ANTI-M ISOIMMUNIZATION - MANAGEMENT AND OUTCOME AT THE OHIO-STATE-UNIVERSITY FROM 1969 TO 1995

Objective: To review the management strategies and outcome in gravidas with anti-M isoimmunization over the past 26 years at The Ohio State University. Methods: Data collected from 115 pregnancies found to have anti-M antibody at The Ohio State University from September 1969 thro ugh February 1996 were reviewed retrospectively. We analyzed indirect antiglobulin tests, amniotic fluid with spectrophotometric examination , direct antiglobulin tests, M antigen status, antepartum course, and perinatal outcome. Results: Anti-M antibody was found in 90 women who had 115 pregnancies over 26 years. Among those with positive indirect antiglobulin tests, 104 pregnancies had titers at or below 1:4. Only o ne patient with an initial low titer experienced more than a three-fol d increase to 1:64. Two women underwent a total of eight amniocenteses when titers were at or above 1:128. Forty-two (60%) of the 70 infants tested were positive for M antigen. Nine infants required phototherap y. Eight of these infants were delivered preterm. There was an increas e in the number of women seen with anti-M antibody in pregnancy at our institution, with nearly 10% of all gravidas with a positive antibody screen having anti-M alloantibodies. There were no cases of hemolytic disease of the newborn, mild or severe. Conclusion: The prevalence of anti-M isoimmunization may be increasing. The incidence of severe hem olytic disease of the newborn due to anti-M is extremely low. We found no cases in our review of 115 pregnancies, although there have been s everal cases of severe hemolytic disease of the newborn reported. If a nti-M is detected in pregnancy, the titer is low (no more than 1:4), a nd there is no history of prior pregnancy complications suggesting a h emolytic disease process, we recommend no further testing other than a n indirect antiglobulin test at 28 weeks to look for the emergence of other alloantibodies. However, if the initial titer is elevated or the re is a concerning obstetric history, serial titers should be performe d and amniocenteses reserved for rising titers. (C) 1997 by The Americ an College of Obstetricians and Gynecologists.