Feto-maternal transfusion after chorionic villus sampling. Evaluation by maternal serum alphafetoprotein measurement

Noninvasive prenatal aneuploidy testing of chromosomes 13, 18, 21, X, and Y, using targeted sequencing of polymorphic loci

OBJECTIVE

This study aims to develop a noninvasive prenatal test on the basis of the analysis of cell-free DNA in maternal blood to detect fetal aneuploidy at chromosomes 13, 18, 21, X, and Y.

METHODS

A total of 166 samples from pregnant women, including 11 trisomy 21, three trisomy 18, two trisomy 13, two 45,X, and two 47,XXY samples, were analyzed using an informatics-based method. Cell-free DNA from maternal blood was isolated, amplified using a multiplex polymerase chain reaction (PCR) assay targeting 11,000 single nucleotide polymorphisms on chromosomes 13, 18, 21, X, and Y in a single reaction, and sequenced. A Bayesian-based maximum likelihood statistical method was applied to determine the chromosomal count of the five chromosomes interrogated in each sample, along with a sample-specific calculated accuracy for each test result.

RESULTS

The algorithm correctly reported the chromosome copy number at all five chromosomes in 145 samples that passed a DNA quality test, for a total of 725/725 correct calls. The average calculated accuracy for these samples was 99.92%. Twenty-one samples did not pass the DNA quality test.

CONCLUSIONS

This informatics-based method noninvasively detected fetuses with trisomy 13, 18, and 21, 45,X, and 47,XXY with high sample-specific calculated accuracies for each individual chromosome and across all five chromosomes.

Role of the vascular endothelial growth factor in the inverse relationship between increased nuchal translucency thickness and fetomaternal transfusion

OBJECTIVE

To elucidate the possible etiological role of the vascular endothelial growth factor (VEGF) in the inverse correlation between nuchal translucency (NT) thickness and fetomaternal transfusion (FMT).

METHODS

The level of FMT was determined prospectively in 80 viable, singleton pregnancies in which 10-14-week ultrasonographic scanning, NT thickness measurement; chorionic villus sampling (CVS) for fetal karyotyping and VEGF concentration determination were performed. The grouping procedures were based either on NT thickness (<2 MoM in Group I, and ≥2 MoM in Group II), or on karyotype (euploid in Group A, and aneuploid in Group B). The level of FMT was determined via maternal serum α-fetoprotein levels before and after CVS. The FMT and the VEGF concentration of the chorionic tissue were analysed in comparisons between Groups I and II, and between Groups "A" and "B".

RESULTS

The mean level of FMT after CVS was 72.5±21.3 μL and 19.28±5.4 μL in Groups I (n=44) and II (n=36), respectively (P<0.02). The VEGF concentration of the chorionic tissue in Groups I and II was 40.6±16.7 pg/mg protein and 21.1±6.3 pg/mg protein, respectively (P=0.28). The mean level of FMT was 57.9±15.0 μL and 8.1±3.9 μL in Groups A and B, respectively (P<0.003). The VEGF concentration of the chorionic tissue in Groups A and B was 25.9±10.7 pg/mg protein and 21.3±11.3 pg/mg protein, respectively (P=0.77).

CONCLUSION

No difference exists in the VEGF concentration in the aspirated chorionic tissue between Groups I and II and between Groups A and B. A higher level of FMT was observed among the aneuploid pregnancies after CVS than among the euploid cases. Chorionic VEGF does not influence the inverse relationship between the pre-CVS NT thickness and FMT.

Fetomaternal hemorrhage in relation to chorionic villus sampling revisited

OBJECTIVE

To investigate whether chorionic villus sampling (CVS) results in a proportional increase of alpha-fetoprotein (AFP) and fetal red cells in maternal blood.

METHODS

Blood samples were collected before and after CVS. The AFP concentration was measured and supervised automated microscopy of Kleihauer-Betke slides was applied to quantify fetal red cells.

RESULTS

AFP analysis was performed in 53 paired samples and automated microscopic scanning in 59 paired samples. Median AFP concentrations before and after CVS were 12.0 microg/L (range 6.4-36.4) and 18.7 microg/L (range 8.2-668.9), respectively, indicating a significant increase (p < 0.0001). Median numbers of fetal red cells detected before and after CVS were 0 (range 0-36) and 0 (range 0-31), respectively. No significant increase of fetal cells was observed (p = 0.72). The delta (Delta) fetal red cells and the Delta AFP correlated poorly (rho = -0.22, p = 0.11). The amount of villi correlated moderately with the Delta AFP (rho = 0.32, p = 0.02) and did not correlate with the Delta fetal red cells (rho = -0.11, p = 0.43).

CONCLUSIONS

Although the AFP concentration after CVS increased, no increase of fetal red cells was detected. These findings suggest that CVS results in a leakage of proteins due to placental tissue damage, rather than increased trafficking of fetal cells.

