Nagoya University Hospital said Wednesday its medical team left gauze inside a woman's body in a 1970 operation and that it stayed there for around 44 years, with the patient complaining of stomach pain for many years.

The thin fabric was found in 2014 when the hospital in central Japan performed an operation on the woman's rectum to remove a tumor. The patient, an Aichi Prefecture resident in her 80s, had been diagnosed with a tumor in her pelvis at the hospital in April that year.

After doctors cut a part of the rectum in the operation, a cloth-like object was found with the tumor, according to the hospital.

The hospital admitted the possibility that the stomach pain or tumor might have been caused by the left gauze.

The woman underwent the 1970 surgery to treat infertility. As she never had an operation afterward until the recent surgery, the hospital concluded there is a high possibility that the doctors forgot to remove the gauze.

The hospital has apologized to the woman and completed paperwork to compensate her. It revealed the malpractice after gaining the woman's consent.