Intussusception is a medical condition in which a part of the intestine folds into the section immediately ahead of itself.¹ In adults, it is mostly caused by pathological factors such as tumors.^2,3 Surgical treatment is needed in 70–90% of cases. Another rare cause is colonoscopy. The cause of intussusception after colonoscopy can be attributed either to the colonoscopy procedure itself or to an additional procedure such as polypectomy that was performed during colonoscopy. We report herein on a rare case of colonic intussusception induced by post-polypectomy electrocoagulation syndrome (PPES). At present, there is no set treatment strategy for this due to the rarity of intussusception after colonoscopy. Therefore, it is valuable to report this case of colonic intussusception following colonoscopy with a literature review to contribute to the design of an appropriate treatment strategy.

The patient was a 44-year-old female who presented to the emergency room with complaints of right-sided abdominal pain. She had no significant past medical history other than hypertension. On the day of admission, a colonoscopy with complete inspection was performed, and it showed a sessile type polyp in the ascending colon. An endoscopic mucosal resection was performed through injection (epinephrine [0.01%]-added normal saline and indigo carmine) and snaring (Captivator medium hexagonal-stiff snare [Boston Scientific]). After hot snare polypectomy (Erbe VIO 300D; ENDO CUT Q mode; Effect 3; Cutting duration 1, Cutting interval 6), six clips (Olympus EZ long clip) were used for hemostasis. (Fig. 1) Five hours after the colonoscopy, the patient began experiencing peristaltic abdominal pain. Vital signs showed a blood pressure of 98/52 mmHg, a pulse rate of 78 beats per minute, and a body temperature of 37°C. Laboratory results indicated leukocytosis of 16,480/μL without other significant findings. Abdominal examination revealed peritoneal irritation in the right upper quadrant. Abdominal CT imaging revealed colocolic intussusception near the hepatic flexure along with fluid collection in the right retro-colic space, without evidence of free air (Fig. 2). Based on the patient's symptoms and imaging results, a diagnosis of intussusception with PPES was made. Endoscopic reduction was considered as a potential treatment. However, this was not attempted due to the high risk of intestinal perforation and the possibility of peritonitis in the PPES. Laparoscopic reduction was attempted but was unsuccessful due to edematous bowel. A laparoscopic right hemicolectomy was ultimately performed, which confirmed that the distal part of the ascending colon was drawn into the proximal part of the transverse colon (Fig. 3). The resected colon presented severely thickened and edematous colonic walls. A hemorrhagic clipped lesion was found in the mid-portion of the ascending colon. Biopsy revealed transmural acute suppurative inflammation with submucosal edema, which was compatible with PPES (Fig. 4). The patient was discharged without complications six days after the surgery. This study was approved by the Institutional Review Board (IRB) of Eulji University (IRB approval no: 2024-01-005). The patient provided informed consent. We also obtained informed consent from the patient for publishing images of the patient’s body parts.

Figure 1. (A) Initial colonoscopic image showing a 20 mm-sized, sessile type adenoma located at the ascending colon. (B–D) Colonoscopic view after endoscopic mucosal resection using hot snare with saline injection.

Figure 2. Abdominal CT, showing colocolic intussusception (arrow). (A) Coronal view (left). (B) Axial view (right) showing a target-like lesion in the right side of the colon with bowel and fatty mesentery inside along with colon wall thickening with submucosal swelling and highly attenuated infiltration of adjacent pericolic fat compatible with post-polypectomy electrocoagulation syndrome.

Figure 3. Laparoscopic view of colocolic intussusception showing the distal part of the ascending colon drawn into the proximal part of the transverse colon.

Figure 4. Histopathologic examination of the resected colon, compatible with post-polypectomy coagulation syndrome. (A) A deep ulcer (thin arrow) with transmural inflammation following the polypectomy (H&E ×12.5) (left). (B) Marked submucosal edema with diffuse neutrophilic infiltration, indicating acute suppurative inflammation (H&E ×100) (right).

