|Early pregnancy loss is the most common complication of human pregnancy. Such commonality requires dependable evaluation tools and informed, standardized criteria for accurate diagnosis. A brief perusal of the data on which most of the practitioners who treat women who are newly pregnant have based their recommendations for the sonographic diagnosis of a non-viable pregnancy raises significant concern since most of these data are based on relatively small patient numbers . Further, recent studies have shown that the measurements used to determine historically-accepted criteria have fairly wide patient-to-patient, hyphenate intra-observer and interobserver variability. This makes the inclusion of investigations based upon small patient numbers even more problematic. This unfortunate combination poses an important problem because the diagnosis of failed pregnancy has immense implications to the physical health of the mother and to the emotional well-being of the mother, her partner, her family and her close friends. The criteria for diagnosing a non-viable pregnancy must have a specificity that is as close to 100% as possible. Still, using commonly accepted historical sonographic criteria; authors have shown that between 1 in 100 and 4 in 100 viable pregnancies might be erroneously deemed non-viable. If these incorrect diagnoses lead to immediate interventions, some pregnancies will be inadvertently terminated. Such outcomes are unacceptable. There should be near zero tolerance for misdiagnosis. Increased awareness of this too common problem has led to efforts to improve our diagnostic accuracy and has required a stringent re-evaluation of historical diagnostic criteria using investigations that include much larger study populations that have been evaluated using the most sensitive, commonly-available diagnostic modalities.