Pattern of twin placentation in Ghana

Abstract

A 2-year study involving macroscopic examination of twin placentae was conducted at the Korle Bu Teaching Hospital in Accra, Ghana to determine the proportions of the various types of twin placentation, cord insertions and number of cord vessels and their relationships. Of 765 twin-pair placentae examined, 398 (52%, 95% confidence interval [CI] 48.4%-55.6%) had fused dichorionic, 247 (32.3%, 95% CI 29.0%-35.7%) had separate dichorionic, and 119 (15.6%, 95% CI 13.1%-18.4%) had monochorionic diamniotic placentae; only one (0.1%, 95% CI 0.0%-0.8%) had monochorionic monoamniotic placentation. Of 1529 cords whose insertion could be determined, 1285 (84%) had disc, 172 (11.2%) marginal and 72 (4.7%) velamentous insertions. Only 10 (0.65%) cords had two vessels (i.e., single umbilical artery). Abnormal cord insertions (marginal and velamentous) were significantly more likely to occur in monochorionic than in dichorionic placentation (odds ratio [OR] 3.56, 95% CI 2.62-4.84), and in two-vessel than in three-vessel cords (OR 5.79, 95% CI 1.44-24.5). The prevalence of two-vessel cord in monochorionic was not significantly different from that in dichorionic placentation (OR = 0.60, 95% CI 0.10-2.67). Zygosity could be determined in 53.3% of twins from placental examination and babies' sex-pair combinations. In conclusion the most common twin placentation in Ghana is fused dichorionic. Abnormal cord insertion is more common in monochorionic than dichorionic placentation. Monoamniotic twins and single umbilical artery are less common than have been reported in other centers. Modern methods of DNA analysis are needed to establish zygosity in almost half of twin pairs.