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)

image Most often trapped between obturator externus and pectineus muscles
image 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)

image Less common complication of pelvic floor laxity
• Acute or recurrent small bowel obstruction, partial > complete

image 80% of patients present with symptoms of bowel obstruction
image Majority require resection of strangulated small bowel
• Rare occurrence and nonspecific signs often lead to late diagnosis

image Correct clinical diagnosis in only 10–30% of cases
image Diagnosis best made by CT/MR rather than clinical exam
image
(Left) Graphic shows a bowel obstruction caused by an obturator hernia. Strangulated bowel image lies deep to the pectineus muscle image and superficial to the obturator externus muscle image.

image
(Right) Axial CECT in a 73-year-old woman shows a protrusion of portions of the bladder into bilateral obturator hernias image. Obturator hernias most commonly contain herniated ileum, but other pelvic viscera can also herniate, as in this case.
image
(Left) Axial CECT in a 90-year-old woman with bowel obstruction shows dilated proximal small bowel loops image and collapsed distal bowel image.

image
(Right) Axial CECT in the same patient shows the herniated and strangulated segment of the ileum image trapped between the obturator externus image and the pectineus image 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

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

Radiographic Findings

• Abdominal radiographs or barium studies

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

CT Findings

• Loop of bowel protruding through obturator foramen

image Hernia most commonly contains loop of Ileum, although can rarely involve other pelvic viscera (i.e., bladder)
image Most often trapped between obturator externus and pectineus muscles
• 3 forms of hernia (in decreasing frequency)

image Extending between pectineus and obturator muscles
image Between superior and middle fasciculi of obturator externus
image 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

image 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

image Females: Course of round ligament into labium majus
image 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

image Defect in pelvic floor or laxity of pelvic muscles and fascia
image Made worse by any chronic increase in abdominal pressure (COPD, constipation, pregnancy, etc.)
image More common in thin or emaciated patients, as preperitoneal fat usually supports obturator canal
• Associated abnormalities

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

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image 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
image May present as tender mass in obturator region on rectal or vaginal examination
• Other signs/symptoms

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

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

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

image Accounts for < 1% of all hernias

– Bilateral obturator hernias rare: 6% of cases

Natural History & Prognosis

• Mortality rates up to 25%

image 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
image
Axial CECT shows a knuckle of bowel image lying between the pectineus image and obturator muscles image in a patient with a obturator hernia.

image
Axial CECT shows an obturator hernia with the small bowel strangulated image between pectineus and obturator externus muscles.
image
Axial CECT shows bilateral obturator hernias image. Bilateral obturator hernias are rare, accounting for only 6% of all cases.
image
CT shows dilated proximal and collapsed distal small bowel, indicating obstruction. The point of obstruction is a segment of small bowel image entrapped within an obturator hernia.
image
A post-evacuation film from a contrast enema in the same patient reveals a “knuckle” of bowel image within the hernia. Only 1 wall of the bowel appears to be trapped.

SELECTED REFERENCES

1. Hodgins, N, et al. Obturator hernia: A case report and review of the literature. Int J Surg Case Rep. 2013; 4(10):889–892.

Lai, CC, et al. Usefulness of CT for differentiating between obturator hernia and other causes of small bowel obstruction. Postgrad Med J. 2013; 89(1058):729–730.

Pandey, R, et al. Obturator hernia: a diagnostic challenge. Hernia. 2009; 13(1):97–99.

Losanoff, JE, et al. Obturator hernia. J Am Coll Surg. 2002; 194(5):657–663.

Bergstein, JM, et al. Obturator hernia: current diagnosis and treatment. Surgery. 1996; 119(2):133–136.

Zinner, MJ, et al. Maingot’s Abdominal Operations, 10th ed., Norwalk, Connecticut: Appleton and Lang; 1996:540–546.

Chan, MY, et al. Obturator hernia—case reports. Ann Acad Med Singapore. 1994; 23(6):911–913.

Lo, CY, et al. Obturator hernia presenting as small bowel obstruction. Am J Surg. 1994; 167(4):396–398.

Zerbey, AL, 3rd., et al. Bilateral obturator hernias: case report, radiographic characteristics, and brief review of literature. Comput Med Imaging Graph. 1993; 17(6):465–468.