Accuracy sonogram dating
critical review of these studies questioning the safety of ultrasound has shown several inconsistencies: 1) reported levels and exposure times far exceeded what is commonly in use; 2) studies done on certain plants, cell cultures, and laboratory animals are not applicable to humans; and 3) studies demonstrating adverse effects in vitro have not been reproducible in humans.
In spite of these reassurances, there remains a remote possibility that adverse effects could be identified in the future; however, current evidence indicates that the potential benefits of ultrasound far outweigh these risks.
Cost-benefit ratios of routine ultrasound use have still not been completely resolved in every practice setting, with one study suggesting that community-based hospitals would actually lose money if routine ultrasound screening is performed.
further states that ultrasound sensitivity in detecting fetal anomalies remains controversial, with higher detection rates reported at tertiary centers and higher sensitivity rates overall for central nervous system and urinary tract versus cardiac anomalies.
in their study of more than 17,000 women, found that the proportion of postterm deliveries decreased from 10.3% with reliable LMP dating to 2.7% when the EDD was determined by ultrasound.
In more recent randomized controlled trials, researchers have continued to report substancially fewer postterm inductions when the EDD was determined by first-trimester ultrasound.
A comprehensive review of this body of literature is beyond the scope of this article; however, there are several studies that warrant mention with regard to pregnancy dating and gestational age assessment.
At first glance, it may appear that some of these studies do not report consistent findings in terms of ultrasound's overall accuracy in predicting gestational age.
In midwifery practices especially, where the focus on nonintervention predominates, a single ultrasound performed before 24 weeks' gestation will not only reliably confirm the EDD but, as many of the previously cited studies suggest, may in fact reduce the likelihood of unnecessary interventions.
What is most surprising, however, is that despite the evidence that supports the reliability and accuracy of ultrasound, its routine use in all pregnancies is still not recommended.
When one also considers the costs of postterm surveillance, which typically includes twice weekly nonstress tests and weekly amniotic fluid measurements, there are potential cost savings with accurate dating by early ultrasound assessment -- not to mention the costs of fetal fibronectin cultures or the clinical and legal implications of inappropriately managing preterm labor.
Does it not then behoove all obstetric providers to discuss and offer routine ultrasound screening to every pregnant woman, even in the absence of medical indications?
They further concluded that the costs associated with routine screening were too prohibitive to justify its use in the absence of clear medical indications.