PHOTO: Investigators used a dummy to determine the exact cause of the fire. (Supplied: Tokyo Medical University Hospital)
The patient, in her 30s, was undergoing a gynecological operation at Tokyo Medical University Hospital in April when a laser being applied to her cervix caught fire.
A recently released report into the incident found her flatulence ignited the laser and caused burns to much of her lower body.
"When the patient's intestinal gas leaked into the space of the operation [room], it ignited with the irradiation of the laser, and the burning spread, eventually reaching the surgical drape and causing the fire," the report said.
To determine the cause of the blaze, investigators used a dummy to recreate the incident.
They ruled out flammable materials or malfunctioning equipment as other potential causes.
The report recommended fire-fighting training for operating room staff and taking steps to physically prevent methane from interacting with laser beams.