Retired neurosurgeon and Republican presidential candidate Dr. Ben Carson has responded to criticism that he blew a surgery by leaving a sponge in the patient’s brain.

Carson responded to the allegations that were originally published in a National Enquirer article, which includes references to several lawsuits against Carson. Carson stated that he has performed thousands of surgeries, and there were bound to be some problems. “But generally speaking there is no one who does the number of operations that I did who aren’t going to find some people who are going to be disgruntled,” said Carson.

When asked by host Alan Colmes about the sponge specifically, Carson offered a vague answer. “It is true that we put a certain type of sponge into pad things away and sometimes there is a reaction to that sponge and that’s what happened,” said Carson.

Listen to the exchange below.