Hank Williams Jr.'s Wife Mary Jane Thomas' Cause of Death Confirmed By Coroner 4 Months After Death

The cause of death for Mary Jane Thomas, the wife of country singer Hank Williams Jr., has been revealed.

Thomas, 58, died on March 22 of a collapsed lung that was punctured during elective surgery the day before, according to a report from the Palm Beach County Medical Examiner as well as an autopsy report, which were obtained by PEOPLE. The cause of death was listed as accidental.

The autopsy lists the cause of death as "pneumothorax due to perforated parietal pleura during liposuction with autologous fat reinjection procedure."

The parietal pleura is a membrane that's bound by connective tissue to the inner surface of the chest wall, and plays a major role in the formation and removal of pleural fluid, according to Science Direct. The autopsy indicates that Thomas' lung collapsed after her surgeon punctured the membrane while completing the fat transfer as part of a breast lift following a breast implant removal.

The former model, who lived in Nashville, had traveled to Jupiter, Florida to undergo liposuction, as well as to remove previous breast implants at Bafitis Plastic Surgery. She was cleared for the procedures by a physician at home, according to the Medical Examiner's report.

Frank Mullen/WireImage Hank Williams Jr. and Mary Jane Thomas in 2002

A representative for Bafitis Plastic Surgery did not immediately respond to PEOPLE's request for comment, nor did a spokesperson for Williams.

She was released from the facility around 7 p.m. on March 21, and was taken to a recovery facility, according to the report. Thomas was "sitting up in bed, speaking normally" the next day when she "suddenly" became unresponsive.

Thomas was rushed to a local hospital and died in the emergency room, the report said.

RELATED: Hank Williams Jr.'s Wife Mary Jane Thomas Has Died: 'A Beautiful Soul'

Jason Kempin/Getty Mary Jane Thomas and Hank Williams Jr. in 2021

The Medical Examiner's report said that Thomas' surgeon said her vitals were normal, and she was given Lovenox, an anticoagulant.

The autopsy report listed seven other findings, including mild brain swelling, mild coronary artery disease and fatty metamorphosis of the liver (which is a common finding in people who, like Thomas, had a history of alcoholism).

She and Williams, the 73-year-old son of late country legend Hank Williams, met in 1985 at one of his concerts and were married in 1990. They shared daughter Katherine, who died in a car crash in 2020, and son Samuel, a musician.

Ron Galella/getty Hank Williams Jr. and wife Mary Jane Thomas in 1989

Sam, 25, paid tribute to his late mother in a statement to PEOPLE shortly after her death.

"My dear Mama Mary Jane was a beautiful soul who forever affected everyone who knew her. She had a smile and presence that lit up every room and she never met a stranger she didn't befriend. Her spirit was gentle and giving. She could take down a ten-point buck and fix dinner for her grandchildren at the same time! Now she gets to radiate from above with my sister Katherine Diana right by her side," he wrote, referencing his late sister.

"She grew up competing in baton and cheerleading and was one of Hawaiian Tropic's top models.  My father fell in love with the Daytona Beach beauty the minute he set eyes on her in the early '80s. They went on to live the most powerful love story of travel and hunting and raising a family. She is survived by my father, her two parents Ramona and Bill, her brother Andy, her sister Angela, myself and her three grandchildren: Beau Weston, Tennyson Hiram and Audrey Jane. Rest in peace Mama, I will always be the son of Mary Jane."