Occasionally, ultrasound in early pregnancy may be inconclusive if the gestation is too early, particularly if you are less than 7 weeks or if you are unsure of your dates. This is because the pregnancy may be too small to be seen before 7 weeks. In order to be absolutely accurate in the diagnosis of early pregnancy before 7-8 weeks, it is recommended by all best practice guidelines, to repeat the scan after an interval of at least a week, if there is uncertainty or doubt.