In adults, 70–90% of intestinal intussusceptions involve a leading point lesion.⁴ The majority of colonic intussusceptions are associated with malignant tumors.^3,5 Therefore, surgical excision without reduction is currently considered to be the optimal treatment strategy to avoid the risk of seeding and dissemination of tumor cells.^6,7 Colonic intussusception can happen in rare cases after a colonoscopy. According to a search on PubMed, there have been 11 reported cases of intussusception following colonoscopy (Table 1). Eight of these cases involved colonic intussusception directly caused by the colonoscopy procedure,^8-15 while the other three cases were associated with polypectomy during colonoscopy.^16-18 It is suggested as a hypothesis that colonic intussusception after colonoscopy can occur due to two possible mechanisms: either excessive peristalsis during the release of gas injected into the colon or a suction effect during the removal of the colonoscope (“vacuum effect”), which causes the upper part of the colon to intrude into the lower part.^8,16 A polypectomy procedure during a colonoscopy can also cause colonic intussusception. The mechanism involves mucosal ischemia caused by the epinephrine injection to submucosa and transmural burns resulting from the coagulation used during the procedure. This can in turn lead to PPES. The edematous bowel can serve as a leading point for intussusception in this case.¹⁷

Table 1 . Review of Reported Intussusception Following Colonoscopy Including Cases with Post-polypectomy Electrocoagulation Syndrome

Clinical presentation of intussusception following colonoscopy is similar to that of typical intussusception, as they are both characterized by colicky abdominal pain, nausea, and vomiting.¹ Moreover, because symptoms typically appear within a few hours after a colonoscopy, colonic intussusception after colonoscopy could be suspected as a complication despite its rarity. In cases of polypectomy combined with colonoscopy, symptoms such as leukocytosis, fever, and signs of peritoneal irritation are indicative of PPES, specifically suggesting the possibility of perforation or ischemia.¹⁹ For the diagnosis of intussusception in adults, although an ultrasound of the abdomen is useful, abdominal CT is more helpful because it reveals the site and cause of intussusception while additionally allowing for the diagnosis of complications such as perforation and necrosis.^4,8 In cases of intussusception by tumor, the location of intussusception can depend on the site of the pathologic tumor, as there are various possible sites. According to a literature review, 90% (10/11) of intussusception cases after colonoscopy occurred on the right side. Most of these cases of intussusception, aside from an ileocolic type 1 case caused by a polyp in the terminal ileum, had a colocolic type. At present, there is no established treatment strategy for colonic intussusception following colonoscopy. When making treatment strategy decisions for colonic intussusception following colonoscopy, we considered the following points: 1) complete or incomplete inspection of quality colonoscopy up to intussusception location, 2) the risk of bowel ischemia or perforation or presence of PPES, and 3) the presence or absence of clinical improvement following conservative treatment (Fig. 5).

Figure 5. Algorithm used to treat intussusception following colonoscopy. The following points should be considered when deciding upon a treatment strategy: 1) complete or incomplete inspection of quality colonoscopy up to intussusception location, 2) risk of bowel ischemia or perforation or presence of post-polypectomy syndrome (PPES), and 3) clinical improvement following conservative treatment.

Obviously, in cases involving the diagnosis of ischemia or perforation, surgical resection should be performed. In cases involving a complete high-quality colonoscopy up to intussusception location without signs of ischemia or perforation, conservative treatment,^9,16 including NPO and intravenous antibiotics, could be initiated first, because, in such cases, intussusception is confirmed to not be due to pathologic tumors, and it can likely be reduced spontaneously. If there is no improvement or worsening, then reduction using colonoscopy can be considered.¹⁰ In cases where PPES is not combined with intussusception, most cases of PPES resolve spontaneously.²⁰ However, in the case of intussusception combined with PPES, there may be a low possibility of spontaneous reduction of intussusception because of the additional edema and ischemia risk due to the addition of intussusception to PPES. Therefore, surgical treatment may be preferred in such cases despite a case report showing that intussusception combined with PPES was resolved through conservative treatment.¹⁶ Moreover, in the case of an ileocolic type, surgical resection may be considered if the inspection of the terminal ileum is insufficient to address potential unrecognized lesions in the terminal ileum. Colocolic intussusception where no pathologic lesions are present during colonoscopy is more likely to spontaneously reduce. Therefore, conservative treatment can be prioritized in such cases.

In conclusion, if there is evidence of no lesion up to the location of intussusception through high-quality colonoscopy without PPES or evidence of ischemia or perforation, conservative treatment for the spontaneous reduction of colon intussusception can be attempted first. However, in the case of intussusception combined with PPES, surgical resection may be preferred. The appropriate treatment strategy should be selected based on each patient's specific situation.

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