Identification of feto-maternal haemorrhage around labour using flow cytometry immunophenotyping

Trauma and pregnancy: Is flow cytometry detection and quantification of fetal red blood cells useful?

OBJECTIVE

To assess whether positive flow cytometry quantification of fetal red blood cells is associated with adverse maternal and neonatal outcomes in cases of mild trauma during pregnancy.

STUDY DESIGN

A retrospective database study was conducted at a single tertiary center between 2013 and 2019. All pregnant women with viable gestation involved in trauma who underwent flow cytometry quantification of fetal red blood cells were included in the study. Flow cytometry was considered positive (≥0.03/≥30 ml). Composite adverse maternal and neonatal outcome was defined as one or more of the following: intrauterine fetal death, placental abruption, pre-term birth <37 weeks of gestation, immediate premature rupture of the membranes, and immediate delivery following trauma. Univariate analysis was performed followed by multivariate logistic regression analysis controlling for potential confounders, to assess the role of flow cytometry in predicting adverse maternal and neonatal outcome. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

During the study period 1023 women met inclusion and exclusion criteria. The mechanisms of injury were motor vehicle accident in 387 women (38%), falls in 367 (36%), direct abdominal injury in 353 (35%) and in 14 women (1%) other mechanism of injury. Flow cytometry was considered positive (≥0.03/≥30 ml) in 119 women (11.6%) with median result of 0.03 [0.03-0.04], and negative in 904 women (88.4%) ((≤0.03/≤30 ml) with median result of 0.01 [0.01-0.02]. Composite adverse outcome occurred in 8% of the women involved in trauma during pregnancy, with no difference between the groups with vs. without positive flow cytometry (4.2% vs. 8.5%; p = 0.1). Positive flow cytometry was not associated with any adverse maternal or neonatal outcome. This was confirmed on multivariate analysis controlling for potential confounders.

CONCLUSION

Flow cytometry result is not related to adverse maternal and fetal/neonatal outcome of women involved in minor trauma during pregnancy. We suggest that flow cytometry should not be routinely assessed in pregnant women involved in minor trauma.

Flow Cytometry in Detection of Fetal Red Blood Cells and Maternal F Cells to Identify Fetomaternal Hemorrhage

Accurate detection and quantitation of fetomaternal hemorrhage (FMH) is critical to the obstetric management of rhesus D alloimmunization in Rh-negative pregnant women. The flow cytometry is based on the detection of fetal red blood cells using a monoclonal anti-HbF antibody, and is the method most indicated for this estimation. The objective of this study was to quantify fetal red blood cell levels of pregnant women using flow cytometry. We analyzed 101 peripheral blood samples from Rh-negative and Rh-positive women, whose mean age was 24 years (20-32 years), after vaginal delivery or cesarean section. Our study showed that 53% of pregnant women had fetal red blood cells levels <2.0 mL, 31% between 2.0-3.9 mL, 16% between 4.0-15.0 mL, and 1% >15.0 mL. Accurate quantitation of fetal red blood cells is necessary to determine the appropriate dose of anti-D (RHD) immunoglobulin to be administered to pregnant or postpartum women.

Reference values of fetal erythrocytes in maternal blood during pregnancy established using flow cytometry

The aim of our study was to assess the fetal RBC count in maternal blood during uncomplicated pregnancies from 26 weeks onward. We used a flow cytometric method specifically designed for use in a routine hematology analyzer. Pregnant women were recruited through midwives. The participating laboratories used the FMH QuikQuant method (Trillium Diagnostics, Brewer, ME) in a CELL-DYN Sapphire hematology analyzer (Abbott Diagnostics, Santa Clara, CA). The method is based on a monoclonal antibody to hemoglobin F. Flow cytometric data were analyzed by 2 independent observers. The 95th percentile reference range was estimated according to Clinical and Laboratory Standards Institute guidelines. A total of 236 samples were statistically analyzed. Gestational ages ranged from 21.6 to 41 weeks (mean, 32.0 weeks), and the fetal RBC count in maternal blood ranged from 0.00% to 0.50% (median, 0.025%). The fetal RBC count in maternal blood shows no correlation with gestational age. The established reference range during normal pregnancy is less than 0.125%.