Search results
Results from the WOW.Com Content Network
Placenta praevia or placenta previa 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]
Besides placenta previa and placental abruption, uterine rupture can occur, which is a very serious condition leading to internal or external bleeding. Bleeding from the fetus is rare, but may occur with two conditions called vasa previa and velamentous umbilical cord insertion where the fetal blood vessels lie near the placental insertion site unprotected by Wharton's jelly of the cord. [11]
Placenta previa is a condition that occurs when the placenta fully or partially covers the cervix. [13] Placenta previa can be further categorized into complete previa, partial previa, marginal previa, and low-lying placenta, depending on the degree to which the placenta covers the internal cervical os.
During the third trimester of pregnancy, thinning of the lower uterine segment or contractions caused by cervical dilation can increase the amount of stress placed on the placental attachment to the uterine wall. In patients with placenta praevia, these stresses can cause detachment of the placenta from the uterine wall causing haemorrhaging.
Risk factors for vasa praevia include velamentous insertion of the umbilical cord, placenta praevia in the second semester of the pregnancy, accessory placental lobes (succenturiate or bilobate placenta []), multiple gestation, and assisted reproduction, especially in vitro fertilisation; [2] an estimated 26% of instances are in pregnancies achieved with medical assistance. [3]
It is used to differentiate whether the blood coming out of vagina is of the mother or fetus during delivery i.e, placenta previa versus vasa previa. It is based on the principle that fetal HbF is resistant to acids and alkali whereas the mother's blood which has HbA is sensitive to acid and alkaline.
Along with placenta previa and uterine rupture it is one of the most common causes of vaginal bleeding in the later part of pregnancy. [6] Placental abruption is the reason for about 15% of infant deaths around the time of birth. [2] The condition was described at least as early as 1664. [7]
If placenta previa is present at the time of delivery, vaginal delivery is contraindicated because the placenta is blocking the fetus's passageway to the vaginal canal. Herpes simplex virus with active genital lesions or prodromal symptoms is a contraindication for vaginal delivery so as to avoid mother-fetal transfer of HSV lesions.