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Von Willebrand disease (vWD) is a genetic condition affecting a very large protein called von Willebrand factor (vWF). The vWF protein is important in making special blood cells called platelets stick together during blood clotting, and also carries another protein, called factor VIII (FVIII), which also is needed in the clotting process. As much as 1.3 percent of the population suffers from vWD, which means that it is the most common inherited bleeding disorder. Unlike the most common types of hemophilia (hemophilia A and hemophilia B), which affect mostly males, vWD tends to affect more females. Genetic mutations underlying vWD are present equally in females and males, but females with vWD experience symptoms more frequently than males with vWD. Most cases of vWD (70–80 percent) are type 1. About 20 percent of cases are type 2, while the remaining 5–10 percent of cases are type 3. Unlike many other genetic disorders, vWD occurs fairly evenly across nationalities and ethnic groups.
There are three main types of vWD. In vWD type 1, the person produces normal vWF, but not enough of it. In vWD type 2, the person makes defective vWF. There are different subtypes of vWD type 2, but in all subtypes, the vWF cannot do its job, even if a lot of it is made. In wVD types 1 and 2, the problem occurs in just one of two copies that each person carries of the gene that encodes vWF (one copy from your mother and the other from your father). The other gene copy is normal. In vWD type 3, on the other hand, neither vWF gene copy is normal. Consequently, the person does not make any functioning vWF.
If you have vWD, then you are susceptible to excessive bleeding, or an exacerbation of bleeding that occurs due to other causes. In women, vWD often shows up as menorrhagia, excessive menstrual bleeding. People with vWD also frequently suffer bruising and nosebleeds. On the other hand, pregnancy tends to improve the clotting of women with vWD types 1 and type 2, so they bruise and bleed less. Scientists think this is because pregnancy stimulates the vWD gene so that it is more active, including the normal copy of the gene, so the woman has higher levels of normal vWF. This helps prepare the woman for delivering her baby, a time when there is normally a lot of blood loss.
In severe cases of vWD, the increase in vWD levels is not adequate for the stress of delivery, and often does not even protect against bleeding earlier in pregnancy –for instance, during diagnostic procedures in which a needle to be inserted into the womb to withdraw amniotic fluid. In such women, bleeding also can occur after mild or moderate trauma. Additionally, because of the increased tendency to bleed, an anesthesiologist may want to avoid epidural anesthesia (used to preventing labor pain without putting the woman to sleep), since it can result in a spinal hematoma, a swelling of clotted blood in the spine.
As noted earlier, vWD is an inherited condition. This means that you inherited vWD from at least one of your parents, but also means that your child is at high risk of having vWD, if you have it. If you have type 1 or type 2 vWD and your male partner does not have any type of vWD, your baby will have at least one normal gene copy for vWF , so she cannot develop type 3 vWD, but there is a 50 percent chance that she will share your condition. If you have type 3 vWD, there is a 100 percent chance that your baby will suffer some type of vWD, but as noted above type 3 vWD is the least common type. If both parents have vWD, the risk for the fetus is increased compared with one parent having it, but genetic counseling prior to birth can help you assess the risk and to prepare.
If your baby does have vWD, she or he will be at risk for developing hematomas in the scalp, and will be at risk for intracranial hemorrhage (bleeding in the brain or in the layers surrounding the brain) during vaginal delivery. The risk is especially high, if the obstetrician uses forceps or other instruments to pull out the child, or if the obstetrician needs to implant monitoring devices.
To eliminate these risks to the child, your obstetrician may decide to perform a cesarean section. For a C-section or even for a vaginal delivery, the mother must be prepared in advance by way of treatment to prevent excessive bleeding. It is therefore important to know in advance whether the fetus has vWD. To find you, you should receive prenatal genetic counseling, and also should consider prenatal genetic testing of the fetus.
For those women suffering from vWD bleeding, treatment consists of an agent called desmopressin, or DDAVP. Similar to a hormone in the body called vasopressin, DDAVP increases blood levels of both vWF and FVIII. It works best in people with vWD type 1, since they make normal vWF but merely not enough of it. It is given intravenously, or injected into a muscle or under the skin, or is administered as a mist that you inhale through your nose. If there is not enough time to wait for DDAVP to take effect, pregnant women can receive a combination of vWF and FVIII or they can be given what’s called cryoprecipitate, which contains vWF and FVIII plus three other clotting factors. Some concern surrounds the possibility that DDAVP may harm the fetus, because it constricts of blood vessels. But the risk seems to be low, especially in comparison with the risk of severe bleeding that can occur if your vWD is severe but not treated.
Although DDAVP can enter breast milk from the blood, the drug does not absorb well into the baby’s body when taken by mouth. This is the reason why you must take DDAVP through the nose, or by injection. As in the case of your baby, DDAVP will not get into your blood in significant quantities if you swallow it.
