Normally, the gestational sac should be visible at 42 days of pregnancy, but for women with irregular menstrual cycles, the gestational sac may not be visible during the ultrasound examination, and for ectopic pregnancies, the gestational sac may not be visible in the uterine cavity at 42 days. Therefore, each woman’s situation is different. At 42 days, a routine ultrasound should be performed, and if the gestational sac is visible in the uterine cavity, it is normal for early intrauterine pregnancy. If the ultrasound indicates no visible gestational sac tissue in the uterine cavity, a blood HCG test is recommended to find out the value of blood HCG and to rule out the possibility of ectopic pregnancy. If the blood HCG value is high, you can wait for 5-7 days for another ultrasound examination.