Trimester-specific diagnostic accuracy of ultrasound for detection of placenta accreta spectrum: systematic review and meta-analysis.

OBJECTIVE: To assess the diagnostic accuracy of ultrasound for detecting placenta accreta spectrum (PAS) during the first trimester of pregnancy and compare it with the accuracy of second- and third-trimester ultrasound examination in pregnancies at risk for PAS. METHODS: PubMed, EMBASE and Web of Science databases were searched to identify relevant studies published from inception until 10 March 2023. Inclusion criteria were cohort, case-control or cross-sectional studies that evaluated the accuracy of ultrasound examination performed at < 14 weeks of gestation (first trimester) or ≥ 14 weeks of gestation (second/third trimester) for the diagnosis of PAS in pregnancies with clinical risk factors. The primary outcome was the diagnostic accuracy of sonography in detecting PAS in the first trimester, compared with the accuracy of ultrasound examination in the second and third trimesters. The secondary outcome was the diagnostic accuracy of each sonographic marker individually across the trimesters of pregnancy. The reference standard was PAS confirmed at pathological or surgical examination. The potential of ultrasound and different ultrasound signs to detect PAS was assessed by computing summary estimates of sensitivity, specificity, diagnostic odds ratio and positive and negative likelihood ratios. RESULTS: A total of 37 studies, including 5764 pregnancies at risk of PAS, with 1348 cases of confirmed PAS, were included in our analysis. The meta-analysis demonstrated that ultrasound had a sensitivity of 86% (95% CI, 78-92%) and specificity of 63% (95% CI, 55-70%) during the first trimester, and a sensitivity of 88% (95% CI, 84-91%) and specificity of 92% (95% CI, 85-96%) during the second/third trimester. Regarding sonographic markers examined in the first trimester, lower uterine hypervascularity exhibited the highest sensitivity (97% (95% CI, 19-100%)), and uterovesical interface irregularity demonstrated the highest specificity (99% (95% CI, 96-100%)). In the second/third trimester, loss of clear zone had the highest sensitivity (80% (95% CI, 72-86%)), and uterovesical interface irregularity exhibited the highest specificity (99% (95% CI, 97-100%)). CONCLUSIONS: First-trimester ultrasound examination has similar accuracy to second- and third-trimester ultrasound examinations for the diagnosis of PAS. Routine first-trimester ultrasound screening for patients at high risk of PAS may improve detection rates and allow earlier referral to tertiary care centers for pregnancy management. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Influence of maternal body mass index on interobserver variability of fetal ultrasound biometry and amniotic-fluid assessment in late pregnancy.

OBJECTIVE: To determine the interobserver reproducibility of fetal ultrasound biometric and amniotic-fluid measurements in the third trimester of pregnancy, according to maternal body mass index (BMI) category. METHODS: This was a prospective cohort study of women with a singleton gestation beyond 34 weeks, recruited into four groups according to BMI category: normal (18.0-24.9 kg/m2 ), overweight (25.0-29.9 kg/m2) , obese (30.0-39.9 kg/m2 ) and morbidly obese (≥ 40 kg/m2 ). Multiple pregnancies, women with diabetes and pregnancies with a fetal growth, structural or genetic abnormality were excluded. In each woman, fetal biometric (biparietal diameter (BPD), head circumference, abdominal circumference (AC), femur length (FL) and estimated fetal weight) and amniotic-fluid (amniotic-fluid index (AFI) and maximum vertical pocket (MVP)) measurements were obtained by two experienced sonographers or physicians, blinded to gestational age and each other's measurements. Differences in measurements between observers were expressed as gestational age-specific Z-scores. The interobserver intraclass correlation coefficient (ICC) and Cronbach's reliability coefficient (CRC) were calculated. Bland-Altman analysis was used to assess the degree of reproducibility. RESULTS: In total, 110 women were enrolled prospectively (including 1320 measurements obtained by 17 sonographers or physicians). Twenty (18.2%) women had normal BMI, 30 (27.3%) women were overweight, 30 (27.3%) women were obese and 30 (27.3%) women were morbidly obese. Except for AFI (ICC, 0.65; CRC, 0.78) and MVP (ICC, 0.49; CRC, 0.66), all parameters had a very high level of interobserver reproducibility (ICC, 0.72-0.87; CRC, 0.84-0.93). When assessing reproducibility according to BMI category, BPD measurements had a very high level of reproducibility (ICC ≥ 0.85; CRC > 0.90) in all groups. The reproducibility of AC and FL measurements increased with increasing BMI, while the reproducibility of MVP measurements decreased. Among the biometric parameters, the difference between the BMI categories in measurement-difference Z-score was significant only for FL. Interobserver differences for biometric measurements fell within the 95% limits of agreement. CONCLUSION: Obesity does not seem to impact negatively on the reproducibility of ultrasound measurements of fetal biometric parameters when undertaken by experienced sonographers or physicians who commonly assess overweight, obese and morbidly obese women. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Indications for caesarean sections at ≥34 weeks among nulliparous women and differential composite maternal and neonatal morbidity.

