Computerized cardiotocography in the management of intrauterine growth restriction associated with Doppler velocimetry alterations

Fetal aortic isthmus Doppler assessment to predict the adverse perinatal outcomes associated with fetal growth restriction: systematic review and meta-analysis

PURPOSE

Fetal growth restriction (FGR) management and delivery planning is based on a multimodal approach. This meta-analysis aimed to evaluate the prognostic accuracies of the aortic isthmus Doppler to predict adverse perinatal outcomes in singleton pregnancies with FGR.

METHODS

PubMed, EMBASE, the Cochrane Library, ClinicalTrials.gov and Google scholar were searched from inception to May 2021, for studies on the prognostic accuracy of anterograde aortic isthmus flow compared with retrograde aortic isthmus flow in singleton pregnancy with FGR. The meta-analysis was registered on PROSPERO and was assessed according to PRISMA and Newcastle-Ottawa Scale. DerSimonian and Laird's random-effect model was used for relative risks, Freeman-Tukey Double Arcsine for pooled estimates and exact method to stabilize variances and CIs. Heterogeneity was quantified using I2 statistics.

RESULTS

A total of 2933 articles were identified through the electronic search, of which 6 studies (involving 240 women) were included. The quality evaluation of studies revealed an overall acceptable score for study group selection and comparability and substantial heterogeneity. The risk of perinatal death was significantly greater in fetuses with retrograde Aortic Isthmus blood flow, with a RR of 5.17 (p value 0.00001). Similarly, the stillbirth rate was found to have a RR of 5.39 (p value 0.00001). Respiratory distress syndrome had a RR of 2.64 (p value = 0.03) in the group of fetuses with retrograde Aortic Isthmus blood flow.

CONCLUSION

Aortic Isthmus Doppler study may add information for FGR management. However, additional clinical trial are required to assess its applicability in clinical practice.

Comparison between Protocols for Management of Fetal Growth Restriction

This comprehensive review compares clinical protocols of important entities regarding the management of fetal growth restriction (FGR), published since 2015. Five protocols were chosen for data extraction. There were no relevant differences regarding the diagnosis and classification of FGR between the protocols. In general, all protocols suggest that the assessment of fetal vitality must be performed in a multimodally, associating biophysical parameters (such as cardiotocography and fetal biophysical profile) with the Doppler velocimetry parameters of the umbilical artery, middle cerebral artery, and ductus venosus. All protocols reinforce that the more severe the fetal condition, the more frequent this assessment should be made. The timely gestational age and mode of delivery to terminate the pregnancy in these cases can vary much between the protocols. Therefore, this paper presents, in a didactic way, the particularities of different protocols for monitoring FGR, in order to help obstetricians to better manage the cases.

Clinical Opinion: The diagnosis and management of suspected fetal growth restriction: an evidence-based approach

This study reviewed the literature about the diagnosis, antepartum surveillance, and time of delivery of fetuses suspected to be small for gestational age or growth restricted. Several guidelines have been issued by major professional organizations, including the International Society of Ultrasound in Obstetrics and Gynecology and the Society for Maternal-Fetal Medicine. The differences in recommendations, in particular about Doppler velocimetry of the ductus venosus and middle cerebral artery, have created confusion among clinicians, and this review has intended to clarify and highlight the available evidence that is pertinent to clinical management. A fetus who is small for gestational age is frequently defined as one with an estimated fetal weight of <10th percentile. This condition has been considered syndromic and has been frequently attributed to fetal growth restriction, a constitutionally small fetus, congenital infections, chromosomal abnormalities, or genetic conditions. Small for gestational age is not synonymous with fetal growth restriction, which is defined by deceleration of fetal growth determined by a change in fetal growth velocity. An abnormal umbilical artery Doppler pulsatility index reflects an increased impedance to flow in the umbilical circulation and is considered to be an indicator of placental disease. The combined finding of an estimated fetal weight of <10th percentile and abnormal umbilical artery Doppler velocimetry has been widely accepted as indicative of fetal growth restriction. Clinical studies have shown that the gestational age at diagnosis can be used to subclassify suspected fetal growth restriction into early and late, depending on whether the condition is diagnosed before or after 32 weeks of gestation. The early type is associated with umbilical artery Doppler abnormalities, whereas the late type is often associated with a low pulsatility index in the middle cerebral artery. A large randomized clinical trial indicated that in the context of early suspected fetal growth restriction, the combination of computerized cardiotocography and fetal ductus venosus Doppler improves outcomes, such that 95% of surviving infants have a normal neurodevelopmental outcome at 2 years of age. A low middle cerebral artery pulsatility index is associated with an adverse perinatal outcome in late fetal growth restriction; however, there is no evidence supporting its use to determine the time of delivery. Nonetheless, an abnormality in middle cerebral artery Doppler could be valuable to increase the surveillance of the fetus at risk. We propose that fetal size, growth rate, uteroplacental Doppler indices, cardiotocography, and maternal conditions (ie, hypertension) according to gestational age are important factors in optimizing the outcome of suspected fetal growth restriction.

