Impact of red blood cell alloimmunization on fetal and neonatal outcomes: A single center cohort study.

BACKGROUND: Alloimmunization can impact both the fetus and neonate. STUDY OBJECTIVES: (a) calculate the incidence of clinically significant RBC isoimmunization during pregnancy, (b) review maternal management and neonatal outcomes, (c) assess the value of prenatal and postnatal serological testing in predicting neonatal outcomes. STUDY DESIGN AND METHODS: A retrospective audit of consecutive alloimmunized pregnancies was conducted. Data collected included demographics, clinical outcomes, and laboratory results. Outcomes included: incidence of alloimmunization; outcomes for neonates with and without the cognate antigen; and sensitivity and specificity of antibody titration testing in predicting hemolytic disease of the fetus and newborn (HDFN). RESULTS: Over 6 years, 128 pregnant women (0.4%) were alloimmunized with 162 alloantibodies; anti-E was the most common alloantibody (51/162; 31%). Intrauterine transfusions (IUTs) were employed in 2 (3%) of 71 mothers of cognate antigen positive (CoAg+) neonates. Of 74 CoAg+ neonates, 58% required observation alone, 23% intensive phototherapy, 9% top up transfusion, and 3% exchange transfusion; no fetal or neonatal deaths occurred. HDFN was diagnosed in 28% (21/74) of neonates; anti-D was the most common cause. The sensitivity and specificity of the critical gel titer >32 in predicting HDFN were 76% and 75%, respectively (negative predictive value 95%; positive predictive value 36%). The sensitivity and specificity of a positive direct antiglobulin test (DAT) in predicting HDFN were 90% and 58%, respectively (NPV 97%; PPV 29%). CONCLUSION: Morbidity and mortality related to HDFN was low; most alloimmunized pregnancies needed minimal intervention. Titers of >32 by gel warrant additional monitoring during pregnancy.

A retrospective study of the added value of parallel titers compared with serial titers.

BACKGROUND: Prenatal antibody titers for alloimmunized patients are subject to multiple sources of variation. A parallel titer on the previous sample at the same time as the current sample is recommended. The purpose of this study was to determine the added value of parallel titers. STUDY DESIGN AND METHODS: This is a retrospective study of samples from consecutive prenatal patients with at least two prenatal antibody titers performed in the same pregnancy at a single institution between October 2010 and March 2017. Prenatal titers were performed using gel technology. Data were collected to determine the sensitivity and specificity of a clinically significant increase (twofold or greater) in serial titers compared with the gold standard of using parallel titers. RESULTS: There were 155 serial prenatal titers performed in 59 alloimmunized pregnant women. Nineteen samples (12%) had a serial titer increase of twofold or greater with eight false positive samples (increase less than twofold when using parallel titers). Thirty-six samples (23%) had a serial titer increase of onefold with two false negative samples (increase of twofold or greater using parallel titers). One hundred samples (65%) had no increase (or a decrease) in serial titer with none having an increase of twofold or greater using parallel titers. The sensitivity of a twofold or greater increase in serial titers was 84.6% (95% CI 55-98%) and the specificity was 94.4% (95% CI 89-98%) when compared with parallel titers. CONCLUSION: This study questions the value of parallel titers on every prenatal titer performed. When no increase in serial titers was observed, parallel titers added no new information.

Examining prescribing practices with respect to oral iron supplementation for post-partum anemia: a retrospective review.

PURPOSE: Treatment for post-partum anemia frequently entails oral iron supplementation, but questions remain regarding optimal dosing, frequency, and efficacy. The objective of this study was to describe oral iron prescribing practices in post-partum women delivered via Cesarean section, and identify factors associated with iron supplementation. METHODS: A retrospective review of Cesarean section deliveries at a single tertiary center between May 2019 and April 2020 was undertaken. Patient demographics, hematological indices, indication for Cesarean section and discharge prescriptions were collected. Univariate and multivariable analyses were performed to identify factors associated with oral iron prescription at discharge. RESULTS: During the study period, 1470 women were eligible for inclusion. The mean age at delivery was 34.4 ± 4.9 years and mean gestational age was 37.2 ± 3.6 weeks. Most pregnancies (92%) were singleton. Ninety-six total patients (6.5%) received intravenous iron post-partum. Fourteen percent of women (210/1470) received prescriptions for oral iron at discharge, most commonly ferrous fumarate (61.9%, 130/210). The most common dose provided was 300 mg (145/210). Ante-partum ferritin was available for most patients (64.3%, 945/1470), but only for 17 post-partum patients (1.2%). Factors significantly associated with oral iron prescription were earlier gestational age at birth (aOR 0.93, 95% CI 0.89-0.97), history of complications during pregnancy or labor (aOR 1.92, 95% CI 1.26-2.98), higher blood loss (aOR 2.66, 95% CI 1.36-5.44), post-partum anemia (aOR 6.28, 95%-CI 4.41-8.96), blood transfusion (aOR 5.43, 95%-CI 1.81-18.19) and antenatal iron supplementation (aOR 5.70, 95%-CI 4.02-8.17). CONCLUSIONS: In summary, a relatively small proportion of women following Cesarean section were prescribed oral iron at discharge. We identified several factors associated with post-partum iron supplementation. This information will inform future prospective studies investigating the efficacy of iron supplementation in the treatment of post-partum anemia.