Placenta previa

placenta previa

1. Placenta previa Pregnancy Q&A

2. What is placenta previa ? After 28 weeks of gestation, the placenta is attached to the lower uterus, and even the lower edge of the placenta reaches or covers the cervical ostia, which is lower than the exposed part of the fetus , and is called the placenta previa . Placenta previa can cause massive bleeding in late pregnancy and jeopardize the life of mother and child, which is a serious complication of late pregnancy.

3. What are the common causes of placenta previa ? Endometrial lesions or injuries: Repeated curettage, childbirth, puerperal infections, uterine scars, etc. can damage the endometrium, cause inflammation and atrophic lesions, and cause endometrial blood vessel defects. When the fertilized egg is implanted, due to insufficient blood supply, the placenta area is expanded to reach the lower uterus in order to ingest enough nutrients. Abnormal placenta : The area of the placenta is too large during twin pregnancy. The placenta is membranous, and the placenta is in a normal position. The fertilized egg trophoblast develops slowly : After the fertilized egg reaches the uterine cavity, the trophoblast has not yet developed to the stage of implantation, and continues to go downstream to the lower uterus, and implanted there to develop a placenta previa .

4. What are the common types of placenta previa ? Complete placenta previa : Also known as central placenta previa , placental tissue completely covers the cervical ostium. Partial placenta previa : Placenta tissue partially covers the cervical ostium. Marginal placenta previa : The placenta is attached to the lower part of the uterus, the edge reaches the cervical ostium, and does not cover the cervical ostium.

5. What are the common symptoms of placenta previa ? Typical symptoms: Induced, painless, and repeated vaginal bleeding during late pregnancy or labor . Vaginal bleeding occurs sooner or later, the number of repeated occurrences, and the amount of bleeding depends on the type of placenta previa . Complete placenta previa : The first bleeding is early, mostly around 28 weeks of gestation, and is called "alert bleeding" Marginal placenta previa : bleeding occurs mostly in late pregnancy or after labor , with less bleeding. Partial placenta previa : the time of first bleeding, the amount of bleeding and the number of repeated bleeding are between complete and marginal.

6. What are the common signs of placenta previa ? The general situation is related to the amount of bleeding. Massive bleeding shows paleness, pulse count, and blood pressure drop. Abdominal examination : the uterus is soft, without tenderness, and the size is consistent with the number of weeks of pregnancy. The small part of the uterus is occupied by the placenta, which affects the fetal exposure to the basin. Repeated bleeding or excessive bleeding can cause hypoxia in the fetus , and severe fetal death. When the anterior placenta is attached to the anterior wall of the uterus, the placental murmur can be heard above the pubic symphysis. During labor inspection, the contractions were seen to be of a regular pattern, and the uterus was completely relaxed during the intermittent period.

7. What are the effects of placenta previa on mother and child? Postpartum hemorrhage , implanted placenta, anemia , infection , premature delivery and high perinatal mortality.

8. How to diagnose placenta previa ? Medical history : 1. There have been multiple previous curettage, childbirth history, uterine surgery history, smoking or anesthetic drug abuse history, or elderly pregnant women, twins and other medical history. 2. With the above clinical symptoms and signs, you can make a preliminary judgment on the type of placenta previa . Auxiliary examination: B-type ultrasound examination can clearly show the position of the uterine wall, placenta, fetal exposed part and cervix, and determine the type of placenta previa according to the relationship between the lower edge of the placenta and the cervical ostium. If the placenta previa is found by B-mode ultrasound examination in the second trimester, the placenta previa should not be diagnosed, but the placenta previa should be called. Postpartum examination (placenta and fetal membranes): For patients with prenatal hemorrhage , postpartum should be carefully checked for vascular rupture at the edge of the placenta's face, which may indicate the presence of para-placenta. If the placenta on the front part of the placenta has an old black purple blood clot attached, or the distance between the rupture of the membrane and the edge of the placenta is less than 7cm, it is the placenta previa .