Clinical monitoring of late fetal growth restriction

Late fetal growth restriction (FGR) poses its own challenges in respect of diagnosis, surveillance and delivery timing. Perinatal morbidity is relatively rare, and mortality extremely unusual, but given that late FGR is much more frequent than early FGR, the burden on neonatal services must not be underestimated. Doppler findings are more subtle than in early FGR, and growth rate rather than absolute fetal size may be important in defining the condition. Though umbilical artery Doppler changes form the basis for triggering delivery: reversed end diastolic flow at 32 weeks, absent at 34 weeks and raised PI at 36 weeks, other modalities of monitoring - for example cardiotocography and cerebral Doppler - are important in surveillance and timing follow up of the condition.

Longitudinal Course of Short-Term Variation and Doppler Parameters in Early Onset Growth Restricted Fetuses

PURPOSE

 To evaluate the longitudinal pattern of fetal heart rate short term variation (STV) and Doppler indices and their correlation to each other in severe growth restricted (IUGR) fetuses.

MATERIALS AND METHODS

 In this retrospective study, pregnancies with a birth weight below the 10th percentile, born between 24 and 34 gestational weeks with serial Doppler measurements in combination with a computerized CTG (cCTG) with calculated STV were included. Longitudinal changes of both Doppler indices and STV values were evaluated with generalized additive models, adjusted for gestational age and the individual. For all measurements the frequency of abnormal values with regard to the time interval before delivery and Pearson correlations between Doppler indices and STV values were calculated.

RESULTS

 41 fetuses with a total of 1413 observations were included. Over the course of the whole study period, regression analyses showed no significant change of STV values (p = 0.38). Only on the day of delivery, a prominent decrease was observed (mean STV d28-22: 7.97 vs. mean STV on day 0: 6.8). Doppler indices of UA and MCA showed a continuous, significant deterioration starting about three weeks prior to delivery (p = 0.007; UA and p < 0.001, MCA). Correlation between any Doppler index and STV values was poor.

CONCLUSION

 Fetal heart rate STV does not deteriorate continuously. Therefore, cCTG monitoring should be performed at least daily in these high-risk fetuses. Doppler indices of umbilical artery (UA) and middle cerebral artery (MCA), however, showed continuous deterioration starting about 3 weeks prior to delivery.

Fetal Growth Restriction - Diagnostic Work-up, Management and Delivery

Fetal or intrauterine growth restriction (FGR/IUGR) affects approximately 5 – 8% of all pregnancies and refers to a fetus not exploiting its genetically determined growth potential. Not only a major cause of perinatal morbidity and mortality, it also predisposes these fetuses to the development of chronic disorders in later life. Apart from the timely diagnosis and identification of the causes of FGR, the obstetric challenge primarily entails continued antenatal management with optimum timing of delivery. In order to minimise premature birth morbidity, intensive fetal monitoring aims to prolong the pregnancy and at the same time intervene, i.e. deliver, before the fetus is threatened or harmed. It is important to note that early-onset FGR (< 32 + 0 weeks of gestation [wks]) should be assessed differently than late-onset FGR (≥ 32 + 0 wks). In early-onset FGR progressive deterioration is reflected in abnormal venous Doppler parameters, while in late-onset FGR this manifests primarily in abnormal cerebral Doppler ultrasound. According to our current understanding, the “optimum” approach for monitoring and timing of delivery in early-onset FGR combines computerized CTG with the ductus venosus Doppler, while in late-onset FGR assessment of the cerebral Doppler parameters becomes more important.

