Role of cerebroplacental ratio for fetal assessment in prolonged pregnancy

The role of the cerebroplacental ratio in predicting pregnancy outcomes at 40-42 gestational weeks: a prospective observational trial

PURPOSE

The cerebroplacental ratio is a sonographic tool used to predict poor pregnancy outcomes. Data are insufficient regarding its use in postdate pregnancy. We evaluated the cerebroplacental ratio's prediction of unfavorable pregnancy outcomes in women at 40-42 weeks gestation with normal amniotic fluid index.

METHODS

This prospective observational study included 101 women with low-risk singleton pregnancy and gestational age > 40 weeks who delivered in a university affiliated hospital during 2020-2021. The middle cerebral artery pulsatility index, the umbilical artery pulsatility index, and the cerebroplacental ratio, which is their quotient, were compared between women with favorable and unfavorable pregnancy outcomes. The latter included: meconium-stained amniotic fluid, cesarean or vacuum-assisted delivery due to pathological cardiotocography (category 2 or 3), 5-min Apgar score < 7, umbilical cord pH < 7.1, neonatal intensive care unit admission, and neonatal death.

RESULTS

Fetal Doppler, performed at a median gestational age of 40.3 (40.0-41.6), did not differ between 75 (74.3%) women with favorable obstetrical outcomes and 26 (25.7%) with unfavorable outcomes. In multivariate analysis, advanced maternal age and a history of a cesarean section were correlated with unfavorable outcomes, while Doppler indices were not found to be predictive. Among women at 41-42 weeks' gestation, for those with intrapartum fetal monitor category 2-3 vs. category 1, the mean umbilical artery pulsatility index was higher: 0.92 ± 0.34 vs. 0.71 ± 0.11 (p = 0.044).

CONCLUSION

According to the study results, fetal Doppler indices, including the cerebroplacental ratio, are not predictive of unfavorable outcome in women with pregnancies exceeding 40 weeks. Larger prospective studies are needed.

Diagnosis, Prevention, and Management of Fetal Growth Restriction (FGR)

Fetal growth restriction (FGR), or intrauterine growth restriction (IUGR), is still the second most common cause of perinatal mortality. The factors that contribute to fetal growth restriction can be categorized into three distinct groups: placental, fetal, and maternal. The prenatal application of various diagnostic methods can, in many cases, detect the deterioration of the fetal condition in time because the nature of the above disorder is thoroughly investigated by applying a combination of biophysical and biochemical methods, which determine the state of the embryo-placenta unit and assess the possible increased risk of perinatal failure outcome and potential for many later health problems. When considering the potential for therapeutic intervention, the key question is whether it can be utilized during pregnancy. Currently, there are no known treatment interventions that effectively enhance placental function and promote fetal weight development. Nevertheless, in cases with fetuses diagnosed with fetal growth restriction, immediate termination of pregnancy may have advantages not only in terms of minimizing perinatal mortality but primarily in terms of reducing long-term morbidity during childhood and maturity.

Prognostic Value of Cerebroplacental Ratio in Appropriate-for-Gestational-Age Fetuses Before Induction of Labor in Late-Term Pregnancies

PURPOSE

 To evaluate the relationship between cerebroplacental ratio (CPR) and the need for operative delivery due to intrapartum fetal compromise (IFC) and adverse perinatal outcome (APO) in appropriate-for-gestational-age (AGA) late-term pregnancies undergoing induction of labor. The predictive performance of CPR was also assessed.

MATERIALS AND METHODS

 Retrospective study including singleton AGA pregnancies that underwent elective induction of labor between 41 + 0 and 41 + 6 weeks and were delivered before 42 + 0 weeks. IFC was defined as persistent pathological CTG or pathological CTG and fetal scalp pH < 7.20. Operative delivery included instrumental vaginal delivery (IVD) and cesarean section (CS). APO was defined as a composite of umbilical artery pH < 7.20, Apgar score < 7 at 5 minutes, and admission to the neonatal intensive care unit for > 24 hours.