9. What is the mechanism of ascending placenta position with increasing gestational age? Due to poor formation of decidual blood vessels in the lower uterine segment or the cervical ostium, the leafy chorion attached to this area gradually degenerates; and the chorion attached to the uterine body grows rapidly due to the abundant blood supply, so the placenta previa appears clinically disappear. The mid-pregnancy placenta occupies half of the uterine wall, so the placenta is more likely to be close to or cover the cervical cervix, and the placenta occupies the uterine wall in the third trimester. The area of the uterine wall decreases to 1/3-1/4, and the extension of the lower uterus increases the cervical ostium The distance from the edge of the placenta.

10. What is the treatment principle of placenta previa ? Inhibit uterine contractions, stop bleeding, correct anemia and prevent infection.

11. What are the indications for the treatment of placenta previa ? It is suitable for pregnant women with little bleeding or no prenatal bleeding, stable vital signs, gestational age <36 weeks, fetal survival, fetal weight <2300g, little vaginal bleeding, and generally good condition.

12. What are the indications for termination of pregnancy with placenta previa ? Repeated heavy bleeding in pregnant women leads to anemia and even shock, regardless of whether the fetus is mature or not, the pregnancy is terminated for the safety of the mother. Gestational age reaches 36 weeks or more A fetal maturity check indicates that the fetal lung is mature. Those whose gestational age is less than 36 weeks, and there are signs of fetal distress, or abnormal fetal heart rate found by electronic fetal monitoring. The amount of bleeding is more dangerous to the fetus ; the fetus has died or has a deformity that is difficult to survive, such as a brainless child.

13. How to expect treatment for placenta previa ? Absolute bed rest: left side lying position, regular oxygen inhalation (oxygen inhalation 3 times a day, 20-30min each time). Sex life, vaginal examination, anal examination, enema and any irritation are prohibited, to keep pregnant women in good mood, and appropriate use of diazepam and other sedatives. Prepare blood and prepare for emergency surgery. Inhibition of contractions: Magnesium sulfate , Litoxan , salbutamol, and other drugs can be used to inhibit contractions, and closely monitor fetal growth in the fetus . For patients greater than 32 weeks of gestation, dexamethasone 6mg intramuscular injection should be used twice daily for 2 days to promote The fetal lung is mature. When needed, 10 mg can be injected into the amniotic cavity at one time. Correcting anemia : iron supplements depending on the level of anemia , or a small number of blood transfusions. Use antibiotics that are less harmful to the fetus to prevent infections, as appropriate. Improve nutrition , promote reasonable weight gain during pregnancy, and dynamically monitor pregnant women's heart rate, blood routine, C-reactive protein, and fetal conditions. For those without prenatal hemorrhage , they can only observe closely without drugs.

14. What are the indications for cesarean section with placenta previa ? Complete placenta previa , continuous vaginal bleeding; Partial and marginal placenta previa more bleeding, the first exposed part floats high, and can not end the delivery in a short time; Abnormal fetal heart rate.

15. What are the indications for vaginal delivery with placenta previa ? It is suitable for marginal placenta previa , with little bleeding, head exposed first, no scalp disproportion and abnormal fetal position, and the cervical opening has been opened. It is estimated that the child will be delivered in a short time. It can artificially rupture the membrane under the condition of preparing blood and infusion, and strengthen the contraction to promote the lowering of the fetal head and press the placenta to stop the bleeding. Once the progress of labor is stagnant or vaginal bleeding is increased, cesarean section should be completed immediately.

16. What should be done before cesarean section for patients with placenta previa ? Organizing obstetrics, interventional medicine, laboratory, blood bank, intensive care medicine, anesthesiology , neonatal department (NICU), etc. enables personnel to discuss cases. Fully estimate the difficulty of the operation, prepare sufficient blood products, establish a good venous access, and select experienced obstetricians and anesthesiologists for the operation. At the same time, do a good job of communicating with patients and their families, fully inform the surgery-related risks and possible measures. Conditional medical centers are feasible for pelvic vascular balloon occlusion, which is to place a balloon tube in the internal iliac artery before surgery. After the fetus is delivered, before the placenta is delivered, expanding the balloon can reduce blood flow to the uterus, thereby winning more treatment time and options A more reasonable treatment plan to avoid massive blood loss in a short period of time.

