A retrospective study of 400 consecutive case records was made to establish the clinical significance of the low lying placenta found on ultrasound. Diagnostic accuracy is discussed. 30% of the patients had a low lying placenta on early scan. Of these, 73% had a follow up scan. There was a progressive drop in the incidence of low lying placentae through pregnancy until at term, in this study, there was no placenta previa. It is considered that a repeat scan is necessary to exclude placenta previa, but not until 34 weeks gestation. Amongst the patients with early low lying placentae the incidence of antepartum haemorrhage of indeterminate type was significantly high (P less than 0.001). A careful surveillance of these patients is therefore required. Dynamic placental migration may be the cause of this bleeding. Further study is necessary to determine the effect of early placental position on subsequent fetal development.
Objectives: To compare the DELFIA Xpress and Quantikine ELISA placental growth factor (PlGF) immunoassay platforms by analysing the same set of early first-trimester maternal serum samples from cases with trisomy 21 and euploid controls. Methods: Thirty-seven trisomy 21 cases and 243 euploid control serum samples, drawn at 8+0 to 10+6 weeks of gestation, were reanalysed by Quantikine PlGF ELISA following original analysis on the DELFIA Xpress platform. Results: PlGF levels increased with gestation in the euploid controls when measured on both platforms, although raw levels were in general lower on the DELFIA Xpress. After conversion to multiples of the median (MoMs), PlGF was increased in trisomy 21 cases when measured on the DELFIA Xpress platform (euploid: 1.00 MoM, trisomy 21: 1.32 MoM, p < 0.0001) but unchanged when measured on the Quantikine ELISA (euploid: 1.01 MoM, trisomy 21: 1.06 MoM, p = 0.84). Conclusions: Discrepancies exist in the measurement of PlGF when performed on these different platforms, which may to some extent contribute to the inconsistencies found in the literature with regard to PlGF in trisomy 21 pregnancies.
Authors' Contribution HK conceived the idea of the research and wrote the manuscript. AW carried out the experimental work and YM, Summaya K and Salman K helped hiim. AK and IK helped in the execution of the experiments. SA and NK analysed of the data statically.
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