Is Middle Cerebral Artery Doppler Velocimetry
A Good Predictor of Fetal Well Being in Fetuses
with Non-Reactive NSTM
Mehmet Çınar*1, Hatice Kansu Çelik1, Ali İrfan Güzel1, Omer Hamid Yumuşak1, Aykut Kadıoğlu2 and Yasemin Taşçı1
1Department of Obstetrics and Gynecology, Zekai Tahir Burak Women’s Health Education and Research Hospital, Turkey
2 Deparment of Radiology, Ufuk University, Turkey
Submission: January 30, 2017; Published: March 28, 2017
*Corresponding author: Dr Mehmet Çınar, Department of Obstetrics and Gynecology, Zekai Tahir Burak Women’s Health Education and Research Hospital, Talatpaşa Boulevard, Hamamönü, Altındağ, 06230, Ankara, Turkey.
How to cite this article: Mehmet Ç, Hatice K Ç, Ali İ G, Omer H Y, Aykut K, Yasemin T. Is Middle Cerebral Artery Doppler Velocimetry A Good Predictor
of Fetal Well Being in Fetuses with Non-Reactive NST. Acad J Ped Neonatol. 2017; 3(5): 555680. DOI: 10.19080/AJPN.2017.03.555680
In this descriptive longitudinal study we aimed to evaluate the predictive role of middle cerebral artery Doppler velocimetry in assessing non-reactive non stress test (NST). 148 cases with recovered non-reactive NST group were classified as group 1 and 151 cases persistent non-reactive NST as group 2. Data collected and age, GW (gestational weeks), gravidity, parity, middle cerebral artery Doppler velocimetry, non stress test (NST) were evaluated of each patients. MCA Doppler PI levels were significantly low in group 2 (p<0.05). The cut-off value of MCA Doppler PI for distinguishing the groups was 1.51 with 89.3% sensitivity, 52.4% specificity, 78.6% and 71.4% for positive and negative predictive values, respectively. Univariate logistic regression method demonstrated that MCA doppler PI<1.51 was a significant risk factor for persistent non-reactive nst with, odds ratios (95% confidence interval) as: 9.167 (2.103–39.958); p=0.001. According to this study, MCA Doppler velocimetry should be a promising marker in predicting fetal well being to evaluate in patients with non-reactive NST.
There are several techniques for ante partum fetal surveillance and electronic fetal heart rate monitoring (EFM) has been the cornerstone for fetal assessment. Non Stress test (NST) is one of the ante partum monitoring method that is used to evaluate the fetal wellbeing and to eliminate fetal distress. NST shows two patterns: reactive which is indicative of fetal well being and non-reactive which may be associated with adverse fetal outcomes. Even though NST is sensitive for detecting fetal distress, it has low specifity; there is no evidence of intrauterine distress or acidosis, in as much as 50–80% of fetuses who had non-reactive NST [1,2].
Doppler ultra sonography examination is a non-invasive procedure for predicting fetal well being with using vascular blood flow velocity like umbilical artery, umbilical vein, aorta, middle cerebral artery (MCA). Doppler velocimetry of the middle cerebral artery (MCA) is a method that is detects impedance-resistance to flow in the fetal brain circulation. Vasodilatation of the MCA is investigated to show a compensatory phenomenon called as the “brain sparing effect” . A reduced pulsatility index reflects
vasodilatation of the MCA and this have been shown to be early signs of fetal compromise and their presence has been shown to be associated with poor labor outcome [4-7].
The technique of MCA PI measurement is comparatively angle independent. For PSV measurement, the angle between the ultrasound cursor and the direction of the blood flow should be provided as possible as to 0°. The measurements at the proximal portion of the preferred site of middle cerebral artery supply this correct angle of measurement, but measurements at the mid and distal portions of the middle cerebral artery give rise to higher PI values and lower PSV values compared to the proximal part .
In this study, we aimed to evaluate the role of MCA Doppler velocimetry in predicting the fetal status and fetal well being in patients with non reactive NST.
This descriptive longitudinal study was designed at Dr Zekai Tahir Burak Women’s Health Education and Research Hospital, from January 2015 to July 2015 and was approved by the local
ethics committee of the institution. This is a tertiary research and
education hospital in middle of Turkey and with approximately
25.000 deliveries per year. Most of the health services are free of
charge and supported by the central government of Turkey. The
study was performed according to the standards of the Helsinki
Declaration. Informed consent was obtained from all participants.
