The MCA Doppler and its Role in the Evaluation of Fetal Anemia and Fetal Growth Restriction
Section snippets
Diagnosis of fetal anemia before the use of the middle cerebral artery peak systolic velocity
Before the widespread use of the middle cerebral artery (MCA) peak systolic velocity (PSV), the management of maternal red cell alloimmunization was based on an indirect measurement of fetal hemolysis using spectrophotometric analysis of the amniotic fluid (optical density [OD] at 450 nm).1 The method to predict the severity of the hemolytic disease of the fetus and neonate was introduced by Liley in 1961.2 The only option in the diagnosis of anemia from causes other than red cell
Fetal MCA: 23 years of literature
Woo and colleagues4 reported serial Doppler flow velocity-time waveforms of the MCA at its origin from the internal carotid arteries in 14 patients with normal singleton pregnancies. The A/B ratio showed a progressive decrease with advancing gestational age. Kirkinen and colleagues5 recorded blood flow velocity waveforms from intracranial arteries in 83 normal and 84 high-risk pregnancies. They concluded that there was a decrease in the resistance index (RI) toward the end of the pregnancy and
MCA-PSV for the diagnosis of fetal anemia: a brief history of its conception
The use of the MCA-PSV for the diagnosis of fetal anemia is considered one of the few practice-changing discoveries in fetal medicine. One of the most important contributions of the MCA-PSV to clinical practice has been the dramatic reduction in the number of invasive procedures performed in the management of red cell alloimmunized pregnancies.25
Mari and colleagues26 reported that the PI of the MCA decreases within 2 hours after intrauterine blood transfusion and that the MCA-PSV was a better
How does the MCA-PSV compare with delta OD450 nm in the diagnosis of anemia?
In 1997, it was reported that the MCA-PSV was at least as good as the delta OD450 in diagnosing anemia; however, it had the advantage of being a noninvasive technique.43 Pereira and colleagues44 confirmed these results. Oepkes and colleagues,39 in a prospective multicenter study, included 165 fetuses of red cell alloimmunized pregnancies with indirect antiglobulin titers of at least 1:64 and antigen-positive fetal blood. The MCA-PSV and delta OD450 methods were applied to all the patients. A
Performing and interpreting the Doppler assessment of the MCA when testing for fetal anemia
The MCA closest to the ultrasound probe should be sampled soon after its origin from the internal carotid artery because the measurement at this level has the lowest intraobserver and interobserver variability, although the peak velocity in the contralateral MCA would still be valid.46, 47 Fig. 3 depicts the area where the spectral Doppler sample volume should be placed once the MCA has been identified. Fig. 4 shows normal and abnormal MCA waveforms.
A total of 50 to 100 waveforms in at least 3
MCA-PSV for the diagnosis of fetal anemia: important considerations in particular scenarios
Important considerations have to be made when using the MCA-PSV for the diagnosis of anemia in fetuses after one or more intrauterine blood transfusions. Detti and colleagues50 examined the MCA-PSV before cordocentesis in 64 fetuses that had previously undergone an intrauterine blood transfusion. Anemia was defined as mild (hemoglobin concentration between 0.65 and 0.84 MoM), moderate (hemoglobin concentration between 0.55 and 0.65 MoM), and severe (hemoglobin concentration <0.55 MoM).
The
Fetal MCA Doppler and IUGR: tracing the concept of IUGR back to its origin
Traditionally, babies born with a low birth weight were likely considered preterm. The concept of IUGR in the literature dates back to the 1960s, when Battaglia and Lubchenco65 and Lubchenco and colleagues66 published their work in which outcomes were recorded based on birth weight adjusted for gestational age. Once such reference values for birth weight by gestational age became available, newborns could be differentiated as small, adequate, or large for gestational age,67 and the concept of
Doppler ultrasonography in the management of IUGR
IUGR represents a threat not only for the fetus but also for the individual as a child and adult. Barker and Osmond73 have described an association between birth weight below the tenth percentile and the later development of hypertension, hypercholesterolemia, coronary heart disease, impaired glucose tolerance, and diabetes mellitus. In utero diagnosis and treatment becomes an appealing approach to reduce the burden exerted by IUGR on society. There are more than 10,000 publications in the
MCA Doppler in the assessment of IUGR fetuses
The structure of the MCA makes it a convenient target for in utero flow velocimetry studies and, at the same time, opens a window to observe the circulation within the central nervous system of the fetus, which is involved in many, if not all, pathologic processes in fetal medicine, including IUGR.
