Role for serial prenatal anti-Vel quantitative serologic monitoring with 2-ME serum treatment during pregnancy: case report.

Anti-Vel is an uncommon antibody to a high-prevalence antigen. Its clinical significance and management in the prenatal setting are not well characterized. We present a case that demonstrates the utility of serial prenatal anti-Vel quantitative serologic monitoring with 2-ME serum treatment during pregnancy. The patient is a 23-year-old Hispanic woman with history of prior pregnancy and prior transfusion who was discovered to have an antibody to the high-prevalence Vel antigen in the first trimester (week 7) of her second pregnancy. Interval measurements of the serologic antibody titers were performed during the next 26 weeks. The untreated serum (IgM and IgG) titer increased from a baseline of 4 to 16 during that interval, while the 2-ME (presumed IgG component) titer remained stable at 4. Responding to ultrasound findings suspicious for fetal anemia, the child was delivered without complications at 34 weeks' gestation. At birth, the DAT was negative and there was no evidence of HDN. Placed in the context of other similar reports, this case demonstrates the importance of separately reporting the IgG fraction (after either DTT treatment or 2-ME treatment) from the untreated (IgM and IgG) fraction and the importance of correlating the treated serum titer with potential clinical significance.

Detecting fetomaternal hemorrhage: a comparison of five methods.

Appropriate postpartum administration of Rh immune globulin relies on sensitive detection and accurate quantitation of fetomaternal hemorrhage (FMH). Recently, the microscopic Du test (micro Du) enhanced with polyethylene glycol (PEG Du) and flow cytometry (FC) have been advocated for this purpose. Three qualitative methods (micro Du, rosette test, and PEG Du) and two quantitative methods (acid elution and FC) for assessing FMH were evaluated with particular attention given to PEG Du and FC. In vitro studies comprised 10 series of dilutions of D+ cord cells in D- adult cells to yield D+ cell concentrations of 0.06, 0.12, 0.25, 0.50, 0.75, 1.0, and 2.0 percent. Additionally, 26 postpartum samples were tested. Of the qualitative techniques, the micro Du test was the least sensitive with 20 percent false-negative results occurring at 0.5 percent fetal cells. The PEG Du test was only slightly more sensitive and offered no clinical advantage. The rosette test was the most sensitive, consistently detecting fetal cells at concentrations of 0.25 percent or greater. FC and acid elution showed similar results, with good correlation obtained between measured and expected quantities of fetal cells (r = 0.99 and 0.96, respectively). One of 26 postpartum samples was positive by all screening techniques; acid elution and FC detected 0.3-percent concentrations of fetal cells and 0.17-percent concentrations of D+ cells, respectively. Although acid elution is a more commonly used method for quantitating FMH, FC offers an acceptable alternative that is capable of analyzing large numbers of cells with objectivity and reproducibility.