Things during pregnancy - Do you know what placenta previa is?

This is the 5277th article of Da Yi Xiao Hu

Pregnancy is a magical journey in life. Pregnant mothers not only bear the miracle of life, but also experience various changes in their bodies. During this process, many professional medical terms may make people feel unfamiliar or even a little uneasy, such as "placenta previa". What exactly is placenta previa? What factors can cause it? What are the effects on pregnant mothers and babies?

What is placenta previa?

Placenta previa is a serious complication during pregnancy, which means that the placenta partially or completely covers the internal os of the cervix. This situation can easily cause a lot of painless vaginal bleeding in late pregnancy or during delivery, which seriously threatens the life safety of pregnant women and fetuses. Placenta previa can be divided into: ① Complete placenta previa (or central placenta previa): the placental tissue completely covers the internal os of the cervix. ② Partial placenta previa: the placental tissue covers part of the internal os of the cervix. ③ Marginal placenta previa: the placenta is attached to the lower segment of the uterus, and the lower edge reaches the internal os of the cervix. ④ Low-lying placenta: the placenta is attached to the lower segment of the uterus, and the edge is <2cm away from the internal os of the cervix.

Figure from the Chinese Medical Association Obstetrics and Gynecology Branch. (2023). Obstetrics and Gynecology (9th edition). People's Medical Publishing House.

What situations may cause placenta previa?

If painless vaginal bleeding occurs and is accompanied by signs of anemia (pale skin and mucous membranes, headache, dizziness, tinnitus, syncope, fatigue, inattention and memory loss, etc.), pregnant women need to go to the hospital immediately.

What causes placenta previa?

High-risk factors that may cause placenta previa include: multiple pregnancy, multiple pregnancies, drug abuse, previous history of cesarean section, history of intrauterine operation, smoking, older pregnant women, drug abuse, assisted reproductive technology, etc.

What impact does placenta previa have on pregnant mothers and fetuses?

Effects on pregnant women

Bleeding, postpartum infection, anemia and premature birth are common during and after delivery.

Effects on the fetus

Repeated bleeding in pregnant women or excessive bleeding in one go can cause fetal intrauterine hypoxia, and in severe cases, intrauterine fetal death.

Do pregnant women with placenta previa need to stay in bed?

1. Bed rest

If a pregnant mother experiences bleeding or the placenta is in a low position, she should minimize activity and rest in bed to reduce the risk of bleeding and alleviate symptoms.

2. Hospitalization for observation

If the bleeding is severe or the pregnancy is early, the pregnant mother may need to be hospitalized for observation and treatment.

3. Regular monitoring

Even if you do not need to stay in bed, pregnant mothers still need to undergo regular ultrasound examinations to monitor the position of the placenta and the health of the fetus.

How far away from the exit should the placenta be safe?

If the distance is more than 2cm, it is relatively safe, and most people's placentas can grow slowly before delivery. However, when the edge of the placenta is within 2cm of the internal cervical os but does not cover the internal cervical os, it is considered a "low-lying placenta." For pregnant women with low-lying placentas, regular ultrasound examinations are usually required to monitor changes in the position of the placenta, and decide whether special measures or follow-up observations are needed based on the specific situation.

How to determine the timing and method of terminating pregnancy due to placenta previa?

1. For asymptomatic pregnant women, it is recommended to terminate the pregnancy at 36 to 38 weeks of gestation.

2. For pregnant women with a history of recurrent vaginal bleeding, placenta accreta or other high-risk factors, consider terminating the pregnancy at 34 to 37 weeks of gestation.

3. Pregnant women with asymptomatic low-lying placenta and no cephalopelvic disproportion, especially those whose placental edge is 11-20 mm from the internal cervical os measured by transvaginal ultrasound after 35 weeks of pregnancy, may consider natural delivery.

Does every case of placenta previa require a cesarean section?

1. If the edge of the placenta is greater than 20mm away from the internal cervical os, vaginal delivery can be performed.

2. If the edge of the placenta is 0-20 mm away from the internal cervical os, the probability of cesarean section is higher.

3. If the placenta covers the internal os of the cervix, a cesarean section is required.

Dear pregnant mothers, you may feel worried or anxious when you learn about placenta previa. It is recommended that pregnant mothers avoid behaviors that may cause endometrial damage, such as avoiding unnecessary intrauterine operations, maintaining good personal hygiene habits, preventing reproductive system infections, and quitting smoking and avoiding drug abuse to reduce the risk of placenta previa. On the other hand, if placenta previa occurs, it is necessary to go to the hospital for a professional ultrasound examination in time, and the doctor will evaluate the position of the placenta and the condition of the fetus, and carry out necessary treatment and care according to the doctor's advice.

And some studies suggest that as pregnancy progresses, most placentas naturally move upward and gradually leave the cervix. For example, one study showed that 66% to 98% of low-lying placentas diagnosed in the second trimester disappeared in the third trimester. This suggests that as pregnancy progresses, most placentas naturally move upward and gradually leave the cervix.

Pregnant mothers please note: Placenta previa is not scary, follow-up monitoring is the most important.

author

Song Xinyi, 2023 Academic Master of Nursing Student, School of Nursing, Shanghai Jiao Tong University

Luo Peiyang, Academic Master of Internal Medicine, Class of 2024, The Sixth People's Hospital Affiliated to Shanghai Jiao Tong University

Gu Kaiyan, Academic Master of Obstetrics and Gynecology, Renji Hospital, Shanghai Jiao Tong University, Class of 2024

Chen Yi, Academic Master of Surgery, Ruijin Hospital, Shanghai Jiao Tong University, Class of 2024

Cao Kejing, 2024, Doctoral student in Internal Medicine, Xinhua Hospital, Shanghai Jiao Tong University

Li Xinru, Master of Nursing, Class of 2024, School of Nursing, Shanghai Jiao Tong University

Instructor

Winfrey Lecturer, School of Nursing, Shanghai Jiao Tong University