Assessing the effect of risk factors on rates of obstetric transfusion over time using two methodological approaches

Antepartum risk factors and outcomes of massive transfusion for elective cesarean section: a nationwide retrospective cohort study

BACKGROUND

Postpartum hemorrhage is one of the leading causes of maternal mortality and morbidity. The etiology of postpartum hemorrhage exhibits variations in relation to the mode of birth; consequently, risk factors for massive transfusion in elective cesarean section might diverge from those encountered in vaginal birth or emergency cesarean section. The main purpose of this study was to investigate antepartum risk factors of massive transfusion for elective cesarean section.

METHODS

We conducted a retrospective cohort study based on data from a nationwide system that collected inpatient medical records from tertiary hospitals in mainland China. We included women who had undergone elective cesarean section from January 2013 to August 2018. Primary outcome was massive transfusion defined as transfusion of more than eight units of red blood cells on the day of childbirth. Candidate risk factors were identified by the 10th revision of International Classification of Diseases Codes of admission diagnoses. The relationship between each factor and massive transfusion was assessed using multivariable logistic regression.

RESULTS

A total of 294,695 women were included and 572 of them received massive transfusion (incidence: 194 per 100,000 elective cesarean sections). Maternal age [adjusted odds ratio (aOR) 1.22; 95% confidence interval (CI) 1.10-1.48], anemia (aOR 1.66; 95% CI 1.34-2.05), thrombocytopenia (aOR 3.54; 95% CI 2.39-5.05), coagulopathy (aOR 25.92; 95% CI 8.59-69.50), hypoalbuminemia (aOR 2.97; 95% CI 1.86-4.53), hepatic dysfunction (aOR 1.65; 95% CI 1.04-2.47), uterine scar (aOR 1.39; 95% CI 1.15-1.67), multiple pregnancy (aOR 2.84; 95% CI 1.74-4.38), polyhydramnios (aOR 2.52; 95% CI 1.19-4.68) and placenta previa (aOR 25.03; 95% CI 21.04-29.77) were associated with massive blood transfusion for elective cesarean section. Among the women receiving massive blood transfusion, 7 (1.2%) died during hospitalization, 126 (22.0%) needed hysterectomy, 25 (4.4%) uterine packing and 57 (10.0%) uterine artery ligation.

CONCLUSIONS

Ten risk factors of massive transfusion were identified in women undergoing elective cesarean section. Our findings may facilitate blood products preparation and provide opportunities for applying prophylactic strategies prior to cesarean section for women at high risk of massive transfusion.

Patterns of red-cell transfusion use in obstetric practice in sweden 2003-2017: A nationwide study

BACKGROUND

There is a paucity of data on patterns of red-cell transfusions in obstetrical care, but some studies have suggested an increase in transfusion rates during the last decade. The purpose of this study was to investigate maternal characteristics, temporal trends and hospital variations in red-cell use in a large contemporary obstetric cohort in Sweden.

STUDY DESIGN AND METHODS

Nationwide observational cohort study of maternal red-cell transfusions for all deliveries in Sweden between 2003 and 2017.

RESULTS

The proportion of deliveries that received red-cell transfusions was stable during the study period, although the number of red-cell units administered per delivery declined. Among transfused women, most received a low-volume transfusion of 1 or 2 units. Red-cell transfusion was more common among the nulliparous, for instrumental and caesarean deliveries, and with increased maternal age. We saw large variations in transfusion rates between hospitals in Sweden, despite adjusting for age and parity.

CONCLUSIONS

In comparison to other high-resource countries we see a high proportion of deliveries with maternal red-cell transfusions. However, we do not see an increase in red-cell use over time.

The contribution of iron deficiency to the risk of peripartum transfusion: a retrospective case control study

Background

Iron deficiency in pregnancy is associated with inferior maternal and fetal outcomes. Postpartum depression, prematurity, intrauterine growth restriction, impaired childhood cognition and transfusion are all sequelae of maternal iron deficiency anemia. Transfusion to women of childbearing age has important consequences including increasing the risk of hemolytic disease of the fetus and newborn with future pregnancies. The relative contribution of iron deficiency to transfusion rates in the peripartum period is unknown. This study aimed to identify the prevalence of iron deficiency and anemia in pregnant women that received peripartum transfusions relative to age-matched non-transfused controls.

Methods

We performed a retrospective case-control study of all women that were transfused in the peripartum period from January, 2014 to July, 2018. Cases were compared to the next age matched control to deliver at our institution. The primary objective was to determine the proportion of patients with iron deficiency in pregnancy or anemia in pregnancy in cases and controls. Charts were reviewed for predisposing risk factors for iron deficiency, laboratory measures of iron deficiency and anemia, iron supplementation history and maternal and fetal outcomes. Factors associated with peripartum transfusion were analyzed using a multivariate logistic regression.

Results

169 of 18, 294 (0.9%) women were transfused in the peripartum period and 64 (44%) of those transfused received 1 unit. Iron deficiency or anemia were present in 103 (71%) transfused women and 74 (51%) control women in pregnancy (OR 2.34, 95% CI: 3.7–18.0). Multivariate analysis identified social work involvement (adjusted OR 4.1, 95% CI: 1.8–10.1), intravenous iron supplementation in pregnancy (adjusted OR 3.8, 95% CI: 1.2–17.4) and delivery by unscheduled cesarean section (adjusted OR 2.8, 95% CI: 1.3–6.2) as significant predictors of peripartum transfusion.

Conclusions

Pregnant women being followed by a social worker, receiving intravenous iron supplementation in pregnancy or who deliver by unscheduled cesarean section are more likely to receive a red blood cell transfusion. Women with iron deficiency or anemia in pregnancy are at increased risk of peripartum blood transfusions and warrant early and rigorous iron supplementation.