From the Supercoder 2011 GI Survival Guide:
For Medicare and other payers that follow Medicare guidelines, you should append modifier 53 (Discontinued procedure) to 45378 (Colonoscopy, flexible, proximal to splenic flexure; diagnostic, with or without collection of specimen[s] by brushing or washing, with or without colon decompression [separate procedure]) for an incomplete colonoscopy.
You can find these instructions in Chapter 12, Section 30.1.B of the Medicare Claims Processing Manual. Medicare also includes a separate fee schedule line item for 45378-53, consistent with the MCPM guidelines, which states:
An incomplete colonoscopy (e.g., the inability to extend beyond the splenic flexure) is billed and paid using colonoscopy code 45378 with modifier 53. Although, failure to extend/evaluate beyond the splenic flexure could also mean that a sigmoidoscopy, 45330 (rather than a colonoscopy, 45378) has been performed. However, 45330 will not be reported in this scenario since, the physician aimed to perform colonoscopy (which remained incomplete due to inability to extend the scope beyond splenic flexure). .
Important: The above guideline assumes that the physician intended to perform a colonoscopy rather than a sigmoidoscopy. If the physician intended to perform a sigmoidoscopy, you would report 45330 (Sigmoidoscopy, flexible; diagnostic, with or without collection of specimen[s] by brushing or washing [separate procedure]) rather than 45378-53.
If your physician intended to do a complete colonoscopy (the patient was prepped for a colonoscopy, he used a standard colonoscope and medicated the patient for a colonos copy), and the documentation clearly states that he passed the splenic flexure, you may report a complete colonoscopy using 45378.
When the physician passes the splenic flexure, CPT considers a colonoscopy complete, and you may report it as such, with no reduced- or discontinued-service modifiers.
If the physician does not pass the splenic flexure, however, (and, again, the physician intended to perform a colonoscopy and prepped the patient as such), the procedure is an incomplete colonoscopy (i.e, 45378 to be reported with modifier 53).
AMA Gives Different Directions
In direct contradiction to CMS guidelines, CPT instructs you, “For an incomplete colonoscopy [in other words, the scope does not progress beyond the splenic flexure], with full preparation for a colonoscopy, use a colonoscopy code with the modifier 52 [Reduced services] and provide documentation.”