More protests erupted. Doctors, patients and physical therapists implored the board to make another exception, this time for gynecologists who had expertise in treating men for chronic pelvic pain, a poorly understood condition that can be severe enough to leave patients unable to work.

At first, the board denied the requests. Then, in December, it said gynecologists could continue to treat men already in their care for pelvic pain, but they were not allowed to take on new cases.

The board’s troubles were still not over. On Jan. 10, a lawyer wrote, threatening to sue unless the prohibition against treating men was withdrawn. The lawyer, Tom Curtis of Nossaman LLP, based in Irvine, Calif., suggested that the ban violated antitrust laws. His client was Dr. David Matlock, an obstetrician-gynecologist in Los Angeles who performs a variety of cosmetic vaginal operations and also does liposuction on men and women. In an interview, Dr. Matlock said 4.7 percent of his patients were men.

A lawyer for the board replied to Mr. Curtis on Jan. 21, stating that the group was considering another revised definition — one that would delete the prohibition on treating men. The lawyer, Stephen L. Tatum, of Cantey Hanger LLP in Fort Worth, asked that Mr. Curtis “consider the revised definition before taking any further legal action.” Mr. Curtis provided copies of the correspondence to The New York Times.

On Thursday, the board announced its decision. The ban on treating men is gone, as is the requirement that members devote at least 75 percent of their practice to obstetrics and gynecology. Now, the board says members must devote “a majority” of their practice to the specialty.

David Margulies, the head of a public relations firm and a spokesman for the board, said in an email that the threat of a lawsuit had nothing to do with the board’s decision, and that “the changes were in the works prior to correspondence from Mr. Curtis.” Mr. Margulies said the board had begun considering the issue in November, after a New York Times article described doctors’ worries about patients at risk for anal cancer.

Stephanie Prendergast, a physical therapist in San Francisco and a past president of the International Pelvic Pain Society, a professional association, said by email that the ban on treating men had interrupted treatment plans for men with pelvic pain, and that Thursday’s decision was “a victory for patients.”