If I remember correctly what my friend told me, hers wasn't caught by ultrasound, either. The test that caught it involved pumping fluid into her uterus and seeing if it came back out (it didn't). I'm not sure how far into pregnancy septums have been linked with miscarriage.
You haven't mentioned if your husband has been tested for fertility issues. Infertility is an equal opportunity problem: 40% of the time that couples have trouble conceiving, it's the man, 40% of the time it's the woman, and 20% of the time, it's both of them. And when miscarriages happen for no discernible reason, it's believed that genetic abnormalities are often involved (even if we don't have the right tests to detect them). If there are genetic abnormalities, they're as likely to come from the father as from the mother.
Was he also the father of the miscarried babies? Or did the miscarriages happen before you were with him? If there's been more than one male partner in these pregnancies, maybe it's your current one who has an infertility problem.
As far as medical astrology goes, his chart is as relevant to this issue as yours.
What you're referring to is called a HSG, when they pump dye through your tubes to check for blockages. I think septums are generally quite uncommon in couples seeking fertility help.
No, my husband has not been tested. Not yet anyway. The way doctors have been guiding me points to me that they believe my issue is of recurrent miscarriage if anything (as i got two quick conceptions consecutively). My impression of male infertility was that often, it concerned sperm motility and the quantity of them.
I've attached my husband's chart - i note the combust mars and venus and the huge fire presence.