The morphology of the foetal sigmoid colon in the African population: a possible predisposition to sigmoid volvulus.

Abstract

This study aimed to determine the morphological types of the foetal sigmoid colon and establish if the anatomical predisposition to sigmoid volvulus is present in Black African foetuses. Sigmoid volvulus affects Black Africans in our province more frequently than other ethnic groups, and males more than females. Its aetiology remains speculative, with factors being proposed that do not suggest the pathogenetic mechanisms or the gender bias. Previous anatomical studies have suggested that Black Africans have a predisposition to sigmoid volvulus due to an elongated sigmoid colon. We investigated whether this phenomenon occurred during foetal development. Foetuses were donated from local hospitals. Population groups were defined as Black African and non-African. After dissection, the anatomy of the sigmoid colon was described according to level of origin, classic or elongated type and shape (broad or narrow). A total of 296 Black African foetuses and 37 non-African foetuses were donated. The sigmoid colon in the majority of foetuses in all gestational age groups had a low level of origin. An elongated colon was seen in 68% of Black African and 17% of non-African foetuses (P < 0.0001). Among Black Africans there was a higher proportion of elongated sigmoid colon among male (73%) than female foetuses (62%) (P = 0.044). In foetuses with an elongated sigmoid colon the broad shape was more common in females than males and the long-narrow shape was more common in males (P = 0.038). The elongated sigmoid colon seen in Black Africans is present in utero and occurs more frequently in Black African males. A narrow shape is more common in male foetuses and the broad shape is more common in female foetuses. These anatomical features may be the cause of the predisposition to sigmoid volvulus in Black African adults.