The purpose of this study was to determine the usefulness of the total
serum IgM level as a screening test for congenital infection in asymp
tomatic or mildly symptomatic infants. A retrospective medical record
review was performed on 168 infants in whom the serum IgM was measured
as a screen for congenital infection. The indications for testing, th
e yield of testing, and the adequacy of follow-up of abnormal values w
ere examined. Only one infant was diagnosed with a congenital infectio
n which was not specifically suspected prior to screening; this was a
case of congenital cytomegalovirus (CMV). Inappropriate screening was
frequently performed in infants in whom indications for specific evalu
ation were present. Appropriate follow-up testing was performed in onl
y 30% (seven of 23) of the infants with elevated serum IgM who receive
d their pediatric care at our institution. Because of the low yield (<
1%) and lack of follow-up shown in this study, as well as poor sensiti
vity, serum IgM was not a useful screening test for congenital infecti
on in our institution.