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Questions and Answers
What is the average diameter of a mature placenta at term?
What is the average diameter of a mature placenta at term?
Which of the following describes the thickest measurement of the placenta at full term?
Which of the following describes the thickest measurement of the placenta at full term?
At what gestational age is the placenta completely formed and functioning?
At what gestational age is the placenta completely formed and functioning?
Which characteristic is NOT a clinical feature of a normal placenta?
Which characteristic is NOT a clinical feature of a normal placenta?
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What is one of the primary functions of the placenta?
What is one of the primary functions of the placenta?
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What feature should be assessed regarding the umbilical cord during examination?
What feature should be assessed regarding the umbilical cord during examination?
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Which statement correctly describes the fetal surface of the placenta?
Which statement correctly describes the fetal surface of the placenta?
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Which of the following is NOT typically assessed during a placental examination?
Which of the following is NOT typically assessed during a placental examination?
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What should be inspected at the cut end of the umbilical cord before counting the vessels?
What should be inspected at the cut end of the umbilical cord before counting the vessels?
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What is an important finding when counting the vessels in the umbilical cord?
What is an important finding when counting the vessels in the umbilical cord?
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Which irregularities should be looked for on the fetal side of the placenta?
Which irregularities should be looked for on the fetal side of the placenta?
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When separating the amnion from the chorion, what should be ensured?
When separating the amnion from the chorion, what should be ensured?
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What should be done before assessing for blood loss in relation to cotyledons?
What should be done before assessing for blood loss in relation to cotyledons?
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What action is recommended when there's suspicion of incomplete placenta or membranes?
What action is recommended when there's suspicion of incomplete placenta or membranes?
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Why might placenta referral for examination be desirable?
Why might placenta referral for examination be desirable?
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Which condition is listed as a reason to refer the placenta for examination?
Which condition is listed as a reason to refer the placenta for examination?
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How does oxygen transfer from the mother to the fetus?
How does oxygen transfer from the mother to the fetus?
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Which nutrient is NOT actively transferred from maternal to fetal blood?
Which nutrient is NOT actively transferred from maternal to fetal blood?
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What hormone is secreted by the placenta to maintain pregnancy?
What hormone is secreted by the placenta to maintain pregnancy?
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Which substance is primarily excreted by the fetus?
Which substance is primarily excreted by the fetus?
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What is the function of the placenta regarding glucose?
What is the function of the placenta regarding glucose?
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Which of the following is true about the placental barrier?
Which of the following is true about the placental barrier?
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What is one of the first steps in the placental examination process?
What is one of the first steps in the placental examination process?
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Which aspect of the placenta is NOT examined during the examination process?
Which aspect of the placenta is NOT examined during the examination process?
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Study Notes
Examination of the Placenta
- Definition: A flat organ, approximately 17.5-20 cm in diameter and 2.5 cm thick, weighing about one-sixth of the infant's birth weight. It forms by the 12th week of pregnancy, originating from the trophoblastic layer of the fertilized ovum.
Mature Placenta
- Fully formed and functional by 10-12 weeks after fertilization.
- Weighs more than the fetus between 12-20 weeks due to fetal organs not being fully developed yet.
- Gradually degenerates later in pregnancy as the fetus's organs take over their functions.
Objectives of Examination
- Identify the size, shape, consistency, and completeness of the placenta.
- Look for accessory lobes, placental infarcts, hemorrhages, and tumors.
- Examine the umbilical cord for length, insertion, number of vessels, thrombosis, knots, and Wharton's jelly.
- Assess the color and odor of the fetal membranes.
Clinical Characteristics of Normal Placenta
- Diameter: 22 cm at term.
- Thickness: 2-2.5 cm.
- Weight: 470 g.
- Umbilical cord: length 55-60 cm, diameter 2-2.5 cm, with 2 arteries and 1 vein, containing Wharton's jelly.
Surface of the Placenta
- Maternal surface: Dark red, divided into cotyledons, should be complete with no missing ones.
- Fetal surface: Shiny, gray, translucent, showing the color of underlying villous tissues.
Functions of Placenta
- Respiration: The lungs do not function in the fetus, so the placenta facilitates oxygen exchange, taking oxygen from the mother's blood and releasing carbon dioxide. The same process happens for carbon dioxide as well.
- Nutrition: Transports nutrients (proteins, carbohydrates, calcium, phosphorus, iron, minerals) from the mother to the developing fetus through the wall of the villi.
- Storage: Stores glucose as glycogen for later use, with iron and fat-soluble vitamins also being stored.
- Excretion: Removes waste products (carbon dioxide, bilirubin, urea, uric acid) from the fetus, as it cannot be fully eliminated by the fetus without function of the liver.
- Protection: Provides limited barriers against infections. Some chemicals/viruses are not filtered, potentially leading to congenital anomalies.
- Endocrine: Secretes hormones like HCG, estrogen, progesterone, and HPL.
Steps of Placental Examination
- Delivery: Hold and gently turn placenta until membranes are twisted, and slowly pull until completely delivered. The membranes should be moved up and down.
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Examination:
- Wash hands, wear appropriate gear, and explain procedure to parents.
- Adequately light the work area.
- Prepare a flat surface to avoid spillage.
- Prepare tools if needed (syringe, needle).
- Lay out the placenta with maternal surface uppermost.
- Note the size, shape, color, and odor.
- Examine the umbilical cord (length, insertion, knots, thrombi, presence of vessels).
- Identify vessel counts in the umbilical cord at its end.
- If membrane tears, examine upper vagina and cervix using sterile gloves and sponge forceps to remove any pieces. Clean up any membrane pieces.
Referral of Placenta for Examination
- Prematurity (30-36 weeks)
- Placental abruption
- Fetal congenital malformation
- Rhesus (and other) isoimmunisation
- Morbidly adherent placenta
- Twins/multiple pregnancies
- Abnormal placental shape
- Abnormal umbilical cord (e.g., two-vessel cord)
- Prolonged rupture of membranes >36 hours
- Gestational diabetes
- Maternal group B streptococcus
- Pre-eclampsia/maternal hypertension
- Maternal coagulopathy
- Maternal substance abuse.
Disposal of Placenta
- Place placenta in a yellow bag, then a yellow container.
- If the woman wishes, the placenta can be taken home.
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Description
This quiz focuses on the anatomy and clinical characteristics of the placenta. Participants will learn about its formation, examination objectives, and normal clinical features. Assess your knowledge on the structure and function of this crucial organ during pregnancy.
