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Androgen insensitivity syndrome
Hypospadias and epispadias
Benign prostatic hyperplasia
Male hypoactive sexual desire disorder
Premature ovarian failure
Polycystic ovary syndrome
Sex cord-gonadal stromal tumor
Surface epithelial-stromal tumor
Germ cell ovarian tumor
Pelvic inflammatory disease
Female sexual interest and arousal disorder
Genito-pelvic pain and penetration disorder
Fibrocystic breast changes
Paget disease of the breast
Preeclampsia & eclampsia
Intrauterine growth restriction
Congenital cytomegalovirus (NORD)
Neonatal herpes simplex
Congenital rubella syndrome
Gestational trophoblastic disease
Fetal hydantoin syndrome
Fetal alcohol syndrome
Disorders of sex chromosomes: Pathology review
Prostate disorders and cancer: Pathology review
Testicular tumors: Pathology review
Uterine disorders: Pathology review
Ovarian cysts and tumors: Pathology review
Cervical cancer: Pathology review
Vaginal and vulvar disorders: Pathology review
Benign breast conditions: Pathology review
Breast cancer: Pathology review
Complications during pregnancy: Pathology review
Congenital TORCH infections: Pathology review
Disorders of sexual development and sex hormones: Pathology review
Amenorrhea: Pathology Review
Testicular and scrotal conditions: Pathology review
Sexually transmitted infections: Warts and ulcers: Pathology review
Sexually transmitted infections: Vaginitis and cervicitis: Pathology review
HIV and AIDS: Pathology review
Penile conditions: Pathology review
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Tanner Marshall, MS
Placenta previa means “placenta first,” because the placenta is the first thing within the uterine cavity.
In this condition, the placenta implants in the lower uterus, close to or even covering the uterine opening, called the internal cervical os, and it can therefore easily bleed, which usually happens after 20 weeks of gestation.
Normally the placenta implants in the upper uterus, and it's unclear why it implants in the lower uterus.
One hypothesis is that the placenta implants lower down when the endometrium in the upper uterus is not well vascularized.
In fact, endometrial damage from things like a previous cesarean section, an abortion (which could be induced or spontaneous), uterine surgery, and multiparity or multiple pregnancies can decrease vascularization and increase the risk of placenta previa.
In other cases, risk factors for placenta previa include having multiple placentas or a placenta with a larger than normal surface area, which can both happen with twins or triplets, as well as maternal age of 35 years or more, intrauterine fibroids, and maternal smoking.
Placenta previa is classified by how close the placenta is to the cervical os, it can be complete where the placenta completely covers the cervical os; partial where the placenta partially covers the cervical os; or marginal where the edge of the placenta extends to within 2 cm of the cervical os.
As the pregnancy progresses, the lower uterine segment grows, and if the placenta’s in the lower uterus, this growth disrupts the placental blood vessels, which can cause bleeding.
This usually a sudden onset of painless bright red bleeding that typically happens after 20 weeks gestation.
Placenta previa is a pregnancy complication in which the placenta implants in the lower uterus and partially or fully covers the internal cervical os, making vaginal delivery difficult or impossible. It can cause heavy vaginal bleeding and a serious threat to both the mother and the fetus. Symptoms include painless vaginal bleeding in the third trimester, and some risk factors are previous placenta previa, multiple gestation, and uterine fibroids.
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