Obturator Hernia

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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Hernia most commonly contains loop of Ileum, although can rarely involve other pelvic viscera (i.e., bladder)

Most often trapped between obturator externus and pectineus muscles

May also be located between superior and middle fasciculi of obturator externus or between internal and external obturator muscles

• Hernia sac exits pelvis near obturator vessels and nerve

• Right side more common

TOP DIFFERENTIAL DIAGNOSES

• Inguinal hernia

• Sciatic hernia

• Perineal hernia

• Femoral hernia

PATHOLOGY

• Defect in pelvic floor or laxity of pelvic muscles and fascia

• Made worse by any chronic increase in abdominal pressure (COPD, constipation, pregnancy, etc.)

• More common in thin or emaciated patients, as preperitoneal fat usually supports obturator canal

CLINICAL ISSUES

• Accounts for < 1% of all hernias

• > 90% occur in elderly women (mean age 82)

Less common complication of pelvic floor laxity

• Acute or recurrent small bowel obstruction, partial > complete

80% of patients present with symptoms of bowel obstruction

Majority require resection of strangulated small bowel

• Rare occurrence and nonspecific signs often lead to late diagnosis

Correct clinical diagnosis in only 10–30% of cases

Diagnosis best made by CT/MR rather than clinical exam

(Left) Graphic shows a bowel obstruction caused by an obturator hernia. Strangulated bowel lies deep to the pectineus muscle and superficial to the obturator externus muscle .

(Right) Axial CECT in a 73-year-old woman shows a protrusion of portions of the bladder into bilateral obturator hernias . Obturator hernias most commonly contain herniated ileum, but other pelvic viscera can also herniate, as in this case.

(Left) Axial CECT in a 90-year-old woman with bowel obstruction shows dilated proximal small bowel loops and collapsed distal bowel .

(Right) Axial CECT in the same patient shows the herniated and strangulated segment of the ileum trapped between the obturator externus and the pectineus muscles. These are the classic imaging findings of an obturator hernia.

TERMINOLOGY

Abbreviations

• Obturator hernia (OH)

Definitions

• Pelvic hernia protruding through obturator foramen

IMAGING

General Features

• Best diagnostic clue

CT evidence of herniated bowel lying between pectineus and obturator muscles in an elderly woman

Radiographic Findings

• Abdominal radiographs or barium studies

Small bowel obstruction with a fixed loop containing gas or contrast medium in obturator region

CT Findings

• Loop of bowel protruding through obturator foramen

Hernia most commonly contains loop of Ileum, although can rarely involve other pelvic viscera (i.e., bladder)

Most often trapped between obturator externus and pectineus muscles

• 3 forms of hernia (in decreasing frequency)

Extending between pectineus and obturator muscles

Between superior and middle fasciculi of obturator externus

Between internal and external obturator muscles

• Hernia sac exits pelvis near obturator vessels and nerve

• Right side is more common

Imaging Recommendations

• Best imaging tool

CECT: Images should include inferior pelvis and upper thigh to ensure hernia is fully imaged

DIFFERENTIAL DIAGNOSIS

Inguinal Hernia

• Abdominal contents within inguinal canal with extension into scrotum

• Does not involve obturator foramen

• Indirect: Through inguinal canal → external ring

Females: Course of round ligament into labium majus

Males: Along spermatic cord → scrotum

Sciatic Hernia

• Hernia extends through greater sciatic foramen with extension laterally into subgluteal region

Perineal Hernia

• Anterior: Through urogenital diaphragm

• Posterior: Between levator ani and coccygeus muscle

Femoral Hernia

• Hernia extends through femoral ring into femoral canal medial to femoral vein

PATHOLOGY

General Features

• Etiology

Defect in pelvic floor or laxity of pelvic muscles and fascia

Made worse by any chronic increase in abdominal pressure (COPD, constipation, pregnancy, etc.)

More common in thin or emaciated patients, as preperitoneal fat usually supports obturator canal

• Associated abnormalities

May be coexistent with other hernias (e.g., inguinal, femoral)

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

Acute or recurrent small bowel obstruction, partial > complete

– 80% of patients present with symptoms of bowel obstruction

– Obstruction is more likely to be intermittent if Richter herniation of bowel into obturator canal

May present as tender mass in obturator region on rectal or vaginal examination

• Other signs/symptoms

Howship-Romberg sign: Pain in medial aspect of thigh/hip with abduction, extension, or internal rotation of knee; flexion relieves pain (25-50% of cases)

– Compression and irritation by hernia of the obturator nerve

Hannington-Kiff sign: Absent adductor reflex in thigh (15-50% of patients)

Obturator neuralgia: Pain or paresthesias along inner surface of thigh to knee

• Rare occurrence and nonspecific signs often lead to late diagnosis, with correct clinical diagnosis in only 10–30% of cases

Demographics

• Gender

> 90% of obturator hernias occur in elderly women (mean age 82)

– Less common complication of pelvic floor laxity (incontinence, prolapse, etc.)

• Epidemiology

Accounts for < 1% of all hernias

– Bilateral obturator hernias rare: 6% of cases

Natural History & Prognosis

• Mortality rates up to 25%

Diagnosis is elusive; best made by CT or MR rather than by clinical exam

Treatment

• Majority require resection of strangulated small bowel

• Abdominal/inguinal approach for reduction and repair

• Contralateral side exploration is recommended

DIAGNOSTIC CHECKLIST

Consider

• Obturator hernia in any elderly, debilitated, chronically ill woman with symptoms of recurrent small bowel obstruction and pain along ipsilateral thigh and knee