Noninvasive techniques to detect fetal anemia due to red blood cell alloimmunization: a systematic review

Assessment of the peak systolic velocity of the middle cerebral artery in twin-twin transfusion syndrome. Part I: preoperative assessment

OBJECTIVE

We sought to assess the incidence of an elevated peak systolic velocity of the middle cerebral artery (MCA-PSV) in twin-twin transfusion syndrome prior to laser surgery and its prognostic value for intrauterine fetal demise 24 hours after surgery (IUFD-24).

STUDY DESIGN

An elevated MCA-PSV was defined as a velocity > .5 multiples of the median by transabdominal pulsed Doppler. Gestational age, Quintero stage, and number and/or type of placental vascular anastomoses were assessed as risk factors for an elevated MCA-PSV. Risk of IUFD-24 was assessed relative to an elevated MCA-PSV.

RESULTS

An elevated MCA-PSV was present in 4.2% of donors, 3.2% of recipients (P = .5), and 1.5% of both twins in 189 patients with twin-twin transfusion syndrome. An elevated MCA-PSV was unrelated to gestational age, stage, and number or type of anastomoses. An elevated MCA-PSV in the recipient twin was associated with an increased risk of IUFD-24 of this fetus (P = .01).

CONCLUSIONS

An elevated MCA-PSV is present in < 5% of donor and recipient twins. An elevated MCA-PSV is a risk factor for IUFD-24 of the recipient twin.

Management of Rh-isoimmunised Pregnancies : Our Experience

BACKGROUND

The aim of this study was to assess the role of middle cerebral artery peak systolic velocity (MCA-PSV), as measured by doppler ultrasound, in detecting foetal anaemia in Rh- isoimmunised pregnancies. Intra-uterine foetal blood transfusion was performed in such anaemic foetuses to tide over the crisis of foetal immaturity till considered fit for extra-uterine survival.

METHODS

Rh-isoimmunised pregnancies reporting to a tertiary institute from 2003 to 2005, were screened by doppler ultrasound to estimate MCA-PSV to detect foetal anaemia. If the foetus developed MCA-PSV of more than 1.5 multiple of median (MoM) for the gestational age, foetal blood sampling through cordocentesis was performed to confirm foetal anaemia, followed by intrauterine foetal blood transfusion to all anaemic foetuses at the same sitting. Neonatal outcome was evaluated by recording gestational age at the time of delivery, duration of gestational time gained and need for blood transfusion in the neonatal period.

RESULTS

A total of thirteen isoimmunised pregnancies were evaluated. Three pregnancies did not require in-utero foetal blood transfusion. Twenty-one intrauterine foetal blood transfusions were performed in the remaining ten patients. Five received blood transfusion in the neonatal period. Intra uterine foetal death occurred in one grossly hydropic foetus and favourable neonatal outcome was recorded in the rest.

CONCLUSION

The clinical outcome of these pregnancies justifies the use of doppler studies of MCA-PSV in detecting foetal anaemia and intra uterine foetal blood transfusion is the only hope of prolonging pregnancy and salvaging such foetuses.

The effect of fetal behavioral states on middle cerebral artery peak systolic velocity

OBJECTIVE

This study was undertaken to determine whether is there a difference in the middle cerebral artery peak systolic velocity (MCA PSV) between active and resting behavioral states in healthy fetuses aged 30 to 32 weeks.

METHODS

MCA blood flow was measured by pulsed Doppler sonography 3 times during each fetal behavioral state (active and resting). The average during active state was compared during the resting state. Statistical analysis was performed by paired t test.

RESULTS

During the fetal active state, there was a significant increase in the mean PSV (51.59 cm/s vs 46.95 cm/s, P < .0001) and mean end-diastolic velocity (9.59 cm/s vs 7.98 cm/s, P=.0015), and a significant decrease in the mean pulsatility index (PI) (2.07 vs 2.19, P=.0226) and the mean resistance index (0.83 vs 0.85, P=.0481).

CONCLUSION

Healthy preterm fetuses have a significantly higher MCA PSV during the active state. Activity state should be considered when interpreting MCA Doppler indices.

A retrospective review of isoimmunized pregnancies managed by middle cerebral artery peak systolic velocity

OBJECTIVE

The purpose of this study was to determine the clinical outcome of isoimmunized pregnancies managed primarily by middle cerebral artery peak systolic velocity.

STUDY DESIGN

A retrospective chart review was conducted of isoimmunized pregnancies that underwent ultrasound examinations from January 1, 2001, through May 1, 2003. Ultrasound reports, laboratory tests, and maternal and neonatal charts were reviewed.

RESULTS

Women with a clinically significant red blood cell antibody and titer value were included. The study population consisted of 39 women (40 pregnancies, 42 fetuses). Patients with a middle cerebral artery peak systolic velocity of > or =1.5 MoM were offered amniocentesis. Seven pregnancies had an abnormal middle cerebral artery peak systolic velocity. Three of these infants had significant anemia. Six of the 7 pregnancies required an exchange transfusion. None of the 33 pregnancies (35 neonates) with normal middle cerebral artery peak systolic velocity measurements resulted in a neonate with significant anemia or severe hyperbilirubinemia.

