Estimation clinique du poids fœtal et hauteur utérine dans le dépistage de l’hypotrophie fœtale à terme

Biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

BACKGROUND

Stillbirth affects 2.6 million pregnancies worldwide each year. Whilst the majority of cases occur in low- and middle-income countries, stillbirth remains an important clinical issue for high-income countries (HICs) - with both the UK and the USA reporting rates above the mean for HICs. In HICs, the most frequently reported association with stillbirth is placental dysfunction. Placental dysfunction may be evident clinically as fetal growth restriction (FGR) and small-for-dates infants. It can be caused by placental abruption or hypertensive disorders of pregnancy and many other disorders and factorsPlacental abnormalities are noted in 11% to 65% of stillbirths. Identification of FGA is difficult in utero. Small-for-gestational age (SGA), as assessed after birth, is the most commonly used surrogate measure for this outcome. The degree of SGA is associated with the likelihood of FGR; 30% of infants with a birthweight < 10th centile are thought to be FGR, while 70% of infants with a birthweight < 3rd centile are thought to be FGR. Critically, SGA is the most significant antenatal risk factor for a stillborn infant. Correct identification of SGA infants is associated with a reduction in the perinatal mortality rate. However, currently used tests, such as measurement of symphysis-fundal height, have a low reported sensitivity and specificity for the identification of SGA infants.

OBJECTIVES

The primary objective was to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth by estimated fetal weight (EFW) and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth, or birth of a SGA infant. Secondary objectives were to investigate the effect of clinical and methodological factors on test performance.

SEARCH METHODS

We developed full search strategies with no language or date restrictions. The following sources were searched: MEDLINE, MEDLINE In Process and Embase via Ovid, Cochrane (Wiley) CENTRAL, Science Citation Index (Web of Science), CINAHL (EBSCO) with search strategies adapted for each database as required; ISRCTN Registry, UK Clinical Trials Gateway, WHO International Clinical Trials Portal and ClinicalTrials.gov for ongoing studies; specialist abstract and conference proceeding resources (British Library's ZETOC and Web of Science Conference Proceedings Citation Index). Search last conducted in Ocober 2016.

SELECTION CRITERIA

We included studies of pregnant women of any age with a gestation of at least 24 weeks if relevant outcomes of pregnancy (live birth/stillbirth; SGA infant) were assessed. Studies were included irrespective of whether pregnant women were deemed to be low or high risk for complications or were of mixed populations (low and high risk). Pregnancies complicated by fetal abnormalities and multi-fetal pregnancies were excluded as they have a higher risk of stillbirth from non-placental causes. With regard to biochemical tests, we included assays performed using any technique and at any threshold used to determine test positivity.

DATA COLLECTION AND ANALYSIS

We extracted the numbers of true positive, false positive, false negative, and true negative test results from each study. We assessed risk of bias and applicability using the QUADAS-2 tool. Meta-analyses were performed using the hierarchical summary ROC model to estimate and compare test accuracy.

MAIN RESULTS

We included 91 studies that evaluated seven tests - blood tests for human placental lactogen (hPL), oestriol, placental growth factor (PlGF) and uric acid, ultrasound EFW and placental grading and urinary oestriol - in a total of 175,426 pregnant women, in which 15,471 pregnancies ended in the birth of a small baby and 740 pregnancies which ended in stillbirth. The quality of included studies was variable with most domains at low risk of bias although 59% of studies were deemed to be of unclear risk of bias for the reference standard domain. Fifty-three per cent of studies were of high concern for applicability due to inclusion of only high- or low-risk women.Using all available data for SGA (86 studies; 159,490 pregnancies involving 15,471 SGA infants), there was evidence of a difference in accuracy (P < 0.0001) between the seven tests for detecting pregnancies that are SGA at birth. Ultrasound EFW was the most accurate test for detecting SGA at birth with a diagnostic odds ratio (DOR) of 21.3 (95% CI 13.1 to 34.6); hPL was the most accurate biochemical test with a DOR of 4.78 (95% CI 3.21 to 7.13). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.88 and median prevalence of 19%, EFW, hPL, oestriol, urinary oestriol, uric acid, PlGF and placental grading will miss 50 (95% CI 32 to 68), 116 (97 to 133), 124 (108 to 137), 127 (95 to 152), 139 (118 to 154), 144 (118 to 161), and 144 (122 to 161) SGA infants, respectively. For the detection of pregnancies ending in stillbirth (21 studies; 100,687 pregnancies involving 740 stillbirths), in an indirect comparison of the four biochemical tests, PlGF was the most accurate test with a DOR of 49.2 (95% CI 12.7 to 191). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.78 and median prevalence of 1.7%, PlGF, hPL, urinary oestriol and uric acid will miss 2 (95% CI 0 to 4), 4 (2 to 8), 6 (6 to 7) and 8 (3 to 13) stillbirths, respectively. No studies assessed the accuracy of ultrasound EFW for detection of pregnancy ending in stillbirth.

