How can a colonoscope become incarcerated in a right-sided reducible inguinal hernia that primarily involves the small intestine during a colonoscopy?

How a Colonoscope Can Become Incarcerated in an Inguinal Hernia Containing Small Intestine

A colonoscope can become incarcerated in an inguinal hernia containing small intestine because large inguinal hernias—particularly left-sided ones—can contain colon (typically sigmoid) that communicates with the abdominal cavity, allowing the colonoscope to pass through the hernia sac during insertion or withdrawal, where it then becomes trapped. 1, 2, 3

Anatomical Mechanism

The key to understanding this phenomenon is recognizing that inguinal hernias, especially large or long-standing ones, can contain both small bowel AND colon simultaneously, or the hernia sac itself can be large enough to accommodate colonic loops that remain in continuity with the intra-abdominal colon. 1, 3

• Left-sided inguinal hernias are most commonly involved because the sigmoid colon has a mesentery and mobility that allows it to herniate into the left inguinal canal alongside or instead of small bowel. 1, 2, 3
• The colonoscope enters the colon normally through the rectum, advances through the sigmoid, and when reaching the area where sigmoid has herniated into the inguinal canal, the scope follows this path into the hernia sac. 1, 2
• Right-sided incarceration can occur in patients with altered anatomy from previous abdominal surgery, where the cecum or ascending colon may be mobilized into a right inguinal hernia. 3

Clinical Presentation Patterns

Incarceration During Insertion

• The colonoscope advances normally but enters the hernia sac as it passes through the sigmoid colon, becoming trapped as it attempts to navigate the acute angulation at the internal inguinal ring. 2
• This is the less common presentation but was documented in a 74-year-old man where the scope became incarcerated during insertion into a left inguinal hernia. 1

Incarceration During Withdrawal

• This is the more frequent scenario—the colonoscope passes through the hernia during insertion without difficulty, but on withdrawal, the tip becomes caught at the internal ring or within the hernia sac itself. 1, 3
• A 73-year-old man experienced colonoscope incarceration in a left inguinal hernia specifically during withdrawal. 1

Critical Recognition Features

The hernia is frequently unsuspected prior to colonoscopy, making this a diagnostic surprise during the procedure. 3

• Inability to advance or withdraw the colonoscope despite normal technique
• Visualization of a bulging mass in the inguinal region that corresponds with colonoscope position
• Patient complaint of sudden inguinal pain during the procedure
• Fluoroscopic confirmation showing the colonoscope tip in the inguinal region 1, 3

Management Algorithm

Immediate Management

1. Attempt manual reduction under fluoroscopic guidance as the first-line intervention—this was successful in both reported cases without requiring emergency surgery. 1
2. Apply external manual pressure to the inguinal hernia while simultaneously withdrawing the colonoscope under fluoroscopy. 3
3. Consider fitting a cap onto the colonoscope tip to facilitate navigation if reduction is difficult. 3

Subsequent Colonoscopy Decision

• Colonoscopy can be safely completed after successful reduction in select circumstances—both patients in the 2023 case series underwent successful colonoscopy after manual reduction, with one revealing advanced sigmoid cancer. 1
• If the clinical indication is urgent (such as suspected malignancy), proceed with colonoscopy after reduction. 1
• For non-urgent indications, consider CT colonography as an alternative. 2

Definitive Hernia Management

• Surgical hernia repair should be performed after the acute event, either as a staged procedure or urgently if reduction fails. 1, 2
• Extraperitoneal approach is appropriate for elective repair after successful reduction. 1
• If manual reduction fails, proceed immediately with general anesthesia and surgical consultation for operative reduction and hernia repair. 2

Prevention Strategy

Examine both groins bilaterally before colonoscopy to identify clinically apparent inguinal hernias, particularly large or irreducible ones. 4

• Document any inguinal bulges or hernias in the pre-procedure assessment
• Consider elective hernia repair before colonoscopy in patients with large, symptomatic inguinal hernias
• Maintain high suspicion in patients with known inguinal hernias, especially left-sided 3

Common Pitfall to Avoid

This complication is likely significantly under-reported in the literature, so maintaining awareness of this possibility is essential even though it appears rare. 3 The assumption that inguinal hernias only contain small bowel can lead to delayed recognition of colonoscope incarceration when the hernia actually contains or can accommodate sigmoid colon.