Small Intestine and Vermiform Appendix Lengths in Healthy Adults: Intraoperative Morphometric Data from a Living Donor Cohort.

Background/Objectives: Small intestine and vermiform appendix lengths are critical anatomical parameters with significant implications for bariatric surgery, transplantation, and the management of short bowel syndrome. However, reliable normative data derived from direct in vivo measurements in healthy individuals remain limited. This study aimed to establish reference values in a homogeneous cohort of healthy living liver donors and to investigate the potential anatomical and functional correlation between these two structures based on their shared embryological origin and immunological roles. Methods: Data from 99 healthy living liver donors representing a multi-ethnic population were analyzed. Intraoperative measurements were performed using a standardized surgical technique: small intestine length was measured from the ligament of Treitz to the ileocecal valve, and appendix length from the base to the tip. Relationships between morphometric measurements and anthropometric variables were evaluated. Results: The mean small intestine length was 630 ± 104.7 cm, and the mean appendix length was 84.8 ± 21.1 mm. Small intestine length was significantly greater in males (p = 0.011), while appendix length showed no sex-based difference. A weak but statistically significant positive correlation was found between small intestine length and appendix length (r = 0.237; p = 0.021). Furthermore, an appendix length ≥ 8 cm was associated with a higher probability of having a small intestine length > 600 cm. Notably, the retrocecal appendix position was observed in only 4.0% of donors, a prevalence substantially lower than that reported in appendicitis series, suggesting it may be a risk factor for inflammation. Conclusions: This study reports descriptive measurements of small intestine and appendix lengths in healthy individuals undergoing donor hepatectomy. The relationship between the appendix and the small intestine appeared weak and should be interpreted as exploratory, warranting further investigation without implications for clinical decision-making.