NEW YORK • A gynecologist who sexually abused vulnerable and trusting patients for over two decades at prestigious New York hospitals cried before he was sentenced Tuesday to 20 years in prison by a federal judge who called his crimes unprecedented.

The sentence for Robert Hadden, 64, was a measure of vindication for hundreds of former patients who accused the doctor of molesting them during examinations but saw an earlier prosecution end with a plea bargain that spared him from jail.

Given his chance to speak Tuesday, Hadden stood with his hands folded before him to say that there was “much I’d like to say” but that he had been advised by his lawyers to keep his statement brief.

“I’m very sorry for all the pain that I have caused,” a sobbing Hadden said before dropping his head down as he sat again. He then took off his glasses and wiped tears from his eyes.

In statements over the past two days, U.S. District Judge Richard M. Berman said the case was like none he’d seen before and involved “outrageous, horrific, beyond extraordinary, depraved sexual abuse.” He noted that at least 245 women Hadden treated said they were abused.

The federal trial involved a smaller number of victims. Hadden was convicted of four counts of enticing women to cross state lines so he could sexually abuse them.

Nine victims testified at the trial, describing how Hadden molested them during gynecology treatments, starting in the late 1980s, at prominent hospitals, including Columbia University Irving Medical Center and NewYork-Presbyterian Hospital.

Allegations of misconduct during examinations first surfaced in 2012. Hadden was indicted on state charges in 2014 as women — 19 and counting — kept coming forward.