|Year : 2020 | Volume
| Issue : 3 | Page : 342-347
Predictive accuracy of cerebroplacental ratio measured at 34–37 weeks’ gestation for perinatal outcome in fetal growth restriction
Khaled M Abdallah, Sileem A Sileem
Department of Obstetrics and Gynecology, Faculty of Medicine, Al-Azhar University, Assiut, Egypt
|Date of Submission||14-May-2020|
|Date of Decision||23-Jun-2020|
|Date of Acceptance||29-Jul-2020|
|Date of Web Publication||30-Oct-2020|
Sileem A Sileem
Faculty of Medicine, Al-Azhar University, Assiut 11651
Source of Support: None, Conflict of Interest: None
Background and aim Fetal growth restriction (FGR) is a clinical and public health challenge that confers an increased risk of intrapartum and neonatal adverse outcomes. Doppler indices, particularly cerebroplacental ratio (CPR), may be useful in predicting adverse outcomes in pregnancies with FGR. We aimed to evaluate the potential value of CPR at 34–37 weeks’ gestation in predicting the perinatal outcome of pregnancies with FGR.
Patients and methods A prospective observational study on singleton pregnancies with FGR, who underwent estimated fetal weight assessment and Doppler indices, including CPR, umbilical artery pulsatility index (PI), and middle cerebral artery pulsatility index (PI) at 34–37 weeks’ gestation. Patient characteristics, and intrapartum and neonatal outcomes were recorded. The main outcomes were a need for urgent cesarean section due to intrapartum fetal compromise, 5-min Apgar score below 7, neonatal death, and admission at neonatal ICU.
Results Out of from 80 women participated in the current study, 16 women had an unfavorable outcome in their newborns. abnormal CPR (<1.08) was present in 27.5% of cases and was associated with a higher risk of adverse outcomes. The sensitivity and specificity of CPR in predicting adverse neonatal outcomes were 62.50 and 81.25%, respectively, and its diagnostic accuracy was superior to either umbilical artery pulsatility index or middle cerebral artery PI alone.
Conclusion CPR measured at late gestation seems to be a useful method for predicting adverse intrapartum and neonatal outcomes in pregnancies with FGR. Routine measurement of CPR may decrease the incidence of these adverse outcomes.
Keywords: cerebroplacental ratio, Doppler indices, fetal growth restriction, perinatal outcome, predictive accuracy
|How to cite this article:|
Abdallah KM, Sileem SA. Predictive accuracy of cerebroplacental ratio measured at 34–37 weeks’ gestation for perinatal outcome in fetal growth restriction. Al-Azhar Assiut Med J 2020;18:342-7
|How to cite this URL:|
Abdallah KM, Sileem SA. Predictive accuracy of cerebroplacental ratio measured at 34–37 weeks’ gestation for perinatal outcome in fetal growth restriction. Al-Azhar Assiut Med J [serial online] 2020 [cited 2020 Dec 4];18:342-7. Available from: http://www.azmj.eg.net/text.asp?2020/18/3/342/299581
| Introduction|| |
Fetal growth restriction (FGR) is defined as a fetal weight below the 10th percentile for gestational age; small-for-gestational-age at birth is a commonly used surrogate measure of FGR. FGR is still an important clinical and public health challenge worldwide. It confers an increased risk of perinatal morbidity and mortality as well as long-term neurological and cognitive impairments ,.
Antenatal diagnosis of FGR depends on sonographic estimation of certain anthropometric measures. However, the clinical practice of FGR management varies around the world. There is no consensus on the best method for monitoring fetal well-being and predicting perinatal outcomes in growth-restricted pregnancies .
The use of Doppler velocimetry of umbilical artery (UA) and middle cerebral artery (MCA) in high-risk pregnancies, including FGR, has been reported to decrease perinatal morbidity and mortality. Cerebroplacental ratio (CPR) is another Doppler index that represents cerebral centralization of fetal blood flow. CPR is calculated by dividing Doppler pulsatility index (PI) of the MCA by the UA Doppler pulsatility index: CPR=MCA-PI/UA-PI ,.
CPR has recently been utilized in the clinical management of pregnancies with FGR. Some studies have shown that using CPR may be superior to either MCA or UA Doppler indices in predicting perinatal outcomes among high-risk pregnancies, including FGR. However, the diagnostic performance of CPR, particularly measured at late gestation, is still questionable and requires proper validation ,,.
In this study, we evaluated the potential value of CPR measured at 34–37 weeks’ gestation in predicting the perinatal outcome of pregnancies with FGR.
| Patients and methods|| |
This was a prospective, observational study conducted at Al-Azhar University Hospital Assiut (Egypt) from October 2018 to September 2019. We recruited singleton pregnant women with a gestational age of between 34 and 37 weeks, who were diagnosed with FGR during routine antenatal care. Cases with multiple pregnancies, congenital/chromosomal fetal abnormalities, and premature rupture of membrane were excluded from the study.
