Fecal immunochemical test and small bowel lesions detected on capsule endoscopy: results of a prospective study in patients with obscure occult gastrointestinal bleeding.

Background: Fecal immunochemical test (FIT) is gaining popularity as a screening tool for colorectal cancer. The introduction of capsule endoscopy (CE) enables an assessment of the relationship between small bowel (SB) lesions and FIT results.

Aim: To determine whether SB lesions found by CE are associated with an increased rate of positive FIT.

Methods: Consecutive patients undergoing CE for obscure occult gastrointestinal bleeding also underwent FIT. CE was performed using the PillCam SB and FIT was performed with OC-Micro (three samples, threshold 75 and 100 ng/ml).

Results: Fifty-one patients were included; the mean lowest hemoglobin was 9.1 ± 2.1 g/dl. Twenty-six patients (51.0%) had SB lesions identified by CE and were classified as the probable or suspected source of bleeding. At the threshold of 75 and 100 ng/ml, 12 of 26 (46.1%) and 10 of 26 (38.4%), respectively had a positive FIT. In contrast, only two of 25 (8.0%) patients without SB lesions had a positive FIT at both thresholds (P=0.002 and 0.010 respectively). The mean fecal hemoglobin in patients with SB lesions classified as probable or suspected source of bleeding versus patients with normal SB was 345.6 ± 773 and 25.0 ± 37.7 ng/ml, respectively (P=0.025).

Conclusion: A positive FIT can be explained by significant SB lesions detected by CE. Further studies are still needed to evaluate whether asymptomatic patients with positive FIT and nonexplanatory colonoscopy should undergo further study of the SB.