One of the earliest reports on this subject was by Echizenya and colleagues.7 They used pulsed Doppler ultrasonography to examine the significance of MCA flow velocimetry as a fetal assessment tool
MCA PI and RI
The RI and PI were used in most of the initial studies on MCA Doppler in IUGR fetuses, and they continue to represent the mainstay of the assessment in such cases. Ishimatsu and colleagues8 reported lower values of the MCA RI in asymmetrical SGA fetuses when compared with normal and symmetric SGA fetuses. van den Wijngaard and colleagues11 demonstrated a reduced PI in IUGR fetuses when compared with normal fetuses, and these findings were later reproduced.78, 79
Chiba and Murakami80 performed
Reversal of brain sparing effect
An IUGR fetus with a previously low PI that suddenly presents with an elevated MCA PI has been linked to poor outcomes.74 Konje and colleagues85 reported reversal of the brain sparing effect in 8 fetuses, 4 of which ended as stillbirths and the remainder died during the neonatal period.
Rowlands and Vyas86 published a study that included 5 IUGR fetuses that were longitudinally monitored until the time of fetal death. Of the 5 fetuses, 2 developed reversal of the brain sparing effect 48 hours
Reverse end-diastolic flow in the MCA: what does it mean?
Sepulveda and colleagues89 describe a case of IUGR with brain sparing effect, in which the MCA PI increased back to normal limits at 29 weeks of gestation. One week later, reverse end-diastolic flow of the MCA was seen on the day of in utero fetal death. Caution must be exerted when interpreting these data because only 1 case is described, and reverse end-diastolic flow of the MCA can be iatrogenically induced by applying excessive pressure over the fetal cranium.
MCA-PSV: a new parameter in the assessment of IUGR fetuses
Mari and colleagues90 performed a longitudinal assessment of the MCA PI and MCA-PSV in 30 growth-restricted fetuses with an EFW less than the third percentile. Perinatal mortality was recorded, and MCA PI and PSV values were classified as normal or abnormal. Forward stepwise logistic regression indicated that the MCA-PSV was the best parameter in the prediction of perinatal mortality (odds ratio, 14; 95% confidence interval, 1.4–130, P<.05; Nagerlke R[2] = 31). This finding may be explained by
Why is the MCA-PSV increased in IUGR fetuses?
Plausible mechanisms that explain the increase of the MCA-PSV in anemic fetuses have been elucidated, but IUGR fetuses are not necessarily anemic. There must be another reason for the increase in the MCA-PSV in this group of fetuses.
Akalin-Sel and colleagues91 postulated that hypoxemia alone or with hypercapnia is responsible for cerebral vascular responses as part of the complex group of regulatory mechanisms that play a role in the circulatory redistribution in human fetal growth restriction.
Where do the MCA Doppler abnormalities fit in the sequence of abnormal fetal testing in IUGR?
The decreased MCA PI has been historically regarded as an early finding in the sequence of abnormal testing in IUGR, whereas its reversal and an abnormal increase have been described as a late finding.86, 87, 88 Reverse end-diastolic flow in the MCA has been anecdotally described in the literature as an agonal sign, although it is possible to iatrogenically create this when applying pressure over the fetal cranium with the ultrasound probe.89 Hecher and colleagues93 serially assessed 93 IUGR
Performing and interpreting fetal MCA Doppler when IUGR is suspected
The literature on Doppler is saturated with many studies that have performed Doppler analysis on 3 continuous waveforms, selected more often from a group of 5 to 15 waveforms. We believe this is insufficient, especially when basing clinical decisions on these results. This belief has been supported by the results of recent studies.98, 99, 100 Several vessels can have abnormal waveforms following maternal contractions or following a fetal deceleration.101, 102 Therefore, incorrect or unreliable
Summary
The MCA Doppler examination is a great resource in the diagnosis and management of fetal anemia and IUGR. As a window into the hemodynamics of the fetal central nervous system, its potential is clearly unlimited. In cases of IUGR, the MCA Doppler flow velocimetry shows early and late changes. The PSV is proposed as a desirable parameter in every evaluation of IUGR fetuses, particularly because it has been demonstrated to perform better than other parameters in the prediction of perinatal
References (102)
Liquor amnil analysis in the management of the pregnancy complicated by rhesus sensitization
Am J Obstet Gynecol
(1961)- et al.
