Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology
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Ultrasound Obstet Gynecol · Oct 2005
Comparative StudyUltrasound dating at 12-14 weeks of gestation. A prospective cross-validation of established dating formulae in in-vitro fertilized pregnancies.
To determine the accuracy of established ultrasound dating formulae when used at 12-14 weeks of gestation. ⋯ We have identified three BPD formulae that are suitable for dating at 12-14 weeks of gestation. They are superior to all 21 CRL formulae tested here, because their random measurement errors were much smaller than those of the three best CRL formulae. The small systematic negative measurement errors associated with the BPD formulae are likely to be clinically unimportant.
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Ultrasound Obstet Gynecol · Oct 2005
Effects of maternal hyperoxia with and without normocapnia in uteroplacental and fetal Doppler studies.
One hundred percent oxygen is given in pregnancy to improve fetal oxygenation, yet has been shown in both animal and human studies ex utero to increase cerebral vascular resistance. Adjusting end-tidal pCO2 (ET-pCO2) levels to normocapnic levels during hyperoxygenation offsets this effect in non-pregnant individuals. We aimed to evaluate the effect of maternal hyperoxygenation with and without maintaining normocapnia on the fetal and uteroplacental circulations in healthy near-term human pregnancies. ⋯ Maternal and fetal circulations exhibit divergent responses to 100% oxygen and NH. While no change is observed in the uteroplacental circulation on 100% oxygen, decreased resistance and increased flow velocity are evident during NH. Increased umbilical artery PI during NH with no change in absolute velocities may suggest a reduction in fetoplacental blood flow. Maintaining normocapnia during hyperoxygenation does not appear to beneficially influence the circulation of the near-term human fetus as it does in non-pregnant individuals.