Little has been published on the thoracic complications following bowel perforation with colonoscopy. We report a woman with tension pneumothorax following this procedure.
A 64-year-old woman presented to the emergency department with severe lower abdominal pain with nausea and vomiting for one day. Her pain was intermittent and described as sharp and cramping; the vomitus was not bilious or bloody. During her initial evaluation, she was found to have a large fecolith in her sigmoid colon with multiple air fluid levels, likely as a result of mechanical obstruction. A colonoscopy was attempted to remove the fecolith. During the introduction of the colonoscope, the patient developed an acute worsening of her abdominal pain. The procedure was immediately terminated, and the patient was moved to the holding room. The patient had a BP of 170/90 and an O2 saturation of 85-90% on a 100% non-rebreather. An acute abdominal series revealed a large, right-sided pneumothorax with contralateral shift (Figure 1). The left lateral decubitus film revealed a large amount of free intraperitoneal air (Figure 2).A small bore chest tube was subsequently placed with partial resolution of the pneumothorax prior to having an emergent laparotomy. At surgery, she was found to have a large, luminal defect in her sigmoid colon. The patient required a left hemicolectomy with ostomy diversion. She had a prolonged postoperative course and was discharged following 16 days of hospitalization.
Colonic perforation is a rare but serious complication of colonoscopy, occurring in 0.14% to 0.2% of diagnostic colonoscopies with a rate of up to three times that for therapeutic colonoscopies. This may be caused by direct manipulation, use of electrocautery devices, or excessive intraluminal pressure from colonic insufflation. Depending on the site and mechanism of injury, intraluminal air may escape into either the peritoneum or retroperitoneum. Once air escapes from the bowel, it may induce a pneumothorax through a variety of mechanisms. First, gas may traverse from the peritoneum through small fenestrations in the diaphragm and enter the pleural space along a pressure gradient. Aside from minute diaphragmatic fenestrations, there is a subset of patients who have undiagnosed diaphragmatic defects which allow the transmission of air also via a pressure gradient. Depending on the site of injury, it is also possible for air to enter the retroperitoneum. When this occurs, a direct communication exists to the mediastinum; a pneumomediastinum can lead to a pneumothorax when the mediastinal parietal pleura ruptures. This mechanism may also account for the advent of bilateral pneumothoraces and also may predispose a patient to pneumopericardium. To date, there have been only eight reported cases of pneumothorax resulting from colonoscopy. These are listed in Table 1. Of the reported cases, it appears that the majority occur via air dissection through the mediastinum, presumably from the retroperitoneum.
Although there is a relative paucity of reports of iatrogenic pneumothorax following colonoscopy, this potential complication exists whenever a colonic perforation occurs given the relatively high pressure system of the colon during insufflation and the negative pressure of the pleural space. Consequently, during a problematic colonoscopy with the use of high insufflation pressures, the possibility of colonic rupture and its consequence, free air in the abdomen, needs to be investigated. The clinician needs to be cognizant that, on occasion, a pneumothorax under tension may develop with potentially serious consequences.
Brian Zeno, None.