Placenta previa is a condition in which the placenta implants low in the uterus and grows over the opening of the cervix.
As the cervix prepares itself for labor the opening will efface and dilate tugging the placentaThe placenta is a large disk shaped membrane responsible for providing nourishment to the fetus during pregnancy. It consists of three parts, the fetal part made up from the chorion membrane surrounding the fetus, the maternal part, formed from the decidua basalis layer of the uterine lining, and the intervillous space between the two plates. It is connected to the fetus by the umbilical cord and consists of tissue from both the mother and the embryo.
Its function is complex. It has been described as a simple organ that combines the functions of a kidney-dialysis machine, heart and lung machine and intravenous drip. It consists of enormous numbers of blood vessel branches that permit the exchange of nutrition and oxygen, from the mother's bloodstream to the fetus and the removal of wastes to the mother to be excreted. The placenta's remarkable quality is that it does so without the blood of the mother mixing with that of the baby.
It also is responsible for the production of vital hormones including, estrogen, progesterone, and human chorionic gonadotropin. After birth, the placenta is delivered, and is sometimes referred to as the afterbirth.
Visit our comprehensive glossary for more pregnancy terms and definitions. away from the uterine wall causing painless vaginal bleeding. Depending on the severity of the condition the supply of blood and oxygen to the fetus may be reduced resulting in prematurity and a perinatal mortality rate ten times greater than normal: about fifteen to twenty percent or 1 in 6 births.
Signs of placenta previa are limited but usually clear: women who have placenta previa will experience painless vaginal bleeding mostly likely starting around week thirty. The quantity of blood varies and may be simply slight spotting or up to two cups.
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This first episode is usually short lived although there may be subsequent vaginal bleeding. While the sight of blood soaked clothes causes many who experience it to faint, the actual loss of blood is limited and is unlikely to cause shock.
If you experience vaginal bleeding any time after week thirty you should call your doctor immediately. An appointment will be made with the time and location depending on the severity of the bleeding and the time of day.
The incidence of placenta previa averages about 0.5% (about 1 in 200) pregnancies. In first time pregnancies the risk of placenta previa is only 0.05% (1 in 2,000) and this rises to five percent (1 in 20) in women who have had four or more births.
While the cause of placenta previa is unknown other factors that increase the risk include a previous pregnancy that was induced or a miscarriage resulting in dilation and curettage, probably because of uterine scarring.
Age is also a factor and the incidence of placenta previa doubles in women over 35. The risk is also doubled in women who smoke or who are carrying twins (probably because of the increased size of the placenta). The incidence is tripled among women who have had a prior cesarean section with a low transverse scar.
It is not unusual for an ultrasound exam to reveal the presence of a placenta previa during the first or second trimesters. As the uterus increases in size the placentaThe placenta is a large disk shaped membrane responsible for providing nourishment to the fetus during pregnancy. It consists of three parts, the fetal part made up from the chorion membrane surrounding the fetus, the maternal part, formed from the decidua basalis layer of the uterine lining, and the intervillous space between the two plates. It is connected to the fetus by the umbilical cord and consists of tissue from both the mother and the embryo.
Its function is complex. It has been described as a simple organ that combines the functions of a kidney-dialysis machine, heart and lung machine and intravenous drip. It consists of enormous numbers of blood vessel branches that permit the exchange of nutrition and oxygen, from the mother's bloodstream to the fetus and the removal of wastes to the mother to be excreted. The placenta's remarkable quality is that it does so without the blood of the mother mixing with that of the baby.
It also is responsible for the production of vital hormones including, estrogen, progesterone, and human chorionic gonadotropin. After birth, the placenta is delivered, and is sometimes referred to as the afterbirth.
Visit our comprehensive glossary for more pregnancy terms and definitions. will move and no longer present a problem as you approach term.
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Your doctor will try and delay the birth of the baby for as long as possible. In about seventy five percent (3 in 4) cases the pregnancy will continue to week thirty six. Depending on the severity of the bleeding you will be hospitalized. If you are very anemic a blood transfusion will be necessary and blood tests will be performed to check for blood typeA system whereby different types of blood are classified according to the presence or absence of antigens on the red blood cells. Understanding a patient's blood group is important in pregnancy to prevent rhesus disease, and in blood transfusion therapy. There are over fourteen different types of blood grouping methods, the most common of which is the ABO method.
The ABO blood group is identified by the presence of two different types of antigens (labeled A and B) on the surface of the red blood cell. Using this method, four different types of blood classification is possible: A for Type A antigens, B for Type B antigens, AB if both are present, and O if neither are present.
The plasma of patients with Type-O blood contains the antibodies anti-A and anti-B agglutinins. Patients with Type-A blood do not have the anti-A agglutinins, and those with Type-B blood have an absense of anti-B agglutinins in the plasma. Blood grouping also notes the rhesus factor in the blood. See also Rhesus Factor, rh-negative and rh-sensitivity.
Visit our comprehensive glossary for more pregnancy terms and definitions., crossmatch and anemia.
If the bleeding stops you will be discharged after about three days. You may require a blood test every 72 hours for cross matching in case a blood transfusion is necessary.
If the bleeding continues you will be given a cesarean section. A general anestheticAn agent or process that removes the body's sensitivity to pain. Anesthetics are usually medically administered chemicals, although they include other forms such as hypnosis, or the body's own ability to cause numbness through shock.
Anesthetics can either be local, whereby only a portion of the body or an individual organ is desensitized or general, in which the entire body is desensitized, with the result the patient is often temporarily unconcious.
Visit our comprehensive glossary for more pregnancy terms and definitions. will be used because an epiduralA regional anesthetic introduced into the base of the spine used during labor and for cesarean sections. Also known as an epidural block.
Visit our comprehensive glossary for more pregnancy terms and definitions. takes too long to administer and the blood loss will require immediate attention.
If the placenta previa is diagnosed after week thirty seven a cesarean section will be performed, although you may be free to choose whether you want an epidural or general anesthetic.
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