RESULTS

 The study included 314 women with 32 (10 %) IVDs and 49 (16 %) CSs due to IFC and 85 (27 %) APO cases. Fetuses with CPR < 10^th percentile showed a significantly higher rate of operative delivery for IFC (40 % (21/52) vs. 23 % (60/262); p = 0.008) yet not a significantly higher rate of APO (31 % (16/52) vs. 26 % (69/262); p = 0.511). The predictive values of CPR for operative delivery due to IFC and APO showed sensitivities of 26 % and 19 %, specificities of 87 % and 84 %, positive LRs of 2.0 and 1.2, and negative LRs of 0.85 and 0.96, respectively.

CONCLUSION

 Low CPR in AGA late-term pregnancies undergoing elective induction of labor was associated with a higher risk of operative delivery for IFC without increasing the APO rate. However, the predictive value of CPR was poor.

Modeling Pulsatility Index nomograms from different maternal and fetal vessels by quantile regression at 24-40 weeks of gestation: a prospective cross-sectional study

OBJECTIVE

Recent evidences highlight a considerable heterogeneity in the methodology of previously published studies reporting reference ranges for maternal and fetal Dopplers, which may have relevant implications in clinical practice. In view of these limitations, a standardized methodology to construct Doppler charts has been proposed. The aim of this study was to develop charts for pulsatility index (PI) of maternal and fetal Dopplers based upon the recently proposed standardized methodology and using quantile regression.

METHODS

Prospective cross-sectional study including 2516 low-risk singleton pregnancies between 24 and 40 weeks of gestation. The mean uterine, umbilical (UA), middle cerebral (MCA) and their ratio (cerebroplacental ratio, CPR) centile values were established by quantile regression in the considered gestational interval. Interclass correlation coefficient (ICC) of each maternal and fetal vessel was also computed to assess the intra- and inter-observer agreement of the results.

RESULTS

There was a good intra- and inter-observer agreement for each of the explored vessels (ICC >0.92 and >0.91 for a single and two observers, respectively). The 5th, 10th, 50th, 90th and 95th centiles of the reference range for gestation were constructed by quantile regression and compared to previously established reference charts. All the Doppler indices significantly changed with gestation. Second-degree polynomial regression models better described the changes with gestation in PCR and MCA PI values while a linear model better predicted the changes of other Doppler indices with advancing gestation. When compared to other studies reporting reference ranges for maternal and fetal Dopplers, the present charts showed similar median values but different distribution from the median.

CONCLUSIONS

We provided prospective charts of maternal and fetal Dopplers based upon a previously proposed standardized methodology and using quantile regression. When compared to previously published studies, these new charts showed similar median values but different deviations from the median which may help in better differentiating cases at higher risk of placental insufficiency and adverse perinatal outcome.

Doppler Ultrasound of the Umbilical Artery: Clinical Application

OBJECTIVE

 To provide a survey of relevant literature on umbilical artery Doppler ultrasound use in clinical practice, technical considerations and limitations, and future perspectives.

METHODS

 Literature searches were conducted in PubMed and Medline, restricted to articles written in English. Additionally, the references of all analyzed studies were searched to obtain necessary information.

RESULTS

 The use of this technique as a routine surveillance method is only recommended for high-risk pregnancies with impaired placentation. Meta-analyses of randomized trials have established that obstetric management guided by umbilical artery Doppler findings can improve perinatal mortality and morbidity. The values of the indices of Umbilical artery Doppler decrease with advancing gestational age; however, a lack of consensus on reference ranges prevails.

CONCLUSION

 Important clinical decisions are based on the information obtained with umbilical artery Doppler ultrasound. Future efforts in research are imperative to overcome the current limitations of the technique.

The correlation between the cerebroplacental ratio and fetal arterial blood gas in appropriate-for-gestational-age fetuses: A cross-sectional study

Background

The cerebroplacental ratio (CPR) is an important index for predicting adverse pregnancy outcomes in small-for-gestational-age and appropriate-for-gestational-age fetuses.

Objective

To find out whether there is an association between the CPR level and the blood cord gases analysis in appropriate for gestational age fetuses.

Materials and Methods

This cross-sectional study included 347 pregnant women at the gestational age of 37-40 wk. Patients had an appropriate-for-gestational-age fetus confirmed from their first ultrasonography results. Participants were divided into two groups based on their CPR, measured before delivery. Finally, after delivery, arterial blood gas level and the incidence of emergency cesarean section, intrapartum fetal distress and neonatal intensive care unit admissions were compared between the two groups.

