From the Guidelines
Yes, Crohn's disease can coexist with perianal fistula and normal colonoscopy results.
Key Points
- Perianal disease is a common manifestation of Crohn's disease, with perianal fistulas developing in 20% of patients and recurring in approximately 30% of cases 1.
- Colonoscopy with ileal intubation allows direct visualization of mucosal inflammation and ulceration, but may not detect transmural disease with overlying normal mucosa, which can be present in patients with perianal fistulas 1.
- Cross-sectional imaging, such as CT enterography or MR enterography, can detect penetrating disease, including fistulas, and is complementary to endoscopy in the diagnosis and management of Crohn's disease 1.
- Pelvic MRI is the most accurate test for the detection and characterization of perianal Crohn's disease, and should be used to assess perianal fistulas before surgical intervention or to assess disease activity 1.
- The presence of perianal fistulas can occur in patients with normal colonoscopy results, as the disease can be transmural and not always visible on endoscopy 1.
From the Research
Coexistence of Crohn's Disease and Perianal Fistula
- Crohn's disease can coexist with perianal fistula, as evident from studies that have investigated the relationship between the two conditions 2, 3, 4, 5, 6.
- Perianal fistulas are a common complication of Crohn's disease, occurring in up to 50% of patients with the condition 5.
- The presence of perianal fistula can be an indicator of Crohn's disease, particularly if the fistula is complex or recurrent 2, 4.
Normal Colonoscopy Results
- It is possible for Crohn's disease to coexist with perianal fistula even if colonoscopy results are normal 2.
- A study found that 16 out of 302 patients with perianal fistula had Crohn's disease, despite normal colonoscopy results 2.
- The study suggests that colonoscopy may not always detect Crohn's disease, particularly if the disease is limited to the perianal area or if the colonoscopy is performed during a period of remission 2.
Diagnostic Considerations
- The diagnosis of Crohn's disease in patients with perianal fistula can be challenging, and may require a combination of clinical evaluation, laboratory tests, and imaging studies 3, 4, 6.
- Parameters such as age, BMI, abdominal pain, and platelet count can be used to predict the presence of Crohn's disease in patients with perianal fistula 2.
- Fecal calprotectin levels can also be used as a screening tool to identify patients with perianal fistula who may have Crohn's disease 4.