should I get an ultrasound?

Hello,
I went in for an ultrasound w/my last pregnancy due to spotting. They found a 7 1/2 week old dead sac at the tip of my cervix that they thought would pass. Due to rising HCG I had 2 more ultrasounds w/the same result and scheduled a D&C. The day of the D&C and new higher HCG results they did one more ultrasound and found a brand new baby in my uterus. These were 2 seperate pregnancies, I just happened to get pregnant again before I miscarried. Note: this was not a lost twin. After being monitored by a perinatologist at 23weeks they considered me safe from miscarrying one and taking the healthy baby. It really wasn't spoke again. I changed OB's at 32 weeks and never discussed this. Had a C-section. I have been trying w/no success to get preg for 3 months. Do you think the old sac is still at the top of the cervix preventing sperm to enter? Thanks so much in advanced for your opinion.

[USF-M.D.-JM]

First, I think you were pregnant with twins from the out set. I love to be proven wrong. the reson is that the bhcg from the initially identified pregnancy should not allow you to ovulate from what we know, but stranger things happen. I have had multiple twins with the second not showing up until the first is well established or lost. Is that because the second was late or we just weren't looking hard enough, I guess both are possibilites.

I don't thing that the first pregnancy is blocking  the cervix, especially with a c-section. But easy enough to solve by doing an SIS, saline infusion sonogram to evaluate the uterine cavity. Make sure you are ovulating also.

Hope this helps,
JM