Should optimal timing between two intrauterine transfusions be based on estimated daily decrease of hemoglobin or on measurement of fetal middle cerebral artery peak systolic velocity?

Performance of middle cerebral artery doppler for prediction of recurrent fetal anemia

OBJECTIVE

To assess the predictive value of middle cerebral artery Doppler peak systolic velocity (MCA-PSV) for moderate-severe fetal anemia following one intrauterine transfusion (IUT) and test the performance of alternate cutoffs to the recommended threshold ≥1.69 multiples of the median (MoM).

METHODS

This was a retrospective cohort study of patients with pregnancies affected by alloimmunization who underwent percutaneous umbilical blood sampling (PUBS) procedures from 2000 to 2020. An MCA-PSV ≥1.69 MoM was the indication for the second IUT. The primary outcome was recurrent moderate-severe fetal anemia. Receiver-operating characteristic (ROC) curves assessed the predictive ability of MCA-PSV for the primary outcome and the Youden index identified the "optimal" cutoff value. Predictive characteristics of MCA-PSV ≥1.69 MoM and the "optimal" cutoff were compared.

RESULTS

Of the 58 patients who underwent IUT during the study period, 36 (62%) did not meet inclusion criteria. Of the remaining 22 patients who underwent a second PUBS, 12 (54.6%) fetuses had moderate or severe anemia. Following one IUT, the AUC for MCA-PSV was 0.86 (95% CI 0.70-1.00) for the primary outcome. The "optimal" cutoff MCA-PSV value was 1.74 MoM, which had a greater specificity than ≥1.69 MoM (90 vs. 50%, p = .05), but was not statistically significant. The sensitivity was similar between the two cutoff values of ≥1.69 and ≥1.74 MoM (83.3 vs. 75.0%, p = .65) (Table 2).

CONCLUSION

Raising the recommended MCA-PSV cutoff to ≥1.74 MoM for recurrent moderate-severe fetal anemia after one IUT would decrease the number of unnecessary procedures without significantly changing the sensitivity of this screening test.

Peak systolic velocity of fetal middle cerebral artery to predict anemia in Red Cell Alloimmunization in un-transfused and transfused fetuses

OBJECTIVE

To assess the accuracy of middle cerebral artery peak systolic velocity (MCA-PSV) in prediction of severe fetal anemia resulting from Red Cell Alloimmunization (Anti-D) in un-transfused and transfused fetuses. In addition to comparing the accuracy of MCA-PSV and the estimation of the daily decline of fetal hemoglobin (Hb), to determine the appropriate time of subsequent transfusions.

STUDY DESIGN

This was a retrospective study of a series of 84 anaemic fetuses due to Red Cell alloimmunization. During each in-utero transfusion session, measurements of (1)MCA-PSV, (2)pre- and (3)post-transfusion Hb levels were recorded. Receiveroperating characteristics (ROC) curves, negative and positive predictive values of MCA-PSV in predicting severe fetal anemia were calculated. Regression analysis assesses the correlation between fetal HB and MCA-PSV, and between observed and expected fetal hemoglobin levels.

RESULTS

Eighty four anemic fetuses were included in the study and had an in-utero transfusion. The positive predictive value (PPV) of MCAPSV decreased sharply from 86.0 % at the first IUT, to 52.0 % and 52.1 % at the second and third IUTs respectively. According to the ROC curves, setting the cut-off at 1.70 MoM would provide the best performance of MCA-PSV with respect to the timing of the second and third IUT. Setting a higher threshold of 1.70 MoM for the 2nd and 3rd transfusions would increase the PPV from 52.0 % to 96.4 % at the second IUT, and from 52.1%-99.8 % at the third IUT.

CONCLUSION

In this study we suggest that a higher MCA-PSV (MoM 1.7 in compared to 1.5MOM) can accurately predict the recurrence of severe fetal anemia requiring serial IUTs. In transfused fetuses, MCAPSV accuracy to detect severe anemia decline slightly with increase number of IUT. In addition to that, the mean projected daily decrease in fetal hemoglobin has a similar accuracy to MCA-PSV in predicting moderate to severe fetal anemia.

Prediction of Fetal Anemia in Subsequent Transfusions: Is There a Need to Change the Threshold of the Peak Systolic Velocity of the Middle Cerebral Artery?

INTRODUCTION

Peak systolic velocity (PSV) of the middle cerebral artery (MCA) shows 100% sensitivity for predicting fetal anemia before the first intrauterine transfusion (IUT). However, its ability to predict subsequent transfusions has remained mostly controversial.

OBJECTIVES

To assess if there is a need to change the threshold of MCA-PSV from 1.5 to 1.69 multiples of the median (MoM) to predict fetal anemia and the need for subsequent IUT.

METHODS

This is a retrospective audit, wherein case records of mothers who underwent IUT at the Bangalore Fetal Medicine Centre between April 2008 and May 2017 were reviewed; 86 cases were included, and the data were analyzed using MS Excel. The MCA-PSV and pretransfusion Hb were converted into MoM. 40 fetuses that had more than 1 IUT were included in the analysis. -Results: 31/40 fetuses that had >1 IUT had an MCA-PSV >1.5 MoM, of which 29 were anemic according to the post-IUT Hb MoM. 20/29 (69%) had an MCA-PSV >1.69, whereas 9/29 (31%) had an MCA-PSV between 1.5 and 1.69 MoM. Our study shows that changing the MCA-PSV threshold from 1.5 to 1.69 MoM will reduce the detection of fetal anemia and hence the need for repeat IUT by 31%.

