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Placenta praevia

Placenta praevia is when the placenta attaches inside the uterus but in a position near or over the cervical opening.[1] Symptoms include vaginal bleeding in the second half of pregnancy.[1] The bleeding is bright red and tends not to be associated with pain.[1] Complications may include placenta accreta, dangerously low blood pressure, or bleeding after delivery.[2][4] Complications for the baby may include fetal growth restriction.[1]

Placenta praevia

Placenta previa

Obstetrics

Bright red vaginal bleeding without pain[1]

Mother: Bleeding after delivery[2]
Baby: Fetal growth restriction[1]

Second half of pregnancy[1]

Older age, smoking, prior cesarean section, labor induction, or termination of pregnancy[3][4]

Ultrasound[1]

Placental abruption[1]

Bed rest, cesarean section[1]

0.5% of pregnancies[5]

Risk factors include pregnancy at an older age and smoking as well as prior cesarean section, labor induction, or termination of pregnancy.[6][3][4] Diagnosis is by ultrasound.[1] It is classified as a complication of pregnancy.[1]


For those who are less than 36 weeks pregnant with only a small amount of bleeding recommendations may include bed rest and avoiding sexual intercourse.[1] For those after 36 weeks of pregnancy or with a significant amount of bleeding, cesarean section is generally recommended.[1] In those less than 36 weeks pregnant, corticosteroids may be given to speed development of the baby's lungs.[1] Cases that occur in early pregnancy may resolve on their own.[1]


Placenta praevia affects approximately 0.5% of pregnancies.[5] After four cesarean sections, however, it affects 10% of pregnancies.[4] Rates of disease have increased over the late 20th century and early 21st century.[3] The condition was first described in 1685 by Paul Portal.[7]

Signs and symptoms[edit]

Women with placenta previa often present with painless, bright red vaginal bleeding. This commonly occurs around 32 weeks of gestation, but can be as early as late mid-trimester.[8] More than half of women affected by placenta praevia (51.6%) have bleeding before delivery.[9] This bleeding often starts mildly and may increase as the area of placental separation increases. Placenta praevia should be suspected if there is bleeding after 24 weeks of gestation. Bleeding after delivery occurs in about 22% of those affected.[2]


Women may also present as a case of failure of engagement of fetal head.[10]

Previous placenta previa (recurrence rate 4–8%), caesarean delivery,[14] myomectomy[10] or endometrium damage caused by D&C.[13]

[13]

Women who are younger than 20 are at higher risk and women older than 35 are at increasing risk as they get older.

Women who have had previous pregnancies (), especially a large number of closely spaced pregnancies, are at higher risk due to uterine damage.[10]

multiparity

;[15] cocaine use during pregnancy[16][17]

Smoking during pregnancy

Women with a large placentae from or erythroblastosis are at higher risk.

twins

is a controversial risk factor, with some studies finding that people from Asia and Africa are at higher risk and others finding no difference.

Race

Placental pathology (, succenturiate lobes, bipartite i.e. bilobed placenta etc.)[13]

velamentous insertion

Baby is in an unusual : breech (buttocks first) or transverse (lying horizontally across the womb).

position

Overfilled bladder compressing lower uterine segment

Myometrial contraction simulating placental tissue in abnormally low location

Early pregnancy low position, which in third trimester may be entirely normal due to differential growth of the uterus.

Antepartum hemorrhage

Malpresentation

Abnormal

placentation

Postpartum hemorrhage

Placenta previa increases the risk of and postpartum hemorrhage because the lower segment to which the placenta was attached contracts less well post-delivery.

puerperal sepsis