eP404 - Pneumopericardium and Pneumomediastinum from Extraperitoneal Perforation After Diagnostic Colonoscopy, a Case Report

Purpose/Background: Colonic perforation at colonoscopy is relatively rare. Polypectomy is an independent risk factor for post-colonoscopy complications. The majority of perforations are intraperitoneal. Extraperitoneal perforation is a rarely reported occurrence, where efflux into the retroperitoneal space can result in atypical findings. We present a case of a 51-year old female with ulcerative colitis who presents with pneumopericardium and pneumomediastinum from extraperitoneal perforation after diagnostic colonoscopy.Methods/Interventions: A 51-year-old female with long-standing for ulcerative colitis presents with shortness of breath after diagnostic colonoscopy. Colonoscopy demonstrated severe pancolitis with a 1.5 cm pedunculated lesion in the ascending colon. The lesion was removed with a cold snare. Following the procedure, the patient reports chest discomfort and shortness of breath. Upon presentation to our facility, she is tachypneic but otherwise stable. Exam notable for subcutaneous emphysema. She is not peritonitic. Labs reveals leukocytosis, WBC, 33. CT abdomen/pelvis shows extensive pneumatosis and free air surrounding the cecum and ascending colon with extensive retroperitoneal air involving the right psoas and right kidney. CT chest shows subcutaneous air within the right and left neck along with extensive pneumomediastinum. Patient exhibits clinical deterioration, with tachycardia, hypotension and persistent tachypnea. She was taken for emergent laparotomy.Results/Outcomes: Midline laparotomy is performed. There is evidence of pancolitis with contamination along the right paracolic gutter. During lateral mobilization of the right colon, the site of perforation is identified on the posterior wall of the right colon. Air tracking is noted into the retroperitoneum. A total colectomy with end ileostomy is performed. She is extubated but initially requires supplemental O2 by nasal cannula. Pneumomediastinum remains unchanged on serial chest x-ray. Supplemental O2 is discontinued by post-operative day 2. Post-operative course is otherwise uneventful. She tolerates regular diet with normal ostomy function by post-operative day 3. Final pathology reveals chronic active ulcerative colitis without evidence of dysplasia. Final polyp pathology consistent with tubular adenoma without evidence of dysplasia. She awaits 3-stage approach to total proctectomy with ileal-pouch anal anastomosis (IPAA).Conclusion/

Discussion: Colonic perforation is a rare, yet, serious complication after colonoscopy. The majority of perforations are intraperitoneal; while extraperitoneal perforation is rarely reported. Extraperitoneal perforation allows air and intracolonic contents to access the retroperitoneal space. A continuum of fascial planes connects the retroperitoneum to the chest and neck, which can result in the atypical findings of pneumopericardium, pneumomediastinum, subcutaneous and/or mediastinal emphysema. High index of suspicion is warranted as delayed recognition is a recognized risk factor for poor clinical outcomes. In our case, patient undergoes emergent total colectomy in the face of worsening clinical instability. The patient requires supplemental O2 for persistent tachypnea that resolves without further intervention. Extraperitoneal perforation is rare and requires high clinical suspicion followed by prompt recognition and management."Figure 1: 1.5cm pedunculated right colon polyp

Figure 2: CT abdomen/pelvis with IV contrast

Extensive pneumatosis and free air surrounding the cecum and ascending colon along with extensive retroperitoneal air
Figure 3: CT chest with IV contrast

Subcutaneous air within the right and left neck along with extensive pneumomediastinum.
Figure 4: Chest radiograph, post-operative day 1and 2

Pnemomediastinum, remains stable on serial imaging"