A total of two hundred and ninety nine healthy pregnant
patients with non-reactive NST whose maternal ages between
22-33 years and carrying pregnancies between 37 and 40
weeks (according to the last menstrual period or first trimester
ultrasound) were enrolled to the study. The risk factors evaluated
were; age, GW (gestational weeks), gravidity, parity, middle
cerebral artery Doppler pulsatility index (MCA Doppler PI),
middle cerebral artery Doppler resistance index (MCA Doppler
RI), middle cerebral artery doppler systolic/diastolic ratio (MCA
doppler S/D), middle cerebral artery doppler peak systolic
velocity (MCA doppler PSV), non stress test (NST). Patients with
maternal systemic disease or known feto-maternal risk factors
(abnormal first or second trimester aneuploidy screening tests,
abnormal glucose tolerance test, fetal anomalies, feto-maternal
infections, hypertensive states of pregnancy, intrauterine growth
restriction, oligohydramnios, placental disorders, and smoking),
which may affect the pregnancy outcome, were excluded from
the study. Data recorded for each patient were obtained from the
patients and hospital database.
Fetal movements, tone, and breathing movements (within a
30-min period), amniotic fluid index (AFI), and measurement of
deepest vertical amniotic fluid pocket (DVP) were determined by
ultrasound. DVP values <2cm and AFI values <5cm were defined
as oligohydramnios .
All women were referred to the Radiology department for
doppler indices of the middle cerebral arteries (MCA) using a
Aloka prosound F37 ultrasound machine (Hitachi, Japan) by a 3.5
or 5mhz trans-abdominal convex transducer. The Doppler was set
at pulse repetition frequency of 2.4khz, normal quality and low
wall motion filter. The angle between the ultrasound beam and the
direction of blood flow was always less than 30°. MCA diameter
was measured at a distance of 6 mm from the circle of Willis, at the
peak systole. The crossbar of the caliper was placed as it converges
with the flow (‘in-in’ measurement). All ultrasonic assessments
were performed by an experienced single sonographer.
Non-stress test was conducted using cardio tocography
machine (Philips Avalon FM30 fetal monitors, Philips Healthcare,
Amsterdam, Netherlands). Normal (reactive) non-stress test was
defined as two or more accelerations that peak at 15bpm or more
above baseline, each lasting 15 seconds or more, and all occurring
within 20 minutes of beginning the test. Accelerations with or
without fetal movements were accepted, and a 40-minute or longer
tracing to account for fetal sleep cycles were performed before
concluding that there was insufficient fetal reactivity. Patients with
non-reactive NST tracings without decelerations were considered
eligible for the study. If the NST was non-reactive and the patient
accepted to participate, MCA Doppler measurement was taken
and PI, PSV was noted. We used vibroacoustic stimulations to get
reactive NST . NST was repeated and patients were divided
two groups according to their second NST results. Patients
whose second NST were activated defined group 1 and persistent
nonreactive defined group 2. Groups were compared in terms of
their MCA Doppler results.
Mean and standard deviation (SD) were calculated for
continuous variables. The normality of the variables was analyzed
by Kolmogorov–Smirnov test. Independent Sample t test and
Mann Whitney U test have evaluated associations between the
categorical and continuous variables. The receiver operator
characteristic (ROC) curve analysis was used to evaluate the
predictive role of MCA Doppler. Logistic Regression Analysis was
performed to find the risk variables for maternal and perinatal
outcomes by including all related variables to the model. Odds
ratios were calculated by logistic regression method. All variables
were included in the backward stepwise procedure. Two-sided
p values were considered statistically significant at p<0.05.
Statistical analyses were carried out by using the statistical
packages for SPSS 15.0 for Windows (SPSS Inc., Chicago, IL, USA).
Table 1 depicted the demographic and clinical characteristics
of the patients. The mean age of the patients in group1 was
27.46±2.74 years and in group 2 27.85±3.15 years (p=0.644). MCA
Doppler PI levels was statistically significantly lower in persistent
non-reactive NST group (group 2) (1.67±0.11 vs 1.54±0.14;
p=0.001). There were no statistically significant differences
between groups in terms of gravidity, parity, gestational weeks,
MCA doppler RI, MCA doppler S/D and MCA doppler PSV levels
(p>0.05) (Figure 1).
According to the ROC curve analysis (Figure 2) MCA Doppler PI
levels was found to be a discriminative parameter in patients. The
area under curve (AUC), cut off values, sensitivity and specificity
are shown in (Table 2). The best MCA Doppler PI cut-off value for
distinguishing the groups was 1.51 with 89.3% sensitivity, 52.4%
specificity, 78.6% and 71.4% for positive and negative predictive
MCA: Middle cerebral artery; p<0.05 is statistically significant.
