A furious and grief-stricken mother in Detroit is threatening to sue after her 9-year-old daughter died after a routine tonsillectomy surgery. Sonia Gambrell is promising to sue Detroit Medical Center, which is the parent hospital of Children’s Hospital of Michigan, the hospital where her daughter, Anyialah Greer, passed away after a routine Dec. 8 surgery to remove her tonsils.

While the autopsy report hasn’t yet been finalized, there are a number of possible factors in Greer’s death, including an undiagnosed heart condition, complications from anesthesia or even an obstructed airway. Gambrell thinks that the doctors who performed the surgery discharged her improperly when she was in no condition to go home, according to media reports.

“Under federal law, you can’t discharge people unless they’re in stable condition. I don’t know how she could be considered stable when she died just hours after discharge,” James J. Harrington IV, a partner with Fieger Law of Southfield who specializes in medical malpractice, whom the family hired for representation, told the Detroit News. “What was the anesthesiologist doing? What happened in the OR? What did the nurses know? As far as I’m concerned, every single person who looked at this kid has to answer questions. I am furious about this.”

It is usually only a 40-minute procedure that involves removing enlarged tonsils and is performed every day all over the United States with almost no fatalities.

The American Academy of Otolaryngology-Head and Neck Surgery Foundation states that “tonsillectomy is one of the most common surgical procedures in the United States, with more than 530,000 procedures performed annually in children younger than 15 years. Tonsillectomy is defined as a surgical procedure performed with or without adenoidectomy that completely removes the tonsil including its capsule by dissecting the peritonsillar space between the tonsil capsule and the muscular wall. Depending on the context in which it is used, it may indicate tonsillectomy with adenoidectomy, especially in relation to sleep-disordered breathing.”