Ten days after an exploratory laparotomy and lysis of adhesions, a patient, who previously underwent a low anterior resection for rectal cancer followed by postoperative chemoradiation, is noted to have succus draining from the wound. She appears to have adequate source control--she is afebrile with a normal white blood count. The output from the fistula is approximately 150 cc per day. Which of the following factors is most likely to prevent closure of the enterocutaneous fistula?