The present study was approved by the Research Ethics Committee of Faculty of Medicine, Al-Azhar University (Assiut). Informed consent was obtained from all included pregnant women for their participation.
We obtained a thorough medical history from enrolled pregnant women, including demographic data, medical history, current/chronic diseases and treatment, and detailed obstetric history. This is followed by general as well as detailed obstetric examination.
The estimation of fetal size was performed through a model Toshiba SSA 270 A mounted with a 3.75 MHz transabdominal transducer. The measured biometric parameters included fetal head circumference, abdominal circumference, femur length, biparietal diameter, amniotic fluid index, and placental grading. The diagnosis of FGR was based on the estimated fetal weight below the 10th percentile for gestational age. We estimated gestational age by dating or by first trimester ultrasound.
Enrolled pregnant women underwent Doppler ultrasound evaluation at 34–37 weeks’ gestation. We calculated the PI of UA and MCA from three consecutive waveforms during fetal quiescence using the automated trace of the spectral Doppler waveform. The CPR was simply calculated as the ratio of the MCA-PI to UA-PI. Doppler study was interpreted based on a cutoff point mentioned in previous published articles, which considered abnormal in case of (a) UA-PI more than 95th percentile for gestational age, (b) MCA-PI less than 5th percentile for gestational age, and (c) CPR less than 1.08 ,.
We followed enrolled cases for the mode and indication of delivery, birth weight, and neonatal outcome. The outcomes of this study were the need for urgent cesarean section (CS) due to intrapartum fetal compromise (IFC), low birth weight (<10th centile), 5-min Apgar score less than or equal to 7, need and duration of admission at neonatal intensive care unit (NICU), and neonatal death.
The collected data were analyzed using the Statistical Package for the Social Sciences (SPSS) program for Windows, version 20 (SPSS Inc., Chicago, Illinois, USA). The data were presented as number and percentage for the qualitative data, mean±SD for normally distributed quantitative data, and median with interquartile range for the quantitative data with nonparametric distribution. Tests for statistical significance between two groups were conducted using Student’s t test and Mann–Whitney test for quantitative data with parametric and nonparametric distribution, respectively, as well as χ2 (and Fisher’s exact when the expected count in any cell was found to be <5) for qualitative data. All calculations were based on a confidence interval of 95% and a margin of error of 5%. P values less than 0.05 and less than 0.01 were considered significant and highly significant, respectively.
| Results|| |
This study included 80 pregnant women with FGR. A summary of the characteristics and perinatal outcome of study participants is shown in [Table 1]; 40% of cases have diabetes mellitus, preeclampsia, or neuropathy, where the others have no remarkable medical history. Of the cases, 60% underwent CS that was urgent due to IFC in five (12.5%) cases. The mean fetal weight was 2054±347.2 g. Of the newborns, 12.5% had a 5-min Apgar score of less than 7, and the outcome was unfavorable in 20% of newborns.
The Doppler indices measured at 34–37 weeks’ gestation demonstrated a mean CPR of 1.48±0.60 (abnormal in 27.5% of cases), a mean UA-PI of 1.06±0.45 (abnormal in 50% of cases), and a mean MCA-PI of 1.33±0.38 (abnormal in 52.5% of cases).
[Table 2] shows the characteristics of participants with normal and abnormal CPR. The gestational age was significantly lower in participants with abnormal CPR. Also, residence and medical history had significant differences between the two groups.
|Table 2 Characteristics of participants with normal and abnormal cerebroplacental ratio|
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Maternal age and parity had no significant differences between the two groups.
On the other side, participants with abnormal CPR had significantly increased incidence of adverse perinatal outcome in terms of the need for urgent CS, lower fetal weight, 5-min Apgar score of less than 7, and neonatal death and NICU admission more than 10 days ([Table 3]).
|Table 3 Perinatal outcomes in pregnant women with normal and abnormal cerebroplacental ratio|
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As shown in [Table 4], the abnormal neonatal outcome was associated with lower gestational age, urgent CS, lower fetal weight, 5-min Apgar score of less than 7, and abnormal neonatal outcome. Other variables, including maternal age, residence, and parity, had no statistically significant association with adverse neonatal outcomes. Also, there is no significant relationship between neonatal outcome and medical history of neuropathy but there is a signifigant relation between neonatal outcome and medical history of diabetes mellitus and preeclampsia and this may be explained by ante-natal fetal distress caused by diabetes mellitus and preeclampsia enhanced fetal lung maturity.
|Table 4 Relationship between characteristics of the study population and neonatal outcome|
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The diagnostic performance of Doppler indices in predicting the adverse neonatal outcome is provided in [Table 5].
