Prospective quantification of fetomaternal hemorrhage with dilation and evacuation procedures

Prenatal diagnosis of fetomaternal hemorrhage by a novel hydrogel fluoroimmunoassay that accurately quantifies fetal haemoglobin

Objective: Fetomaternal hemorrhage (FMH) is an alloimmunization resulting caused by the incompatibility between fetal and maternal blood. For the prevention of newborn haemolytic disease (HDN), it is crucial to quantify the amount of fetomaternal hemorrhage. However, the classical Kleihauer-Betke test (K-B test) for detecting fetomaternal hemorrhage is limited by experimental tools and conditions and is not suitable for routine clinical use. Consequently, the method of prenatal diagnosis of fetomaternal hemorrhage applicable to the clinic is a topic worthy of further study. Therefore, it is worthwhile to further investigation on the clinically applicable prenatal diagnosis method for fetomaternal hemorrhage. Methods: This experiment demonstrates hydrogel's ability to separate sensitized red blood cells from soluble antibodies. Using flow cytometry the fluorescence values of sensitized red blood cells and fluorophore-labeled antibodies were measured, and the testing steps for the detection products of a novel technology were determined. The properties of a hydrogel fluoroimmunoassay were evaluated by distinguishing between the amounts of fetal and adult haemoglobin. The precision of this technology is evaluated using the Kleihauer-Betke test as a comparison. Results: This experiment compared the detection of haemoglobin fluorescence in adults (n = 2) and fetuses (n = 6). At the same time, the fluorescence intensity of different fetal haemoglobin (HbF) in adult haemoglobin (HbA) was calculated. The fluorescence value is 1.6% when the fetal hemoglobin concentration is 0.1%. Conclusion: The novel hydrogel fluoroimmunoassay can accurately determine the fluorescence intensity by flow cytometry to differentiate fetal haemoglobin from adult haemoglobin, quantitatively prenatally diagnose fetal haemoglobin, address the incompatibility between fetal and maternal blood types, and prevent alloimmunization.

A novel enzyme-linked immunostaining technique based on silk membrane for the prenatal detection of fetomaternal haemorrhage

Objective: Developing a simple, rapid, reliable, sensitive, and cost-effective method for prenatal detection of fetomaternal haemorrhage by combining multi-aperture silk membrane with enzyme-linked immunosorbent assay (ELISA), which does not require any complicated instruments and can be visually colored, so as to provide a new method for clinical detection of fetomaternal haemorrhage. Methods: As a carrier, a chemically treated silk membrane was used to immobilize anti-A/anti-B antibody reagent. PBS washed slowly after vertically dropping red blood cells. After adding biotin-labeled anti-A/anti-B antibody reagent, PBS is slowly washed, enzyme-labeled avidin is added, and TMB is used for color development after washing. Results: When there were both anti-A and anti-B fetal erythrocytes in pregnant women's peripheral blood, the final color was dark brown. When there are no anti-A and anti-B fetal red blood cells in pregnant women's peripheral blood, the final color development results do not change, which corresponds to the color of chemically treated silk membrane. Conclusion: The new enzyme-linked immunosorbent assay (ELISA) based on a silk membrane can distinguish fetal red blood cells from maternal red blood cells prenatally and can be used for prenatal detection of fetomaternal haemorrhage.

Clinical interventions are more accurate than quantitative measurements for defining hemorrhage with dilation and evacuation

OBJECTIVES

To assess if quantitative blood loss (QBL) with dilation and evacuation (D&E) procedures correlated with clinically relevant outcomes or hemorrhage.

STUDY DESIGN

We used a de-identified database to review D&E procedures performed at UC Davis Health from April 2019 through March 2020. Surgeons determined QBL during procedures and estimated blood loss, when excessive, during post-procedure recovery. We extracted patient demographic and procedure-related information. We defined clinically relevant bleeding as cases with bleeding-related interventions within 24 hours post-procedure including use of ≥2 uterotonics, tranexamic acid administration, cervical injury requiring repair, uterine balloon tamponade, blood transfusion, uterine artery embolization, hospitalization, or return to operating room; the latter 5 criteria defined hemorrhage. We used χ2 test for trend to evaluate bleeding outcomes.

RESULTS

We evaluated 431 procedures with a mean gestational age of 19 weeks and 3 days. Clinically relevant bleeding outcomes occurred in 6/319 (2%), 15/97 (15%) and 7/12 (58%) patients with total blood loss <250mL, 250-500mL and >500mL, respectively (p<0.0001); 11 had bleeding related to cervical injuries. Hemorrhage occurred in 0, 4/97 (4%) and 5/12 (42%) patients, respectively (p<0.0001). Patients with relevant bleeding outcomes had QBLs ranging from 150-1800mL (median QBL 312.5mL, interquartile range [IQR] 250-550mL) while those without clinically relevant bleeding ranged from 10-900mL (median QBL 150mL, IQR 75-200mL).

CONCLUSION

Most patients (75%) with clinically relevant bleeding outcomes had QBL ≤500mL. Although higher QBL correlates with clinical interventions, the need for significant interventions rather than a single blood loss amount should be used to define hemorrhage with D&E procedures.

IMPLICATIONS

Clinical hemorrhage is best defined by the necessary clinical interventions required to manage bleeding rather than any quantified amount of blood loss.

Fetomaternal hemorrhage assessment in Rh-negative patients undergoing dilation and evacuation between 20 and 24 weeks' gestational age: A retrospective cohort study

OBJECTIVE

To estimate the rate of requiring more than one 300-mcg Rh D immune globulin dose for fetomaternal hemorrhage (FMH) at the time of second-trimester dilation and evacuation (D + E).

STUDY DESIGN

We performed a retrospective cohort analysis of patients at greater than 20 weeks' gestation who underwent D + E, had Rh D-negative blood type, and received FMH quantification testing.

RESULTS

Of 25 eligible patients, 24 had negative quantification of FMH; one had positive quantification that did not meet the clinical threshold for additional dosing.

CONCLUSIONS

The absolute risk of requiring additional Rh D immune globulin after D+E for pregnancies greater than 20 weeks' gestation was 0%.