Is computerized cardiotocography useful in monochorionic twins with selective intrauterine growth restriction?

Objective: To assess the value of using computerized cardiotocography (cCTG) short-term variation (STV) for intrapartum monitoring in monochorionic twins (MC) complicated by selective intrauterine growth restriction (sIUGR).Material and methods: All available cCTGs retrieved from computerized medical records of MC with sIUGR were retrospectively studied regarding the behavior of the STV. sIUGR was defined as intertwin estimated fetal weight (EFW) discordance of ≥20% with the abdominal circumference (AC) below the fifth percentile and/or the EFW of the smaller twin below the 10th percentile. The sIUGR classification system proposed by Gratacos et al. was used using types I-III on the basis of umbilical artery Doppler characteristics of the IUGR twin. The admission (entry) STV and final pre-delivery (last) STV values were analyzed. Cases with intrauterine demise, with structural or chromosomal abnormalities, with twin anemia polycythemia sequence (TAPS) and/or twin-to-twin transfusion syndrome (TTTS) were excluded.Results: During the study period, 64 consecutive cases were managed within our department. Thirty-two cases fulfilled the inclusion criteria for analysis. Mean gestational age at assessment and at delivery was 28.4 ± 2.7 and 31.5 ± 2.2 weeks, respectively. The entry STV and last STV before delivery were not statistically different (mean IUGR STV entry: 9.3 ± 3.4 ms versus last 8 ± 2.2 ms; p = .051; mean co-twin STV entry: 9.1 ± 2.8 ms versus last 9.2 ± 3 ms; p = .87). Neither was the sIUGR-type adjusted STV.Conclusions: In MC pregnancies complicated by sIUGR, the cCTG STV does not distinguish between fetuses, nor does it show differences in cases of fetal deterioration monitored by conventional CTG.

The prognostic accuracy of short term variation of fetal heart rate in early-onset fetal growth restriction: A systematic review

OBJECTIVE

Cardiotocography (CTG) is an important tool for fetal surveillance in severe early-onset fetal growth restriction (FGR). Assessment of the CTG is usually performed visually (vCTG). However, it is suggested that computerized analysis of the CTG (cCTG) including short term variability (STV) could more accurately detect fetal compromise. The objective of this study was to systematically review the literature on the association between cCTG and perinatal outcome and the comparison of cCTG with vCTG.

STUDY DESIGN

A systematic search was performed in MEDLINE, EMBASE and Google Scholar. Studies were included that assessed prognostic accuracy of STV or compared STV to vCTG in patients with FGR. Risk of bias and concerns about applicability were assessed with the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies-2) instrument.

RESULTS

Of the 885 records identified in the search, five cohort studies (387 patients) were included. We found no randomized studies comparing STV with visual CTG in patients with FGR. The risk of bias of all studies was generally judged as 'low'. One small study found an association of low STV with neonatal acidosis. One study observed no association of STV with long-term outcome. Composite analysis of all five studies showed a non-significant relative risk for acidosis after a low STV of 1.4 (95% CI 0.6-3.2, N = 387). Further meta-analysis was hampered due to heterogeneity in outcome reporting and use of different thresholds.

CONCLUSION

The evidence from the included studies did not support an association of STV and short or long term outcome. However, available data are limited and heterogeneous, and influenced by management based on STV. Solid evidence from a randomized controlled trial comparing STV with vCTG including long term infant outcome is needed before STV can be used clinically for timing of delivery in patients with FGR.

