A pregnant U.K. woman suffering from appendicitis died after a doctor removed one of her ovaries instead of her appendix, an investigation into her death revealed.

Maria De Jesus was admitted into a hospital in Essex, England with abdominal pains in October 2011, The Telegraph reported. But the surgeon who operated on De Jesus, who was also 21 weeks pregnant, took out her right ovary instead of her appendix. De Jesus gave birth to a stillborn and died three weeks later.

A medical tribunal in Manchester is currently looking into the actions of two doctors involved, a trainee and his supervisor, to determine the proper repercussions.

Several hospital staff was present in the operating room at Queens Hospital when De Jesus' ovary was removed on Oct. 23. A fifth-year trainee surgeon, Yahya Al-Abed, took over the operation after another trainee made the first incision, the newspaper reported.  

"Patient A had begun to bleed quite heavily. Something was not right," Peter Horgan, from the General Medical Council, said in front of the Medical Practitioners Tribunal Service, referring to De Jesus as "Patient A."

"In the midst of this, Mr. Al-Abed removed what he clearly believed to be the appendix. He thought he found it, removed it and gave to a nurse what later turned out to be Patient A's ovary," Horgan said.

Senior Surgical Consultant Dr. Babatunde Coker, who was supposed to supervise Al-Abed, was not present.

De Jesus was discharged from the hospital on Oct. 31, but was re-admitted on Nov. 7 due to abdominal pains. Two days later, the doctors realized Al-Abed's error. Two days after that, De Jesus gave birth to a stillborn boy, The Telegraph reported.

De Jesus agreed to have another operation to remove her appendix, "but sadly later that afternoon Patient A died whilst on the operating table," Horgan said. An autopsy concluded De Jesus died from multiple organ failure caused by septicemia.

Al-Abed has admitted to making several mistakes the day he operated on De Jesus. Coker admits that he too failed to be present during the operation, the newspaper reported.

It is not yet clear what will happen to both doctors when the tribunal reaches a decision.