#A negative blood type pregnancy serial#
On the contrary, if the titer is 1:16 or higher, fetal wellness assessment is mandatory by ultrasonography to evaluation of middle cerebral artery peak systolic velocity (MCA-PSV) or serial amniocentesis for delta OD450 if the former is not available ( 5- 7).įetal detailed ultrasonography assessment has an essential role in diagnosis and management of fetal anemia. Usually, pregnancies in which antibody titers are 1:8 or lower can be managed by serial monitoring of maternal antibody titers. If titers remain below the critical titer, delivery can occur at term.Ī critical titer is defined as the titer associated with a significant risk for fetal hydrops. These are usually performed monthly until 24 weeks of gestation, after which time titers should be repeated every 2 weeks. Titers tend to correlate more reliably with the severity of fetal disease in the first sensitized pregnancy than in subsequent pregnancies. In general, women with titers higher than 1:4 should be considered Rh alloimmunized. In case of first affected pregnancy, Rh alloimmunizated women should undergo determination of their anti-D antibody titers. Management in first affected Rh alloimmunizated pregnancy
However, if the paternal phenotype is D antigen positive and his genotype is heterozygous, fetal antigen status should be determined by amniocentesis at 15 weeks’ gestation (by PCR of fetal cells).Ĭhorionic villus sampling is possible as well but it has the disadvantage of potentially worsening of maternal antibodies titers due to possible fetomaternal hemorrhage.Īnyway, because of the small risk of invasive prenatal diagnosis, many centres choose to perform amniocentesis only if the anti-Rh titer reaches the critical value of 1:16 or higher. If he is homozygous for the D allele, the fetus is Rh D positive ( 3, 4). If the father is Rh D positive, he can be either homozygous or heterozygous for the D allele. When paternity is certain, if the father is Rh D negative the fetus is also Rh D negative. In fact, if the fetus is Rh D-negative doesn’t require any intervention irrespective of maternal antibodies titers. The following step should be the assessment of fetal Rh D status to determining if the pregnancy is at risk for the development of hemolytic disease of the fetus and newborn.
Women who are Rh D negative with a positive anti D antibody screen test are considered Rh alloimmunized ( 1, 2). Evaluation of maternal ABO blood group, Rh type and anti D antibodies (indirect Coombs test) should detected at every first prenatal visit.
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