Univariate logistic regression method demonstrated that MCA
doppler PI<1.51 was a significant risk factor for persistent nonreactive
NST with, odds ratios (95% confidence interval) as: 9.167
In this descriptive longitudinal study we evaluated MCA
Doppler in patients with non-reactive NST and divided patients
into two groups with non-reactive NST that subsequently
recovered to reactive NST and persistent non-reactive NST. To
the best of our knowledge this is the first study evaluating the
MCA Doppler is a predictive factor of persistent non-reactive NST.
For this, we assign the pregnant patients ages, gravidity, parity,
gestational weeks and also fetus MCA Doppler and electronic fetal
heart rate pattern (NST). We found that a lower MCA Doppler PI
level has a predictive value for the patients with persistent nonreactive
NST. According to the ROC curve analysis MCA Doppler PI
levels was 1.51 (89.3-52.4) for detecting persistent non-reactive
NST. In linear regression analysis, we found that lower MCA
Doppler PI levels mostly attributable to persistent non-reactive
NST (β coefficient: 0.786, p=0.001).
The primary goal of antenatal evaluation is to identify fetuses
at risk for intrauterine injury and death so that intervention
and timely delivery can prevent progression to stillbirth. Ideally,
antenatal tests would decrease fetal death without putting large
numbers of healthy fetuses at risk for premature delivery and the
associated morbidity and mortality. Although several techniques
are used to monitor fetal well-being in both low and high risk
pregnancies such as NST, biophysical profile, etc., the most suitable
time to apply these techniques and their diagnostic value to detect
fetal complications is controversial .
Non stress test is one of the available non invasive screening
techniques suggested for detecting fetal well being during the
prenatal period via using the relationship between fetal movement
and heart rate. However, in the third trimester, normal fetuses
spend 25% of their time in a quiet sleep state. During the normal
sleep state the fetal heart rate variability is reduced, and there
may be infrequent breathing movements . Tests performed
while a fetus is in a resting state may be incorrectly classified as
an abnormal test. Therefore, when using tests to evaluate fetal
condition, clinicians need to appreciate whether a fetus is simply
in a temporary quiet sleep state or neurologically compromised.
Thus, we demonstrated in our study that MCA Doppler PI levels
may be a predictor factor to find out the fetus with neurologically
In a present study Raouf et al.  found in their study that
patients with nonreactive NST results had more fetal complications
than those with reactive NST results, moreover they found a
statistically significant difference between the groups in terms of
the Apgar scores and cesarean ratios. We found in our study that
all of patients with non-reactive NST did not have corrupted MCA
Doppler velocity. Using MCA Doppler in patients with non-reactive
NST may be a reduction in the cesarean ratios.
Knowledge of Doppler flow velocimetry of the fetal MCA may
assist in perinatal diagnosis and management of complicated
pregnancies. A low index of pulsatility in the middle cerebral artery associated with fetal compromise has been described. In fetal
hypoxia to protecting brain tissues a vasodilatation occur in the
middle cerebral arteries [14,15]. Using the MCA pulsatility index to
assess fetal well being make a decrease the likelihood of admission
to the newborn intensive care unit and neonatal complications in
pregnant [3,16]. Recently, a meta-analysis of 35 eligible studies
including 4025 fetuses was performed. It is worth noting that
even within the included studies the definition of SGA varied, the
timing of MCA recordings in relation to outcomes differed, and the
definition of abnormal MCA also varied, though most used PI<2 SD
or PI<5th centile . In our study we demonstrated that PI values
under 1.51 was associated with poor fetal well-being in patients
with non-reactive NST. So we must make a second stage diagnostic
test in these patients.
The use of the MCA Doppler 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 Doppler PSV to clinical practice has been the dramatic
reduction in the number of invasive procedures performed in the
management of red cell allo immunized pregnancies [18,19]. In
our study we found no statically significant difference in our study
groups in terms of MCA Doppler PSV levels. This suggested that
there was no anemic fetus in our study population.
An abnormal non stress test has approximately 50% false
positive rate. One strength of our study; we were use all of the
parameter of MCA Doppler velocimetry to predict the second NST
results in patients with non-reactive NST. Generally, only the one
parameters of Doppler velocimetry were used and PI levels most
studied to evaluate fetal well being, PSV levels most studied to
evaluate fetal anemia. The limitation of this study is small sample
size. However, this sample size was sufficient to show statistically
significant differences in MCA Doppler velocimetry parameters
between the groups. In addition, no other sono graphic factors
such as umbilical artery Doppler velocimetry, biophysic profile,
etc. was performed to evaluate fetal well being before delivery.
In conclusion, we think that MCA Doppler velocimetry should
be a promising marker predicting fetal well being in patients with
non-reactive nst. Further randomized controlled studies with
more participants are needed to evaluate the accurate effects of
MCA Doppler velocimetry on patients with non-reactive NST.