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Communication and Teaching Resource pack
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4.8
A multigravid patient presents to the antenatal clinic at 24/40. She has recently moved from India and has had no antenatal care. The GP that referred her in to the clinic arranged antenatal bloods that are as follows:
- A Neg
- Anti-D titre 1/512
- Hep B/C/HIV/RPR neg
- Rubella immune
On examination, you notice that the symphysial-fundal height is 30cm.
(a) What test should be arranged immediately?
This fetus is at high risk of intrauterine haemolysis and the higher-than-expected fundal height raises the possibility of hydrops with polyhydramnios. An urgent ultrasound should be arranged.
(b) The ultrasound confirms fetal hydrops with bilateral pleural effusions, ascites and polyhydramnios. What do you do next?
This fetus will require blood sampling to confirm anaemia and intrauterine transfusion. This is performed in a tertiary center by an obstetrician specializing in ultrasound or a maternal fetal medicine specialist. Intrauterine transfusion carries a small risk of causing premature labour and this patient should be given corticosteroids to promote lung maturity in case of this occurring.
(c) Should other causes of fetal hydrops be considered?
Yes. Although severe anaemia due to rhesus isoimmunisation is the most likely cause of this fetus´ cardiac failure, other caused of hydrops should be considered. These include cardiac abnormalities, chromosomal abnormalities, haematological abnormalities (such as thalassaemia) and intrauterine infections.
(d) What risks are associated with intrauterine transfusion?
The risk of fetal loss with transfusion in a nonhydropic fetus is approximately 1%. However, for a fetus with established hdyrops this may be as high as 10-20% as these fetuses are less able to tolerate a significant volume load. The risks can be reduced by monitoring the umbilical vein pressure during the procedure and, in a fetus with hydrops, transfusing a smaller volume of blood in the first transfusion and repeating the transfusion in 24 to 48 hours.
(e) Are ongoing transfusions likely to be necessary?
Yes. This fetus will require ongoing transfusions. The second will usually be performed relatively soon after the first. Once the fetal haematocrit has stabilized, the frequency of transfusion will be decreased and are usually required two to four weekly.
(f) Should this fetus be delivered?
No. The prognosis for a premature, hydropic neonate is poor. The aim of intrauterine transfusion is to deliver a non-anaemic fetus near term. Ideally, delivery is delayed until 37/40. However, if complications related to transfusion occur after 32/40, delivery may be considered. It is not advisable to continue the pregnancy beyond 37-38/40 as the placental permeability to antibodies increases after this time and this is associated with an increase in the level of haemolysis.
(g) With what blood group should the fetus be transfused?
The fetus should be transfused with Rh negative blood that is compatible with the maternal blood. In this case A negative or O negative blood could be used.
4.9
You review a patient in the antenatal clinic at 14/40. A routine RBC antibody screen is positive for anti-Kell antibodies.
(a) Are anti-Kell antibodies significant in pregnancy?
Yes. Anti-Kell antibodies are associated with haemolytic disease of the newborn.
(b) What monitoring should be instituted?
The titres should be monitored as for Rh isoimmunisation. Surveillance for fetal anaemia is undertaken with ultrasound, with or without fetal blood sampling. Amniocentesis and amniotic fluid spectography cannot be used with Kell isoimmuisation as the antibody affects red blood cell precursors as well as red blood cells. This means that the amount of bilirubin in the amniotic fluid (a marker of haemolysis) will underestimate the severity of the fetal anaemia.
(c) Are there any other RBC antibodies that are significant in pregnancy?
Yes. There are many possible RBC antibodies, all directed at different proteins on the RBC surface. Some of these, such as Duffy (anti-Fy) and Kell (anti-K) are usually associated with intrauterine haemolysis. Others, such as anti Lewis antibodies (anti-L) are not.