OBJECTIVE: To compare composite maternal and neonatal morbidities (CMM, CNM) among nulliparous women with primary indications for caesarean section (CS) as acute clinical emergency (group I; ACE), non-reassuring fetal heart rate (group II) and arrest disorder (group III). DESIGN: A multicentre prospective study. SETTING: Nineteen academic centres in the USA, with deliveries in 1999-2002. POPULATION: Nulliparous women (n = 9829) that had CS. METHODS: Nulliparous women undergoing CS for three categories of indications were compared using logistic regression model, adjusted for five variables. MAIN OUTCOME MEASURES: CMM was defined as the presence of any of the following: intrapartum or postpartum transfusion, uterine rupture, hysterectomy, cystotomy, ureteral or bowel injury or death; CNM was defined as the presence of any of the following: umbilical arterial pH <7.00, neonatal seizure, cardiac, hepatic, renal dysfunction, hypoxic ischaemic encephalopathy or neonatal death. RESULTS: The primary reasons for CS were ACE in 1% (group I, n = 114) non-reassuring FHR in 29% (group II; n = 2822) and failed induction/dystocia in the remaining 70% (group III; n = 6893). The overall risks of CMM and CNM were 2.5% (95% confidence intervals, CI, 2.2-2.8%) and 1.9% (95% CI 1.7-2.2), respectively. The risk of CMM was higher in group I than in group II (RR 4.1, 95% CI 3.1, 5.3), and group III (RR 3.2, 95% CI 2.7, 3.7). The risk of CNM was also higher in group I than in group II (RR 2.8, 95% CI 2.3, 3.4) and group III (RR 14.1, 95% CI 10.7, 18.7). CONCLUSIONS: Nulliparous women who have acute clinically emergent caesarean sections are at the highest risks of both composite maternal and neonatal morbidity and mortality.

Calcium channel blockers as tocolytics.

This article reviews the clinical and basic science investigations regarding the safety and efficacy of calcium channel blockers as tocolytic agents. The authors reviewed the English language literature on the pharmacology and clinical applications of calcium antagonists in obstetrics. A MEDLINE (1966-2000) search was performed with the terms "calcium channel blockers," "randomized controlled trial," "preterm labor," "calcium antagonist," "tocolysis," and "nifedipine." References from these data sources were then used to find additional studies. Animal data and clinical trials in humans were included. The safety of these agents was researched in published data from the nonobstetric as well as obstetric literature. The calcium channel blockers most commonly used as tocolytics are nifedipine and nicardipine. These agents act to inhibit calcium influx across cell membranes, thereby decreasing tone in the smooth muscle of the vasculature. They act as profound vasodilatory agents and have minimal effect on the cardiac conduction system. Numerous randomized clinical trials have shown them to be as effective as beta-mimetics and magnesium in achieving tocolysis. When used for tocolysis, calcium antagonists have fewer maternal side effects than other tocolytics and have no adverse effect on fetal outcome.

