Related articles: Placenta Previa
Definition
Placenta previa is a disorder that occurs during pregnancy, due to the implantation of the placental membrane at or near the internal orifice of the uterus, a sort of "funnel" that leads to the cervix.
Generally, the placenta starts to develop in the upper part of the uterine cavity, but in about 1 case out of 200 it can settle in the lower part of the organ.
At the time of labor, the presence of this alteration can favor detachment of the placental membrane, since the internal uterine orifice dilates to allow the passage of the fetus. This can result in risky complications for the child and the expectant mother.
The placenta previa can cover the uterine orifice completely or partially; compared to the latter, moreover, the membrane can be central or marginal. At other times, the placenta may have a low implant, ie it is inserted into the lower part of the uterus, but without ever reaching the orifice.
Risk factors for placenta previa include uterine abnormalities that inhibit the normal embryo implantation (eg previous surgery or caesarean section, fibroids, etc.), multiparity, smoking habits and maternal age over 35 years.
Most common symptoms and signs *
- Miscarriage
- Small child for gestational age
- Premature release of the placenta
- Pelvic pain
- Postpartum hemorrhage
- Vaginal hemorrhage in the early stages of pregnancy
- Fetal death
- Growth delay
- Vaginal bleeding
Further indications
Placenta previa typically occurs with a vaginal discharge of bright red blood after the 20th week of gestation. Bleeding can be massive, sometimes hesitating in a hemorrhagic shock. Placenta previa can also involve pelvic pain and uterine contractions.
Complications of the disorder are different and include fetal growth retardation, vasa praevia (ie the arteries and / or veins of the umbilical cord crossing the surface of the uterus above the internal orifice of the same organ) and premature rupture of the membranes. Moreover, the breech or distocic presentation of the baby during labor and the veiling insertion of the umbilical cord are possible (ie the latter joins the peripheral margin of the placenta, rather than at the center of the same).
Placenta previa is diagnosed by transvaginal ultrasound. This accurate and safe investigation also makes it possible to distinguish the problem from the premature detachment of the placenta (abruptio placentae). The manual pelvic examination can promote a sudden and massive blood loss. The presence of placenta previa should be considered in all women with abnormal vaginal bleeding after the 20th week of gestation. Fetal heart rate monitoring is indicated for all women with suspected placenta previa symptoms.
Treatment consists of hospitalization, bed rest and abstinence from sexual intercourse, if a first poor vaginal bleeding (sentinel episode) occurs before the 36 weeks of gestation. If the bleeding is severe or refractory to the therapeutic measures undertaken or the conditions of the fetus are unstable, instead, immediate delivery is indicated, almost always performed by caesarean section. The birth of the child can also be programmed once lung maturity is reached (generally at the 36th week).
