Mother-of-three Maria De Jesus, 32, was 20 weeks pregnant with her fourth child when she was admitted to Queen's Hospital in Romford, Essex, a Fitness to Practise Panel of the Medical Practitioners Tribunal Service (MPTS) heard.
The "complicated" operation was carried out at the weekend by a junior surgeon who removed her ovary in error, while the more senior consultant had gone home.
Less than three weeks later she was readmitted with abdominal pains and the mistake was discovered.
Two days after that Ms De Jesus, from Dagenham, miscarried her baby boy and died on the operating table after having the appendix removed. Dr Yahya Al Abed admitted removing Ms De Jesus' right ovary in error at the panel hearing sitting in Manchester. He denies misconduct.
Peter Horgan, lawyer for the MPTS told the panel the patient was first admitted suffering abdominal pains on October 21, 2011, to Queen's Hospital.
She was seen by a surgical registrar, Dr Christopher Liao and the consultant general and surgical lead Dr Babatunde Coker. An appendectomy was recommended.
Ms De Jesus was put on the emergency surgery list. It was agreed Dr Al Abed would carry out the procedure and Dr Coker left. Ms De Jesus was discharged eight days later then re-admitted on November 7.
Two days later another doctor found her ovary had been removed. On November 11, she had a stillborn baby and her appendix was removed.
The hearing continues.