Comedian Joan Rivers' daughter filed a lawsuit Monday against the Manhattan clinic where she suffered brain damage when her oxygen supply was cut off during a routine procedure. A complaint filed in state court outlines a series of alleged missteps at Yorkville Endoscopy on Sept. 4, including a 12-minute delay in calling 911.The lawsuit also charges there was an unauthorized doctor in the procedure room, the doctors failed to properly monitor Rivers' deteriorating vital signs, and one of them took photos of the celebrity with his cellphone while she was under sedation. The doctors allegedly waited too long to intubate Rivers.The lawsuit by Melissa Rivers and the comedian's estate asks for unspecified damages. The attorneys say they found not fault with the response of emergency medical technicians or the hospital where Rivers later died."Filing this lawsuit was one of the most difficult decision I've ever had to make," Melissa Rivers said in a statement."What ultimately guided me was my unwavering belief that no family should ever have to go through what my mother, Cooper and I have been through.