Anatomical Survey Versus Fetal Echocardiograms for Diagnosis of Cardiac Defects with a Single Umbilical Artery Cases: A Retrospective Cohort Study and Diagnostic Meta-analysis
Tiffany Tonismae 1, Jessica H Kline 1, Jennifer J Choe 1, Frank Schubert 1, Methodius Tuuli 1, Anthony Shanks 1
J Ultrasound Med. 2020 Sep 4. doi: 10.1002/jum.15483. Online ahead of print. PMID: 32885858. DOI: 10.1002/jum.15483
- In a fetus with a Single Umbilical Artery, a standard anatomic survey with recommended cardiac screening highly predicts congenital heart disease.
- Addition of fetal echocardiogram does not yield more when cardiac views are normal on anatomic survey.
Commentary from Dr. Venu Amula (Salt Lake City, USA), section editor of Pediatric & Fetal Cardiology Journal Watch: Single Umbilical Artery ( SUA) in the fetus is associated with cardiac and extracardiac anomalies. The American Institute of Ultrasound in Medicine recommends a fetal anatomic survey for prenatal detection of significant abnormalities. Standard cardiac screening includes a four-chamber view, left ventricular, and right ventricular outflow tract views at a minimum. A question arises whether those with isolated SUA would benefit from a fetal echocardiogram to rule out congenital heart disease in addition to anatomic ultrasound.
To answer this question, Tonismae et al. performed this retrospective cohort study of prenatally diagnosed SUA over ten years at a single institution. The authors hypothesized that in isolated SUA, there is no additional benefit to performing a fetal echocardiogram. The study reviewed patients with documented SUA who had both an anatomical survey and a fetal echocardiogram available. They compared cardiac anatomy on a detailed anatomy survey with a fetal echocardiogram in the fetuses with SUA. Additionally, they report a diagnostic meta-analysis of studies with similar comparison during the period 2010 and 2019. Predictive characteristics of anatomical ultrasound were estimated with a fetal echocardiogram to detect congenital heart disease as a “gold standard.”
Of the 22,666 anatomical surveys during the study period, the authors identified SUA in 320 cases. The analysis was done on 93 patients that met inclusion criteria. Forty-four of these had normal anatomic surveys, and all were subsequently reported to have normal fetal echocardiograms. Of the 49 who had suboptimal or abnormal anatomic surveys, thirteen had a normal fetal echo, while 36 had an abnormal fetal echo. The sensitivity and specificity of the anatomic ultrasound were found to be 100% and 77% (p < 0.01), respectively, while the positive predictive value was 73% (p < 0.01).
When an anatomical ultrasound evaluation of the fetal heart was compared with the fetal echocardiogram in this population, the ultrasound had a negative predictive value (NPV) of 100% (p < 0.01). The diagnostic meta-analysis reported a pooled sensitivity of 97% (95% CI 81, 100%) and a pooled specificity of 95% (95% CI 72, 99%). The summary ROC curve showed that the anatomic survey was highly predictive of cardiac defect on fetal echo. The risk of selection bias was assessed, and the authors show significant heterogeneity between studies for both sensitivity and specificity.
The study is well-conducted and addresses an essential question of fetal echocardiogram utility in those with isolated SUA and the anatomical survey showing normal cardiac anatomy. The authors highlight that fetal echocardiography is a specialized imaging modality and can impose a high cost on the mother and the health care system. Besides, the personal cost of travel to some patients living remotely and the anxiety provoked by the investigation would make it hard to recommend when a standard anatomic survey is normal. However, the conclusions have to be read in the face of the limitations of this single-center study. The study is performed at a single prenatal diagnosis center with experience conducting anatomic surveys and standard cardiac views. Any extrapolation to other centers with heterogeneous expertise should be made with caution. Besides, no information exists on postnatal confirmation of congenital heart disease, and the authors acknowledge the limitation of using prenatal echocardiography as the “gold” standard.
The current updated guidelines of the American Institute of Ultrasound in Medicine recommend obtaining the 4-chamber heart, left ventricular outflow tract, right ventricular outflow tract views, and the addition of 3-vessel view and 3-vessel trachea view. They recommend a fetal echocardiogram with SUA if the anatomical ultrasound is suspicious for CHD or if cardiac views are suboptimal. The study reaffirms this statement. It also offers credible evidence to the debate of the lack of utility of prenatal echocardiogram when the cardiac screening, done in conformity with the standard guidelines, is normal. However, the center’s experience and technical expertise to meet the guidelines will continue to dictate individual decision-making.