Hello
thank you for your query.
Sometimes, an early
pregnancy is associated with equivocal BHCG blood results, so a repeat test is required to confirm viability.
A serum
progesterone would not give as much information as the doubling of BHCG would.
If the doctor suspects an ectopic pregnancy ( pregnancy outside the
uterus ) also, this would provide the needed information.
Also, for twins, a
transvaginal ultrasound would be more reliable rather than B HCG levels.
Take care, and please go for the appointments as advised.
take care.