Results

Fifty-four (15.6%) cases had a CPR below the detection limit of the assay. The incidence of fetal distress, emergency cesarean section, neonatal hospitalization in the neonatal intensive care unit, and pH < 7.2 were significantly lower in women with CPR ≥ 0.67 multiples than in women with a CPR < 0.67 multiples of the median.

Conclusion

The third-trimester CPR is an independent predictor of stillbirth and perinatal mortality and morbidity. The role of UA/MCA Doppler and the CPR in assessing the risk of adverse pregnancy outcomes should be evaluated prospectively.

Middle cerebral artery Doppler pulsatility index as a predictor of intrapartum meconium release in prolonged pregnancies

OBJECTIVES

The aim of this study was to asses the correlation of middle cerebral artery pulsatility index (MCA-PI) and perinatal outcomes in prolonged pregnancies.

STUDY DESIGN

This was a prospective study of all consecutive pregnant women beyond 41 weeks' gestation attending for obstetric surveillance during a two years period. We evaluated the predictive value of MCA-PI lower than the 5th percentile (<p5) and the occurrence of: cesarean delivery for fetal distress, 5-min Apgar score <7, arterial cord pH < 7.15, presence of thick meconium at delivery, need for admission to the neonatal intensive care and/or neonatal death.

RESULTS

Three hundred and one pregnancies met the inclusion criteria and were managed expectantly. Of them, 31 (10.3%) fetuses had an MCA-PI < p5, which showed a significant relationship with the presence of thick meconium at birth (p < 0.001), but was not related to any of the other perinatal outcomes.

CONCLUSION

In prolonged pregnancies, the finding of MCA-PI < p5 is related to meconium emission at the time of delivery, but is not associated with an increased risk of adverse perinatal outcome.

Reference values for pulsatility index of fetal anterior and posterior cerebral arteries in prolonged pregnancy

OBJECTIVE

To establish consistent normal reference values for fetal anterior cerebral artery (ACA) and posterior cerebral artery (PCA) pulsatility index (PI) in prolonged pregnancy.

METHODS

This prospective cross-sectional observational study included singleton normal prolonged pregnancies into two study groups according to the gestational age: from 40 + 0 to 40 + 6 and from 41 + 0 to 41 + 6 weeks. The PI was assessed in both anatomical segments of ACA (ACA-S1 and ACA-S2) and of PCA (PCA-S1 and PCA-S2) with color Doppler imaging and pulsed Doppler examination, and reference centiles charts were generated. PI values from the two investigated segments of each vessel were also compared.

RESULTS

Data were obtained in 771 patients: n = 448 in the 40 + 0 and 40 + 6 weeks group, and n = 323 in the 41 + 0 and 41 + 6 weeks group. A moderate decrease in PI was observed as pregnancy progressed. No differences in PI values were found between the two anatomical segments of ACA and PCA.

CONCLUSION

This study provides Doppler reference values for the fetal ACA and PCA PI. It also shows that Doppler examination could be performed indifferently in one of the two anatomical segments of these arteries.

Ultrasound Probe Pressure on the Maternal Abdominal Wall and the Effect on Fetal Middle Cerebral Artery Doppler Indices

Background and objectives: Doppler ultrasound of umbilical and fetal vessels is useful for monitoring fetal well-being, fetal anemia, intrauterine growth retardation, and other perinatal outcomes. The adverse perinatal outcome and circulatory changes can be reflected in fetal Doppler studies. The aim of this study was to evaluate the effect of increased pressure exerted on the maternal abdominal wall during routine ultrasound on the middle cerebral artery (MCA), resistance index (RI), pulsatility index (PI), and peak systolic velocity (PSV). Materials and Methods: A prospective study was conducted, in which we included 40 pregnant women between 24 + 0 and 41 + 3 gestational weeks (GW), with singleton pregnancies, without any associated pathologies, undergoing routine US examination. We recorded the flow velocity waveforms in the MCA, and we measured the RI, PI, PSV, and the applied pressure on to the maternal abdominal wall-needed for a proper evaluation of MCA. We then repeated the same measurements at two different higher pressure levels, at the same time having a proper image of the targeted vessel. Results: We found significant differences for the PI and RI levels with an increase in abdominal pressure (median PI 1.46, 1.58, and 1.92, respectively; median RI 0.74, 0.78, and 0.85, respectively; p < 0.05), for both PI and RI. At the same time, we found no significant differences for PSV in the studied group in relationship with increase in abdominal pressure (median PSV 39.56, 40.10, and 39.70, respectively; p > 0.05). Conclusions: The applied abdominal pressure by the examiner's hand, during routine US scan in pregnancy, can modify the MCA parameters of blood flow resistance (PI and RI) when measured by Doppler US, thus influencing the diagnostic accuracy in a series of pregnancy associated pathologies, such as chronic fetal distress (CFD) or intrauterine growth restriction (IUGR).

