Thanks for the query.
Sometimes early pregnancy
loss occurs without the notice of the patient.
But that usually occurs around 4 weeks of gestation and before positive pregnancy test.
So if you had positive pregnancy test before pain abdomen, there is possibility of miscarriage
If you rule out this possibility, go for testing of beta hCG
levels in the blood.
Usually these levels will take sometime to come to zero after miscarriage.
So with this the possibility of miscarriage can be ruled out.