The comedian died in September of brain damage due to lack of oxygen after she stopped breathing during an endoscopy. She was 81.
The federal Centers for Medicare and Medicaid Services cited the clinic, Yorkville Endoscopy, for several errors, including failing to identify deteriorating vital signs and provide timely intervention.
PHOTOS: Joan Rivers Through The Years
The clinic had until Jan. 7 to correct problems. The federal agency said Thursday that compliance date has been postponed, because its final report isn't ready.
The clinic could lose its Medicare accreditation. It hasn't returned a call for comment.
Following Rivers' death, there were also changes to the clinic's management; Dr. Lawrence Cohen is no longer the clinic's medical director as of September 2014.
Negligence was not alleged. Rivers' daughter has hired a malpractice attorney to look into her death.
A report issued in November 2014 indicated that Joan Rivers did not consent to a laryngoscopy during which she lost consciousness due to lack of oxygen, and also claimed that physicians did not intervene properly as her condition worsened.
Rivers' daughter, Melissa Rivers, said through her attorneys that the "multiple failings" amounted to more "misconduct and mismanagement" at the clinic.
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