Assessment of ultrasound and Doppler parameters in the third trimester of pregnancy as predictors of adverse perinatal outcome in unselected pregnancies

Uterine Artery Pulsatility Index in Pregnant Kidney or Liver Recipients and Its Impact on Perinatal Outcome

BACKGROUND

The uterine artery pulsatility index (UtA PI) is associated with blood flow to the placenta. Its increased values imply impaired placentation. This study aimed to evaluate UtA PI measurements in first-trimester ultrasound in pregnancies after kidney (KTx) or liver transplantation (LTx) and its relationship with perinatal outcome.

MATERIALS AND METHODS

A retrospective analysis of 72 pregnancies in female kidney (35) or liver (37) transplant recipients between 2017 and 2023 was performed. Data concerning UtA PI were available for 17 kidney and 19 liver recipients. Statistical analysis of variables between KTx and LTx groups and the correlation with perinatal outcomes was performed using Student's t test and Pearson's correlation with P < .05 considered statistically significant.

RESULTS

The mean UtA PI results were similar, and there were no statistical differences between the group of pregnant kidney and liver recipients with mean values of 1.46 (SD 0.44] and 1.73 (SD 0.51] respectively (P = .10). The mean neonate birth weight was lower in KTx group (2158 g ([SD 723 g]) compared with the LTx group (2780 g [SD 754g]; P =.02). In the KTx and LTx groups, mean UtA PI was in negative correlation with Apgar score in the first minute (P = .04, P = .01 respectively).

CONCLUSIONS

Uterine artery Doppler is useful in predicting perinatal outcomes in the general population and organ recipient pregnancies, even in the early stages of pregnancy, as we observed the correlation between UtA PI and Apgar score. Pregnant kidney recipients remain at higher risk for complications and more unpredictable outcomes than liver recipients.

Improved detection of coarctation of the aorta using speckle-tracking analysis of fetal heart on last examination prior to delivery

OBJECTIVE

The false-positive rate for prenatal diagnosis of coarctation of the aorta (FP-CoA) commonly exceeds 50%, with an accurate detection rate of < 50%. This study was conducted to determine if the sensitivity for prenatal detection of true CoA and the FP-CoA rate could be improved by evaluating the fetal epicardial size and shape in the four-chamber view (4CV) and the endocardial right (RV) and left (LV) ventricular size, shape and contractility.

METHODS

We analyzed retrospectively Digital Imaging and Communications in Medicine (DICOM) clips of the 4CV from the last examination prior to delivery in a series of 108 fetuses with CoA suspected prenatally by pediatric cardiologists using traditional diagnostic criteria. Postnatal evaluation distinguished those fetuses which subsequently required CoA surgery (true positives; true CoA) from those that were FP-CoA. Postnatal cardiac abnormalities were identified for each group. For the prenatal evaluation, we measured the 4CV end-diastolic epicardial area, circumference, length, width and global sphericity index. Speckle-tracking analysis was used to compute the endocardial RV and LV end-diastolic area, length, 24-segment sphericity index, 24-segment transverse width and the following functional parameters: fractional area change; global longitudinal, free-wall and septal-wall strain; basal-apical-length, basal free-wall and basal septal-wall fractional shortening; septal-wall annular plane systolic excursion; 24-segment transverse-width fractional shortening; and LV end-diastolic and end-systolic volumes, stroke volume, cardiac output and ejection fraction. In addition, the RV/LV end-diastolic area ratio was computed. Using a control group of 200 normal fetuses, the mean and SD for each of the above cardiac measurements was used to compute the Z-scores for each measurement in each of the 108 study fetuses. Logistic regression analysis was then performed on the Z-score values to identify variables that separated the true CoA group from the FP-CoA group.

RESULTS

Of the 108 study fetuses, 54 were confirmed postnatally to have true CoA and 54 were FP-CoA. Right/left area disproportion > 90^th  centile was present in 80% (n = 43) of the true-CoA fetuses and 76% (n = 41) of the FP-CoA fetuses. Fetuses with true CoA had a significantly greater number of associated cardiac abnormalities (93%, n = 50) compared with the FP-CoA fetuses (61%, n = 33) (P < 0.001). The most common associated malformations were bicuspid aortic valve (true CoA, 46% (n = 25) vs FP-CoA, 22% (n = 12); P < 0.01), aortic arch hypoplasia (true CoA, 31% (n = 17) vs FP-CoA, 11% (n = 6); P < 0.01), ventricular septal defect (true CoA, 33% (n = 18) vs FP-CoA, 11% (n = 6); P < 0.05) and mitral valve abnormality (true CoA, 30% (n = 16) vs FP-CoA, 4% (n = 2); P < 0.01). Logistic regression analysis identified 28 variables that correctly identified 96% (52/54) of the fetuses with true CoA, with a false-positive rate of 4% (2/54) and a false-negative rate of 4% (2/54). These variables included the epicardial size in the 4CV, size and shape of RV and LV, and abnormal contractility of RV and LV. The area under the receiver-operating-characteristics curve was 0.98 (SE, 0.023; 95% CI, 0.84-1). There was no significant difference in the percent of fetuses with RV/LV area disproportion between those with CoA and those that were FP-CoA.

CONCLUSIONS

Speckle-tracking analysis of multiple ventricular measurements may be helpful to refine the diagnosis in fetuses that are suspected to have CoA prenatally. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

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.

Utility of Doppler parameters at 36-42 weeks' gestation in the prediction of adverse perinatal outcomes in appropriate-for-gestational-age fetuses

Aim

To investigate the potential value of Doppler ultrasound and to assess cerebroplacental ratio (CPR) in the prediction of adverse perinatal outcome defined as Apgar score < 7 at 1 minute.

Material and methods

This was a retrospective cross-sectional study in selected pregnant women undergoing an ultrasound examination between 36 and 42 weeks of gestation. We measured estimated fetal weight (EFW), mean umbilical artery pulsatility index (UA PI), mean middle cerebral artery pulsatility index (MCA PI), CPR, and Apgar score in 1 minute. Multiples of medians (MoM) were calculated for MCA PI and UA PI.

Results

The study group consisted of 446 women, 236 were primipara and 210 were multipara. The average age was 29.6 years (range 16–46 years). The average week of delivery is 39.5 weeks of gestation (range 36–42). Mean MCA PI and UA PI were 1.3 (0.1–2.45) and 0.8 (0.39–1.66), respectively. The mean values were 1.03 (0.1–1.9) for MCA PI MoM and 1.04 (0.5–2.1) for UA PI MoM. Primiparas had lower values of MCA PI (1.27 vs. 1.34), MCA PI MoM (1.00 vs. 1.05), CPR (1.62 vs. 1.73), EFW (3479.53 g vs. 3579.25 g) and birth weight (3513.50 g vs. 3617.79 g). For CPR cut-off point of 1.08: sensitivity was (0.945), specificity 0.1, positive predictive values 0.979, negative predictive values 0.04 and accuracy 0.926. The ROC curves for CPR were: area under the curve was 0.52 at CI 95% (0.342–0.698), p = 0.8271.

Conclusion

Screening in pregnancies with appropriate-for-gestational-age fetuses at 36–42 weeks of gestation using Doppler parameters is not useful in the prediction of adverse perinatal outcomes like an Apgar score < 7 at 1 minute.