conception during missed miscarriage?

[dh85]

Could someone with medical or similar experience please offer some advice? I had a miscarriage 1 week ago, I was 8 weeks by dates but the fetus had only grown to 5.6mm (5-6 weeks) and no heartbeat seen. The sonographer advised me I must have ovulated later than I thought but I'm very sure of when I ovulated and when I got the first positive test. At 8 weeks gestation I began to lightly bleed and 2 days after I completely passed the entire contents of my womb with no fuss, very little pain or loss of blood, and continued to bleed lightly for another few days. I examined the fetal sac and could clearly see the embryo so I am positive I have miscarried. 1 week on, and I have been having very strong pregnancy symptoms that I never had before, and today I done a urine pregnancy test which was positive. My question is, if my pregnancy failed to progress, could have I ovulated and gotten pregnant before I passed the failed products of conception? or could I have been carrying twins and lost one? I am not keen on returning to the ED for scanning as they refused to see or assess me last week on the day of my miscarriage to confirm the loss. Also I'd like to note that I had a spontaneous miscarriage at 5 weeks, 4 months ago, I went straight to A&E that night as I was in agony and my urine pregnancy test came up as negative so the ED insisted on taking blood before referring me for an emergency scan that night, which only came back borderline. Again I think this was very quick for hcg to drop so why is my urine still positive one week on? Please help?

Your HCG would be much higher at 8 weeks than 5, so will take longer to drop. I have had 4 MC at 8-10 weeks and it has taken 3 weeks to get a negative HPT each time (testing at weekly intervals, so still positive at 2 weeks)
I think it's extremely unlikely that you could ovulate whilst pregnant / whilst still getting a positive HPT , and if you ovulated after the MC you would not yet get a positive test.
It is possible to lose one twin, and the fact you didn't get much bleeding suggests your uterus has not completely emptied itself of lining. Odd that a second sac was not seen on your scan in that case though.
I think your options are either to arrange a follow up scan now, or to retest in another week. If you are still getting a positive 2 weeks on then your GP will monitor HCG in blood to make sure it is dropping. If it's rising you'd be referred back to EPU to check there is not a continuing twin pregnancy or for rare conditions like molar pregnancy.

Thanks, I should have mentioned that I passed a full sized/shaped clot of my womb with the gestational sac attached (tmi i'm sorry) and the bleeding continued to be very light afterward. I suppose I'm just letting my hope get the better of me, I'll just retest in another week and again the week after.