Correlation of short-term variation and Doppler parameters with adverse perinatal outcome in low-risk fetuses at term

OBJECTIVE

To evaluate the association of short-term variation (STV) and Doppler parameters with adverse perinatal outcome in low-risk fetuses at term.

METHODS

This was a retrospective study of 1008 appropriate-for-gestational age (AGA) term fetuses. Doppler measurements [umbilical artery (UA), middle cerebral artery (MCA), and cerebroplacental ratio (CPR)] and computerized CTG (cCTG) with STV analysis were performed prior to active labor (≤ 4 cm cervical dilatation) within 72 h of delivery. The association between Doppler indices and STV values with adverse perinatal outcome was analyzed using univariate regression analysis.

RESULTS

No significant association between Doppler parameters and the need for secondary cesarean delivery (CD) or operative vaginal delivery (OVD) was shown. Regarding fetuses delivered by CD due to fetal distress, regression analyzes revealed significantly higher UA PI MoM. However, the differences in MCA PI MoM and CPR MoM were not statistically significant. Fetuses with the need for emergency CD showed significantly higher UA PI MoM, lower MCA PI MoM and lower CPR MoM. Neonates with a 5-min Apgar score < 7 had significantly lower MCA PI MoM and neonatal acidosis (UA pH ≤ 7.10) showed a significant association with UA PI MoM. None of the assessed outcome parameters were significantly associated to STV.

CONCLUSION

Doppler indices assessed close to delivery in low-risk fetuses at term show a moderate association with adverse outcome parameters, whereas STV does not appear to predict poor perinatal outcome in this group of fetuses.

Validation of a new algorithm for the short-term variation of the fetal heart rate: an antepartum prospective study

AIMS

Currently one of the most widespread systems for the computerized analysis of the fetal heart rate (FHR) is the Dawes-Redman system, where the short-term variation (STV) of the FHR is measured by dividing each minute into 16 segments (STV16). Technical progress has allowed for the development of a new algorithm, which measures the STV by dividing each minute into 240 segments (STV240), thus approximating the beat-to-beat variation. The STV240 still lacks reference values. Our aim was to develop clinically relevant reference values for the STV240 and compare them to the ones for the STV16.

METHODS

In a single centre, observational study, a total of 228 cardiotocograms were registered and subsequently analyzed with both algorithms (STV240 and STV16).

RESULTS

The 95% confidence interval (CI) was calculated for both algorithms. The values of the STV240 were significantly lower in comparison to the ones of the STV16. Not only the mean values but also the 95th percentile of the STV240 lay beneath the existent cut-off value for the STV16.

CONCLUSIONS

Every clinician using the new algorithm must be aware that the normal values for the STV240 lie beneath the, up until now, established cut-off values for the STV16.

Intrauterine Growth Restriction. Guideline of the German Society of Gynecology and Obstetrics (S2k-Level, AWMF Registry No. 015/080, October 2016)

AIMS

The aim of this official guideline published and coordinated by the German Society of Gynecology and Obstetrics (DGGG) was to provide consensus-based recommendations obtained by evaluating the relevant literature for the diagnostic treatment and management of women with fetal growth restriction.

METHODS

This S2k guideline represents the structured consensus of a representative panel of experts with a range of different professional backgrounds commissioned by the Guideline Committee of the DGGG.

RECOMMENDATIONS

Recommendations for diagnostic treatment, management, counselling, prophylaxis and screening are presented.

Longitudinal changes of cardiotocographic parameters throughout pregnancy: a prospective cohort study comparing small-for-gestational-age and normal fetuses from 24 to 40 weeks

OBJECTIVE

To compare longitudinal trends of cardiotocographic (CTG) parameters between small-for-gestational-age (SGA) and normal fetuses, from 24 to 41 weeks of pregnancy.

