Placenta previa is the malposition of the placenta in the area of the inner end of the cervix (inner cervix). It occurs in three different forms: placenta praevia totalis, placenta praevia partialis and placenta praevia marginalis.
Below you will find further information and selected specialists for placenta praevia.
The placenta is an important organ for supplying the growing baby with nutrients inside the uterus. The embryo is connected to the placenta via the umbilical cord. Another important function of the placenta is to produce the hormones oestrogen and progesterone to maintain a normal pregnancy. In the placenta, the maternal and fetal blood circulation connect via a multi-layered filter membrane, the placental barrier. Here it is precisely controlled which materials and substances pass into the baby's blood, for example oxygen, glucose or substances of the immune system.
When fully mature, the placenta weighs around 500 grams and is around 15 to 20 centimeters in diameter. Normally, the placenta is located in the upper part of the uterus. During pregnancy, the placenta moves upwards, leaving the birth path free for the unborn child. With placental abruption, the placenta does not move upwards - the placenta remains in the lower part of the uterus. This means that the natural birth canal can be completely or partially covered.
Placenta praevia is the incorrect position of the placenta in the area of the inner end of the cervix (inner cervix). It manifests itself in three different forms:
Placental abruption in placenta praevia: the natural birth canal is blocked by the placenta below. © bilderzwerg / Adobe Stock
What all forms have in common is the placenta lying too low in the inner cervix. As the uterus continues to grow, it is possible for the placenta to shift into the body of the uterus. If the birth canal remains blocked by placental tissue, the delivery must be performed by caesarean section.
A typical sign and often the only indication of placenta previa is sudden, painless and bright red bleeding from the vagina (vaginal bleeding) from the 20th week of pregnancy (second half of pregnancy). The cause of vaginal bleeding is not necessarily a malposition of the placenta. Placenta previa can only be detected by an ultrasound examination. Medical prenatal care also includes two ultrasound examinations to detect placental abnormalities. Regular check-ups during pregnancy are therefore very important.
In a placenta praevia, the blastocyst is not located on the posterior or anterior uterine wall (normal placental location), but near the cervix. The blastocyst develops from the fusion of egg and sperm cell to form a zygote. This divides several times and migrates as a morula (cluster of cells) through the fallopian tube into the uterus. There it implants as a blastocyst in the lining of the uterus (endometrium). The triggers for impaired implantation in the inner cervix are unknown.
Risk factors that favor placenta previa are
If there is no bleeding with placenta previa, the pregnancy will proceed without any problems. However, there are precautionary measures for cooperative patients. The following should be avoided
Pregnant women are encouraged to keep their appointments for check-ups and to visit the clinic immediately for clarification in the event of vaginal bleeding. Before the 20th week of pregnancy, a physical examination of the vagina and the external cervix with a medical instrument (speculum) is used to localize the bleeding, its cause and intensity.
From the 20th week of pregnancy , the first and most important method is ultrasound examination (sonography) of the abdomen and pelvis. It visualizes the position of the placenta and leads to a possible diagnosis of placenta previa. The doctor may use vaginal sonography or color Doppler sonography (color imaging of the blood flow) for further diagnosis. Due to the high risk of bleeding, the vagina and cervix should not be palpated.
If vaginal bleeding occurs from the 20th week of pregnancy, clinical, conservative treatment is recommended. This is carried out under inpatient conditions and initially aims to continue the pregnancy until at least the 34th week of pregnancy. To achieve this, the bleeding must be controllable. Management includes the administration of
If the risks of renewed bleeding are minimized in the course of the pregnancy, the aim should be to reach the 37th week of pregnancy. In the case of total placenta previa, a caesarean section is performed one to two weeks before the due date.
In the active treatment of placenta previa, the pregnant woman is delivered immediately by caesarean section regardless of the week of pregnancy.
The specialists for the care of pregnant women with placenta previa are specialists in gynecology and obstetrics. They are available in the mother-child and perinatal centers of the various clinics. In addition to providing antenatal care, they also specialize in obstetric emergencies. If you experience bleeding during pregnancy, contact the clinic immediately and directly. Do not be afraid to call the emergency services.
The treatment methods lead to a maternal mortality rate of less than one percent. The mortality rate for the child within the first 7 days of life is around 3%, which is around three times higher than with normal placenta previa. With very few exceptions, patients with placenta previa are delivered by caesarean section.
All forms of placenta previa have in common that the placenta is too low in the inner cervix. If the birth canal remains blocked by placental tissue, the delivery must be performed by caesarean section. A typical sign and often the only indication of a placenta previa is sudden, painless and bright red bleeding from the vagina (vaginal bleeding).
If there is no bleeding with placenta previa, the pregnancy proceeds without any problems. Regular check-ups are important for the course of the pregnancy, mother and child. In the event of vaginal bleeding, the clinic should be consulted immediately for clarification.
The aim of clinical, conservative treatment is to continue the pregnancy at least until the child's lungs have reached maturity. The lungs are usually mature after 34 weeks of pregnancy.
In the active treatment of placenta previa, delivery takes place immediately after stabilization of the pregnant woman's circulation, regardless of the week of pregnancy. With very few exceptions, patients with placenta previa are delivered by caesarean section.
