Colonoscope incarceration in an inguinal hernia complicated by ischemic bowel disease: A case report

Abstract

BACKGROUND

Colonoscopy is widely used for the diagnosis and treatment of colorectal diseases, with bleeding and perforation being the most recognized complications. Colonoscope incarceration within an inguinal hernia is an exceptionally rare mechanical complication, and secondary ischemic bowel injury has not been previously reported.

CASE SUMMARY

A 67-year-old man undergoing colonoscopy developed sudden complete fixation of the colonoscope at approximately 40 cm from the anal verge. Physical examination revealed a palpable mass in the left inguinal region. Pelvic X-ray demonstrated incarceration of the colonoscope in a characteristic reversed “S” configuration. Two-person manual reduction successfully released the scope. Subsequent colonoscopy showed continuous congestion, edema, and superficial necrosis of the sigmoid colon mucosa with clear demarcation from adjacent normal tissue. Histopathological examination confirmed ischemic mucosal injury. Computed tomography demonstrated a left inguinal hernia. The patient subsequently underwent elective hernia repair and recovered without further gastrointestinal complications. This case represents the first reported instance of ischemic bowel injury secondary to colonoscope incarceration within an inguinal hernia. Early recognition, prompt groin examination, imaging confirmation, coordinated manual reduction, and post-reduction mucosal assessment are essential for optimal management.

CONCLUSION

Routine pre-colonoscopy screening for inguinal hernia should be considered to prevent this rare but potentially severe complication.

Key Words: Colonoscopy; Inguinal hernia; Colonoscopy incarceration; Ischemic bowel injury; Case report

Core Tip: Colonoscope incarceration in an inguinal hernia is an exceedingly rare mechanical complication, and its association with secondary ischemic bowel injury has never been reported. We present a 67-year-old male in whom the colonoscope became completely fixed during routine colonoscopy, with pelvic X-ray revealing a classic reversed “S” configuration within a left inguinal hernia. Two-person manual reduction successfully released the scope, but subsequent endoscopic and histopathological examination confirmed ischemic mucosal necrosis. This case is the first to document ischemic bowel injury following hernia-related scope incarceration. Early recognition, prompt groin examination, imaging confirmation, and post-reduction mucosal assessment are critical. Routine pre-colonoscopy hernia screening warrants consideration.

INTRODUCTION

With the widespread use of colonoscopy, common complications such as bleeding and perforation are well recognized in clinical practice. However, incarceration of a colonoscope within an inguinal hernia is an extremely rare mechanical complication. According to published reports, the number of reports is limited and no secondary ischemic intestinal injury has been observed[1-5]. Here, we report the first case of acute ischemic changes in the sigmoid colon resulting from colonoscope incarceration within a left inguinal hernia. We aim to elucidate its distinctive clinical course, proposed mechanism of injury, and key management considerations, thereby guiding the recognition and prevention of this rare emergency.

CASE PRESENTATION

Chief complaints

A 67-year-old man undergoing colonoscopy developed sudden complete fixation of the colonoscope at approximately 40 cm from the anal verge. Right-sided facial paralysis for 3 days.

History of present illness

Three days before admission, the patient suddenly developed right-sided facial paralysis without an apparent trigger. The corner of the mouth deviated to the left, and the “Bell’s phenomenon” was observed in the right eye. The patient was unable to frown, close the right eye, puff out the right cheek, show the teeth, or whistle. During eating, food frequently accumulated in the right buccal space, and saliva dribbled from the right side of the mouth. The patient also reported reduced taste sensation, hyperacusis in the right ear, excessive tearing of the right eye, and pain around the ear. The patient denied chills, fever, headache, chest pain, hemoptysis, tinnitus, hearing loss, slurred speech, limb weakness, or sensory deficits.

History of past illness

Gastric ulcer and chronic constipation.

Personal and family history

No remarkable personal or family history.

Physical examination

Temperature was 36.6 °C, pulse 102 beats/minute, respiratory rate 21 breaths/minute, and blood pressure 149/101 mmHg. Cardiovascular, pulmonary, and abdominal examination were unremarkable, with no lower extremity edema. The patient was alert and oriented with intact higher cortical functions. Neurological examination revealed diminished right forehead wrinkling, incomplete closure of the right eyelid, full extraocular movements without nystagmus, flattening of the right nasolabial fold, deviation of the angle of the mouth to the left, and midline tongue protrusion. The pharyngeal reflex was intact. The remainder of the cranial nerve examination was unremarkable. Muscle strength and tone were normal in all four limbs. Finger-to-nose and heel-to-shin testing showed no abnormalities. Superficial and deep sensations were intact and symmetrical bilaterally. Deep tendon reflexes were 2+ throughout, with no pathological reflexes or meningeal signs.