Developmental characteristics of blood flow in the middle cerebral artery in the human fetus in utero, assessed using the linear-array pulsed Doppler method
Early Hum Dev
(1988) - et al.
Doppler assessment of the pulsatility index in the cerebral circulation of the human fetus
Am J Obstet Gynecol
(1989) - et al.
Changes in vascular resistance in the umbilical and middle cerebral arteries in the human intrauterine growth-retarded fetus, measured with pulsed Doppler ultrasound
Early Hum Dev
(1989) - et al.
Middle cerebral artery blood flow in normal and growth-retarded fetuses
Am J Obstet Gynecol
(1990) - et al.
Doppler assessment of the fetal and uteroplacental circulation during nifedipine therapy for preterm labor
Am J Obstet Gynecol
(1989) - et al.
Doppler assessment of the pulsatility index of the middle cerebral artery during constriction of the fetal ductus arteriosus after indomethacin therapy
Am J Obstet Gynecol
(1989) - et al.
Doppler examination of the middle cerebral artery in anemic fetuses
Am J Obstet Gynecol
(1990) - et al.
Fetal venous, arterial, and intracardiac blood flows in red blood cell isoimmunization
Obstet Gynecol
(1995) - et al.
Conventional management of maternal red cell alloimmunization compared with management by Doppler assessment of middle cerebral artery peak systolic velocity
Am J Obstet Gynecol
(2003)
Ultrasound assessment of the fetal middle cerebral artery peak systolic velocity: A comparison of the near-field versus far-field vessel
Am J Obstet Gynecol
Longitudinal assessment of the middle cerebral artery peak systolic velocity in healthy fetuses and in fetuses at risk for anemia
Am J Obstet Gynecol
Doppler ultrasound velocimetry for timing the second intrauterine transfusion in fetuses with anemia from red cell alloimmunization
Am J Obstet Gynecol
Erythropoietic suppression in fetal anemia because of Kell alloimmunization
Am J Obstet Gynecol
Noninvasive diagnosis by Doppler ultrasonography of fetal anemia resulting from parvovirus infection
Am J Obstet Gynecol
The value of middle cerebral artery peak systolic velocity in the diagnosis of fetal anemia after intrauterine death of one monochorionic twin
Am J Obstet Gynecol
A practical classification of newborn infants by weight and gestational age
J Pediatr
Investigation of abdominal masses by pulsed ultrasound
Lancet
An evaluation of two equations for predicting fetal weight by ultrasound
Am J Obstet Gynecol
A United States national reference for fetal growth
Obstet Gynecol
Infant mortality, childhood nutrition, and ischaemic heart disease in England and Wales
Lancet
Doppler vascular changes in intrauterine growth restriction
Semin Perinatol
Middle cerebral artery flow velocity waveforms in normal and small-for-gestational-age fetuses
Am J Obstet Gynecol
Fetal cardiac function in intrauterine growth retardation
Am J Obstet Gynecol
The Doppler cerebroplacental ratio and perinatal outcome in intrauterine growth restriction
Am J Obstet Gynecol
Abnormal Doppler velocimetry and blood flow volume in the middle cerebral artery in very severe intrauterine growth restriction: is the occurrence of reversal of compensatory flow too late?
