Three values are needed to determine the shape of the gestational sac and two values alone cannot be used to assess the shape of the gestational sac.
Ultrasound can show the size of the gestational sac, and there are usually three values, i.e. length x width x height, which can be used to determine whether the gestational sac is round or aubergine in shape. However, it is not possible to determine the shape of the gestational sac with just two values.
The shape of the gestational sac does not have much clinical significance for the fetus. Whether the gestational sac is well developed depends on whether there is a yolk sac growing inside the gestational sac under ultrasound, whether there is a fetal heartbeat, and whether there are fetal buds, which can be used to determine the corresponding gestational week and whether the development of the fetus is normal.