17. How to deal with cesarean section in patients with placenta previa ? Choose a midline longitudinal incision in the lower abdomen to facilitate the exposure and rescue of the surgical field. After entering the abdomen, carefully check the shape of the uterus and the lower part of the uterus. If the lower part of the uterus is thin and the blood vessels are enraged, there is a sponge-like feeling when touching the lower part of the uterus. The fetal first exposure is far away from the surface of the uterus. Push down the bladder to reverse the peritoneum to prevent injury to the bladder during emergency hysterectomy. The uterine incision uses a horizontal incision. When the placenta is located in the anterior wall of the uterus, the horizontal incision may cut through the placenta and cause fetal blood loss. Therefore, in these cases, a vertical incision is also desirable. However, under normal circumstances, even if the placenta is remembered, it will not risk the mother and child. Safety. After the fetus is delivered quickly, apply uterine contractions to check the placenta attachment site. Once it is found to be a fully implantable placenta previa , it should be considered to leave the placenta intact and inject chemotherapy drugs at multiple places on the placenta (requires fertility preservation requirements) Person), quickly close the uterine incision, close the abdomen, and continue conservative treatment; Those without reproductive function requirements, timely hysterectomy to reduce bleeding, infection and other crisis maternal life. Blind stripping of the placenta with bare hands may cause severe bleeding and should be avoided as much as possible. Conservative surgery can also be used for part of the implanted placenta previa , such as wedge-shaped resection of the implanted part, local scraping of the placenta implantation and 8-line suture with absorbable thread, Affronti uterine square hemostasis suture method, uterine gauze packing, Intrauterine Bakri balloon compression, B-lynch suture, etc. Bilateral uterine artery ligation is possible if necessary. Various hemostatic methods can be used flexibly to reduce patients' bleeding and retain uterine and fertility functions. Once the bleeding is difficult to control, the decision to make a hysterectomy should be made immediately to save the patient's life.

18. What is a dangerous placenta previa ? The term " dangerous placenta previa " was first proposed by Chattopadbyay , and its meaning refers to the last cesarean section, the pregnancy was the placenta previa , and the placenta implantation accounted for 30-50%. placenta. In recent years, with the increase of cesarean section rate, the incidence of dangerous placenta previa has also increased. Because of its few cases, the current clinical understanding is relatively shallow. Once it occurs, it will seriously threaten the life of the pregnant woman.

19. How to deal with the dangerous placenta previa ? Pay attention to early diagnosis: pregnant women who become pregnant again after cesarean section should undergo color Doppler ultrasound examination, paying special attention to the place of attachment of placenta. Reasonable disposal of pregnancy: according to different gestational weeks. No blind flow during early pregnancy; no induction of labor in the middle period; late period emphasizes clear diagnosis before birth, notation blind and unprepared, strict high-risk management. Must go to a hospital with first-aid capabilities.

20. How to prevent placenta previa ? Do a good job in family planning, prevent prolific births, curettage or intrauterine infection many times, and reduce endometrial damage. Strengthen prenatal education, seek medical treatment in a timely manner, early diagnosis, and correct handling.

21. What are the three types of placenta implants? According to the degree of placental villi invading the myometrium, the placenta implants are divided into 3 categories: Adhesive placenta: the villi attach directly to the myometrium. The adhesion between the placenta and the uterine wall can not be peeled off and discharged, which often causes the placenta leaflets to remain in the uterine cavity and postpartum hemorrhage . Implanted placenta: The villi invade part of the myometrium, and the incidence is less than that of the adhesive placenta, which is mostly confirmed by observing the removed uterine specimen with a microscope. Penetrating placenta: The placenta villi penetrate the uterine muscle wall to reach the serosal surface. In severe cases, the bladder, urethra, and rectum are damaged, which often causes the uterus to rupture and cause great harm.