Laboratory examinations

Routine blood tests, serum biochemistry, coagulation profile, and ascitic fluid amylase and creatinine levels were all within normal levels.

Imaging examinations

Deep sedation was induced with an intravenous 1-mg bolus of midazolam followed by propofol 1-2 mg/kg, with supplemental doses of 0.2-0.5 mg/kg administered as needed. During colonoscopy, when the endoscope reached 40 cm from the anal verge, where no mucosal abnormalities were observed, it suddenly became completely immobile and could neither be advanced nor withdrawn. Assisted abdominal compression was applied, and the patient’s position was changed repeatedly from the left lateral decubitus to the supine position, and then to the right lateral decubitus, and back to the supine position. Despite these maneuvers, the scope remained incarcerated for approximately one hour. Physical examination revealed a firm left groin mass measuring approximately 6 cm × 6 cm × 4 cm, within which the colonoscope could be clearly palpated. Further questioning disclosed a more than 10-year history of a reducible left inguinal hernia that had not been treated. An urgent bedside pelvic X-ray demonstrated the colonoscope incarcerated in a reverse “S” configuration in the left pelvis (Figure 1A).

Figure 1 Abdominal X-ray. A: Pelvic X-ray showing the colonoscope stuck in a reverse “S” configuration in the left pelvic cavity; B: Successful withdrawal of the colonoscope following manual reduction of the inguinal hernia.

After informed consent was obtained, a two-person manual reduction was performed. An assistant stabilized the hernial ring with one hand while gently reducing the hernial sac contents with the other, as the endoscopist slowly and carefully withdrew the scope. The sudden release of resistance indicated successful reduction of the incarceration (Figure 1B). Further examination (air insufflation was continued during the colonoscopy instead of using carbon dioxide) revealed continuous mucosal congestion, edema, and granular changes in the sigmoid colon, 15 cm to 35 cm from the anal verge. The affected segment was covered with necrotic material and blood-tinged mucus, with well-demarcated margins (Figure 2). Biopsy specimens demonstrated mucosal congestion, superficial necrosis, and inflammatory cell infiltration (Figure 3).

Figure 2 Colonoscopy images. A: Colonoscopic view showing a well-demarcated boundary between the ischemic intestinal segment and the adjacent normal mucosa; B: Colonoscopic view of the sigmoid colon showing continuous congestion and edema, a granular and uneven texture, and areas covered with necrotic material and dark red blood-tinged mucus.

Figure 3 Histopathological section demonstrating mucosal congestion, mild inflammatory cell infiltration, and superficial mucosal necrosis with sloughing (× 20).

FINAL DIAGNOSIS

Colonoscope incarceration within a left inguinal hernia complicated by ischemic bowel disease.

TREATMENT

The patient was kept nil per os, received intravenous fluid replacement, and was treated with oral compound glutamine enteric-coated capsules.

OUTCOME AND FOLLOW-UP

Postoperative computed tomography confirmed a left inguinal hernia with redundant sigmoid colon (Figure 4). Two weeks later, the patient underwent successful laparoscopic inguinal hernia repair. Intraoperatively, the hernial ring measured approximately 3 cm in diameter. At the latest follow-up, the patient remained free of gastrointestinal symptoms such as abdominal pain or rectal bleeding.

Figure 4 Computed tomography scan demonstrating a left inguinal hernia. The orange arrows indicate the hernia ring (approximately 3 cm in diameter).