Long-term outcome in twin-twin transfusion syndrome treated with serial aggressive amnioreduction.

OBJECTIVE: The purpose of this study was to determine long-term outcomes among pregnancies complicated by twin-twin transfusion syndrome and treated in a tertiary center with serial aggressive amnioreduction. STUDY DESIGN: Thirty-three pregnancies with a diagnosis of twin-twin transfusion syndrome were treated with > or =1 amnioreduction. The perinatal outcome was assessed according to 15 parameters, whereas the main outcome at age > or =2 years was the absence of cerebral palsy. RESULTS: Gestational age at diagnosis ranged from 14.5 to 33 weeks' gestation (median, 20.6 weeks' gestation), whereas gestational age at delivery was between 18.5 and 37 weeks' gestation (median, 30.5 weeks' gestation). The number of amnioreductions per pregnancy ranged from 1 to 15 (median, 2). At initial examination hydrops of the recipient and absence of the end-diastolic velocity of the umbilical artery in one of the twins were associated with poor prognosis. Fifty-one (77%) twins were born alive. At 24 months after birth both infants from 57% of the pregnancies (19/33) were alive, whereas at least one infant from 70% of the pregnancies (23/33) was alive. Thirty-three infants (78% of the survivors) were older than 36 months at last follow-up. Cerebral palsy was diagnosed in 2 of 42 infants (4.7%). One of the affected infants was born after the fetal death of the cotwin; the other infant was born with congenital cardiac malformations. CONCLUSIONS: In the group of fetuses in which both twins were delivered alive after 27 weeks' gestation without congenital malformations and survived the neonatal period, no major neurologic handicaps developed in any of the infants. At initial examination both hydrops of the recipient and absence of end-diastolic flow velocity waveforms of the umbilical artery in one of the twins were poor prognostic signs.

Abdominal wall and umbilical cord anomalies.

This article begins with a presentation of the embryology of the anterior abdominal wall and umbilical cord. Abnormal embryology and resulting anomalies are presented in tabular form and later reviewed in chronologic order of embryologic development. Techniques involved in the prenatal diagnosis of these abnormalities are also described.

Color Doppler of the splenic artery in the prenatal diagnosis of heterotaxic syndromes.

The objective of this paper is to determine whether color and pulsed Doppler of the splenic artery is helpful in the prenatal diagnosis of polysplenia or asplenia in heterotaxic syndromes. Over a 3-year period, localization of the splenic artery by color and pulsed Doppler was attempted on all fetuses with the diagnosis of heterotaxic syndromes. Postnatal follow-up was obtained on all neonates. The diagnosis of heterotaxic syndromes was performed on eight fetuses during the study period. Mean gestational age at diagnosis was 20.1 weeks. All fetuses had situs ambiguous and complex cardiac abnormalities. All pregnancies were managed expectantly and none were terminated. The splenic artery was imaged by color and pulsed Doppler in 6 of 8 fetuses, all with one or multiple spleens confirmed postnatally. The splenic artery could not be imaged in two fetuses, both with asplenia confirmed postnatally. The perinatal mortality rate was 88% (7 of 8) and the one surviving infant is currently alive and well at 3 years of age. Color and pulsed Doppler of the splenic artery can aid in the prenatal diagnosis of heterotaxic syndromes. This information is of value and should result in improved prenatal counseling and management of affected pregnancies.

Effect of maternal hydration on fetal renal pyelectasis.

