Hi and thanks for the query,
I suggest its really too early to worry. At 4 weeks, the ultrasound
might not able to give clear and exact findings on the nature and aspects of the fetus. Beta HCG
level measurements are very sensitive measurements. A single measure, which off course might be subject to fluctuations might be insufficient to actually be conclusive with respect to the vitality of the fetus. Repeat measures two to three times later might be sufficient to conclude on the vitality as either normal, dead fetus or a probable extra uterine pregnancy
. Clinical and laboratory finding correlations and critically important in such cases to make any conclusions. The opinion of your gynecologist/obstetrician might be of great importance in this case.
Thanks and best regards,