Vasa previa is a rare complication of pregnancy in which the blood vessels which supply oxygen and nutrients to the developing fetus cross between the fetus and the opening to the birth canal. During pregnancy, this complication may not cause any problems. However, once the amniotic sac breaks and the mother goes into labor, these blood vessels can be pinched or torn, causing the baby to experience oxygen deprivation or exsanguination. This condition can be fatal if it is not identified in time; mortality rates for babies with vasa previa can approach 90%.
There are several risk factors which can lead to vasa previa. The first is placental abnormalities, such as a bilobed placenta or a placenta which is unusually low lying. Women who have had multiple pregnancies are at increased risk of having babies with this condition, and it can also be a complication of in vitro fertilization. Vasa previa rarely occurs in cases where these risk factors are not present, which some doctors argue is strong evidence for screening all women with these risk factors.
It is possible to screen for vasa previa before birth with the use of transvaginal Doppler ultrasound, which can be used to map out the blood vessels and to identify unusual arrangements of blood vessels. The fragile and unsupported blood vessels characteristic of vasa previa may also rupture during gestation, causing painless vaginal bleeding which can be a warning sign of a complication.
The treatment for this complication of pregnancy is a Cesarean section to get the baby out before the amniotic sac ruptures. This should be scheduled close enough to the due date to limit the risks associated with premature birth, but not so close that a woman might spontaneously go into labor before her scheduled surgery. If this condition is not identified until a woman goes into labor an emergency C-section is needed to get the baby out before she or he goes into distress.
This complication of pregnancy is not anyone's fault. Women cannot avoid the risk factors for vasa previa; all they can do is be aware of the risk. Receiving ample prenatal care and preventative screenings can help women identify complications of pregnancy early so that plans can be made to address them. Women should make sure that their obstetricians are familiar with their complete medical history so that any risk factors which could complicate the pregnancy will be known beforehand.