The prevalence of ABO-HDN
We carried out screening on 7 513 mothers and 7 810 newborns between
November 2016 and April 2020. Hospitalization information was collated
from all neonates diagnosed with ”ABO haemolytic disease of the newborn”
(including ”ABO haemolytic jaundice” and/or ”ABO haemolytic anaemia”),
including maternal blood group, gestation at delivery, mode of delivery,
the infant’s sex and birth weight, date of birth, time of admission,
blood type, direct anti-globulin test (DAT), indirect anti-globulin test
(IAT), eluate test, peak total serum bilirubin (TSB, μmol/L),
haemoglobin (Hb, g/L), and treatment measures. All maternal blood
groups, including Rh and irregular antibody screens, were tested at
least once during pregnancy.
Neonates were assessed for blood type and subjected to DAT, IAT, and the
eluate test if the newborn ABO was incompatible with that of the mother
and the newborn developed neonatal jaundice simultaneously. Once the
eluate test was positive and clinically significant jaundice occurred,
infants were continuously monitored in an inpatient setting, whereas
those who did not develop clinically significant jaundice were evaluated
as outpatients. TSB and Hb were tested anytime when visual assessment
and transcutaneous bilirubin were abnormal during hospitalization. ”ABO
haemolytic jaundice” was defined when the eluate test was positive and
the infant developed clinically significant jaundice, which was judged
as any single total bilirubin result above the newborn infant 35 or more
weeks of gestation phototherapy treatment threshold on charts from the
American Academy of Paediatrics on Neonatal Jaundice [15]. ”ABO
haemolytic anaemia” was defined as eluate test positive and Hb ≤ 145
g/L.
DAT and IAT tests were performed routinely at the blood bank of the
Affiliated Hospital of Qingdao University on umbilical cord blood with
an agglutination technique. The eluate test was performed by the heat
dispersion method to remove RBC-bound antibodies. EDTA-anti-coagulated
peripheral whole blood was centrifuged at 1 760 ×g for 5 min, drawing at
least 2 ml of erythrocytes with a pipette tip for testing. After six
washes of erythrocytes with 0.9% normal saline, the last release
solution was used as the negative control. An equal volume of saline was
added, and samples were incubated with shaking in a 56°C water bath for
ten minutes. Samples were next centrifuged at 1 000 ×g for three
minutes, immediately followed by transferring the supernatant red
emission solution to the other three test tubes. One drop of A, B, and O
RBC reagent (Changchun Boxun Biotechnology, Changchun, China) was added
to the test tube, after which the samples were centrifuged and observed.
Agglutination indicated that the RBC was attached to the corresponding
antibodies and the eluate test was regarded as positive.