Amniotic fluid delta OD 450 values accurately predict severe fetal anemia in D-alloimmunization.
OBJECTIVE
To assess the diagnostic accuracy of amniotic fluid Delta OD 450 values in the second and third trimesters of D-alloimmunized pregnancies.


METHODS
We searched our database for singleton D-alloimmunized pregnancies with nonhydropic fetuses, where amniocentesis was performed within 4 days of first fetal blood sampling. Amniotic fluid Delta OD 450 values were plotted on an extrapolated Liley's chart. Sensitivity and specificity were calculated for two commonly used cutoff levels, Liley's zone 3 and the upper third of Liley's zone 2. Severe fetal anemia was defined as a hemoglobin concentration of more than 5 standard deviations below the normal mean for corresponding gestational age.


RESULTS
Seventy-nine pregnancies met our inclusion criteria. Overall accuracy of the extrapolated Liley's curve in predicting severe fetal anemia was 75% (95% confidence interval [CI] 64, 84) for zone 3 and 86% (95% CI 77, 93) when the upper third of zone 2 was included. Sensitivity of Delta OD 450 values in Liley's zone 3 or the upper third of Liley's zone 2 was 95% (95% CI 74, 100) before and 98% (95% CI 89, 100) after 27 weeks.


CONCLUSIONS
Liley's extrapolated curve predicts severe fetal anemia with reasonable accuracy and high sensitivity.
Sikkel
Esther
E
Department of Obstetrics and Gynecology, Leiden University Medical Center, The Netherlands.
Vandenbussche
Frank P H A
FP
Oepkes
Dick
D
Meerman
Robertjan H
RH
Le Cessie
Saskia
S
Kanhai
Humphrey H H
HH
D000328:Adult; D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry / Q000276:immunology*; D016001:Confidence Intervals; D004899:Erythroblastosis, Fetal / Q000097:blood* / Q000175:diagnosis* / Q000401:mortality; D005260:Female; D005313:Fetal Death; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies; D012203:Rh Isoimmunization / Q000276:immunology*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index