OBJECTIVE: To assess the effect of maternal hydration on fetal pyelectasis. METHODS: Thirteen pregnant women with fetal pyelectasis and 13 controls matched for gestational age were recruited during the same period. Ultrasound and Doppler studies and maternal urine specific gravity measurements were carried out before and after maternal oral hydration. The data were analyzed by either a two- or three-factor analysis of variance. RESULTS: Renal artery Doppler pulsatility index was significantly greater in the study group than in the controls (2.37 versus 1.83; P=.009) and this finding was unaffected by maternal hydration status. After hydration, the maternal urinary specific gravity decreased significantly (1.018 versus 1.009; P < .001), the amniotic fluid index (AFI) increased significantly (14.27 versus 18.24 cm; P < .001), and the fetal renal pelvis diameter increased significantly (0.29 versus 0.46 cm; P=.002) in both the study and control groups. Renal pelvis anteroposterior diameter after hydration did not differ significantly whether the fetal bladder was full or empty (0.7 versus 0.6 cm; P=.1). In this study, each subject served as her own control (ie, from before to after hydration). Three of 13 controls met the diagnostic criteria for pyelectasis after maternal hydration. CONCLUSION: The AFI increases after maternal hydration in both normal fetuses and those with pyelectasis. The fetal renal pelvis anteroposterior diameter increases with maternal hydration in both normal fetuses and those with pyelectasis and is independent of the state of the fetal bladder. The renal artery Doppler pulsatility index is significantly greater in fetuses with pyelectasis than in controls.

Superior mesenteric artery Doppler velocimetry and ultrasonographic assessment of fetal bowel in gastroschisis: a prospective longitudinal study.

OBJECTIVE: Our purpose was to determine whether Doppler velocimetry of the superior mesenteric artery and its mesenteric branches and ultrasonographic assessment of bowel can predict postnatal outcome in fetuses with gastroschisis. STUDY DESIGN: The normal reference range for the superior mesenteric artery pulsatility index was determined by studying 161 normal fetuses. Over a 24-month period superior mesenteric artery pulsatility index, superior mesenteric artery mesenteric branches systolic/diastolic ratio, bowel diameter, and bowel wall thickness were prospectively and longitudinally obtained from 17 fetuses with gastroschisis. Poor neonatal outcome was defined by bowel resection or staged repair of the defect or a hospital stay > 50 days. RESULTS: Doppler velocimetry of the superior mesenteric artery and its mesenteric branches proved minimally useful in prognosticating neonatal outcome. No difference was found in the superior mesenteric artery pulsatility index between the good and poor neonatal outcome groups (p = 0.99). Longitudinal data analysis on all fetuses with gastroschisis showed an increase in bowel diameter with advancing gestation (p < 0.0001). A greater rate of increase in bowel diameter with advancing gestation was noted in the poor-neonatal-outcome group compared with the good-neonatal-outcome group (p < 0.01). Mean bowel diameter obtained before delivery was significantly greater in the poor-neonatal-outcome group (p = 0.03). Bowel diameter obtained at 28 to 32 weeks was the best predictor of poor neonatal outcome. A cutoff value of bowel diameter > 10 mm at 28 to 32 weeks had a sensitivity of 83%, a specificity of 88%, a positive predictive value of 83%, and a negative predictive value of 88% for poor neonatal outcome. CONCLUSIONS: Doppler velocimetry of the superior mesenteric artery and its branches is not predictive of poor neonatal outcome in fetuses with gastroschisis. A bowel diameter > 10 mm between 28 and 32 weeks appears to be the best predictor of poor neonatal outcome. This newly defined variable warrants further investigation given its significant predictive power.

Umbilical artery Doppler velocimetry waveform abnormality in fetal gastroschisis.

Two cases of notching in the umbilical artery Doppler waveform in a pregnancy with gastroschisis are reported. The etiology of the abnormal Doppler pattern in relation to the displacement of the fetal stomach in this congenital abnormality is discussed.

Is the fetal brain-sparing effect a risk factor for the development of intraventricular hemorrhage in the preterm infant?

