obturator membrane may be necessary in some cases to reduce tension and prevent nerve injury.
Supportive Care:
Postoperative care includes monitoring for pain, wound infection, urinary retention (due to proximity to obturator nerve), and bowel function
Early mobilization and gradual diet advancement are encouraged
Pain management with appropriate analgesics.
Complications
Early Complications:
Wound infection
Seroma
Hematoma
Urinary retention
Injury to the obturator nerve causing transient or permanent weakness of hip adductor muscles and sensory loss in the medial thigh
Bowel strangulation and ischemia
Perforation
Deep vein thrombosis (DVT).
Late Complications:
Recurrence of the hernia
Chronic thigh pain due to obturator nerve irritation or injury
Mesh-related complications (infection, migration)
Adhesions.
Prevention Strategies:
Careful dissection during surgery to avoid injury to the obturator nerve and vessels
Secure closure of the hernia defect, often with mesh
Aggressive DVT prophylaxis
Prompt recognition and management of any signs of strangulation or perforation.
Prognosis
Factors Affecting Prognosis:
The prognosis is generally good with timely surgical intervention
However, it is significantly poorer in cases of strangulation and delayed diagnosis, where rates of morbidity and mortality increase substantially due to bowel resection or sepsis.
Outcomes:
Successful repair leads to resolution of symptoms and prevention of recurrence
Long-term outcomes are usually excellent, provided no permanent nerve damage or bowel complications occur
Patients with strangulated hernias requiring bowel resection have a more guarded prognosis.
Follow Up:
Follow-up typically includes clinical assessment for recurrence, wound healing, and resolution of symptoms
Patients with nerve injury may require further neurological assessment and rehabilitation
Routine imaging is not usually required unless symptoms suggestive of recurrence arise.
Key Points
Exam Focus:
Howship's Rome sign (medial thigh pain radiating to knee) is a classic symptom
High incidence of strangulation and bowel obstruction
Predominantly seen in elderly, emaciated women
CT scan is the investigation of choice
Surgical repair is mandatory
Risk of obturator nerve injury during repair.
Clinical Pearls:
Always consider obturator hernia in elderly patients with unexplained bowel obstruction and thigh pain
The obturator sign (pain on passive internal rotation/adduction of hip) is a valuable diagnostic clue
Be vigilant for neurological deficits post-operatively, particularly motor weakness of hip adduction.
Common Mistakes:
Missing the diagnosis due to its rarity
Delaying surgical intervention, leading to strangulation
Inadequate exploration of the obturator canal during surgery
Causing injury to the obturator nerve or vessels
Inadequate repair leading to recurrence.