|Table 5 Diagnostic accuracy of Doppler indices in predicting neonatal outcomes|
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In general, CPR had a higher diagnostic accuracy (77.5%), compared with MCA-PI (67.5%) and UA-PI (55%). Moreover, [Table 6] shows the diagnostic accuracy of CPR in predicting a 5-min Apgar score of less than 7 and NICU admission of 86.96 and 76.32%, respectively.
|Table 6 Diagnostic accuracy of cerebroplacental ratio in predicting low Apgar score and neonatal intensive care unit admission|
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| Discussion|| |
Pregnancies with FGR are associated with a high risk of antepartum and intrapartum fetal distress with increased perinatal morbidity and mortality as well as long-term neurological impairments ,. Our study results demonstrated that the diagnostic performance of CPR value of less than 1.08 measured at 34–37 weeks’ gestation is superior to either MCA-PI or UA-PI alone in predicting adverse intrapartum and neonatal outcomes, including the need for urgent CS due to IFC, low fetal weight, 5-min Apgar score less than or equal to 7, NICU admission, and neonatal death. Therefore, CPR should be integrated into the assessment of pregnancies with FGR to identify high-risk cases that may benefit from certain timely intervention.
From a physiological viewpoint, CPR is a surrogate of cerebral centralization of fetal blood flow. CRP represents the interaction of increased MCA diastolic flow secondary to cerebrovascular dilatation because of hypoxia and decreased diastolic flow in UA secondary to increased placental resistance. CPR has been shown to gradually increase until around the 34th week of gestation and then slowly decreases until term ,. Several studies have described the use of CPR in the prediction of IFC , NICU admission , and adverse perinatal outcome  as well as the assessment of fetal well-being in pregnancies with small-for-gestational-age .
This study demonstrated that the sensitivity and specificity of CPR in predicting adverse neonatal outcomes are 62.5 and 81.25%, respectively. A recent meta-analysis of 22 studies showed that CPR has a moderate-to-high predictive ability for perinatal death with an overall sensitivity and specificity of 93 and 76%, respectively .
Our study has shown a high diagnostic performance of CPR in predicting 5-min Apgar score of less than 7 with a sensitivity and specificity of 100 and 85.37%, respectively. However, Conde-Agudelo et al.  meta-analysis showed a lower predictive performance with a sensitivity and specificity of 54 and 72%, respectively.
On the other side, the sensitivity and specificity of CPR in predicting NICU admission were comparable in our study (50 and 81.3%) and Conde-Agudelo et al.  meta-analysis (45 and 79%).
Of note, Conde-Agudelo et al.  meta-analysis reported a low predictive ability of CPR for CS due to IFC, neonatal acidosis, neonatal brain lesion, and use of mechanical ventilation. However, all results of this meta-analysis must be cautiously interpreted given the marked differences among included studies in terms of the definition of FGR and cutoff values of Doppler indices used for defining abnormal CPR, which limit the generalizability of findings.
The association between abnormal CPR and adverse intrapartum and neonatal outcomes in pregnancies with FGR has been reported by several studies. However, the predictive accuracy of CPR varies among different outcomes as well as among various studies ,,,,,,,,,,.
We assessed CPR in this study at late gestation (between 34 and 37 weeks). The proximity of CPR assessment to delivery may enhance the predictive accuracy of CPR. Indeed, Dunn et al.  have shown that CPR taken at later gestation had equal if not better predictive value than that performed at an earlier time. However, Conde-Agudelo et al.  reported an opposite finding.
This study has shown that CPR outperformed UA-PI and MCA-PI in predicting adverse neonatal outcomes. This agrees with the Vollgraff Heidweiller-Schreurs et al.  study, which showed that CPR is superior to UA-PI and MCA-PI in predicting the composite adverse outcomes as well as urgent CS due to IFD but not for other outcomes.
We acknowledge some limitations of the present study. First, the small number of participants, which might impact the statistical significance of some results. Second, the lack of blinding to CPR results. Women with abnormal CPR findings might have undergone more intensive follow-up and/or certain intervention, resulting in a possible bias in evaluating the predictive accuracy of CPR. Third, the scope of this study did not include some important neonatal outcomes, such as hypoxia, metabolic acidosis, brain lesions, and long-term neurodevelopment impairment. Fourth, the observational nature of the study did not allow us to evaluate the benefit of using CPR. Large blinded controlled clinical trials are highly warranted to evaluate whether the use of CPR actually decreases adverse intrapartum and neonatal outcomes in pregnancies with FGR.
| Conclusion|| |
In conclusion, our study showed that CPR measured at late gestation seems to be a useful method for predicting adverse intrapartum and neonatal outcomes in pregnancies with FGR. Integrating CPR in the routine clinical management of pregnancies with CPR may decrease the incidence of these adverse outcomes.
The authors thank the physicians and nurses involved in the management of study participants for their dedication and kind care.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]