The intrauterine identification of fetuses at risk of developing intraventricular hemorrhage would be helpful to the perinatologist, in light of the recent results which suggest that indomethacin given to the infant reduces the risk of developing intraventricular hemorrhage. We hypothesized that fetuses undergoing brain sparing, as identified by a lowered pulsatility index (PI) in the middle cerebral artery, and delivered prior to 34 weeks may differ in terms of being at risk for intraventricular hemorrhage from those fetuses without the brain-sparing effect. The middle cerebral artery PI was studied in 43 fetuses between 25 and 33.6 weeks' gestation. The pregnancies were complicated by pre-eclampsia, intrauterine growth restriction (IUGR) and preterm labor. A cranial sonogram was performed during the first postnatal week in all the neonates. Intraventricular hemorrhage was present in 6/22 infants with a normal middle cerebral artery PI (group A) and 0/21 with an abnormal middle cerebral artery PI (group B) (p < 0.05). The mothers of the six fetuses who developed intraventricular hemorrhage underwent preterm labor. IUGR fetuses and pre-eclampsia were more common in group B. No difference was found between the two groups when the following variables were compared: (1) gestational age at the time of the Doppler study; (2) gestational age at delivery; (3) antenatal exposure to steroids; (4) antenatal exposure to magnesium; (5) Apgar score greater than 6 at 5 min; (6) respiratory distress syndrome in the newborn; (7) necrotizing enterocolitis; (8) Cesarean section; and (9) sepsis in the infant. Although the mean birth weight was significantly lower in group B than group A, no fetus in this group developed intraventricular hemorrhage. The fetal brain-sparing effect, pre-eclampsia and IUGR were associated with a lower risk of neonatal intraventricular hemorrhage than was preterm labor. Preterm labor appears to be a key factor in the development of intraventricular hemorrhage and must be included when testing associations with intraventricular hemorrhage.

Adrenal artery velocity waveforms in the appropriate and small-for-gestational-age fetus.

The purpose of this study was to compare adrenal artery flow velocity waveforms in the appropriately grown and the small-for-gestational-age fetus. Adrenal artery flow velocity waveforms were prospectively obtained from 131 appropriate- and 21 small-for-gestational-age fetuses with pulsed Doppler ultrasonography. The success rate in recording the adrenal artery was 84% (131/155) and 100% in the appropriate- and small-for-gestational-age fetuses, respectively. The pulsatility index (PI) was used to quantify the waveforms. The PI in the appropriate-for-gestational-age fetuses decreased linearly with gestational age (PI = 1.7-0.016 x gestational age). In ten small-for-gestational-age fetuses the adrenal artery PI was below the 95% confidence interval. Small-for-gestational-age fetuses with abnormal adrenal artery PI had a significantly higher incidence of fetal heart rate decelerations, preterm delivery and Cesarean sections when compared to small-for-gestational-age fetuses with normal adrenal artery PI. Our data indicate that the PI of the adrenal artery in the normal fetus decreases with advancing gestation, and they suggest that in the small-for-gestational-age fetus there is an increased blood flow to the adrenal gland. We postulate that management of the small-for-gestational-age fetus may be aided by the study of the adrenal artery flow velocity waveforms.

Familial recurrence of pulmonary sequestration.

BACKGROUND: Pulmonary sequestration is not believed to be familial. We report two male infants with this anomaly who were born to the same parents. CASES: The prenatal diagnosis of pulmonary sequestration was made in a woman's two consecutive pregnancies by demonstrating systemic arterial supply to an echogenic mass located in the left lower lung of each fetus. Postnatal radiographic evaluation confirmed the prenatal diagnoses. CONCLUSION: Recurrent pulmonary sequestration in two male offspring from the same parents raises the possibility of a genetic predisposition for this condition.

Renal duplication anomalies in the fetus: clues for prenatal diagnosis.