Reference ranges for Doppler indices of umbilical and fetal middle cerebral arteries and cerebroplacental ratio: systematic review

OBJECTIVE

To assess studies reporting reference ranges for umbilical artery (UA) and fetal middle cerebral artery (MCA) Doppler indices and cerebroplacental ratio (CPR), using a set of predefined methodological quality criteria for study design, statistical analysis and reporting methods.

METHODS

This was a systematic review of observational studies in which the primary aim was to create reference ranges for UA and MCA Doppler indices and CPR in fetuses of singleton gestations. A search for relevant articles was performed in MEDLINE, EMBASE, CINAHL, Web of Science (from inception to 31 December 2016) and references of the retrieved articles. Two authors independently selected studies, assessed the risk of bias and extracted the data. Studies were scored against a predefined set of independently agreed methodological criteria and an overall quality score was assigned to each study. Linear multiple regression analysis assessing the association between quality scores and study characteristics was performed.

RESULTS

Thirty-eight studies met the inclusion criteria. The highest potential for bias was noted in the following fields: 'ultrasound quality control measures', in which only two studies demonstrated a comprehensive quality-control strategy; 'number of measurements taken for each Doppler variable', which was apparent in only three studies; 'sonographer experience', in which no study on CPR reported clearly the experience or training of the sonographers, while only three studies on UA Doppler and four on MCA Doppler did; and 'blinding of measurements', in which only one study, on UA Doppler, reported that sonographers were blinded to the measurement recorded during the examination. Sample size estimations were present in only seven studies. No predictors of quality were found on multiple regression analysis. Reference ranges varied significantly with important clinical implications for what is considered normal or abnormal, even when restricting the analysis to the highest scoring studies.

CONCLUSIONS

There is considerable methodological heterogeneity in studies reporting reference ranges for UA and MCA Doppler indices and CPR, and the resulting references have important implications for clinical practice. There is a need for the standardization of methodologies for Doppler velocimetry and for the development of reference standards, which can be correctly interpreted and applied in clinical practice. We propose a set of recommendations for this purpose. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Amniotic fluid and umbilical cord serum erythropoietin in term and prolonged pregnancies

OBJECTIVE

Erythropoietin - a hormone regulating erythropoiesis - is a biomarker of chronic fetal hypoxia. High erythropoietin levels in fetal plasma and amniotic fluid are associated with increased risk of adverse neonatal outcome. Since the risk of perinatal morbidity and mortality is increased in pregnancies beyond 41 gestational weeks, we evaluated erythropoietin levels in amniotic fluid and umbilical cord serum in apparently low-risk term (≥ 37 gestational weeks) and prolonged pregnancies (≥ 41 gestational weeks) with labor induction.

STUDY DESIGN

This prospective cohort study comprised 93 singleton pregnancies at 37⁺⁰-42⁺¹ gestational weeks, of which prolonged pregnancies numbered 63 (67.7%). Amniotic fluid samples were collected at time of labor induction by amniotomy. Umbilical cord blood samples for evaluation of pH, base excess, and umbilical cord serum erythropoietin were collected at birth. Erythropoietin levels were measured by immunochemiluminometric assay. Normal value of amniotic fluid erythropoietin level was defined as ≤ 3 IU/L, and abnormal value as ≥ 27 IU/L. Normal umbilical cord serum erythropoietin was defined as < 40 IU/L. Data on maternal pregnancy and delivery characteristics and short-term neonatal outcomes such as Apgar score were obtained from the hospital charts. Associations were calculated using Spearman's rank correlation coefficient. The Chi-square test, Fisher's exact test and the Mann-Whitney U test were utilized to determine differences in the study groups.

