The incident took place at a clinic in Motala during a procedure to remove a polyp from the intestine of a man in his mid-sixties, The Local reported Monday.
After removal of the polyp, doctors began an electrocautery, a procedure where the edges of the intestine where the polyp was located were burned to seal them and prevent any bleeding.
"Suddenly, there was a powerful blast in the room and the patient felt pain in his stomach," doctors said in reporting the incident.
"The patient turned pale and his head began to nod."
A subsequent X-ray examination revealed small bubbles of methane gas had built up in the fatty tissues at the base of the patient's large intestine.
After an overnight say for observation, the patient was released without any further complications from the blast of colonic gas, doctors said.