Sigmoid colon morphology in the population groups of Durban, South Africa, with special reference to sigmoid volvulus.

Sigmoid volvulus demonstrates geographical, racial, and gender variation. This autopsy study was undertaken to establish morphological differences of the sigmoid colon and its mesocolon in which the length and other characteristics were assessed. A total of 590 cadavers were examined (403 African, 91 Indian, and 96 White). Length and height of the sigmoid colon and mesocolon were significantly longer in Africans, and mesocolon root was significantly narrower in Africans. Mesocolic ratio for Africans, Indians, and Whites was 1.1 ± 0.8, 1.8 ± 0.7, and 1.9 ± 1.0, respectively. Africans had a significantly high incidence of redundant sigmoid colon with the long-narrow type and suprapelvic position predominating (P = 0.003); the opposite applied to the classic type. There was no difference in sigmoid colon length, mesocolon height, and width between males and females in all population groups. Among Africans, the long-narrow type was more common in males, and the classic and long-broad types were more common in females. Splaying of teniae coli and thickening of the mesentery were more common in Africans. Tethering of the sigmoid colon to the posterior abdominal wall was less common in Africans compared with other population groups. In conclusion, the sigmoid colon was longer, and the sigmoid mesocolon root was narrower in Africans compared with the other population groups, and the sigmoid colon had a suprapelvic disposition among Africans. In Africans, the sigmoid colon was longer in males with a long-narrow shape. These differences may explain geographical and racial differences in sigmoid volvulus.