METHODS

A prospective cohort study was carried out in singleton pregnancies without fetal malformations. At least one CTG was performed in each of the following intervals: 24-26 weeks+6 days, 27-29 weeks+6 days, 30-32 weeks+6 days, 33-35 weeks+6 days, 36-38 weeks+6 days and ≥39 weeks. Tracings were analyzed using the Omniview-SisPorto® 3.6 system. Cases with a normal pregnancy outcome, including a birthweight ≥10th percentile for gestational age, were compared with two groups of SGA fetuses: with birthweight <10th percentile (SGA<p10) and <3rd percentile (SGA<p3; a subgroup of the latter). Generalized linear mixed-effects models were used for analysis.

RESULTS

A total of 176 fetuses (31 SGA) and 1256 tracings (207 from SGA fetuses) were evaluated. All CTG parameters changed significantly throughout pregnancy in the three groups, with a decreasing baseline and probability of decelerations, and an increasing average long-term variability (LTV), average short-term variability (STV) and accelerations. Baseline showed a more pronounced decrease (steeper slope) in SGA fetuses, being higher in these cases at earlier gestational ages and lower later in pregnancy. Average LTV was significantly lower in SGA<p3 fetuses, but a parallel increase occurred in all groups. There was a considerable inter-fetal variability within each group.

CONCLUSION

A unique characterization of CTG trends throughout gestation in SGA fetuses was provided. A steeper descent of the baseline was reported for the first time. The findings raise the possibility of clinical application of computerized CTG analysis in screening and management of fetal growth restriction.

Cardiotocography and the evolution into computerised cardiotocography in the management of intrauterine growth restriction

Timely recognition and appropriate management of high-risk pregnancies, such as intrauterine growth restriction (IUGR), are of paramount importance for every obstetrician. After the initial screening of IUGR fetuses through sonographic fetometry and Doppler, the focus is shifted to the appropriate monitoring and timing of delivery. This can, especially in cases of early IUGR, become a very difficult task. At this point, cardiotocography (CTG) is introduced as a major tool in the day-to-day monitoring of the antenatal well-being of the IUGR fetus. Since the first introduction of CTG up to the nowadays widely spreading implementation of computerised CTG in the clinical practice, there has been great progress in the recording of the fetal heart rate, as well as its interpretation. Focus of this review is to offer an understanding of the evolution of CTG from its early development to modern computerised methods and to provide an insight as to where the future of CTG is leading, especially in the monitoring of IUGR.

Cardiotocographic parameters in small-for-gestational-age fetuses: How do they vary from normal at different gestational ages? A study of 11687 fetuses from 25 to 40 weeks of pregnancy

AIM

The aim of this study was to assess how cardiotocographic (CTG) parameters differ between small-for-gestational-age (SGA) and normal fetuses at different gestational ages.

METHODS

This was a retrospective cross-sectional study using the first antepartum tracing of singleton pregnancies with no malformations. Fetuses with birthweight ≥10th percentile for gestational age and other normal pregnancy outcome criteria (term birth, normal umbilical artery pH and Apgar scores, no intensive care unit admission) were compared with fetuses with birthweight <10th and <3rd percentiles for gestational age (SGA < p10 and SGA < p3, a subgroup of the latter). Each CTG parameter was compared, by gestational age, using both statistical tests and percentile curves derived from normal outcome cases. Tracings were analyzed with the OmniviewSisPorto® 3.7 system.

RESULTS

A total of 11 687 tracings (from the same number of fetuses) were analyzed: 9701 normal, 1986 SGA < p10, and 543 SGA < p3. SGA fetuses had lower long- and short-term variability, and number of accelerations, with more pronounced differences between around 28 and 35 weeks. In contrast, baseline was lower in SGA fetuses from 34 weeks onwards. All differences were more pronounced for SGA < p3 fetuses. Similar trends throughout gestation occurred in all groups: decrease in baseline, and increase in long- and short-term variability, and accelerations.

CONCLUSIONS

This study represents an important step for accurate CTG interpretation in SGA fetuses and, consequently, management of fetal growth restriction (FGR), as it contributes to differentiate between maturational CTG changes that occur physiologically throughout pregnancy, and possible signs of fetal compromise in FGR.