RESULTS

Amniotic fluid erythropoietin levels correlated with gestational age (r = 0.261, p = 0.012) and were higher among prolonged pregnancies as compared to term pregnancies (p = 0.005). There were 78 (83.9%) vaginal deliveries, and among these erythropoietin levels in amniotic fluid correlated with the levels in umbilical cord serum (r = 0.513, p < 0.000). Umbilical cord serum erythropoietin levels correlated with gestational age among vaginal deliveries (r = 0.250, p = 0.027). Erythropoietin levels in amniotic fluid and umbilical cord serum did not correlate with umbilical artery pH or base excess, or other adverse pregnancy outcome.

CONCLUSIONS

In vaginal deliveries erythropoietin levels in amniotic fluid correlated with the levels in umbilical cord serum. Erythropoietin levels correlated with gestational age, probably due to weakening placental function and relative hypoxemia occurring in advanced gestation. However, in this relatively low-risk study population erythropoietin was not related to adverse delivery outcome.

Fetal cerebral and cardiac hemodynamics in postdate pregnancy

Objective: We aimed to determine the fetal cerebro-placental Doppler indices and modified myocardial performance index (Mod-myocardial performance index (MPI)) in this homogenous group of postdated pregnancies. Methods: A total of 92 singleton pregnant women were included in this prospective study. The study involved three groups; full term control (Group 1, n = 42, 39 0/7 to 40 6/7 week' gestation), late term (Group 2, n = 34, 41 0/7 to 41 6/7 week' gestation) and post term (Group 3, n = 16, ≥ 42 0/7 weeks' gestation). Each participant underwent a Doppler assessment of the fetal umbilical artery (UA), middle cerebral artery (MCA), Mod-MPI. We determined the correlation of the Doppler indices and mod-MPI in patients with unfavorable outcome. Results: MCA pulcatility indices (PI), cerebroplacental ratio (CPR) values were significantly higher in the control group than those in the late-term and post-term groups (Group 1: 1.63 ± 0.3, Group 2: 1.27 ± 0.51, Group 3: 1.13 ± 0.22, respectively, p < .001). The Mod-MPI was significantly higher in the late-term and post-term groups than in the control group (Group 1:0.38 ± 0.1, Group 2: 0.59 ± 0.09, Group 3: 0.60 ± 0.08, respectively, p < .001. MCA PI and CPR were only significantly lower in patients with unfavorable outcome). The threshold value for CPR levels for predicting unfavorable outcome in postdate pregnancies was calculated as 1.11 (area under curve [AUC] 0.762, confidence interval [CI] 0.575-0.95) with 72.7% sensitivity and 71.8% specificity. Conclusions: Fetal Mod-MPI does not differ in postdate pregnancies with favorable and unfavorable outcome. The monitorization of fetal well-being with CPR may help to clinicians to select patient for expectant management in postdate pregnancies.

Review: Systematic review of the utility of the fetal cerebroplacental ratio measured at term for the prediction of adverse perinatal outcome

AIM

This systematic review evaluates the utility of the fetal cerebroplacental ratio (CPR) when assessed at term (from 37 + 0 weeks gestation) as a predictor of adverse obstetric and perinatal outcomes.

DATA SOURCES AND SEARCH STRATEGY

An electronic search of Pubmed and Embase using variations of 'cerebroplacental ratio' and 'cerebroumbilical ratio' was conducted by two independent reviewers. Full text studies written in English that reported on low CPR and its correlation with relevant obstetric and perinatal outcomes were included.

RESULTS

Twenty one studies satisfied inclusion with 13 prospective and eight retrospective analyses. Fetal CPR was predictive of caesarean section for intrapartum fetal compromise, small for gestational age and fetal growth restriction and neonatal intensive care unit admission. Low CPR was also significantly associated with abnormal fetal heart rate pattern, meconium stained liquor, low Apgar score, acidosis at birth and composite adverse perinatal outcome scores. The CPR when taken at term had comparable if not better predictive value than that when taken at preterm. Most studies included small for gestational age fetuses and postdate pregnancies. Subtle variation existed in the threshold for low CPR.

CONCLUSION

The CPR at term has a strong association with adverse obstetric and perinatal outcomes. This review suggests the predictive utility of CPR at term is promising however there is insufficient evidence to demonstrate its value as a stand-alone test. Inclusion of CPR as a component of clinical care may help better identify fetuses at risk of adverse outcome, and this should be tested with randomised control trials.