Red cell and platelet alloimmunization

Intrauterine therapy for fetal anaemia and thrombocy-topaenia by intravascular fetal transfusion was probably the first major success story in fetal medicine. There have been two recent advances which have revolutionized the management of fetal anaemia. First, the development of PCR techniques to identify fetal Rh genotype from freefetal DNA in the maternal serum [19]. Rh D status of the fetus can now be accurately determined non-invasively in Rh D negative women and is now a routine test offered by the International Blood Group Reference Laboratory (IBGRL) to alloimmunized women in the UK. This has significantly reduced the number of invasive procedures required for genotyping for Rh D in the UK. In the study by Finning et al. [20] only 7 out of 230 cases could not have their Rh status confirmed using this technique. Currently the IBGRL are also offering genotyping for Rhc and Kell using a similar technique as these can both cause fetal haemolytic anaemia.

The second major advance is in the abandonment of invasive amniocentesis for detecting ODA450 in amniotic fluid as a surrogate for fetal haemolysis, in favour of non-invasive monitoring for fetal anaemia by using fetal middle cerebral artery Doppler velocimetry. Mari et al. [21] demonstrated using a cut of 1.5 multiples of the median (MOM) that the middle cerebral artery Doppler peak systolic velocity (MCA PSV) could be used with a sensitivity of 100% and false positive rate of 12% to detect fetal anaemia (Plate 17.1, facing p. 562).

Current practice is to perform maternal sera fetal Rh D genotyping in all Rh D negative alloimmunized women. In women who have a Rh D positive fetus maternal serum titres of Rh D antibodies are monitored and the patient referred for weekly MCA PSV monitoring using ultrasound once maternal serum levels reach 4 IU/ml or if there has been a previously affected child. If the MCA PSV is above 1.5 [21] a FBS under continuous ultrasound guidance is performed with immediate access to fetal blood analysis. If the fetus is anaemic it is transfused using maternally cross-matched O Rh negative, cytomegalovirus negative, irradiated, concentrated (haematocrit 70-90%) blood. Weekly MCA PSV monitoring is continued and further FBS is performed if indicated on MCA PSV or at a 3-5 week interval to assess the rate of fall of haemoglobin. Women who have been transfused are usually delivered electively at 37-38 weeks and the neonate should go onto double phototherapy post-natally.

Fetal alloimmune thrombocytopaenia is caused by maternal sensitization to the human platelet antigens (HPA) and can lead to devastating intracranial haemorrhage in 10-20% of affected pregnancies. The diagnosis is usually made following the birth of a previously affected child. Previous management was based on frequent FBS and platelet transfusion, with the timing based on the gestation and severity of a previously affected pregnancy. However, the risk to the fetus of repeated FBS are considerable with a procedure-related loss rate per procedure of 1.2% and up to 8.4% per pregnancy. More recently a European collaborative study concluded that the start of treatment can be stratified on the basis of sibling history and that maternal intravenous immunoglobulin (IVIG) treatment should be the first-line treatment of choice thereby delaying and limiting the number of invasive procedures as the procedure-related complication rate was high [22].

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Pregnancy Diet Plan

Pregnancy Diet Plan

The first trimester is very important for the mother and the baby. For most women it is common to find out about their pregnancy after they have missed their menstrual cycle. Since, not all women note their menstrual cycle and dates of intercourse, it may cause slight confusion about the exact date of conception. That is why most women find out that they are pregnant only after one month of pregnancy.

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