3: Placenta And Fetal Membranes Flashcards
Two components of the placenta
Fetal part: chorion
Maternal part: derived from endometrium
Formation of lacunar networks during implantation
- Lacunae appear in syncytiotrophoblast layer -> fill with blood and uterine secretions
- Adjacent lacuae fuse -> intervillous space
Extraembryonic coelom
Fluid-filled cavity around amnion and umbilical vesicle
What does the amnion become once it obliterates?
Epithelial covering of the umbilical cord
Polyhydramnios
Excess amniotic fluid due to genetic/CNS/or GI abnormalities
Clinical signs of polyhydramnios
Abdominal pain, significant swelling, SOA
Polyhydramnios increases risk for what?
PROM (premature rupture)
Oligohydramnios definition
Insufficient amniotic fluid, less than 400 mL
What can oligohydramnios cause?
Anomalies in development (renal agenesis, pulmonary hypoplasia), placental abnormalities, maternal hypertension
Three things that do not cross placenta
- Protein hormones
- Bacteria
- Drugs with AA structure
Things that can cross placenta
Nutrients, IgG, insulin, T3/T4, cholesterol hormones, waste products, drugs, infectious agents
Name some drugs that do cross placenta
Alcohol, cocaine, heroine, labor management drugs
Name some infectious agents that can cross placenta
cytomegalovirus, rubella, varicella, measles, herpes, toxoplasma Gondii, etc
Histo of umbilical cord
Wharton’s jelly
Formation of the umbilical cord
Connecting stalk enveloped by amnion
Umbilical arteries and veins
2 arteries: deox fetal blood
1 vein: 80% oxygenated fetal blood
What can absence of 1+ umbilical artery cause?
Can impact third trimester outcomes
Most common type of abnormal placentation
Placenta previa
Two predisposing factors for placenta previa
Prior placenta previa (60%), Hx previous Caesarian
Hydatidiform mole
Replacement of normal villi by dilated/hydropic translucent vesicles
Dx of invasive mole vs gestational choriocarcinoma
Invasive mole: persistent high blood hCH
Gestational choriocarcinoma: increasing hCG titer with no uterine elargement
Dizygotic twins anmions and chorions
Each have thier own
Three stages of monozygotic twin membrane division
2-8 cell stage -> diamniotic + dichorionic
Blastocyst (4-8 cells) -> diamniotic + monochorionic
Implanted (9-12 days) -> monoamniotic + monochorionic