CONCLUSION

The clinical outcome of these pregnancies supports the use of middle cerebral artery peak systolic velocity measurements in the management of isoimmunized pregnancies.

Intravenous Fetal Exchange Transfusion before 22 Weeks of Gestation in Early and Severe Red-Cell Fetomaternal Alloimmunization

OBJECTIVES

To determine the perinatal outcome in severe red-cell fetomaternal alloimmunization.

METHODS

Retrospective series of 32 affected fetuses treated with intravenous fetal exchange transfusion (IFET) before 22 weeks of gestation. The main outcome measures were the degree of fetal anemia, fetal transfusions and perinatal outcome.

RESULTS

The first IFET was performed at 19.8 +/- 1.8 weeks of gestation. All fetuses were severely anemic and hemoglobin levels were not different between 20 hydropic and 12 nonhydropic fetuses (4.1 +/- 2.5 vs. 5.6 +/- 2.8 g/dl, p=0.33). The initial maternal anti-D level ranged from 4 to 76 microg/l and was not correlated to fetal anemia (r=-0.07).

CONCLUSION

The overall perinatal survival rate was 78% compared to a previous perinatal loss rate excluding first pregnancies of 55.5%.

Testing for hematologic disorders and complications

This review summarizes state-of-the-art and emerging techniques in the antenatal diagnosis of fetal anemia and hemoglobinopathies. Fetal anemia may result from hemolytic disease, hemorrhage, suppression of erythropoiesis, infection (eg, parvovirus B19), or trauma. The clinical laboratory plays an essential role in the evaluation of these disorders by way of the use of various hematologic, biochemical, serologic, cytometric, and molecular genetics methods. Hemoglobinopathies are the most common class of single gene disorders worldwide. The authors have used the example of homozygous alpha-thalassemia major (Hb Barts disease) as a paradigmatic case for antenatal hemoglobinopathy screening. Perhaps the most familiar indication for hematologic screening in pregnancy is HDFN, most commonly in pregnancies previously sensitized to the RhD antigen. All pregnant women, regardless of their past medical or obstetric history or previous antibody screens, should have ABO/Rh blood typing and a red cell antibody screen performed at the first prenatal visit. Long-established methods for assaying FMH (KB method), microcytosis (hemogram with red cell indices), and blood group incompatibility (direct antigen test, serologies) remain critical for rapid, sensitive diagnosis. Analysis of fetal free DNA in maternal plasma holds the promise for rapid, ultrasensitive, and noninvasive detection of many fetal hematologic disorders.

Doppler blood flow in obstetrics

PURPOSE OF REVIEW

Our review on Doppler ultrasound in obstetrics aims to identify which vessels have a definite clinical role in obstetrics.

RECENT FINDINGS

The use of Doppler ultrasonography in the diagnosis and management of the intrauterine growth-restricted fetus improves the perinatal morbidity and mortality. However, the timing of delivery of the intrauterine growth-restricted fetus, based on Doppler ultrasonography, remains the subject of investigation. Robust data exist on the management of fetuses at risk for anemia because of red cell alloimmunization by using the middle cerebral artery peak systolic velocity. Appropriate training for the correct assessment of this vessel is fundamental. Doppler ultrasonography of the umbilical artery is useful in the counseling of patients with pregnancies complicated by twin-twin transfusion syndrome.

SUMMARY

Recently, Doppler ultrasonography has been shown to be helpful to the obstetricians in the diagnosis of the IUGR fetus, diagnosis of fetal anemia, twin-twin transfusion syndrome. These are the basis for timing the delivery of the IUGR fetus. However, more data are necessary. Doppler ultrasonography should be used to assess the fetal ductus arteriosus in patients treated with prostaglandin inhibitors. Doppler is also an important part of the fetal echocardiogram.

Prediction of fetal anaemia

The perinatal outcome of the anaemic fetus has dramatically improved over the last 20 years, as a result of early recognition of the problem and treatment by intrauterine transfusion. Traditionally assessment of the anaemic fetus relied on obstetric history and maternal antibody titre, which proved to be inadequate tests to accurately predict fetal condition. More recently, invasive testing with techniques such as amniocentesis and cordocentesis have allowed a more accurate evaluation of the degree of anaemia, while at the same time enabling transfusion to take place. Such techniques are not without danger, with perinatal loss and fetomaternal haemorrhage being significant risks. The clinical community has therefore sought to find accurate, non-invasive methods for assessing the degree of fetal anaemia, thereby reducing the number of unnecessary invasive procedures, while at the same time providing more precise data on the quantity and timing of the transfusion. Recent publications focusing on the diagnosis and management (including plasmapheresis, immunoglobulins and intrauterine transfusion) of fetal anaemia will be discussed.