Current practices in determining amnionicity and chorionicity in multiple gestations

Objective: To evaluate the accuracy of amnionicity and chorionicity (A/C) diagnosis of referral physicians and a tertiary care center as compared to histopathologic diagnosis. Method: A retrospective study of 289 multi-fetal gestations was performed comparing A/C diagnoses of referring physicians, a tertiary care center, and histopathology. Results: Two hundred and eighty-nine multi-fetal pregnancies were referred for evaluation; only 43.6% (126/289) carried an accurate diagnosis of A/C before tertiary care center evaluation. The tertiary care center accurately identified A/C in 94.8% (274/289) overall and 100% in first trimester twins and triplets. Referrals with an unspecified A/C diagnosis included 46.1% (113/245) twins and 64.1% (25/39) triplets. Conclusion: Accurate diagnosis of A/C can be obtained by the early assessment of key sonographic findings. Referral providers are less accurate at determining A/C of mutifetal gestation when compared to a tertiary center, suggesting that an emphasis should be placed on enhancing these diagnostic skills in the general community or encouraging referral when diagnosis is ambiguous.