Longitudinal measurement of peak systolic velocity in the fetal middle cerebral artery for monitoring pregnancies complicated by red cell alloimmunisation: a prospective multicentre trial with intention-to-treat

Abstract

Objective To evaluate the utilisation measurements of peak systolic velocities in the middle cerebral artery combined with B-mode ultrasound imaging to predict anaemia in an unselected population of pregnancies complicated by alloimmune antibodies known to cause immunological hydrops. Design Prospective study on an intention-to-treat basis.Setting Multicentre study in five large tertiary referral centres.Population One hundred twenty-five fetuses with maternal alloantibodies known to cause immunological hydrops. Methods If peak systolic velocity and B-mode scan were reassuring the pregnancy was monitored at 7 -14 days interval. If either method showed signs of anaemia, an umbilical fetal blood sampling was performed. When the gestational age was greater than 35 weeks, labour was induced. Main outcome measure Moderate to severe anaemia at delivery.Results Overall sensitivity to detect moderate to severe anaemia below 35 weeks (haemoglobin level below 0.65 multiples of median) was 88%. Specificity was 87%; positive predictive value was 53% and negative predictive value was 98%. The diagnosis of severe anaemia was missed in one fetus; however, the final outcome was good. The method was not useful after 35 weeks. Conclusions Middle cerebral artery peak systolic velocity is a highly sensitive non-invasive means for determining the degree of anaemia present in red blood cell alloimmunised pregnancies. The widespread use of the Doppler method will minimise fetal complications associated with amniocentesis and fetal blood sampling. Non-invasive measurement of middle cerebral artery peak systolic velocities is more convenient and acceptable to alloimmunised pregnancies and may significantly lower health care costs. A Doppler interval of seven days is recommended.

Middle Cerebral Artery Doppler for Managing Fetal Anemia

“…5 The MCA-PSV may be falsely increased when the measurement is performed during a period of rest that follows a period of fetal activity, or late in gestation in accordance with fetal heart rate accelerations. 7 A third prospective, international trial performed by the The Decision Aids for Mode of Next Delivery study group supported the replacement of invasive testing (amniocentesis) with MCA-PSV Doppler studies, confirming the sensitivity of the original study. 6 In a study of the Collaborative Group for Doppler Assessment of the Blood Velocity in Anemic Fetuses, 3 MCA-PSV values were collected from a group of at-risk fetuses undergoing cordocentesis.…”

“…7 A third prospective, international trial performed by the The Decision Aids for Mode of Next Delivery study group supported the replacement of invasive testing (amniocentesis) with MCA-PSV Doppler studies, confirming the sensitivity of the original study. 3,7 The noninvasive nature of MCA-PSV inherently avoids risks such as premature rupture of the membranes, infection, worsening alloimmunization, and fetal loss associated with amniocentesis and cordocentesis. 3,4 In addition, the MCA-PSV more accurately reflects hemoglobin concentrations in severe anemia up to a hemoglobin level of 1 to 3 g/dL, at which point blood velocity no longer increases.…”

The Effect of Fetal Heart Rate on the Peak Systolic Velocity of the Fetal Middle Cerebral Artery

“…In the retrospective analysis of Mari et al4, a MCA-PSV of greater than 1.5 MOM was associated with a false positive rate of 10% for the detection of moderate to severe anemia. Zimmerman et al10 undertook a prospective multi-center trial and reported a similar false positive rate of 13%. Finally, Oepkes and coworkers11 noted a slightly higher false positivity of 18% for the detection of severe fetal anemia when the MCA-PSV was greater than 1.5 MOM.…”

Evaluation of fetal and uteroplacental blood flow

“…Normative data have been published by the group of Mari et al (Fig. 51 A recent comprehensive multicentre study by Oepkes et al in which MCA PSV and amniocentesis were performed prior to cordocentesis reported that MCA PSV is superior to amniocentesis in detecting fetal anaemia in red cell alloimmunization cases and can be safely used for the timing of cordocentesis and/or intrauterine transfusion. In this study, all fetuses with moderate or severe anaemia had peak systolic values above 1.5 times the median.…”