"Does short-term variation in fetal heart rate predict fetal acidaemia?" A systematic review and meta-analysis

OBJECTIVE

To evaluate the association of short-term variation (STV) of the fetal heart rate in predicting fetal acidaemia at birth.

METHODS

The search strategy employed searching of electronic databases (MEDLINE, Web of Science, Scopus, and Google Scholar) and reference lists of relevant studies. Data were extracted from studies, adhering strictly to the following criteria: singleton pregnancy at ≥24 weeks' gestation, computerized CTG (index test) and calculation of STV before delivery. The outcome measure was arterial pH assessed in cord blood obtained at birth.

RESULTS

Meta-analysis showed moderate accuracy of STV in predicting fetal acidaemia with a sensitivity of 0.57 (95% CI: 0.45-0.68), specificity of 0.81 (95% CI: 0.69-0.89), positive likelihood ratio of 3.14 (95% CI: 2.13-4.63) and negative likelihood ratio of 0.58, (95% CI: 0.46-0.72). However, in intra-uterine growth restricted fetuses, a small improvement in detecting acidaemia was observed; with a sensitivity of 0.63 (95% CI: 0.49-0.75) and negative likelihood ratio of 0.50 (95% CI: 0.31-0.80).

CONCLUSION

STV appears to be a moderate predictor for fetal acidaemia. However, its usefulness as a stand-alone test in predicting acidaemia in clinical setting remains to be determined.

Short-Term Variation of the Fetal Heart Rate for Predicting Neonatal Acidosis in Preeclampsia

Introduction: The aim of this study was to measure the performance of short-term variation (STV) in predicting the onset of neonatal acidosis in fetuses at risk due to maternal preeclampsia. Material and Methods: This retrospective study examined data from a series of 159 women with singleton pregnancies, hospitalized for preeclampsia in a level 3 reference maternity hospital in northern France, with an STV measurement in the 24 h preceding cesarean delivery and a measurement of the newborn's arterial cord pH at birth. The main outcome was determined by a correlation between STV and neonatal pH. Results: The last computerized fetal heart rate analysis took place a mean of 7.9 ± 6.3 h before birth, and neonatal acidosis was diagnosed in 38 newborns (23.9%). Although STV and umbilical artery pH at birth were significantly correlated (ρ = 0.16, p < 0.05), the performance of STV in predicting neonatal acidosis was poor, with an area under the ROC curve of 0.63. The sensitivity reached only 50.0% and the specificity 71.9% at the best STV threshold for predicting acidosis. Conclusion: The performance of STV for screening for neonatal acidosis is poor in women with preeclampsia. The divergent results between studies are probably due to the variable intervals between STV measurement and birth.

IUGR management: new perspectives

AIM OF THE STUDY

Analyzing velocimetric (umbilical artery, UA; ductus venosus, DV; middle cerebral artery, MCA) and computerized cardiotocographic (cCTG) (fetal heart rate, FHR; short term variability, STV; approximate entropy, ApEn) parameters in intrauterine growth restriction, IUGR, in order to detect early signs of fetal compromise. POPULATION STUDY: 375 pregnant women assisted from the 28th week of amenorrhea to delivery and monitored through cCTG and Doppler ultrasound investigation. The patients were divided into three groups according to the age of gestation at the time of delivery, before the 34th week, from 34th to 37th week, and after the 37th week. Data were analyzed in relation to the days before delivery and according to the physiology or pathology of velocimetry. Statistical analysis was performed through the t-test, chi-square test, and Pearson correlation test (P < 0.05). Our results evidenced an earlier alteration of UA, DV, and MCA. The analysis between cCTG and velocimetric parameters (the last distinguished into physiological and pathological values) suggests a possible relation between cCTG alterations and Doppler ones. The present study emphasizes the need for an antenatal testing in IUGR fetuses using multiple surveillance modalities to enhance prediction of neonatal outcome.

Does the anti-hypertensive drug clonidine affect the short-term variation in CTG recordings?

