Q&A: Rectal fistula scenario with new ICD-10-CM code

Q: An elderly male patient has a rectal fistula with an abscess requiring complex packing of the wound. The most recent wound documentation reports “complex persistent rectal fistula with underlying abscess present, cultures show positive for E. coli and Klebsiella.” The patient will be administered daily IV antibiotics via a PICC line that has been placed. How would this encounter be reported in ICD-10-CM?

A: The ICD-10-CM codes for this encounter are:

• K60.422, rectal fistula, complex, persistent
• K61.1, rectal abscess
• B96.20, unspecified Escherichia coli [E. coli] as the cause of diseases classified elsewhere
• B96.1, Klebsiella pneumoniae [K. pneumoniae] as the cause of diseases classified elsewhere
• Z45.2, encounter for adjustment and management of vascular access device
• Z79.2, long term (current) use of antibiotics

According to the provider’s statement, the primary diagnosis is a complex persistent rectal fistula with an underlying abscess. For FY 2025, coders can now find multiple codes for rectal fistulas under ICD-10-CM subcategory K60.4.-. A complex persistent rectal fistula is reported with code K60.422, found under subcategory K60.42- (rectal fistula, complex).

There is a note to also code abscesses, if applicable, with codes from the K60.42- subcategory. In this case, coders would reference category K61.- (abscess of anal and rectal regions) to find the appropriate code. Then coders would report the organisms involved with the abscess: B96.20 for the E. coli and B96.1 for the Klebsiella. That will cover the infected rectal abscess.

Make sure to code both the fistula and abscess, although the coder could sequence the codes in a different order. If you had a patient with the same conditions, you could code the abscess and bacteria first and then code the fistula after. The code also note used earlier is not sequencing directions; it is just a note saying that both conditions should be coded. As long as both conditions are reported, the coder can report either one first based on the focus of care.

Coders want to make sure codes are assigned to identify that the patient will have long-term use of antibiotics through a PICC line. Code Z45.2 is used for routine care of vascular access devices, including peripheral, PICC, and central lines.

Codes classifiable to ICD-10-CM category Z79.- (long term [current] drug therapy), however, should not be assigned as primary diagnoses. When the management of any of these medications is integral to the plan of care, consider the confirmed diagnosis for which the patient is taking the medication as the primary diagnosis. 

Editor’s note: This question and answer was originally excerpted from the DecisionHealth webinar, “Ensure Compliance with the Final 2025 ICD-10 Code Update,” presented by Brandi Whitemyer, RN, CDIP, COS-C, HCS-D, HCS-O, an independent home health and hospice coding consultant with expertise in post-acute billing and coding education. It was also republished in JustCoding.