Combination of the sensitivity of real-time PCR with an improved RHD typing assay to distinguish RHD from RHDpsi enables highly accurate prediction of fetal D status from maternal plasma. This has resulted in the implementation of a clinical noninvasive fetal RHD genotyping service.

Since ffDNA levels are normal in pregnancies without a fetus, the data support the hypothesis that the trophoblastic cells are the major source ffDNA in maternal plasma.

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Background: Mucinases and sialidases contribute to the process of invasion and colonisation in many conditions and infections of the female reproductive tract by degrading the protective cervical mucus. The role of hydrolytic enzymes in the pathogenesis of sexually transmitted diseases and their eVect on cervical mucus are discussed in this review. Methods: Articles were searched for using the keywords "sialidase," "mucinase," "protease," and "sexually transmitted infections." As well as review and other articles held by our group, searches were conducted using PubMed, Grateful Med, and the University of Bath search engine, BIDS. Results: Numerous publications were found describing the production of hydrolytic enzymes in sexually transmitted diseases. Because the number of publications exceeded the restrictions imposed on the size of the review, the authors selected and discussed those which they considered of the most relevance to sexually transmitted infections. (Sex Transm Inf 2001;77:402-408)

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Objectives To assess the accuracy of fetal RHD genotyping using cell-free fetal DNA in maternal plasma at different gestational ages.Design A prospective multicentre cohort study. Setting Seven maternity units in England.Participants RhD negative pregnant women who booked for antenatal care before 24 weeks' gestation.Interventions Women who gave consent for fetal RHD genotyping had blood taken at the time of booking for antenatal care and, when possible, at other routine visits such as for Down's syndrome screening between 11 and 21 weeks' gestation, at the anomaly scan at 18-21 weeks, and in the third trimester when blood was taken for the routine antibody check. The results of cord blood analysis, done routinely in RhD negative pregnancies, were also obtained to confirm the fetal RHD genotyping. Main outcome measuresThe accuracy of fetal RHD genotyping compared with RhD status predicted by cord blood serology.Results Up to four analyses per woman were performed in 2288 women, generating 4913 assessable fetal results. Sensitivity for detection of fetal RHD positivity was 96.85% (94.95% to 98.05%), 99.83% (99.06% to 99.97%), 99.67% (98.17% to 99.94%), 99.82% (98.96% to 99.97%), and 100% (99.59% to 100%) at <11, 11-13, 14-17, 18-23, and >23 completed weeks' gestation, respectively. Before 11 weeks' gestation 16/865 (1.85%) babies tested were falsely predicted as RHD negative.Conclusions Mass throughput fetal RHD genotyping is sufficiently accurate for the prediction of RhD type if it is performed from 11 weeks' gestation. Testing before this time could result in a small but significant number of babies being incorrectly classified as RHD negative. These mothers would not receive anti-RhD immunoglobulin, and there would be a risk of haemolytic disease of the newborn in subsequent pregnancies.

Intervillous, umbilical venous and umbilical arterial blood samples were obtained by cordocentesis or fetoscopically from 200 pregnancies at 16–38 weeks gestation. The fetuses were either not affected by the condition under investigation or it was one which would not affect blood gas and acid-base status. Blood pH, pO₂ pCO₂, bicarbonate, base excess and plasma lactate concentration were determined and ranges for each parameter are presented. Samples obtained fetoscopically were more acidotic, hypercapnic and had a greater base deficit than those obtained by cordocentesis. In the umbilical venous samples, the pCO₂ decreased, while the bicarbonate, base excess and lactate increased with gestation. In the umbilical arterial samples the pO₂ decreased and pCO₂ increased; there were no other significant changes with gestation. Similarly, in the intervillous samples the only significant change with gestation was that of a ecrease in pO₂·