First trimester maternal serum alpha-fetoprotein screening for Down syndrome and other aneuploidies

Low maternal serum AFP (MSAFP) values in the first trimester of pregnancy have been associated with an increased risk for chromosome disorders. In our own first trimester chorionic villus sampling (CVS) series, MSAFP determinations were carried out in 1,448 singleton pregnancies. Aneuploidies were detected in 26 of these. The pre-CVS MSAFP values in these pregnancies were compared to those in pregnancies with normal outcome. Statistical analysis did not show a diagnostically useful correlation between low first trimester MSAFP values and aneuploidy in our cohort.

Improvement of the Kleihauer-Betke test by automated detection of fetal erythrocytes in maternal blood

BACKGROUND

Reliable detection and quantification of fetal red cells in maternal blood is important in routine obstetric practice. The manual Kleihauer-Betke test (KBT) is widely used, but it is imprecise and subjective. This study investigated whether automated readout of the KBT could improve sensitivity and accuracy.

METHODS

Glass slides containing dilutions of fetal red cells in adult blood were prepared and stained by using acid elution. Standard manual evaluation of the KBT was performed for all slides by one investigator. In addition, automated microscopy and image analysis of the same slides were performed, whereby detected fetal cells were reviewed by two independent investigators.

RESULTS

Ten replicate measurements of fetal cell numbers showed high reproducibility and very small interobserver and intraobserver variabilities. Typical coefficients of variation were 3-4% for concentrations ranging from 0.001% to 0.1%. The automated KBT showed strong correlation between theoretical and detected concentrations of fetal cells (r2 = 0.999). In the range from 0.0001% to 0.001%, the standard KBT underestimated the fetal cell percentage, whereas the automated KBT was very precise. The correlation between methods was good (r2 = 0.999).

CONCLUSION

Automated readout of the KBT improved accuracy of fetal cell detection in the range from 0.0001% to 1% fetomaternal hemorrhage, particularly when larger numbers of cells were analyzed.

Increased nuchal translucency and decreased fetomaternal transfusion after chorionic villus sampling

OBJECTIVE

To investigate the relationship between nuchal translucency (NT) and fetomaternal transfusion (FMT) after chorionic villus sampling (CVS).

METHODS

The level of FMT was determined in 272 viable, singleton pregnancies in which 10-14-week ultrasound scanning, NT measurement and CVS for fetal karyotyping had been performed. The pre-CVS NT was measured transvaginally, and the women were divided into two groups, i.e. those with NT < 2.5 mm (Group 1) or >or= 2.5 mm (Group 2). The level of FMT was determined via the maternal serum alpha-fetoprotein levels before and after CVS. FMT was analyzed in relation to the pre-CVS NT.

RESULTS

Of the 272 pregnancies, 213 were in Group 1 and 59 in Group 2. The mean levels of FMT after CVS were 23.3 +/- 12.2 and 5.4 +/- 2.9 micro L in Groups 1 and 2, respectively (P < 0.01). An FMT > 100 micro L was found in 19 cases in Group 1, whereas the maximum in Group 2 was 67.2 micro L. Aneuploidies were diagnosed in 17 cases, 15 (88.2%) of them in Group 2. When the pregnancies with adverse outcome were excluded from the two groups, a higher level of FMT was observed in Subgroup 1 than in Subgroup 2 (P < 0.01).

CONCLUSIONS

The mean level of FMT after CVS was significantly lower in pregnancies with an increased pre-CVS NT, a relationship observed in euploid pregnancies also. An increased pre-CVS NT seems to be inversely correlated with the FMT increase after CVS. Further studies are planned to investigate the background to this phenomenon.

Overexpression of the wild type p73 gene in human bladder cancer

p73, a first p53 relative, was recently identified and shown to be monoallelically expressed in a number of different human tissues. To determine the potential role of this gene in human bladder cancer, we investigated p73 expression levels, allelic expression patterns, and analysed p73 mutations in 23 unselected primary invasive bladder cancers with matched normal tissues and in seven bladder cancer cell lines. In a comparison between normal and tumor tissues using quantitative RT-PCR analysis, we found that p73 was overexpressed in 22/23 bladder cancers, sometimes as great as 20-fold. Allelic expression analysis using a C/T polymorphism in exon 2 and a newly identified T/C polymorphism in exon 5 revealed that p73 was biallelically expressed in both normal bladder and cancer tissues, suggesting that p73 is not imprinted in bladder tissue. Mutation screening of the p73 gene in bladder cancer DNAs using denaturing high-performance liquid chromatography analysis and DNA sequencing revealed no tumor-specific mutations in any coding exons of the p73 gene. These data suggest that the p73 is unlikely to be a tumor suppressor gene, but that overexpression of p73 may contribute to tumorigenesis in bladder cancer.