AUTHORS' CONCLUSIONS

Biochemical markers of placental dysfunction used alone have insufficient accuracy to identify pregnancies ending in SGA or stillbirth. Studies combining U and placental biomarkers are needed to determine whether this approach improves diagnostic accuracy over the use of ultrasound estimation of fetal size or biochemical markers of placental dysfunction used alone. Many of the studies included in this review were carried out between 1974 and 2016. Studies of placental substances were mostly carried out before 1991 and after 2013; earlier studies may not reflect developments in test technology.

[Investigating into whether systematic fetal weight estimation by ultrasound in the delivery room increases the risk of cesarean delivery]

Ultrasound is a valuable tool commonly used in the delivery room. It has multiple applications. The objective of this study was to investigate whether systematic fetal weight estimation by ultrasound in the delivery room increases the risk of cesarean delivery. Monocentric cohort study. All parturients with singleton pregnancies who gave birth full-term at = 39 weeks were enrolled in the study. We excluded all patients with a contraindication to vaginal birth as well as those in whom fetal weight estimation (FWE) by ultrasound on day of delivery was deemed necessary in making obstetric decision. Parturients enrolled in the study were divided into two groups: - G1: parturients who systematically underwent FWE - G2: parturients who never underwent FWE. We compared cesarean delivery rate with adjustment for potentially confounding factors according to logistic regression. 838 parturients were enrolled in the study. Prematurity, FWE and weight at birth were risk factors for cesarean delivery. After adjustment for confounding factors, FWE by ultrasound systematically performed in G1 proved to be an independent risk factor for cesarean delivery with OR = 3.8 (CI 95% = [2.67 to 5.48]). This risk increased significantly with estimated fetal weight (EFW): OR=2,27(CI 95;1,15-4,47; p=0.018) for 3500 < EFW < 4000g and OR = 10.64 (CI 95; 4.28 to 26.41; p < 0.001 ) for EFW > 4000 g. FWE by ultrasound systematically performed in the delivery room represents an independent and potentially modifiable risk factor for cesarean delivery.

A descriptive study of perinatal asphyxia at the University Hospital of Kinshasa (Democratic Republic of Congo)

BACKGROUND

Perinatal asphyxia is the third cause of neonatal death after prematurity and infection.

OBJECTIVE

The purpose of this study was to determine the incidence, the etiology and the HIE score at the first day in term and near-term newborns with perinatal asphyxia at the University Hospital of Kinshasa.

METHODS

50 term and near-term neonates with perinatal asphyxia were studied prospectively after they were admitted in neonatal intensive care from November 2009 to January 2011. For each patient admitted the perinatal data were collected. Clinical assessment was performed by the Sarnat grading and the Thompson score within twenty-four hours. Medcalc® was used for statistics.

RESULTS

50 babies were scored. The median maternal age was 31 years. In 22% of the mothers preeclampsia was diagnosed. Urogenital infection, IUGR were other prenatal diagnoses. Median Apgar score was 4 after 1 minute, 5 after 5 minutes and 6 after 10 minutes. Sarnat grade 1 was seen in 16 patients, Sarnat grade 2 in 20 patients and grade 3 in 8. Thompson score in the first 24 hours was more than 7 in 60% of the patients. A good correlation was found between the Thompson score and the Sarnat grade (r: 0,77; p < 0,0001). 14 of the 50 babies died. Both Sarnat and Thompson score correlated significantly with mortality.

CONCLUSION

The incidence of perinatal asphyxia at the University Hospital of Kinshasa remains high and the majority of patients had a severe HIE.