Doppler or Amniocentesis to Predict Fetal Anemia
Doppler or Amniocentesis to Predict Fetal Anemia
In pregnancies complicated by Rhesus disease, the mother has developed antibodies which cross
 the placenta and can cause anemia and death of the fetus. When the anemia is detected on
 time, the fetus can be saved by giving it blood transfusions during the pregnancy.

 The standard test to predict whether the fetus needs a blood transfusion is examination of
 the amniotic fluid. To obtain this fluid a needle has to be inserted in the womb, which has a
 risk of preterm delivery, infection, and making the disease worse. This is called
 amniocentesis.

 A new safe test, using Doppler ultrasound, has been developed to possibly replace the
 amniocentesis.

 The aim of this study is to compare the new Doppler test with the standard amniocentesis. If
 the Doppler test is at least as good, this safe test may replace the amniocentesis in the
 management of pregnancies with Rhesus disease.
In pregnancies complicated by red cell alloimmunization, the fetus may suffer from chronic
 progressive hemolytic anemia. Severe fetal anemia leading to hydrops and fetal demise can
 occur as early as 17 weeks' gestation, while in other pregnancies the only manifestation of
 the disease is neonatal hyperbilirubinemia. The standard of care in the management of these
 pregnancies is to select patients at risk of fetal anemia using information about their
 obstetric history, and serial maternal serum antibody measurements. The selected patients are
 followed closely, usually in referral centers with a special interest and expertise in
 managing this now relatively rare disease. Ultrasound evaluation of fetal condition, with
 emphasis on signs of fetal hydrops, is performed regularly. In addition, serial amniocentesis
 is done to assess amniotic fluid bilirubin (deltaOD450) values. This spectrophotometric
 method estimates the level of bilirubin in the amniotic fluid, which correlates with the
 severity of the hemolytic process.

 Although this diagnostic test, introduced by Liley in 1961, has served fetal medicine
 specialists well for almost 40 years, the invasive nature of the method is considered a
 serious disadvantage. Furthermore, its reliability has been questioned, especially when used
 in the second trimester. In the past decade, noninvasive alternative methods to predict the
 degree of fetal anemia have been developed.

 The most promising of these new diagnostic tests is Doppler measurement of fetal blood flow
 velocities. Fetal blood flow velocity has been shown to correlate linearly with the degree of
 anemia. Recently, middle cerebral artery (MCA) peak flow velocity measurements have been
 reported to reliably predict presence or absence of fetal anemia.

 The aim of this study is to compare the performance of this new noninvasive diagnostic test
 with the standard test, amniocentesis for amniotic fluid deltaOD450 values. In an
 international multicenter setting, a large cohort of consecutive Rh-alloimmunized pregnancies
 will be studied prospectively. Both diagnostic tests will be performed simultaneously in all
 patients, and compared with the "gold standard", fetal blood sampling (FBS) to assess the
 actual hemoglobin concentration.
Inclusion Criteria:

 -  Pregnant women with red cell alloimmunization associated with a risk of fetal anemia
 (D, E, c or Duffy (Fya )antibodies, alone or in combination with other antibodies)

 -  Gestational age between 12 and 34 weeks at study entry, viable fetus and accurate
 dating

 -  Maternal serum test-result, above the threshold at which the fetus is considered to be
 at risk of developing hemolytic anemia and thus a potential candidate for invasive
 testing.

 Exclusion Criteria:

 -  Presence of Kell-antibodies

 -  Presence of fetal hydrops at first ultrasonographic examination

 -  Major fetal congenital or chromosomal anomalies