This is a normal fetal ultrasound performed at 19 weeks gestation. This ultrasound shows two interesting features. In the foreground, to the left and middle of the screen, you can see the placenta, following the curve of the uterus. In the background on the right, where the cross hair is pointing, you can see the face with all the facial features visible.
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The ultrasound has become a standard procedure used during pregnancy. It can demonstrate fetal growth and can detect increasing numbers of conditions including meningomyelocele, congenital heart disease, kidney abnormalities, hydrocephalus, anencephaly, club feet, and other deformities. Ultrasound does not produce ionizing radiation and is considered a very safe procedure for both the mother and the fetus.

Definition

A condition that may occur during pregnancy when the placenta implants in the lower part of the uterus and obstructs the cervical opening to the vagina (birth canal).

Possible causes of placenta previa include a scarred endometrium (lining of the uterus), a large placenta, or abnormal formation of the placenta. The incidence of placenta previa is approximately 1 out of 200 births. The incidence increases with each pregnancy, and it is estimated that the incidence in women who have had 6 or more previous deliveries may be as high as one in 20 births. The incidence is doubled in multiple pregnancy (such as twins and triplets). Risk factors include multiparity (previous deliveries), multiple pregnancy, and a previous C-section if the scar is low and close to the vaginal cervix region.

• spotting during the 1st and 2nd trimesters
• sudden, painless, and profuse vaginal bleeding in pregnancy during the third trimester (usually after 28 weeks)
• uterine cramping may occur with onset of bleeding
• bleeding may not occur until after labor starts in some cases

Note: Labor sometimes starts within several days after initial heavy vaginal bleeding.

The uterus is usually soft and relaxed. The infant position is oblique ( // ) or transverse ( == ) in about 15% of cases. Fetal distress is not usually present unless vaginal blood loss has been heavy enough to induce maternal shock, placenta abruptio occurs, or unless a cord accident occurs.
An abdominal ultrasound indicates low positioning of the placenta.

The course of treatment depends on the amount of abnormal uterine bleeding, the point in pregnancy and consequent potential viability of the fetus, the amount of placenta over the cervix, the position of the fetus , the parity ( number of previous births) for the mother, and the presence or absence of labor.
Early in pregnancy, transfusions may be given to replace maternal blood loss and medications given to prevent premature labor, prolonging pregnancy to at least 36 weeks. Beyond 36 weeks, the benefits of additional infant maturity have to be weighed against the potential for major hemorrhage.
Cesarean section is the preferred method for delivery. It has proven to be the most important factor in reducing maternal and infant death rates.

When managed appropriately by hospitalizing those at risk who are exhibiting signs and symptoms and by performing C-section delivery, the maternal prognosis (probable outcome) is excellent.
The infant death rate is 15 to 20%, approximately 10 times that of normal pregnancies. This rate may be reduced with ideal obstetrical and newborn care available at major medical centers.

Maternal complications include major hemorrhage, shock, and death. The potential for infection or embolism (blood clot ) also increases.
Prematurity (infant is less than 36 weeks gestation) is responsible for about 60% of infant deaths secondary to placenta previa. Fetal blood loss or hemorrhage may occur because of the placenta tearing away during labor. It may also occur with entry into the uterus during a C- section delivery.

Call your health care provider if vaginal bleeding in pregnancy occurs at any point in the pregnancy. Placenta previa can endanger both the mother and the baby.

This condition is probably not preventable.