Pattern of twin placentation in Ghana.

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. had monochori-onic diamniotic placentae; only one (0.1%, 95% CI 0.0%–0.8%) had monochorionic monoamniotic pla-centation. 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 vela-mentous) 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. Twin pregnancies may have monochorionic diamni-otic, monochorionic monoamniotic, fused dichorionic or separate dichorionic placentation. In general, a greater proportion of twins are dichorionic than monochorionic (Hanley et al. Victoria et al., 2001) although a greater proportion of monochorionic was reported in Japan over 20 years ago (Yoshida & Soma, 1984). Monochorionic twins have been reported, when compared to dichorionic, to have higher incidences of preterm birth, severe birthweight discordance, low birthweight, perinatal mortality of at least one twin and admission to the neonatal intensive care unit (Ferreira et al. The prevalence of abnormal umbilical cord insertion (UCI; velamentous or marginal) and of single umbilical artery are more common in twin than in singleton pregnancies (Benirschke, 1995), and in twins the prevalence of abnormal UCI is reported to be higher in monochorionic than in dichorionic pla-centation (Hanley et al., 2002). Both abnormal UCI and single umbilical artery are associated with increased risk of adverse pregnancy outcomes (Hanley et al., 2002; Victoria et al., 2001) Where there is a single placental mass, macro-scopic examination of the fetal surface and the septum separating the two cavities should be used …