A 28-year-old man with Crohn's disease has a fistula from the terminal ileum to the sigmoid colon (enteroenteric fistula). He is on infliximab for 12 months with poor fistula response. Montreal classification of his disease is A2L3B3p. Per ECCO 2023 guidelines on complex perianal/internal fistulising Crohn's, the next step is:
- A Switch to adalimumab — interchangeability between anti-TNFs improves fistula closure
- B Add azathioprine to infliximab — combination shown to improve mucosal healing in SONIC trial which should apply to fistulising disease
- C Ustekinumab or vedolizumab as second-line biologic after anti-TNF failure for complex fistulising disease ✓
- D Surgical resection of the involved terminal ileum is preferred over any further biologic therapy
Explanation
Montreal classification B3 indicates penetrating/fistulising behaviour. After failure of first anti-TNF (infliximab), second-line biologic options include ustekinumab (anti-IL-12/23, UNIFI/CERTIFI trials in CD) and vedolizumab (anti-integrin α4β7, GEMINI-2 trial). ECCO 2023 guidelines recommend switching mechanism of action — not simply to a different anti-TNF — for secondary anti-TNF failure in fistulising disease. Ustekinumab has demonstrated fistula response in real-world data. Surgical resection is appropriate for simple enteroenteric fistulas not responding to medical therapy but should be preceded by optimised medical management per ECCO guidance.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.