The association between alpha-fetoprotein and beta hCG levels prior to and following chorionic villus sampling in cases that spontaneously miscarried

Maternal serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta hCG) measurements taken prior to chorionic villus sampling (CVS) in 21 patients who subsequently miscarried were compared with measurements in a control group of 113 patients with uneventful pregnancies. Patients with AFP levels of 10 iu/ml or more prior to the CVS had a 4.3 times greater risk of miscarriage (95 per cent confidence interval 1.3-13.6). AFP levels obtained 1 week after the CVS in the 13 patients with late miscarriages were higher than in the control group (P = 0.06). Patients miscarrying had a greater rise in AFP (P = 0.06) and a greater fall in beta hCG levels (P = 0.04) following the CVS procedure, compared with the control subjects. Each 10-unit change in the difference between AFP or beta hCG levels prior to and 1 week following the CVS was associated with a significantly increased risk for late miscarriage. Elevated maternal serum AFP levels early in pregnancy and changes in AFP and beta hCG levels following CVS may predict an increased risk for subsequent miscarriage.

First-trimester alpha-fetoprotein screening for Down syndrome

Screening for Down syndrome and other chromosomal aneuploidies by biochemical parameters in maternal serum is well established for the second trimester. With screening as late as 16 weeks of gestation, the option of chorionic villus sampling (CVS) unfortunately is lost. In our study population, the maternal serum alpha-fetoprotein (MSAFP) concentration was determined in 2471 women in the first trimester immediately prior to CVS. Although in this sample MSAFP tended to be lower in Down syndrome (DS) pregnancies than in pregnancies with a chromosomally normal fetus, at this early gestational age neither a fixed cut-off level of 0.5 multiples of the normal median (MOM) nor one of 0.6 MOM was suitable for identifying pregnancies at higher risk for DS. This also applied to trisomy 18, although on average MSAFP in trisomy 18 pregnancies was lower than in normal and DS pregnancies.

Genetic diagnosis by chorionic villus sampling before 8 gestational weeks: efficiency, reliability, and risks on 317 completed pregnancies

Transabdominal chorionic villus sampling (TA-CVS) was attempted in 328 high-risk pregnancies at 6-7 weeks of gestation. Sampling was feasible in 97.7 per cent of cases; chorionic tissue specimens of more than 10 mg were obtained in 94.4 per cent of cases at the first needle insertion and in 100 per cent after a second attempt. Fetal karyotyping succeeded in 99.4 per cent of cases, while no diagnostic failures were reported in enzymatic and DNA analyses. Fetal loss rate in the first 4 weeks after CVS was significantly higher than in the later CVS series (7.2 vs. 2.5 per cent), but 50 per cent of losses were observed within 2 weeks in cases of inviable aneuploidies. A high incidence of severe limb abnormalities (1.6 per cent) was detected in pregnancies intended to continue, confirming the aetiological role of early CVS. Unclear visualization of the placental limits and poor control of the needle path are thought to be the main reasons for the vascular disruption of the chorionic plate, and thereby hypoxic embryo tissue damage. A better selection of cases, together with high-resolution vaginal ultrasound visualization, and analytical techniques requiring a minimal amount of tissue should avoid any teratogenic effect of early CVS.

Ratio of fetal to maternal DNA is less than 1 in 5000 at different gestational ages in maternal blood

Using Southern hybridization with the DNA probe pY3.4, we were not able to detect fetal DNA in blood of 36 pregnant women carrying male fetuses. Gestational ages ranged from 8-40 weeks of pregnancy. Using the same DNA probe, we were able to detect the male-specific signal in experimental dilution series down to 1/5000 on autoradiograms. We conclude that the ratio of fetal DNA in maternal circulation, in contrast to previous estimations, must be lower than 1/5000.

Validity of cytogenetic analyses from trophoblast tissue throughout gestation

Cytogenetic findings in the Münster Chorionic Villi Sampling (CVS) program are presented after 1,184 first trimester transcervical samplings and 131 second and third trimester placentacenteses. In the first trimester series the abnormality rate is low (2.4%) in patients with only an age-dependent aneuploidy risk. In this group terminations were performed in only 1.6% because of aneuploidy. True mosaicism was found more frequently after CVS, and the risk of maternal cell contamination seems higher as compared to amniocentesis. There are no obvious differences in the overall rate of diagnostic errors after both procedures, when metaphases after direct preparation and chorionic cell cultures are analysed and doubtful findings such as mosaicism are adequately followed up by amniocentesis. The cytogenetic techniques also offer a very rapid approach to karyotyping in the second and third trimester. We found a high rate of aneuploidy (15%) when placentacentesis was performed after sonographic diagnosis of fetal abnormalities. We conclude that cytogenetic analysis from trophoblast tissue is an accurate diagnostic tool applicable from first to third trimester of pregnancy.