Small-bowel capsule endoscopy (SBCE) allows a functional segmentation of the intestine into temporal tertiles (SB1-SB3). Although vascular lesions are often described in proximal and distal regions, the overall topography of small-bowel pathology and its relationship with transit and diagnostic yield remain poorly defined.

This study aimed to characterize the functional distribution of small-bowel lesions and to explore how small-bowel transit time (SBTT) influences diagnostic performance.

We retrospectively reviewed 604 complete SBCEs with measurable gastric (GTT) and small-bowel transit times.

Lesions were classified as vascular, erosive, ulcerative, hemorrhagic, structural, or neoplastic, and localized within SB1–SB3 using standardized text-based mapping.

To assess the relationship between SBTT and diagnostic yield, transit time was stratified into three duration groups (short, intermediate, long) corresponding to the lower, middle, and upper thirds of its distribution. Statistical comparisons used χ², Mann–Whitney, and Kruskal–Wallis tests.

The cohort had a mean age of 63.7 ± 17.7 years (50.2% female).

Mean gastric transit time (GTT) was 35.2 ± 24.6 min, showing a mild, non-significant trend toward longer values with age (p > 0.05) and no sex-related differences (p > 0.3). Mean SBTT was 295.7 ± 118.1 min, increasing significantly with age (p < 0.01) and in males (p < 0.05).

Vascular, erosive, ulcerative, and hemorrhagic lesions followed a bimodal proximal–distal pattern (all p < 0.0001), while structural and neoplastic lesions were evenly distributed.

Overall diagnostic yield was 80%. Examinations with positive findings had longer SBTT (300.6 vs 276.1 min, p < 0.05). The likelihood of detecting relevant lesions increased progressively across the three SBTT duration groups (76.8%, 77.4%, and 85.6%; p < 0.05).

Functional topography analysis reveals distinct proximal–distal clustering of vascular and inflammatory lesions, suggesting specific pathophysiologic mechanisms along the small-bowel axis. Longer SBTT was associated with higher diagnostic yield, identifying transit time as a potential quality metric in SBCE. These findings support a more physiologic interpretation of capsule studies and may inform strategies to optimize visualization and reporting.