Minimally invasive management of RH alloimmunization: Can amniotic fluid deltaOD450 be replaced by Doppler studies? A prospective multicenter trial

Abstract

FLUID DELTAOD450 BE REPLACED BY DOPPLER STUDIES? A PROSPECTIVE MULTICENTER TRIAL DICK OEPKES, GARETH SEAWARD, FRANK VANDENBUSSCHE, JOHN KINGDOM, RORY WINDRIM, JOSEPH BEYENE, HUMPHREY KANHAI, ARNE OHLSSON, GREG RYAN, FOR THE DIAMOND STUDY GROUP, Leiden University Medical Center, Dept. of Obstetrics, Leiden, Netherlands, Fetal Medicine Unit, Mount Sinai Hospital, Toronto, Ontario, Canada, Dept. of Paediatrics, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada OBJECTIVE: In pregnancies complicated by red cell alloimmunization, the fetus may suffer from progressive hemolytic anemia, leading to hydrops and death if untreated. The standard management is to select at risk patients on the basis of obstetric history and maternal serum antibody levels. Evaluation is done by ultrasound for signs of hydrops, and serial amniocentesis for bilirubin (DOD450) values. Recently, middle cerebral artery (MCA) peak systolic velocity measurements have been reported to reliably predict fetal anemia. Our aim was to compare the performances of MCA Doppler and amniotic fluid DOD450. STUDY DESIGN: Prospective, international multicenter study of a cohort of consecutive Rh-D, c, E and Fy alloimmunized pregnancies with titers of R64 and antigen-positive fetuses. Both tests were performed simultaneously in all patients, and compared with the ‘‘gold standard’’ of fetal or cord blood sampling (at birth) to assess the actual hemoglobin (Hgb). Abnormal DOD450 was defined as a value on Liley’s chart in zone 2c or 3. Severe anemia was defined as Hgb of R5 SD below the mean for gestational age. RESULTS: In a total of 164 pregnancies with 165 fetuses (one set of twins), 74 fetuses were found to be severely anemic. MCA Doppler correctly predicted severe anemia in 65/74 (88%, 95% confidence interval: 83-93), with a specificity of 82% (77-88), positive predictive value 80% (74-86), NPV 89% (85-94), likelihood ratio pos. 5.00 (3.18-7.90), LR neg. 0.15 (0.08-0.27). Amniotic fluid DOD450 had a sensitivity of 76% (69-82), specificity 77% (70-83), PPV 73% (66-80), NPV 80% (73-86), LR pos. 3.28 (2.21-4.88), LR neg. 0.32 (0.21-0.48). CONCLUSION: MCA peak velocity measurement showed better test characteristics in the prediction of severe fetal anemia than traditional amniotic fluid DOD450 assessment. In addition, MCA Doppler is a noninvasive technique. This study shows that MCA Doppler can safely replace amniotic fluid DOD450 in the management of Rh-alloimmunized pregnancies. S2 SMFM Abstracts