Interesting case. Not a frequent one too. In short,
pregnancy test is positive but since levels of BHCG are below the discriminatory levels nothing is seen at the Transvaginal (endocavitary) scan. You need about 2000 mIU/dL BHCG for a pregnancy to be seen in a high resolution scan. You have a condition called PUL (Pregnancy of Unknown Location) and serial measurements of BHCG can lead to the right diagnosis, options are: in this order of frequency
1.- Normal intrauterine pregnancy (IUP), 75%
2.-
Miscarriage (
spontaneous abortion, SA), 25%
3.- Ectopic pregnancy (EP), 1%
Since BHCG duplicate its levels every 72 hs and considering 7 as the initial level by sept 29th your BHCG levels should have been about 400-500, this means that:
1.- no normal duplication pattern is seen, pregnancy might not be right and there might a miscarriage or an ectopic pregnacy
2.- discriminatory levels are not met and that explains why a gestacional sac GS is not seen
3.- there is still the posiibility of a normal pregnancy
What would I do? Wait, repeat BHCG in about a week and perform another scan with the new results
Levels fall, no GS on scan: miscarriage
Levels rise, duplicate and GS seen: IUP
Levels rise but do not duplicate or reach about 2000, no GS is seen: considering EP and new levels are measured and scan performed about a week later
if more than 2000 units are measured and no sac is seen, I would consider / perform a laparoscopy