Doppler evaluation of the fetus

Reducing stillbirths: screening and monitoring during pregnancy and labour

BACKGROUND

Screening and monitoring in pregnancy are strategies used by healthcare providers to identify high-risk pregnancies so that they can provide more targeted and appropriate treatment and follow-up care, and to monitor fetal well-being in both low- and high-risk pregnancies. The use of many of these techniques is controversial and their ability to detect fetal compromise often unknown. Theoretically, appropriate management of maternal and fetal risk factors and complications that are detected in pregnancy and labour could prevent a large proportion of the world's 3.2 million estimated annual stillbirths, as well as minimise maternal and neonatal morbidity and mortality.

METHODS

The fourth in a series of papers assessing the evidence base for prevention of stillbirths, this paper reviews available published evidence for the impact of 14 screening and monitoring interventions in pregnancy on stillbirth, including identification and management of high-risk pregnancies, advanced monitoring techniques, and monitoring of labour. Using broad and specific strategies to search PubMed and the Cochrane Library, we identified 221 relevant reviews and studies testing screening and monitoring interventions during the antenatal and intrapartum periods and reporting stillbirth or perinatal mortality as an outcome.

RESULTS

We found a dearth of rigorous evidence of direct impact of any of these screening procedures and interventions on stillbirth incidence. Observational studies testing some interventions, including fetal movement monitoring and Doppler monitoring, showed some evidence of impact on stillbirths in selected high-risk populations, but require larger rigourous trials to confirm impact. Other interventions, such as amniotic fluid assessment for oligohydramnios, appear predictive of stillbirth risk, but studies are lacking which assess the impact on perinatal mortality of subsequent intervention based on test findings. Few rigorous studies of cardiotocography have reported stillbirth outcomes, but steep declines in stillbirth rates have been observed in high-income settings such as the U.S., where cardiotocography is used in conjunction with Caesarean section for fetal distress.

CONCLUSION

There are numerous research gaps and large, adequately controlled trials are still needed for most of the interventions we considered. The impact of monitoring interventions on stillbirth relies on use of effective and timely intervention should problems be detected. Numerous studies indicated that positive tests were associated with increased perinatal mortality, but while some tests had good sensitivity in detecting distress, false-positive rates were high for most tests, and questions remain about optimal timing, frequency, and implications of testing. Few studies included assessments of impact of subsequent intervention needed before recommending particular monitoring strategies as a means to decrease stillbirth incidence. In high-income countries such as the US, observational evidence suggests that widespread use of cardiotocography with Caesarean section for fetal distress has led to significant declines in stillbirth rates. Efforts to increase availability of Caesarean section in low-/middle-income countries should be coupled with intrapartum monitoring technologies where resources and provider skills permit.

Current concepts in intrauterine growth restriction

Regulation of fetal growth is multifactorial and complex. Diverse factors, including intrinsic fetal conditions as well as maternal and environmental factors, can lead to intrauterine growth restriction (IUGR). The interaction of these factors governs the partitioning of nutrients and rate of fetal cellular proliferation and maturation. Although IUGR is probably a physiologic adaptive response to various stimuli, it is associated with distinct short- and long-term morbidities. Immediate morbidities include those associated with prematurity and inadequate nutrient reserve, while childhood morbidities relate to impaired maturation and disrupted organ development. Potential long-term effects of IUGR are debated and explained by the fetal programming hypothesis. In formulating a comprehensive approach to the management and follow-up of the growth-restricted fetus and infant, physicians should take into consideration the etiology, timing, and severity of IUGR. In addition, they should be cognizant of the immediate perinatal response of the growth-restricted infant as well as the childhood and long-term associated morbidities. A multi disciplinary approach is imperative, including early recognition and obstetrical management of IUGR, assessment of the growth-restricted newborn in the delivery room, possible monitoring in the neonatal intensive care unit, and appropriate pediatric follow-up. Future research is necessary to establish effective preventive, diagnostic, and therapeutic strategies for IUGR, perhaps affecting the health of future generations.

Apport pronostique du Doppler de l’isthme aortique fœtal dans la prise en charge du retard de croissance intra-utérin

OBJECTIVE

Our purpose was to determine whether the use of aortic isthmus Doppler waveform analysis in growth restricted fetuses delivered at 28 to 38 weeks predicts perinatal outcomes.

MATERIAL AND METHODS

Prospective longitudinal study including singleton non-malformed euploid fetuses with accurate dating and diagnosed as growth restricted (abdominal circumference<10th percentile) and who were followed up at our institution and delivered<10 days after the last Doppler. Timing of delivery was collegial. Perinatal mortality and morbidity outcomes were compared in cases with anterograde blood flow versus retrograde net blood flow in aortic isthmus. Relative risk (RR) were calculated with 95% CI and P<0,05 was considered significant.

RESULTS

Thirty-two cases were considered for analysis: growth-restricted foetuses with anterograde blood flow (n=26) versus retrograde net blood (n=6). Maternal demographic characteristics in the two groups were similar and exceptions made of femur length average values for fetal biometrics were not significantly different. Doppler velocimetry results at the uterine, umbilical and cerebral arteries were similar in the two groups. Gestational age at delivery and birth weight were similar in both groups (respectively (239.65 20.1 vs. 247.3 16.4 (days) (p=0.349) and 1748.8 gr 468.7 vs. 1933.3 gr 468.7 (p=0.408)). There was a statistically significant increase in perinatal mortality in retrograde net blood flow group: 8.66 [IC 95% 2.03 - 36.84]. An interesting finding was that neonates with aortic isthmus retrograde net blood flow were more frequently born by cesarean delivery because of a suspected fetal compromise RR=3.22 CI 95% [1.29-8].

CONCLUSION

In our study Doppler identification of aortic isthmus retrograde net blood flow in growth-restricted fetuses was associated with an increase of perinatal death.