CONCLUSIONS

Increasing the fetal MCA-PSV threshold from 1.5 to 1.69 will miss out one-third of the fetuses that will require a 2nd, 3rd, or 4th IUT. This is more relevant in geographical areas where the parents must travel long distances for IUTs, which are performed in tertiary fetal care centers.

Effect of maternal corticosteroid provision on middle cerebral artery peak systolic velocity readings in the potentially anaemic fetus prior to planned intrauterine transfusion

Purpose

Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV) is the main tool for determining need for and timing of intrauterine transfusions (IUT) for severe fetal anaemia. It has been suggested that steroids temporarily decrease MCA-PSV, potentially increasing false-negative MCA-PSV findings in anaemic fetuses. We therefore aimed to assess whether maternal corticosteroid administration prior to IUT is associated with clinically significant temporary decreases in MCA-PSV.

Methods

Retrospective review 2005-2016 of steroid provision prior to IUT, with correlation of MCA-PSV pre- and post-steroid administration and haemoglobin at IUT.

Results

In 23 identified cases, there was no significant difference between average MoM pre- and post-steroid (1.71 ± 0.41 vs. 1.66 ± 0.38, -2.9% mean, P = 0.4). There was also no significant difference between pre- and post-steroid MoM taken within 3 days of each other (n = 19, P = 0.21). However, post-steroid MCA-PSV decreased by >15% in 6/23 cases (A-B zone in two cases, B-C zone in one case).

Conclusions

This study found no sizeable, generalised effect of corticosteroid administration on MCA-PSV readings in the potentially anaemic fetus. A minority showed substantial shifts where reliance on post-steroid MCA-PSV could have unfavourably altered clinical management. Ultimately, further large-scale research is required before we can discount the potential impact of steroids on MCA-PSV values.

Fetal middle cerebral artery Doppler to time intrauterine transfusion in red-cell alloimmunization: a randomized trial

OBJECTIVES

To evaluate whether Doppler measurement of middle cerebral artery peak systolic velocity (MCA-PSV) for timing subsequent intrauterine transfusions (IUTs) in fetuses that had undergone one IUT for anemia secondary to red-cell alloimmunization is non-inferior to timing based on expected decrease in fetal hematocrit (Hct) or fetal hemoglobin level, without compromising infant hemoglobin at birth.

METHODS

This was an international, pragmatic multicenter randomized controlled trial. Women with a pregnancy complicated by fetal anemia secondary to red-cell alloimmunization (due to any antibody alone or in combination), as indicated by the need to undergo a single IUT, were eligible for inclusion. Women were randomized to the determination of timing of further transfusion(s) by Doppler measurement of MCA-PSV (MCA-PSV Group), with a serial upward trend of values >1.5 multiples of the median considered indicative of the need for another IUT, or timing of transfusion by a decrease in fetal Hct (fetal Hct Group), with subsequent IUTs timed according to an estimated fall in fetal Hct of 1% per day or fetal hemoglobin of 0.3 g/dL per day, to maintain fetal hemoglobin level between 7 and 10 g/dL. The primary outcome was infant hemoglobin level measured at birth.

RESULTS

A total of 71 women were randomized, 36 to the MCA-PSV Group and 35 to the fetal Hct Group. Median gestational age at randomization was 30.3 weeks, the majority of women were Caucasian and non-smokers, 9.9% of women had Kell alloimmunization, and 14% of fetuses were hydropic at their first IUT. No statistically significant differences between the two treatment groups were observed with regard to mean hemoglobin levels at birth (MCA-PSV Group, 10.36 ± 3.82 g/dL vs fetal Hct Group, 12.03 ± 3.14 g/dL; adjusted mean difference -1.56 g/dL (95% CI, -3.24 to 0.13 g/dL); P = 0.070), or the number of IUTs performed after randomization (MCA-PSV Group, 1.75 ± 1.79 vs fetal Hct Group 1.80 ± 1.32; adjusted relative risk 0.88 (95% CI, 0.61-1.26); P = 0.474). There was no statistically significant difference between the two groups with respect to the risk of adverse infant outcomes related to alloimmunization or procedure-related complications.

CONCLUSION

Both Doppler measurement of MCA-PSV and estimation of the decrease in fetal Hct or hemoglobin can be used to determine the timing of second and subsequent IUTs in fetuses with red-cell alloimmunization. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Management of red blood cell alloimmunization in pregnancy

The main cause of fetal anemia is maternal red blood cell alloimmunization (AI). The search of maternal antibodies by indirect antiglobulin test allows screening for AI during pregnancy. In case of AI, fetal genotyping (for Rh-D, Rh-c, Rh-E and Kell), quantification (for anti-rhesus antibodies) and antibody titration, as well as ultrasound monitoring, are performed. This surveillance aims at screening for severe anemia before hydrops fetalis occurs. Management of severe anemia is based on intrauterine transfusion (IUT) or labor induction depending on gestational age. After intrauterine transfusion, follow-up will focus on detecting recurrence of anemia and detecting fetal brain injury. With IUT, survival of fetuses with alloimmunization is greater than 90% but 4.8% of children with at least one IUT have neurodevelopmental impairment.