Spring 2024 OB/GYN Ch 19

• when endometrial cells transform into glycogen and lipoid cells, this is called?

  decidual reaction
• decidual reaction occurs when endometrial cells transform into glycogen and lipid cells
• what part of the decidua forms the placenta?

  decidua basalis
• what is the major functioning unit of the placenta?

  chorionic villus
• trophoblast develops into chorionic villi by week 5
• what part of the blastocyst forms the placenta?

  trophoblast
• the trophoblast divides into syncytiotrophoblast and cytotrophoblast
• within the chorionic villus are intervillous spaces which the maternal blood enters

  A) intervillous space

  
• syncytiotrophoblast

  epithelial covering of the chorionic villi
• cytotrophoblast

  inner layer of the trophoblast/chorionic villi
• :)

  :)

  A) cytotrophoblast

  B) syncytiotrophoblast

  
• embryo and membranes grow, the decidua capsularis is stretched
• the chorion laeve is the smooth side of the chorion that atrophies and disappears, and the chorion frondosum is the side with rapidly growing finger-like structures that help create the placenta
• :)

  A) chorion laeve

  B) chorion frondosum

  
• The placenta has two parts:

  1. The part from the mother's uterus lining is called the basal plate.
  2. The part from the baby's side is called the chorionic plate.
• Maternal blood enters intervillous space to transfer oxygenated and nutrient rich blood across the placental membrane into the fetal blood by diffusion. Carbon dioxide passes in the opposite direction.
• list the 6 functions of the placenta

  respiration

  nutrition

  excretion

  protection

  storage

  hormonal production
• Respiration◦ placenta acts as “fetal lungs”
• Nutrition:Water, inorganic salts, carbohydrates, fats, proteins, and vitamins pass from maternal blood through the placental membrane into fetal blood
• Excretion: Waste products cross membrane from fetal blood and enter maternal blood. Excreted by mother’s kidneys.
• Storage: Carbohydrates, proteins, calcium, and iron are stored in placenta and released into fetal circulation.
• Hormonal production: The placenta produces hormones such as hCG and progesterone, and there is a process where fetal steroids are converted into estrogen. These hormonal changes are essential for supporting and maintaining the pregnancy.
• Chorionic villi are functional endocrine units of placenta
• the placenta inner layer produces neuropeptidesthe placenta outer layer produces protein hormones: hCG, human placental lactogen (hPL) and sex steroids (estrogen and progesterone)
• the placenta weighs 480-600 grams at term
• placenta previa is when implantation of the placenta occurs within lower uterine segment
• sono characteristics of placenta: homogenous, midlevel gray echogenicity with smooth boarders up to 20 weeks
• >20 weeks placental lakes and placental calcifications begin to appear
• AP measurement of placenta <4 cm
• sono characteristics of chorionic plate: echogenic coursing along placental tissue
• linear echogenicity further enhanced by strong interface of amnion covering the chorionic plate
• maternal blood vessels from endometrium run behind basal plate;may be confused with placental abruption
• :)

  A) basal

  B) chorionic

  
• Placental lakes are blood filled spaces or pools within the placenta
• Placental sonolucencies (hypoechoic area) referred to as placental lakes
• blood flow will not be detected with color Doppler when evaluating placental lakes
• Always show the relationship between placental edge and internal os of cervix
• Over distended maternal bladder can make the cx appear falsely elongated
• over distended maternal bladder could give false impression of placental previa
• To better demonstrate internal cervical os when scanning transabdominally: tilt patient in slight trendelenburg position. It can relieve pressure of uterus on LUS