Is a third-trimester antibody screen in Rh+ women necessary?
OBJECTIVE
To determine the need for routine third-trimester antibody screening in Rh+ women.


METHODS
An analytic case-control study.


METHODS
We identified Rh+ pregnant women who had received prenatal care and retrospectively analyzed their laboratory data. Patients were grouped into those with a positive third-trimester antibody screen (cases) and those with a negative third-trimester screen (controls). Because entry into a group was decided by the investigators, it could not be randomized. We reviewed the maternal medical records for antibody identification and final pregnancy outcome. We also reviewed the neonatal medical records for evidence of direct Coombs-positive cord blood, anemia, need for transfusion or phototherapy, other medical complications, and death.


RESULTS
Using a computerized laboratory database from 2 teaching hospitals, we identified 10,581 obstetric patients who underwent routine first- and third-trimester antibody screening between 1988 and 1997. Of these, 1233 patients were Rh- and 9348 were Rh+. Among the Rh+ patients, 178 (1.9%) had 1 or more atypical antibodies at the first-trimester screen, and 53 (0.6%) had a positive third-trimester antibody screen despite a negative first-trimester screen. Although 6 of these 53 patients (0.06% of the study population) had clinically relevant antibodies for hemolytic disease of the new-born, no significant neonatal sequelae occurred among these 6 patients.


CONCLUSIONS
Based on the patient and hospital records studied, a repeat third-trimester antibody screen for Rh+ patients is clinically and economically unjustified. Eliminating this laboratory test from clinical practice will not adversely affect pregnancy outcomes and will decrease the costs of prenatal care.
Rothenberg
J M
JM
Indiana University School of Medicine, Department of Obstetrics and Gynecology, Indianapolis, IN, USA. jrothenb@iupui.edu
Weirermiller
B
B
Dirig
K
K
Hurd
W W
WW
Schilder
J
J
Golichowski
A
A
D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D003362:Cost-Benefit Analysis; D003625:Data Collection; D003955:Diagnostic Tests, Routine / Q000706:statistics & numerical data*; D005260:Female; D006302:Health Services Research; D006784:Hospitals, Teaching; D006801:Humans; D007196:Indiana; D008485:Medical Audit; D011247:Pregnancy; D011256:Pregnancy Outcome; D011263:Pregnancy Trimester, Third; D012204:Rh-Hr Blood-Group System / Q000276:immunology*; D019564:Unnecessary Procedures
D001323:Autoantibodies; D012204:Rh-Hr Blood-Group System