Doctors at a Tripura medical college cut open a patient's lower abdomen and operated upon the urethra instead of conducting a biopsy of his mouth -- in an apparent case of mistaken identity. Jhulan Das wife of the patient Ratan Das 53 a small-time trader of Ampi Bazaar in southern Tripura filed a complaint on Saturday in this regard with the police and the state health minister.In her complaint she said: ‘Following the advice of senior doctors my husband was admitted to the Gobinda Ballav Pant Medical College and Hospital last week. He was to undergo a biopsy of his mouth.