A medical malpractice plaintiff properly amended his lawsuit three years after filing to add an allegation that his gastroenterologist failed to diagnose him with appendicitis, a divided appeals court ruled.

On April 13, 2009, Divyang Parikh performed a colonoscopy on plaintiff Peter Mackauer, according to court papers.

About one week later, Mackauer returned to Parikh in a “highly emotional state” and complaining of abdominal pain. Parikh allegedly refused to physically examine him and advised him to see a psychiatrist.

On April 23, 2009, Mackauer went to an emergency room and was diagnosed with acute perforated appendicitis.

In 2011, Mackauer sued Parikh and Parikh’s employer, alleging that Parikh punctured his appendix during the colonoscopy.

Expert witnesses for both sides agreed Mackauer’s appendix was not perforated by the colonoscopy, but Mackauer’s witness said the plaintiff showed symptoms of appendicitis during his follow-up visit.

In 2014, Mackauer served an amended bill of particulars in Mackauer v. Parikh, 102150/11, that, while not mentioning “appendicitis” specifically, added the theory that Parikh failed to conduct tests to determine why Mackauer was suffering abdominal pain.

Staten Island Supreme Court Justice Judith McMahon denied the defendants’ subsequent motion for summary judgment.

On Wednesday, a 3-2 panel of the Appellate Division, Second Department affirmed McMahon. Justices Jeffrey Cohen, Sylvia Hinds-Radix and Francesca Connolly found that Mackauer’s new bill adequately theorized that Parikh deviated from the accepted standard of care.

Writing in dissent, Justice Mark Dillon, joined by Justice Sheri Roman, wrote that Mackauer advanced a new theory of liability in his amended bill and thus it should not have been admitted.

Theodore Thornton of the Law Offices of Joseph Lichtenstein represented Mackauer.

Neil Schreffler of Vaslas Lepowsky Hauss & Danke represented the defendants.