BACKGROUND

Cardiotocographic (CTG) recordings of the fetal heart remain standard obstetric practice among hypertensive women. Changes in the short-term variation (STV) in the fetal heart are often attributed to the effect of anti-hypertensive medications, regardless of the fact that this principle has never been validated.

AIM

To assess the STV of CTG recordings pre- and post- the anti-hypertensive medication, clonidine.

METHODS

Forty hypertensive pregnant women, already receiving the anti-hypertensive clonidine, were recruited. The CTGs were conducted pre- and post-dose administration. The CTGs were assessed by the Sonicaid Team® automated CTG analysis (Oxford Instruments, UK) to avoid CTG assessor bias. Baseline fetal heart rate (FHR) (delta change from pre- and post-dose) and STV were compared using spss v.14® utilising Student t-tests.

RESULTS

No statistical difference was found in the pre- and post-baseline FHRs (P = 0.48). The mean delta baseline heart rate before and after drug administration was -0.54 bpm. The STV of the CTGs recorded pre- and post-clonidine dose was also not affected by administration of the drug (P = 0.34). The mean delta STV before and after drug administration was 0.39 ms. Two women received betamethasone 12 mg intramuscularly within the 12-h period prior to CTG recordings to enhance fetal lung maturity. The mean STV for the fetuses of these women pre-drug was 4.8 ms and 13.2 ms post-administration. This was the largest delta seen in all STVs recorded in this dataset.

CONCLUSION

The anti-hypertensive drug clonidine does not alter baseline FHRs or affect the STV of the FHR in hypertensive pregnant women.

Multiparameter analysis of heart rate variability signal for the investigation of high risk fetuses

The purpose of this study is to evaluate the information content provided by the fluximetry information and the analysis of fetal heart rate (FHR) signals, obtained from cardiotocographic recordings, during prenatal monitoring, in a high risk population. The parameters assessed on FHR signals are divided in: (i) time domain parameters (ii) frequency domain parameters, and (iii) the complexity parameters: Approximate Entropy (ApEn), Sample Entropy (SampEn), Multiscale Entropy (MSE), the Lempel Ziv Complexity (LZC) and the Detrended Fluctuation Analysis (DFA). The fetuses were classified as fetal growth restricted (FGR). The results have shown that the FGR fetuses preterm delivered have produced a markedly reduced heart rate variability in respect with those fetuses which were characterized by an alteration in the fluximetric indices. The normal range in cord blood sampling analysis excludes the prolonged hypoxia as a causing factor. Finally, it seems that the residual cardiovascular response in FGR fetuses could be correlated to an alteration in the flow of the main vessels.

Obstetric management of intrauterine growth restriction

The aim of obstetric management is to identify growth-restricted foetuses at risk of severe intrauterine hypoxia, to monitor their health and to deliver when the adverse outcome is imminent. After 30-32 gestational weeks, a Doppler finding of absent or reverse end-diastolic flow in the umbilical artery of a small-for-gestational age foetus is in itself an indication for delivery. In very preterm foetuses, the intrauterine risks have to be balanced against the risk of prematurity. All available diagnostic information (e.g., Doppler velocimetry of umbilical artery, foetal central arteries and veins and of maternal uterine arteries; foetal heart rate with computerised analysis of short-term variability; amniotic fluid amount; and foetal gestational age-related weight) should be collected to support the timing of delivery. If possible, the delivery should optimally take place before the onset of late signs of foetal hypoxia (pathological foetal heart rate pattern, severely abnormal ductus venosus blood velocity waveform, pulsations in the umbilical vein).

Diagnosis and management of fetal growth restriction: the role of fetal therapy

Fetal growth restriction remains a major cause of perinatal morbidity and mortality in modern obstetric practice. Placental insufficiency is the most common association, but is often a diagnosis of exclusion. Currently, no treatment can ameliorate or reverse established growth restriction: maximising gestational age and judicious timing of steroid administration and delivery are the primary tasks for the obstetrician. Although comprehensive surveillance of the preterm fetus now includes ductus venosus Doppler studies, its effectiveness in timing delivery has yet to be confirmed in randomised controlled trials. More basic research on the regulation of fetal growth is needed before specific therapies for established growth restriction can be developed.

