Objective: To determine whether labor or fetal membrane rupture adversely affects the ability of ultrasound to accurately estimate fetal weight (EFW) in a twin gestation.
Study design: A medical record audit was performed of the two-year experience of women delivering live born twins and undergoing a complete ultrasound examination within 72 hours of delivery. Those patients experiencing labor or membrane rupture at the time of the previous ultrasound examination were compared to those without these factors to determine if there was any detrimental impact on the accuracy of ultrasound to EFW.
Results: The overall ability of ultrasound to accurately EFW was in the range of 64-76%. This was not significantly different from the accuracy in women experiencing labor (62-80%) or in women with membrane rupture (63-81%). The ability of ultrasound to detect fetal discordance is this series ranged from 78% to 100%, with specificity that ranged from 84% to 89%.
Conclusion: The ability of sonography to accurately EFW as well as detect discordant twin gestation is not altered by the presence of labor or membrane rupture.