Title: P17 Quantitative analysis of placental microstructure in pregnancies complicated by pre-eclampsia with and without intrauterine growth restriction.
Abstract: The aim of this study was to quantify placental morphology in pregnancies complicated by pre-eclampsia with and without intrauterine growth restriction, paying particular attention to the dimensions and composition of peripheral (intermediate + terminal) villi. Placentas from control pregnancies (n = 9) and cases of pre-eclampsia (PE, n = 5), intrauterine growth restriction (IUGR, n = 5) and pre-eclampsia with intrauterine growth restriction (PE+IUGR, n = 5) were randomly sampled for microscopic evaluation. PE was defined by significant maternal proteinuria (greater than 300 mg/L in a 24 h collection in the absence of urinary tract infection) and a blood pressure in a previously normotensive woman of higher than 140/90 mmHg on 2 or more occasions. IUGR cases were identified by deficient fetal growth on ultrasound scans and the final decider was an individualised birth weight ratio (IBR) below 10. IBR relates to a predicted birth weight calculated using factors including fetal sex, gestational age, parity, ethnic origin, maternal age, maternal height and booking weight. It provides a better correlation with perinatal outcomes than birthweight for gestational age alone. Most IBR values in IUGR were below 5. Only one IUGR case was confirmed as having absent end-diastolic flow in the umbilical artery. Formalin-fixed, wax-embedded sections stained by the Masson trichrome method were analysed stereologically in order to estimate the volumes of placental components and the surfaces and diameters of villi and fetal capillaries. Group comparisons were drawn using 2-way analysis of variance. Fetal weights were reduced in all complicated pregnancies but only IUGR was accompanied by a significantly smaller placenta. PE had no main effect on placental morphology and (except for trophoblast thickness) there were no interaction effects involving PE. In contrast, IUGR was associated with a placenta which had reduced volumes of intervillous space and all types of villi (stem, intermediate, terminal). The impoverished growth of peripheral villi affected all tissues (trophoblast, stroma, capillaries) and was accompanied by smaller exchange surface areas and a thicker trophoblastic epithelium. Mean diameters of villi and capillaries were not affected. This study emphasises the importance of proper categorisation of subjects when studying cases of PE and IUGR. We conclude that IUGR, but not PE, produces substantial changes in placental morphology including impoverished growth of villi and fetal microvessels. These changes are likely to reduce placental oxygen diffusive conductances and contribute to fetal hypoxic stress.
Publication Year: 2002
Publication Date: 2002-11-01
Language: en
Type: article
Indexed In: ['pubmed']
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Cited By Count: 1
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