There is no way to tell if the gestational sac is round or long through the naked eye, and you need to rely on the three diameters measured during an ultrasound to determine this. The gestational sac refers to the sac-like structure formed by the combination of sperm and egg to form a fertilized egg and the continuous division of cells. 1. Round: If the upper and lower diameters, the left and right diameters, and the anterior and posterior diameters of the gestational sac are close to each other or the difference between the diameters is relatively small, the gestational sac is considered round. 2. Elongated: If the difference between the upper and lower diameters, the left and right diameters, and the anterior and posterior diameters are relatively large, especially if the left and right diameters, and the anterior and posterior diameters are significantly smaller than the upper and lower diameters, the gestational sac is considered to be elongated. Regardless of whether the gestational sac is round or elongated, as long as the embryo develops normally, it is mostly a normal phenomenon and does not need to be treated.