D.C. Code § 44-303.01: When a health care provider leaves a plan.

If a contract between an insurer and a health care provider is terminated by either party for any reason other than termination for failure to meet applicable quality standards of care or fraud, and a member is undergoing a course of treatment from the physician at the time of the termination, the insurer shall notify the member on a timely basis of the termination. When medically necessary, persons with serious illness undergoing a course of treatment or who are in the second trimester of a pregnancy shall be permitted to continue to receive medically necessary covered services, with respect to the cause of treatment, by the physician, certified nurse-midwife, or certified midwife during a transitional period of at least 90 days from the date of the notice under the same terms and conditions as specified under the provider contract.