BJOG
Reverse end-diastolic flow in the middle cerebral artery: an agonal pattern in the human fetus
Am J Obstet Gynecol
The composition of liquor amnii in haemolytic disease of the newborn
J Obstet Gynaecol Br Emp
Presse Med
Middle cerebral artery Doppler flow velocity waveforms
Obstet Gynecol
Blood flow velocity waveforms in human fetal intracranial arteries
Obstet Gynecol
Significance of velocimetry as a monitor of fetal assessment and management
Fetal Ther
Cerebral artery blood flow velocity waveforms in normal and small for dates fetuses
Kurume Med J
Fetal blood velocity waveforms in normal pregnancies. A longitudinal study
Acta Obstet Gynecol Scand
Cerebral Doppler ultrasound of the human fetus
Br J Obstet Gynaecol
Doppler velocimetry of the uterine, umbilical and fetal middle cerebral arteries in pregnant women undergoing tocolysis with oral nifedipine
Ultrasound Obstet Gynecol
Nifedipine therapy for preterm labor: effects on placental, fetal cerebral and atrioventricular Doppler parameters in the first 48 hours
Ultrasound Obstet Gynecol
Uterine and fetal flow velocity waveforms in hypertensive pregnancy: the effect of a single dose of nifedipine
Obstet Gynecol
Mid-trimester fetal-placental velocimetry response to nifedipine may predict early the onset of pre-eclampsia
In Vivo
Changes in blood velocities of fetal circulation in association with fetal heart rate abnormalities: effect of sublingual administration of nifedipine
Am J Perinatol
Lack of effect of antenatal indomethacin on fetal cerebral blood flow
Am J Obstet Gynecol
Is the fetal brain-sparing effect a risk factor for the development of intraventricular hemorrhage in the preterm infant?
Ultrasound Obstet Gynecol
Cerebral blood flow changes associated with fetal intracranial hemorrhages
Acta Obstet Gynecol Scand
No Shinkei Geka
Noninvasive diagnosis by Doppler ultrasonography of fetal anemia due to maternal red-cell alloimmunization. Collaborative Group for Doppler Assessment of the Blood Velocity in Anemic Fetuses
N Engl J Med
Flow velocity waveforms of the umbilical and cerebral arteries before and after intravascular transfusion
Obstet Gynecol
Effects of hematocrit variations on regional hemodynamics and oxygen transport in the dog
Am J Physiol
Diagnosis of fetal anemia with Doppler ultrasound in the pregnancy complicated by maternal blood group immunization
Ultrasound Obstet Gynecol
Increase of fetal hematocrit decreases the middle cerebral artery peak systolic velocity in pregnancies complicated by rhesus alloimmunization
J Matern Fetal Med
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2016, European Journal of Obstetrics and Gynecology and Reproductive BiologyCitation Excerpt :However, the outcome for non-immune hydrops may be improving, as >75% of these fetuses survived in our series, compared to a previously reported 23% survival [10], likely due to the increased use of MCA Dopplers to screen for fetal anemia before PUBS is performed. MCA Doppler abnormalities have been well correlated with rates of anemia in both hydropic and non-hydropic fetuses, with >1.5 multiples of the median (MoM) being traditionally used as a cutoff; this technique is frequently used to evaluate fetal anemia [11,12]. This method is now the preferred diagnostic measure for fetal anemia per guidelines from the Society for Maternal Fetal Medicine [13].
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2013, Clinics in PerinatologyCitation Excerpt :The development of acidemia indicates that the fetus is not able to compensate; acidosis shifts the oxygen dissociation curve to the right, thereby decreasing fetal hemoglobin oxygen saturation but improving the release of oxygen from hemoglobin. Blood flow during periods of hypoxia increases more than 100% to the brainstem but only 60% to the cerebral hemispheres.38 The fetus exists in an environment of low oxygen tension, with Po2 being approximately one-fourth that of the adult.
Prediction of fetal anemia by middle cerebral artery Doppler
2012, Middle East Fertility Society JournalCitation Excerpt :Doppler velocimetry of the middle cerebral artery (MCA) has played a major role in the fetal medicine for the last 23 years, both in intrauterine growth-restricted (IUGR) and anemic fetuses. Its utility in the diagnosis and management of cases of fetal anemia was initially demonstrated in the cases of red cell alloimmunization and later extended to other types of anemia (16,15). Data of the present findings confirm that MCA peak systolic velocity compared with hemoglobin levels at either fetal blood sampling, or cord sampling at delivery if antenatal intervention had not been indicated is significantly increased in the cases of fetal anemia owing to red cell antibodies.
Intra-observer variability of Doppler measurements in umbilical artery (UA) and middle cerebral artery (MCA) in uncomplicated term pregnancies
2022, Journal of Maternal-Fetal and Neonatal MedicineIs fetal middle cerebral artery peak systolic velocity correlated with hemoglobin levels in cases of nonimmune fetal anemia?
2022, Journal of Maternal-Fetal and Neonatal Medicine
The authors have nothing to disclose.