The health insurer Anthem is coming under intense criticism for denying claims for emergency room visits it has deemed unwarranted. A new congressional report suggests Anthem has effectively reversed that policy, even as it is being hit with a new lawsuit about it from doctors.

The insurer initially rolled out the policy in three states, sending letters to its members warning them that, if their emergency room visits were for minor ailments, they might not be covered. Last year, Anthem denied more than 12,000 claims on the grounds that the visits were “avoidable,” according to data the insurer provided to Senator Claire McCaskill, a Democrat from Missouri, one of the affected states.

But when patients challenged their denials, Anthem reversed itself most of the time, according to data the company gave Ms. McCaskill. The report concludes that the high rate of reversals suggests that Anthem did not do a good initial job of identifying improper claims, meaning some patients who did not challenge their denials may have been stuck paying big bills they should not have been responsible for.

The report also indicates Anthem has largely abandoned the avoidable visits policy, in keeping with findings The Times presented in May, using a similar data set. This year, Anthem added a list of exceptions to the policy, including emergency room visits made during the weekend, visits in which children are treated, or visits in which an advanced imaging test was ordered.