22. How to diagnose placenta previa combined with placenta implantation? Clinical manifestations: The diagnosis of placenta previa combined with placenta implantation is mainly based on clinical manifestations and findings during surgery. For the placenta previa without antepartum hemorrhage , we should consider the possibility of placenta implantation, and we should not relax the placenta previa , but also the possibility of placenta implantation. During the operation, there is no gap between the placenta and the uterine wall, or a large amount of bleeding continues at the placenta attachment. Ultrasound diagnosis : multiple irregular echoless areas in the placenta with abundant blood flow signals or continuous midsection of the bladder wall strongly suggest the possibility of placenta implantation. Other ultrasound signs with suggestive significance and diagnostic reference value include thinning of uterine muscle wall (thickness <1mm), and unclear boundary between placenta and uterus. MRI diagnosis : MRI has a lot of help in the diagnosis of placental implantation. It can more clearly show the depth of placenta implantation in the muscle layer, local anastomosis blood vessel distribution and parauterine invasion. It can provide accurate local anatomical levels and guide the surgical path.

23. What are the prerequisites for conservative treatment of placenta implantation? Indications for conservative treatment: Vital signs are stable, no active bleeding or uterine contractions are strengthened, local compression stops bleeding, less bleeding, normal liver and kidney function, fertility requirements, no signs of infection, understand the limitations and complications of conservative treatment Of patients. Necessary conditions for conservative treatment of placenta implantation: timely blood transfusion. Emergency hysterectomy, high-efficiency antibiotics to prevent infection, ultrasound measurement of intrauterine contents, B-HCG measurement to understand villi activity, etc.

24. What are the commonly used drugs for conservative treatment of placental implant drugs? Commonly used drugs for conservative treatment of placental implants include methotrexate (MTX), fluorouracil, mifepristone, and traditional Chinese medicine.

25. When to choose cesarean section for placenta previa combined with placenta implantation? Asymptomatic placenta previa combined with placenta implantation is recommended for surgery after 36 weeks of pregnancy. The placenta previa combined with placenta implantation accompanied by repeated bleeding symptoms promoted premature lung termination after pregnancy.

26. How to choose cesarean section operation for placenta previa combined with placenta implantation? It is recommended to elect cesarean section to terminate pregnancy. The posterior wall placenta or anterior wall placenta is implanted, and the lower uterine segment cesarean section is feasible; the anterior wall placenta implantation, the uterine body cesarean section is performed. After the fetus is delivered, depending on the amount of bleeding, the degree of implantation, whether the patient has fertility requirements and illness, the treatment method is determined, including hysterectomy and conservative treatment. Hysterectomy : Indications : large implanted area of ​​placenta, thin uterine wall, penetrating placenta, poor uterine contraction, massive bleeding in a short period of time (bleeding >2000ml in a few minutes) and failure of conservative treatment. It has been reported in the literature that the mortality rate of patients with immediate hysterectomy is 5.8-6.6%, and the mortality rate of patients trying to preserve the uterus is 12.5-28.3%.. No fertility requirements can be used as a reference indication for hysterectomy. Hysterectomy type: Hysterectomy is recommended. After the fetus was delivered, the incision of the placenta was directly sutured and the hysterectomy was performed .

27. 2. Conservative treatment: Conservative treatment should be performed for those with stable vital signs, little bleeding, and a small implantation range. This includes conservative surgery, medication, and embolization. Conservative surgery: local suturing to stop bleeding can be done by "8" suture, intermittent loop suture or B-lynch suture to compress hemostasis . In order to reduce the bleeding caused by forcible peeling of the placenta, the placenta can be partially or completely left in the uterine cavity during cesarean section, and it can be treated with methotrexate or other embolization treatment after surgery. Postpartum should be closely followed, antibiotics to prevent infection, strengthen uterine contractions, observe vaginal bleeding, signs of infection and so on. Drug treatment : Methotrexate, mifepristone , etc. are used to treat placenta implants. The route of administration and dosage vary according to the place, depth and area of ​​the placenta implantation. Embolization treatment: The effect of preventive ligation or pelvic vascular obstruction on placenta implantation is unclear and needs further study.

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