NEW YORK (CBSNewYork) — There was a shocking mistake at one of New York City’s top hospitals. A patient went in to Mount Sinai Medical Center for kidney surgery, and the wrong one was removed.

One of the city’s most prestigious teaching hospitals in the country was under scrutiny Friday after admitting that one of its surgeons removed the wrong kidney from a patient.

“That’s horrible, that’s horrible. I mean, how did he make that mistake?” Mount Sinai patient Deborah Sutton told CBS 2’s Janelle Burrell.

Officials at Mount Sinai said the mistake happened in part because the 76-year-old patient had two bad kidneys, but the doctor took the wrong one out.

Sutton said she has had surgery at the hospital before.

“Anything can happen, but you’re a professional, you should make sure,” Sutton said.

Mishaps during surgery happen more often than you may think. According to a Johns Hopkins study, these so-called “never-events” happen more than 4,000 times a year in the United States.

The study revealed that surgeons across the country perform wrong procedures on patients 20 times a week, and that doctors operate on the wrong body parts 20 times per week as well.

“There’s no good excuse for removing the wrong organ. There’s no way you can say this is the normal course of doing business,” malpractice attorney Rosemarie Arnold told CBS 2’s Burrell.

Arnold said the error is grounds for malpractice.

Mount Sinai security tried to block CBS 2’s camera from filming outside on Friday. Meanwhile, hospital officials offered a statement, which said: “This event should never have occurred at Mount Sinai. Immediately after completing an initial investigation, we relieved the surgeon from his clinical and administrative responsibilities pending further review and investigation.”

Some of the hospital’s patients came to its defense.

“It’s been totally professional here. Everything is above the board and I feel great. They did a great job on me,” patient Paul DelPriore said.

As for the kidney patient, the hospital said surgeons went back and removed the second kidney and that the patient is doing fine and living on dialysis. According to the hospital, the 76-year-old man said he still has enormous faith in the doctor, who has operated on him before.

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