Management of fetal growth restriction

Fetal growth restriction (FGR) is challenging because of the difficulties in reaching a definitive diagnosis of the cause and planning management. FGR is associated not only with a marked increased risk in perinatal mortality and morbidity but also with long-term outcome risks. Combinations of fetal biometry, amniotic fluid volume, heart rate patterns, arterial and venous Doppler, and biophysical variables allow a comprehensive fetal evaluation of FGR. However, no evidence supports that the use of cardiotocography or the biophysical profile improves perinatal outcome. Therefore, obstetricians aim to identify fetuses with early FGR so delivery can be planned according to gestational age and severity of the condition. The balance of risks and the need for the availability of services mean that the involvement of neonatologists in FGR management is vital. In this review, the focus is on the pathophysiology and management of FGR caused by placental diseases.

Prognostic value of umbilical-middle cerebral artery pulsatility index ratio in fetuses with growth restriction

OBJECTIVE

To study the utility of Doppler velocimetry and computerized cardiotocography in the management of intrauterine growth restriction and prediction of neonatal outcome.

PATIENTS AND METHODS

Seventy-two pregnant women with fetuses showing growth restriction and delivered within 48 h of their last Doppler velocimetry evaluation. The last computerized cardiotocographic trace from these fetuses was used for statistical analysis, and the last trace from the healthy fetuses of 93 consecutive women undergoing cesarean section was used as control. Umbilical artery pulsatility index (UA PI), middle cerebral artery pulsatility index (MCA PI), UA PI/MCA PI ratio, and uterine artery resistance index (Ut RI) were assessed.

RESULTS

Among women with growth-restricted fetuses, all parameters were significantly higher in those who had hypertension; and in those who had diabetes, only the UA PI/MCA ratio was significantly higher. Umbilical artery PI values and the UA PI/MCA ratio were higher in those who had a nonreassuring result to computerized nonstress test immediately before delivery. A multiple logistic analysis showed that the UA PI/MCA ratio was the only Doppler velocimetry parameter predicting cardiotocographic nonreactivity; furthermore, the predictivity of extended newborn hospitalization (longer than 15 days) was verified, with a sensitivity of 56% and a specificity of 92% when the ratio was higher than 1.26.

CONCLUSION

The MCA PI of fetuses with growth restriction should be assessed. The UA PI/MCA ratio is predictive of a nonreactive computerized cardiotocography trace and of prolonged neonatal hospitalization.

Intrauterine growth restriction

PURPOSE OF REVIEW

Intrauterine growth restriction remains one of the major problems in obstetrics. Recent published literature on this problem is summarized in this review.

RECENT FINDINGS

Intrauterine growth restriction contributes disproportionately to neonatal mortality and morbidity in both preterm and term babies, and is a predisposing factor to major psychiatric sequelae such as depression, suicide and suicidal attempts. More evidence is accumulating to show that fetal Doppler changes of the ductus venosus and umbilical vein are good surrogate markers for fetal academia. The timing of delivery remains controversial, however. The Growth Restriction Intervention Trial showed that delayed delivery in those up to 30 weeks may be associated with lower rates of cerebral palsy and Griffiths development quotient under 70. In dichorionic twins, selective fetocide of one severe intrauterine growth restriction fetus in midtrimester twin pregnancies complicated by severe preeclampsia may abort the disease process and prolong the pregnancy. For monochorionic twins, the finding of intermittent absent or reversed end diastolic flow in the umbilical artery may be a manifestation of the transmission of the bi-directional waveforms of arterio-arterial anastomosis, but has been shown to be associated with an increased risk of intrauterine death in the growth restricted fetus and brain damage in the larger fetus.

SUMMARY

The timing of delivery of the preterm growth restricted fetus remains controversial. Intrauterine growth restriction with intermittent absent or reversed end diastolic flow in the umbilical artery of monochorionic twins poses difficulties in assessment.