A British man had to undergo emergency surgery after doctors left a pair of eight-inch long forceps inside his body during an appendix operation.
British medics in a hospital in Kent discovered the surgical instrument weeks after the man returned to the clinic for a routine X-ray.
Authorities from East Kent Hospitals University NHS Foundation Trust said Monday that an investigation has been launched.
"These are events that shouldn't happen and happen very, very rarely," said Julie Pearce, chief nurse at East Kent Hospitals University Foundation Trust, according to KentOnline.
"In the last three years, we've only had one of those events and each year we do about 90,000 surgical procedures," Pearce said.
Doctors are usually required to count for all surgical tools before and after an operation to check if any are missing.
"What normally happens is that if the count doesn't match up, an X-ray is done while the patient is still in theater," she said. "In this case, staff hadn't completely adhered to policy. They had scanned the patient's abdomen, but hadn't done a full X-ray."
The recent case of the forceps being left in a patient's body happened in April, and is one of three similar incidents at hospitals in the UK in the last three years.
In one case, documented by the Medway NHS Foundation Trust, a drill bit had broken off in a patient's femur bone and another patient had a small piece of a drill left inside the palm of their hand.
While the man from Kent who had an eight-inch surgical tool left in his body had to undergo emergency surgery, in both previous cases, doctors decided that the drill bits should be left inside the patients.
"If the dangers of going in again to remove it are greater than leaving it there, that's something that needs to be assessed at the time," said Dr. Mike Smith, vice chairman of the Patients' Association, according to KentOnline.
"But whenever there are humans involved something must go wrong - obviously if it could be avoided completely that would be ideal," he added.