Deciphering the difficult English abbreviations on the pregnancy test sheet 1. CS stands for fetal sac. For women with regular menstruation, the gestational sac can be seen in the uterine cavity on B-ultrasound 35 days after menopause. At 1.5 months of pregnancy, the diameter of the gestational sac is approximately 2 cm, and at 2.5 months of pregnancy, the diameter is approximately 5 cm. The position of the fetal sac at the fundus, front wall, back wall, upper part, and middle part of the uterus is normal; it is normal if the shape is round, oval, and clear; if you have abdominal pain or vaginal bleeding, it may be a miscarriage. 2.CRL stands for crown and rump