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| Carolyn M. Salafia, MD's FAQ
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What is a genetic and acquired thrombophilia?
Thrombo means 'clot' and philia means 'love of'; thrompholia is a tendency to clot. Acquired thrombophilias are tendencies to clot that develop in adulthood or older age, and are not inherited. Phospholipid antibodies are an example of acquired thrombophilias. Genetic thrombophilias involve any of a number of genes that disrupt the ability to break down blood clots. (All normal, healthy people continually make blood clots and then break them down.) The balance between bleeding and clotting is much more delicate in pregnancy than at most other times in life due to dramatic changes in blood vessel flow and blood vessel structure. The placental cells grow into the uterine blood vessels and destroy their linings and muscle layers and create basically a free flow, pressure passive system. The balance between bleeding and clotting is generally more tenuous in this system and any inefficiency can then push that delicate balance in favor of clotting.
As a reproductive pathologist I look for clots that could cause a pregnancy to fail and take special note of where they occurred in order to see whether an appropriate course of treatment can be determined or if further testing is required. It is very important to remember that clotting is part of how your body will prepare tissues to be miscarried, and it is critical to distinguish any clotting that could have begun AFTER the baby died (and be part of the miscarrying process) from clotting that began while the baby was alive, and therefore could have caused death. Abnormal clots can be in three places:
- In the mother's blood vessels. Clotting here is common in specimens miscarried naturally. Your body will need to protect you from bleeding too much if you pass tissue on your own, so clotting is your "protection". We need therefore to know how you lost your pregnancy in order to appropriately assign meaning to any clotting we see here. It is VERY easy to over-interpret tissues, and that can mean that many women end up treated with powerful medicines who may not really need them. Heparin seems, from what my clinical colleagues tell me, to be the most effective course of treatment in these cases of clotting.
- On the surface of the placenta and/or in the maternal blood space where the placenta floats. Some little clotting can be "within the normal range" here too, and again we have to be careful to make certain we have accurate clinical information, and whenever we can, a large sample of the placenta to look at. The larger the sample we have to look at, the more sure we can be that we aren't missing something, or just seeing a very unusual area of the placenta that was sampled by chance. There's some controversy as to the best way to treat these clots. I have seen this type of clotting in patients with inheritable thrombophilias but I've also seen this type of clotting in people with immune problems. If this is the location of your clots, you will need additional workup to distinguish between clotting and immune issues.
- Within the baby's blood vessels themselves. When I see clots here then I'll want your doctor to go back to the father's family history and start asking about the possibility that this is a child who has inherited thrombophilia from both parents and because of this double-whammy of dual inheritance blood vessels may spontaneously combust or may have an exaggerated damage response to any placental injury process. From a recurrence risk point of view, you'll want to optimize the pregnancy environment so there is as little trauma to the fetal circulation as possible. Your obstetrician will most likely prescribe aspirin and heparin and may feel comfortable monitoring you with uterine artery waveforms. This is a uterine artery Doppler test that look at resistance to flow in your uterine arteries. Normally in pregnancy, uterine artery resistance decreases in the first trimesters, and remains low. If resistance does not decrease, or begins to go up, some of my clinical colleagues have considered that a reason to begin blood vessel treatment. Uterine artery Doppler is a relatively new technique, and there's a lot we don't understand about how normal uterine arteries can behave and still deliver a healthy pregnancy, but some of my clinical friends tell me that they feel this gives them the best and most technically advanced way to monitor their patients, and to get the best data medical technology can presently offer that uterine artery flow is low-resistance and as gentle as can be.
By examining your placenta a reproductive pathologist can determine exactly where the clots were so that your obstetrician can determine the proper course of treatment for your next pregnancy.
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