Iatrogenic colon perforation during operative colonoscopy: imaging triage

Clinical History

Onset of abdominal pain 24 hours after operative colonoscopy in a female patient affected with primary biliary cirrhosis, pulmonary fibrosis, diabetes and sigmoid colon diverticulosis.
Physical examination reveals bilateral pelvic tenderness without frank peritonism. Laboratory reveals anaemia (10.5 g/dl), increased lactate-dehydrogenase (300 U/l) and C-reactive protein (90 mg/l).

Imaging Findings

Operative colonoscopy included resection of a 7-mm sessile polyp of the sigmoid colon and argon plasma coagulation of ascending colon angiodysplasias.
At admission, chest and abdominal radiographs (Fig.1) excluded subphrenic pneumoperitoneum, and revealed some ileal air-fluid levels in the right hemiabdomen and a circumscribed “bubbly” gaseous infrahepatic radiolucency, which was partly superimposed to the right colonic flexure.
Immediate multidetector CT investigation (Fig.2) confirmed absence of free pneumoperitoneum, and a sizeable extraperitoneal gas surrounding the right hepatic flexure and ascending colon, consistent with iatrogenic perforation of the right colon from argon plasma coagulation. No abnormalities were seen nearby the polypectomy site at the sigmoid. Additionally, moderate perihepatic peritoneal effusion, recanalized paraumbilical vein and partial portomesenteric venous thrombosis were noted.
Considering the absent clinical and imaging signs of peritonitis, attending surgeons opted for nonsurgical treatment including bowel rest, intravenous fluids and broad-spectrum antibiotics, obtaining clinical, imaging and laboratory improvement within a few days.

Discussion

A widely used diagnostic and curative procedure, colonoscopy may result in occasional complications such as intestinal perforation. Risk factors for iatrogenic colon perforation include advanced age, female gender, obesity, diverticulosis, haemodialysis, hospitalized and intensive care patients, emergency conditions and obstruction. Reported perforation incidence is 0.04-0.33% for diagnostic endoscopy and may reach 5% for some interventions such as resection of more than four and/or larger than 1 cm polyps, mucosal resection, submucosal dissection and argon plasma coagulation [1-3].
Mechanisms include barotrauma from air insufflation, mechanical force from the endoscope especially in a diseased wall, and direct injury from therapeutic procedures. Perforation most usually occurs in the site of endoscopic treatments and of underlying diseases such as tumour, chronic inflammation and diverticulosis, particularly at the mobile, sharply angulated sigmoid colon and rectosigmoid junction (75% of cases). Perforation of intraperitoneal segments including the transverse, sigmoid and caecum causes free intraperitoneal air and fluid, whereas injury to the ascending, descending colon and rectum usually results in retroperitoneal extravasation [3, 4].
Less than 30% of iatrogenic colon perforation are detected during endoscopy and may be successfully treated with endoluminal clipping. Conversely the commonest presentation includes symptoms and signs of peritonitis hours to three days after the procedure. Although occurring in a “prepared” bowel, contamination from colonoscopy-related perforation can progress to peritonitis and sepsis, resulting in serious morbidity particularly in patients treated later than 24 hours, and in non-negligible (8-15%) mortality related to comorbidities [2, 3, 5].
Perforation is suspected if patients complain of abdominal pain, distension and fever following colonoscopy. As this case exemplifies, due to its excellent sensitivity for detection of even minimal extraluminal air and fluid, CT is the preferred modality for investigation of suspected perforation, particularly those involving the retroperitoneum. Coalescent foci of extraluminal gas usually hint at the perforation site. Plain radiographs have 50-70% sensitivity for free pneumoperitoneum, particularly when upright projections are impossible [4, 6].
Since early (within 24 hours) recognition and treatment are associated with fewer intestinal resections and reduced morbidity, high level of suspicion and prompt CT investigation are useful. The treatment choice should consider the injury features, bowel preparation, underlying colonic disease, and clinical conditions. Conservative treatment is feasible in afebrile patients with limited abdominal pain, proper colonic preparation, and early diagnosis without signs of peritonitis. Laparoscopic or open surgical management may involve primary suture (70%) or bowel resection with colonic anastomosis or stoma creation [2-5, 7].

Differential Diagnosis List

Final Diagnosis

Iatrogenic colon perforation during operative colonoscopy

URL:	https://www.eurorad.org/case/11594
DOI:	10.1594/EURORAD/CASE.11594
ISSN:	1563-4086