Am J Obstet Gynecol MFM. 2024 Apr 5:101373. doi: 10.1016/j.ajogmf.2024.101373. Online ahead of print.
ABSTRACT
BACKGROUND: In low-risk pregnancies, third trimester ultrasound examination is indicated if fundal height measurement and gestational age discrepancy is observed. Despite potential improvement in detection of ultrasound abnormality, prior trials to date on universal third trimester ultrasound examination in low-risk pregnancies, compared to indicated ultrasound examination, have not demonstrated improvement in neonatal or maternal adverse outcomes.
OBJECTIVE: The primary objective was to determine if universal third trimester ultrasound examination in low-risk pregnancies could attenuate composite neonatal adverse outcome. The secondary objectives were to compare change in composite maternal adverse outcomes and detection of abnormalities of fetal growth (fetal growth restriction or large for gestational age) or amniotic fluid (oligo- or poly-hydramnios).
STUDY DESIGN: Our pre- and post-intervention study at 9 locations included low-risk pregnancies; those without indication for ultrasound examination in the third trimester. Compared to indicated ultrasound in the pre-implementation period, in the post-implementation period all patients were scheduled for ultrasound examination at 36.0 – 37.6 weeks. In both periods clinicians intervened based on abnormalities identified. Composite neonatal adverse outcomes included any of: Apgar score ≤ 5 at 5 min, cord pH < 7.00, birth trauma (bone fracture or brachial plexus palsy), intubation for > 24 hours, hypoxic ischemic encephalopathy, seizure, sepsis (bacteremia proven with blood culture), meconium aspiration syndrome, intraventricular hemorrhage grade III or IV, periventricular leukomalacia, necrotizing enterocolitis, stillbirth after 36 weeks, or neonatal death within 28 days of birth. Composite maternal adverse outcomes included any of: chorioamnionitis, wound infection, estimated blood loss >1000mL, blood transfusion, deep venous thrombus or pulmonary embolism, admission to intensive care unit, or death. Using Bayesian statistics, we calculated a sample size of 600 individuals in each arm to detect >75% probability of any reduction in primary outcome, (80% power; 50% hypothesized risk reduction).
RESULTS: During the pre-intervention phase, 747 individuals were identified during the initial ultrasound examination and among them 568 (76.0%) met the inclusion criteria at 36.0 to 37.6 weeks; during the post-intervention period, the corresponding numbers were 770 and 661 (85.8%). The rate of identified abnormalities of fetal growth or of amniotic fluid increased from between pre- and post-intervention period (7.1% versus 22.2%, p< 0.0001; number needed to diagnose, 7; 95% confidence interval, 5-9). The primary outcome occurred in 15 of 568 (2.6%) individuals in the pre- and 12 of 661 (1.8%) in the post-intervention group (83% probability of risk reduction, posterior relative risk, 0.69; 95% credible interval, 0.34-1.42). The composite maternal adverse outcomes occurred in 8.6% in the pre- and 6.5% in post-intervention group (90% probability of risk (posterior relative risk, 0.74; 95% credible interval, 0.49-1.15). The number needed to treat to reduce composite neonatal adverse outcomes was 121 (95% confidence interval, 40-200), to reduce composite maternal adverse outcomes was 46 (95% confidence interval, 19-74), and to prevent cesarean delivery was 18 (95% confidence interval, 9-31).
CONCLUSION: Among low-risk pregnancies, compared to routine care with indicated ultrasound examination, implementation of a universal third-trimester ultrasound examination at 36.0-37.6 weeks attenuated composite neonatal and maternal adverse outcomes.
PMID:38583714 | DOI:10.1016/j.ajogmf.2024.101373
