Accurate detection of anomalies by routine ultrasonography in an indigent clinic population

Abstract

Objective: The study's objective was to determine the accuracy of routine ultrasonography in the detection of anomalies in an indigent clinic population by sonographers trained to perform complete anatomic screens.

Study design: This is a retrospective study of women undergoing obstetric ultrasonography between 15 and 26 weeks' gestation during an 18-month period. Ultrasonography was performed with an ATL Ultramark 4 (ATL Ultrasound, Bothell, Wash) in the resident clinic by a rotating group of sonographers who each spent 80% of the time performing advanced sonography and 20% screening. Images were reviewed by attending physicians at the end of each day. Abnormalities were followed up with ultrasonography by an attending physician. Obstetric and neonatal charts were reviewed in all cases.

Results: There were 901 women scanned (44 others were unavailable for follow-up, and complete data were unavailable in 22 cases). Twenty-one percent of all patients were referred for advanced scans; in half the only indication for referral was an abnormal ultrasonographic result. There were 28 anomalies (3.1%). Anomalies that were undiagnosed were a 5-mm ventricular septal defect, transposition of the great arteries with ventricular septal defect, extralobar sequestration, misshapen ear, clubfoot, imperforate anus, 1 x 1-cm skin-covered meningomyelocele, and an uncharacterized dysmorphic syndrome. The sensitivity, specificity, and negative and positive predictive values of the screening ultrasonography were 71.4%, 99.4%, 99.1%, and 80%, respectively (P < .0001). Of patients in whose fetuses anomalies were detected, 30% elected termination of pregnancy and 1 patient whose fetus had trisomy 18 elected no fetal monitoring in labor, resulting in a stillbirth. Two neonates required surgery and 2 died in the immediate neonatal period. There were 5 suspected anomalies at screening that were excluded by targeted scan.

Conclusion: Routine screening ultrasonography performed by well-trained sonographers is extremely accurate in the detection of anomalies in an indigent population. It allows women counseling and options that they otherwise might not be offered.