TRANSVAGINAL ULTRASOUND IN THREATENED ABORTIONS WITH EMPTY GESTATIONAL SACS

Objective: To determine whether transvaginal ultrasound criteria alone can distinguish viable from non-viable gestational sacs at a single e xamination. Method: A prospective descriptive study was undertaken and analysis performed on 211 pregnancies complicated by threatened abort ion and empty gestation sacs diagnosed by transvaginal ultrasound. The main outcome measure was the final diagnosis of viable or non-viable gestation on subsequent transvaginal sonography. Results: The study sh ows that a single transvaginal ultrasound examination is useful in dif ferentiating viable from non-viable gestation sacs. The mean sac diame ter (MSD) was found to be the most useful criterion for determining no n-viability. An MSD of greater than or equal to 17 mm that lacked an e mbryo and an MSD of 113 mm without visible yolk sac were reliable pred ictors of non-viable gestation sacs at a single examination with 100% specificity and 100% positive predictive value. An MSD greater than or equal to 13 mm without visible yolk sac was the most sensitive criter ion. Using MSD criteria, 73% of non-viable gestations could be reliabl y identified without any false-positive diagnoses. Deformed shape, low position and thin decidual reaction are strong indicators of non-viab le gestations but are not 100% accurate. There is still a significant proportion of empty sacs, where no accurate distinction between viable and non-viable can be made according to one criterion at a single exa mination and in these cases serial examinations should be carried out before any active management is advocated. Conclusion: In most cases, transvaginal sonographic criteria alone can distinguish viable from no n-viable empty gestational sacs at a single examination.