Acute pancreatitis followed by retroperitoneal perforation of the descending colon and a duodenal fistula: Report of a case

Highlights • Retroperitoneal perforation of the colon must be considered in patients with acute pancreatitis.• The most common site of perforation is the transverse and descending colon.• Retroperitoneal drainage may lead to expansion of the perforation site, necessitating a diverting stoma.


Introduction
There are several reports of colon perforation in patients with acute pancreatitis, but the mechanism is not fully understood. We describe a patient with acute pancreatitis followed by retroperitoneal perforation of the descending colon. This work is reported in conformity with the Surgical CAse REport (SCARE) Guidelines [1].

Case presentation
A 51-year-old male presented with epigastric pain and was diagnosed with acute pancreatitis at an outside facility. Despite fluid resuscitation, there was no improvement and he was transferred to our hospital the following day. His medical history was remarkable for hypertension and hyperuricemia. He drinks alcohol (56 g) every day. Physical examination revealed temperature 36.4 • C, blood pressure 138/101 mmHg, pulse 121/min, and respiratory rate 22/min. He was in acute distress with tenderness in the epigastrium without rebound tenderness. Laboratory data included white blood cell (WBC) count of 11,900/l, serum creatinine 2.28 mg/dl, total bilirubin 1.14 mg/dl and C-reactive protein 32 mg/dl. Serum lipase was 894 U/L. Computed tomography scan showed peripancreatic and a mesocolic fluid collection classified as Balthazar grade E.
On the day of admission, aggressive fluid resuscitation continued for the treatment of pancreatitis. With continued tachycardia and respiratory failure (SpO2 88% mask 5 L), he was brought to the intensive care unit (ICU) and supported with mechanical ventilation. By hospital day 5, there was improvement in the respiratory failure and renal failure. He was extubated and left the ICU to a general ward on hospital day 13. Although the patient appeared to be in no distress, the fever and elevated WBC continued after leaving the ICU. On hospital day 23 a CT scan was obtained which showed a gas and fluid collection in the left retroperitoneum. There was no contrast in one segment of the wall of the descending colon and perforation was suspected. To confirm the perforation, a contrast enema was performed after the CT scan which showed extraluminal contrast adjacent to the descending colon ( Fig. 1). This conformed the diagnosis of a perforation of the descending colon.
To control leakage from the perforation, retroperitoneal drainage was established by placing a 28Fr catheter percutaneously. As the drain was inserted, feculent material spontaneously  drained, with a total of 700 mL. To control the leak, a loop ileostomy was performed for diversion ( Fig. 2) on hospital day 34. After the diversion, discharge from the retroperitoneal drain decreased but fever persisted. A CT scan at that time revealed ascites. A 12Fr catheter was placed through the abdominal wall and water soluble contrast injected which demonstrated a duodenal fistula (Fig. 3). The fever resolved after drainage of the ascites. Previously placed drains in the retroperitoneum were removed after the volume of discharge decreased and the patient was discharged on hospital day 106.

Discussion
There are several reports of colon perforation in patients with acute pancreatitis. An extensive search was conducted (http:// www.pubmed.com) for previous studies related to this topic, using the following search terms: "pancreatitis" and "colon perforation." A total of 19 previously reported patients were identified and are summarized in Table 1.
Although the mechanism of colon perforation in patients with acute pancreatitis is not fully understood, there are several theories. One is that direct retroperitoneal spread of pancreatic enzymes to  Alive the mesocolon, causes pericolitis, transmural necrosis, and perforation [2]. A fluid collection in at least 2 locations (Balthazar grade E) on the initial CT scan is considered a risk factors for colon perforation [3]. From the data in Table 1, the rate of perforation is greatest in the transverse colon and descending colon (Fig. 4). This may be due to the fact that the splenic flexure is a vascular watershed area prone to poor perfusion, which may ultimately cause ischemia. In this patient, the main site of inflammation was pancreatic body and tail, which led to perforation of the duodenum and descending colon. After diagnosing the colon perforation by contrast enema and CT scan, we chose to perform retroperitoneal drainage, which may have applied pressure at the perforation site and leading it to expand with persistent feculent drainage. The decision to perform retroperitoneal drainage near the site of colon perforation resulted the need for a in loop ileostomy. From the data in Table 1, most authors describe performing a colectomy and ileostomy similar to treatment of the present patient, but there are also reports of closing the perforation site with an endoscopic clip or enteral stent followed by planned colon resection [4,5]. Using these devices prior to the retroperitoneal drainage might have prevented the need for a loop ileostomy.

Conclusion
Retroperitoneal colon perforation must be considered in patients with acute pancreatitis. If the patient is clinically stable, closing the perforation site using an endoscopic clip or enteral stent followed by planned colon resection is a reasonable treatment option which may avoid the need for an ileostomy.

Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Ethical approval
Ethical approval was exempted by our institution.

Consent
Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available and can be reproduced whenever needed.

Author contribution
Kentaro Yoshikawa gathered patient's date, designed the case report, and drafted manuscript. Tadao Kubota and Alan Kawarai Lefor supervised the report. All authors read and approved the final manuscript.

Registration of research studies
This work is case report and there is no need of registration.

Provenance and peer review
Not commissioned, externally peer-reviewed.

Declaration of Competing Interest
None of the authors has any conflict of interest to declare.