Duplex kidneys are one of the most common major congenital abnormalities of the urinary tract. The antenatal diagnosis of duplex kidney and its associated ureterocele is infrequent. We report on our experience with the prenatal diagnosis of duplex kidneys in seven fetuses over the past 24 months. In all fetuses, the sagittal length of the duplex kidney was above the 95th centile for gestational age. A 'cyst-like' structure in the upper pole of the duplex kidney and a ureterocele in the urinary bladder were present in all of the seven fetuses. An ipsilateral dilated ureter was seen in six of seven fetuses. Postnatal confirmation of renal duplication anomalies was obtained in all neonates. Increased familiarity of the prenatal sonographer with duplex kidney will allow for its antenatal diagnosis and thus early postnatal treatment.

Prenatal ultrasonographic fetal rib length measurement: correlation with gestational age.

The availability of normal data on fetal rib bone length would be of value in a variety of circumstances under which ultrasound examinations are performed. Fetal rib length measurements were obtained in 257 singleton fetuses in a prospective cross-sectional study. The study population consisted of pregnancies between 14 and 40 weeks with no evidence of growth disturbances, or structural or karyotypic abnormalities. Fetal rib length, as a function of gestational age, was expressed by the regression equation: RL = -0.5834 + 0.2030 (GA), where RL is the rib length in centimeters and GA the gestational age in weeks. The correlation was R = 0.94 (p < 0.0001). The normal limits of fetal rib length are defined, and a high correlation between fetal rib length, gestational age, and other standard determinants of fetal growth is demonstrated. Our results indicate that fetal rib length can be a useful adjunct in determining normal fetal growth and in the management of the pregnancy with fetal skeletal dysplasia.

Prognostic implications of fetal echogenic bowel.

BACKGROUND: An increased frequency of hyperechogenic bowel on ultrasound has been reported in fetuses with cystic fibrosis (CF) and trisomy-21. However, the diagnostic application of this observation has been hampered by the absence of a means of measuring echogenicity. METHODS: We devised an ultrasonic grading system in which echogenicity was quantified by linear gain reduction and comparison with fetal iliac crest. From 7400 second-trimester ultrasound referrals, 145 patients were identified as having a fetus with abnormally echogenic bowel. They were offered genetic counselling, parental and (if appropriate) CF carrier testing, and amniocentesis for karyotype and CF status if parents were informative. Follow-up was to 4 months of age. FINDINGS: Of 40 fetuses with mild increase in bowel sonodensity (grade 1), none had CF or aneuploidy. Of 81 patients identified with a moderate increase (grade 2), 2 had trisomy 21 and 2 had CF. And of 24 pregnancies with a pronounced increase (grade 3), 5 had CF and 6 had trisomy-21. INTERPRETATION: Parental CF carrier testing and amniocentesis to identify aneuploidy or fetal CF status has a high positive ascertainment rate in fetuses with echogenic bowel grades 2 and 3.

Antenatal diagnosis and treatment of fetal goitrous hypothyroidism: case report and review of the literature.

The recognition and treatment of fetal hypothyroidism are believed to be important to optimize growth and intellectual development in affected fetuses. We present a case of fetal goiter diagnosed by ultrasonography in the second trimester of pregnancy. Cordocentesis performed at 28 weeks confirmed the presence of fetal hypothyroidism. Fetal therapy was performed with weekly intra-amniotic injections of thyroxine from 29 to 36 weeks. A repeat cordocentesis at 35 weeks showed normalization of fetal thyroid function. The fetal goiter decreased rapidly in size following fetal treatment. Amniotic fluid levels of thyroid stimulating hormone (TSH) and free thyroxine were obtained with each amniocentesis. Sulfated iodothyronine concentrations in maternal blood were obtained before and after fetal thyroxine treatment. This report discusses the role of amniotic fluid levels of TSH and free thyroxine and maternal levels of sulfated iodothyronine in the diagnosis and management of fetal hypothyroidism. A review of the English literature is presented.