FIRST-TRIMESTER US PARAMETERS OF FAILED PREGNANCY

PURPOSE: To test the reliability of established ultrasound (US) parame ters in predicting the outcome of first-trimester pregnancy. MATERIALS AND METHODS: The authors retrospectively reviewed 2,655 first-trimest er US scans in 2,285 patients. Parameters tested against outcome were (a) a yolk sac and mean gestational sac diameter of 8 mm on transvagin al US scans, (b) an embryo and mean sac diameter of 16 mm on transvagi nal US scans, and (c) a difference between the mean sac diameter and c rown-rump length of less than 5 mm (oligohydramnios) at 5.5-9.0 weeks gestation. RESULTS: Thirty (22%) of 135 patients without yolk sacs and with an 8-mm mean sac diameter developed live embryos: 24 had normal follow-up or delivery; six were lost to follow-up. Five (8%) of 59 pat ients with no depiction of embryos and with a 16-mm mean sac diameter developed live embryos: Two delivered, one spontaneously aborted, one had death of one twin embryo before being lost to follow-up, and one w as lost to follow-up. Seventeen (0.74%) of 2,285 patients had early ol igohydramnios: Six (35%) had normal follow-up scans or delivery, two ( 12%) spontaneously aborted, and nine (53%) were lost to follow-up. CON CLUSION: Established parameters predictive of early pregnancy failure potentially result in misdiagnosis of nonviability or poor prognosis w hen applied to a large, unselected patient population. Close follow-up is necessary in cases with borderline abnormal findings.