Reproducibility and Accuracy of 2D and 3D ultrasound parameters in the prediction of birthweight in pregnancies with low serum PAPP-A

Abstract

Background: Currently used methods to estimate fetal size in the third trimester, are suboptimal in detecting fetal growth restriction. Inclusion of a 3D ultrasound fractional thigh volume within an estimated fetal weight model may provide a more accurate estimate of fetal size. Low first trimester maternal serum Pregnancy associated plasma protein-A (PAPP-A 0.99) and have a low measurement error especially in the third trimester. Inclusion of Tvol within an estimated fetal weight (EFW) model provided a more accurate in utero-assessment when compared to birthweight than any 2D EFW model (BPD-AC-Tvol ICC 0.96 [0.93 – 0.98] Versus Hadlock HC-AC-FL ICC 0.93 [0.85 – 0.96]). Findings from this thesis suggest that pregnancies affected by low PAPP-A are associated with a reduction in skeletal growth across gestation compared with a non-low PAPP-A. The reduction in skeletal growth remained consistent for low PAPP-A with and without PD. Reduction of skeletal and adipose growth was also shown in those with PD and low PAPP-A. Discussion: The addition of Tvol, especially in the third trimester, improved the accuracy and reproducibility of EFW models. While within the low PAPP-A cohort, a novel growth pattern of reduced skeletal growth was identified. A subgroup of fetuses within the low PAPP-A cohort were identified as SGA; One cohort with reduced skeletal mass without PD, the other with PD, likely leading to a nutritional deficit leading to a smaller overall size. Therefore, women with low PAPP-A without PD may benefit from alternative scan surveillance, antenatal care and timing of delivery from current practice.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Edward Johnstone (Supervisor) & Jenny Myers (Supervisor)