In cases where there is any question as to whether a given pregnancy is progressing based on an ultrasound scan, the doctor will usually order a follow-up ultrasound after a few days. However, the presence of other diagnostic information may help the clinician interpret the ultrasound results, even if there is only one ultrasound. For example, a woman took a pregnancy test or donated blood for hCG on the day of her missed period and it was negative, and after another two weeks of delay, an ultrasound scan showed 4-5 weeks of pregnancy. So, with a high probability, pregnancy did not occur on the 14th day of the menstrual cycle, but 7-10 days later. And vice versa, if on the day of the delay of the monthly test was already positive, and two weeks later we see a picture characteristic of 5 weeks of pregnancy, there is a high probability of a non-developing pregnancy.
The data of a blood test for hCG are very important in cases where a fetal egg is not visible in the uterine cavity. At an hCG level of more than 1000 mIU / ml, the fetal egg should be determined in the uterine cavity. If this is not the case, then this situation requires the exclusion of an ectopic pregnancy. On the contrary, with low hCG numbers, despite the fact that there is a pregnancy, we do not expect to see its signs with the help of ultrasound.
With a normally developing pregnancy, the level of hCG increases according to certain laws:
Normal HCG doubling time
HCG level Doubling time
1200 mIU/ml 48-72 hours
1200 - 6000 mIU / ml 72-96 hours
More than 6000 mIU/ml More than 96 hours
Since the level of hCG has a large variability, it is not used to determine the exact gestational age.
The information in this step-by-step guide applies to ultrasounds performed in early pregnancy, especially early in the first trimester, during the first seven weeks of pregnancy. As pregnancy progresses, ultrasound becomes an increasingly accurate and informative method for assessing the condition and intrauterine development of your baby.