DISCUSSION

Identification of clinical features

When resistance is encountered during colonoscopy, it is essential to differentiate between common loop formation and true incarceration. Typical loop formation, including N, α, or P loops[6-9], is characterized by difficulty advancing the endoscope but relative ease of withdrawal. In contrast, endoscope incarceration presents as complete fixation, with the inability to either advance or withdraw the instrument. In the present case, the incarceration was recognized after approximately one hour. The delayed identification was primarily attributable to failure to consider an inguinal hernia in the emergency differential diagnosis. Furthermore, deep sedation renders the patient unable to verbalize localized pain during colonoscope impaction, thereby impairing early detection of the complication by the endoscopist. This highlights the importance of routinely assessing for a history or physical signs of inguinal hernia before colonoscopy, particularly in high-risk populations such as elderly men and patients with chronic constipation or chronically increased intra-abdominal pressure. Previous case reports suggest that gentle manual reduction under close coordination is the preferred initial management strategy for colonoscope incarceration, while forceful extraction should be strictly avoided due to the risk of bowel perforation[5,10,11]. When the endoscope becomes completely fixed without an apparent intraluminal cause, both inguinal regions should be palpated immediately, and the course of the endoscope should be confirmed with bedside imaging (such as X-ray). This is the first diagnostic step.

Reduction technique and clinical characteristics

Successful reduction requires close collaboration between the endoscopist and the assistant. Stabilization of the hernia ring, combined with gentle, gradual withdrawal of the endoscope, should be performed simultaneously. Reported cases of colonoscope entrapment in China have involved middle-aged and elderly men, with entrapment occurring during either insertion or withdrawal[3]. With the exception of one case involving a right inguinal hernia[4], all reported cases occurred in the left inguinal region. Manual reduction was successful in all cases. The present case is consistent with these observations. The patient was a 67-year-old man with a history of inguinal hernia. Incarceration occurred during scope insertion, and the entrapment site was the left inguinal hernia. Manual reduction was successfully performed, with complete resolution of the incarceration.

Mechanism of ischemic injury

Colonoscopy can lead to iatrogenic ischemic colitis, which is thought to be associated with microvascular injury, mechanical compression, excessive insufflation leading to increased intraluminal pressure, and excessive stretching of the bowel wall[12-15]. To date, no published reports have described secondary intestinal mucosal ischemia resulting from colonoscope incarceration within an inguinal hernia. This likely reflects the fact that most cases are recognized and reduced promptly. In the present case, the incarceration persisted for approximately one hour. Colonoscope incarceration produces a reverse-S configuration at the level of the hernia sac neck, which intensifies mechanical pressure on the herniated bowel. Prolonged compression of the intestinal loop can compromise venous outflow, thereby initiating a cascade of ischemic events[16]. This mechanism is analogous to the pathophysiology of a strangulated hernia[17]. Delayed recognition of colonoscope incarceration, combined with a prolonged procedure and the use of air rather than CO₂ insufflation, increases intraluminal pressure and promotes intestinal ischemia and necrosis. Even after relief of the incarceration, continuation of the examination with air insufflation rather than CO₂ may worsen ischemia and heighten the risk of delayed perforation. Notably, although histopathological examination confirmed mucosal congestion and superficial necrosis (Figure 3), no transmural injury occurred after reduction. This reflects a staged progression of intestinal ischemia and suggests that the severity of mucosal injury correlates with the duration of incarceration.

Key points for management

Based on this case, the management approach can be summarized as follows. Rapid diagnosis is essential. Sudden and complete fixation of the endoscope, identification of a palpable groin mass, and a characteristic reverse “S” configuration on X-ray are key diagnostic features. Standardized reduction should be undertaken promptly. Two-person collaborative manual reduction is the preferred method. Essential elements include firm stabilization of the hernia ring with appropriate countertraction and gentle, synchronous, and continuous withdrawal of the endoscope. Forceful manipulation must be avoided. A comprehensive assessment is required after reduction. Subsequent evaluation should be continued whenever feasible to directly assess the extent and severity of damage to the previously incarcerated intestinal segment, and a biopsy should be obtained to clarify the pathology. Close short-term follow-up is necessary to monitor for delayed perforation or stenosis. Definitive management consists of timely inguinal hernia repair to correct the underlying anatomical defect and prevent recurrence.

CONCLUSION

When the colonoscope becomes completely fixed during colonoscopy, an incarcerated inguinal hernia should be considered as a primary differential diagnosis. This case, the first reported instance of secondary ischemic bowel injury caused by colonoscope incarceration, underscores the potential severity of this complication. Successful management depends on early detection, prompt groin examination, imaging confirmation, coordinated reduction, and careful assessment of bowel injury. During manual reduction, close coordination between the endoscopist and assistant is crucial, with simultaneous stabilization of the hernia ring and gentle withdrawal of the scope. We recommend that screening for inguinal hernia be included in routine precolonoscopy assessment. Patients with known hernias should receive appropriate counseling and individualized procedural planning to prevent this rare but serious complication.