I'm passing large blood clots and clumps of gray tissue, and my period is unusually heavy (in addition to being later than usual this month). Am I having a miscarriage?
It is definitely possible that you are passing miscarriage tissue, but there are also other possible explanations. It would be a good idea to call your doctor to find out whether you need treatment and what type. Your doctor should be able to give you an educated guess as to the cause of the bleeding.
As for the appearance of miscarriage tissue, note that tissue from an early miscarriage may not be obvious to the naked eye. Many early miscarriages simply look like heavy menstrual periods, sometimes with tiny blood clots in the discharge. If the miscarriage happened with development beyond four or five weeks gestational age, it is possible that there may be a small, transparent gestational sac with the rudimentary beginnings of a placenta on its edge. If your miscarriage happened beyond six weeks, you may pass an identifiable embryo or fetus in the early stages of development, which may be as small as a pea or larger than an orange depending on how far along you were when the baby stopped growing. (Remember that it is a good idea to see a doctor if you are miscarrying, especially if you are in the later part of the first trimester or beyond). Sometimes even in a later first-trimester miscarriage there may not be recognizable tissue, as sometimes the baby stops growing and begins to deteriorate before the onset of the miscarriage bleeding.
Again, your doctor is your best resource for advice on that matter, so give her a call. She may want you to come in for a checkup or may recommend that you go to the emergency room if you are bleeding heavily. Your doctor may also advise that you save a sample of the tissue so that she can make a determination of what the source might be. If you already have a history of miscarriages, your doctor may be able to have the tissue from the baby tested for chromosome abnormalities that might explain what happened.
Even if it is a miscarriage, it doesn't mean there is inherently anything wrong with you. Most miscarriages are one-time events that occur because of random chromosome abnormalities in the baby and not because of anything you did or did not do.
Concerns Regarding Early Fetal Development. American Pregnancy Association. Accessed: May 23, 2009. http://www.americanpregnancy.org/pregnancycomplications/earlyfetaldevelopment.htm