A patient presents for a diagnostic colonoscopy but experiences a large obstruction at the splenic flexure. What code should be reported for the procedure?

The appropriate code to report in this scenario is 45378-53. This is because 45378 refers to a diagnostic colonoscopy with the application of an additional procedure or the use of a modifier indicating that a significant portion of the procedure was altered. The "-53" modifier specifically denotes that the procedure was discontinued due to extenuating circumstances, in this case, the large obstruction discovered at the splenic flexure.

Using the correct modifier is crucial as it provides additional context about why the procedure did not proceed to completion. In this scenario, since the colonoscopy encountered an obstruction that prevented further exploration, using the -53 modifier accurately reflects the situation to meet coding guidelines. This reinforces the importance of not only selecting the appropriate procedure code but also applying the correct modifiers to convey the specifics surrounding the completion of the procedure.

The other codes listed either do not accurately represent the scenario (as they do not account for the obstruction or the discontinuation of the procedure with the necessary modifier) or describe different procedures that would not apply in this context.