Chapter 55 Placenta First 1/2 PPT

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Function of the Placenta:

  • Respiration
  • Nutrition
  • Excretion
  • Protection
  • Storage
  • Hormonal Production
2

Placenta

decrease

Placental

Fetal-Placental-Uterine Circulation:

  • _____is dedicated to survival of the fetus
  • May be reduced by a variety of conditions that ____ uterine blood flow
    • hypertension, renal disease, or placental infarction.
    • _____defects can cause intrauterine fetal growth restriction (IUGR).
  • The net effect is that there is a reduction of flow between the fetal and maternal blood.
3

center

Battledore

Velamentous

Cordal Attachments:

  • Attachment of cord is usually near ____ of placenta
  • _____ placenta- at margin, within 10 cm of the edge.
  • ____ cord- inserts into membranes
4

Secondary

28

Yolk Sac:

  • _____ yolk sac forms after regression of primary yolk sac
  • It forms on the ventral surface of the embryonic disk at __ menstrual days.
  • Has role in the transfer of nutrients to the embryo during second and third weeks of gestation while uteroplacental circulation developing
5

amnion; chorion

9

5

Yolk Sac:

The yolk sac becomes displaced from the embyo and lies between the _____ and the _____.

By __ weeks, the yolk sac has diminished to less than __ mm in diameter.

6

placenta previa

Implantation of the Placenta:

  • Normally placenta implants on anterior, fundal, posterior, or lateral wall of uterus
  • Occasionally, implantation will occur within lower uterine segment, resulting in condition called ____ _____
7

Allantois

Membranes:

  • Fetal membranes
    • Chorion
    • Amnion
    • Allantois
    • Yolk sac
  • ____ is webbed with blood vessels, function is to collect liquid waste from the embryo, as well as to exchange gases used by the embryo.
8

Chronic villi

protein

estrogen; progesterone

Placenta as Endocrine Gland:

  • ____ ____ are functional endocrine units of placenta
  • Outer layer produces ____ hormones
    • Human chorionic gonadotropin (hCG)
    • Human placental lactogen (hPL)
    • Sex steroids: ____ and ____
9

7th; syncytiotrophoblast

Progesterone

estrogen

Placenta as Endocrine Gland:

  • After __ week, most progesterone produced by ______
  • _____ production is a maternal-placental interaction; no contribution from fetus
  • Production of placental ____ involves pathway requiring maternal, placental, and fetal contributions
10

8

homogenous

smooth

Normal Placenta:

  • Can be identified with sonography as early as ___ menstrual weeks
  • Has relatively ____ mid-level gray appearance between 8 and 20 weeks
  • Easily recognized, with ____ borders
11

20; sonolucenies; calcification

4

Normal Placenta:

  • After ___ weeks’ gestation, intraplacental _____ and placental ____ may begin to appear
  • Thickness varies with gestational age, but is usually 2 to 3 cm in fetuses >23 weeks
  • Normal placenta rarely exceeds __ cm
12

internal

Placental Position:

  • Survey transabdominally
    • Longitudinally from side to side
    • Tranversely from inferior to superior
  • Insertion of cord into placenta
    • Visualize
    • Describe as mid placental, marginal, or velamentous
  • Inferior edge documented to evaluate its relationship to ____ cervical os
13

elongated

previa

Placental Position:

  • If maternal bladder full, cervix is falsely _____
  • Normally implanted placenta may appear to be covering internal cervical os
  • May give false impression of ____
  • Emptying maternal bladder reduces pressure on lower uterine segment
  • Allows cervix to assume normal position
14

transabdominally

Trendelenburg

Placental Position:

  • To better demonstrate internal cervical os when scanning _____:
    • Tilt patient in slight _____ position (head lower than body)
    • Relieve pressure of uterus on lower uterine segment
15

succenturiate

Succenturiate

Placental Position:

  • If anterior and posterior placenta does not appear to communicate, _____ placenta should be considered
  • ______, or accessory lobe placenta, is when additional placental lobes are joined to main placenta by blood vessels
16

Low

hypertrophy

Placental Position:

  • Placental position appears changed because of physiologic changes in the lower uterine segment (LUS)
  • ___ blood supply in the LUS causes the placenta in that area to atrophy and disappear
  • Areas of rich blood supply toward the fundus and mid portion of the uterus cause the placenta to _____
17

high

low

spiral; low

Doppler of the Placenta:

  • Uterine artery: ___-resistance flow pattern first trimester
  • Second trimester should show ___-resistance flow pattern
  • Normal trophoblastic invasion of ____ arteries produces ___-resistance Doppler pattern
  • In first trimester, flow-velocity waveform shows notched appearance in early diastole
18

trophoblastic; spiral

insufficiency

abruption

Doppler of the Placenta:

  • Abnormal _____ invasion of ____ arteries of maternal uteroplacental circulation associated with:
    • Placental ____
    • IUGR
    • Preeclampsia
    • Placental ____
19

15 to 20

Discoid

600

4

Evaluation of Placenta after delivery:

  • Normal term placenta has several characteristics at delivery
    • Measures about ___-___ cm in diameter
    • _____ in shape
    • Weighs about ___ g
    • Measures <__ cm in thickness
20

diabetes

anemia

PLACENTOMEGALY:

  • Maternal ____
  • Maternal _____
  • α-Thalassemia
  • Rh sensitivity
21

hemorrhage

infections

PLACENTOMEGALY:

  • Fetomaternal _____
  • Chronic intrauterine _____
  • Twin-twin transfusion syndrome
  • Congenital neoplasms
  • Fetal malformations
22

infection

Small Placenta:

  • Intrauterine growth restriction
  • Intrauterine _____
  • Aneuploidy
23

internal

1 of 200

cesarean

Placenta Previa:

  • Implantation of placenta over ____ cervical os
  • Normally implants in body or fundus of uterus
  • In _____ pregnancies placenta implants over or near to internal os of cervix
  • Risk increases with history of _____ delivery
24

Cocaine

cesarean

surgery

Placenta Previa:

  • Multiple factors associated with placenta previa
    • Advanced maternal age
    • Smoking
    • ____ abuse
    • Prior placental previa
    • Multiparity
    • Prior _____ section
    • Uterine _____
25

Preterm

hemorrhage

invasion

hemorrhage

Placenta Previa:

Complications of placenta previa

  • _____ delivery
  • Maternal _____
  • Increased risk of placental ____
  • Increased risk of postpartum _____
  • IUGR
26

painless

25; 30

20

Placenta Previa:

  • Clinically, may present with ____, bright red vaginal bleeding in third trimester
  • __% of patients will present with bleeding during first ___ weeks
  • __% of cases associated with uterine focal myometrial contractions
  • Abnormal lie also associated with placenta previa
27

life-threatening

cervical os

rupture; hemorrhage

Vasa Previa:

  • Vasa previa potentially ___ ______ fetal complication
  • Occurs when large fetal vessels run in fetal membranes across ___ ____
  • Vessels at risk of _____ and life-threatening ____
28

Velamentous

Succenturiate

Vasa Previa:

  • Most common causes of vasa previa:
    • ______ insertion of umbilical cord into placental membranes, which cross over the cervix
    • _____ lobe present, and connecting vessels traverse the cervix
29

exsanguination

cesarean

Vasa Previa:

  • When delivery imminent, unsupported fetal vessels prone to tear as cervix dilates
  • Can result in _____ of fetus
  • Rapid _____ delivery may prevent fetal demise
30

accreta

increta

percreta

Placental Invasion:

  • Abnormal penetration of placental tissue beyond endometrial lining of uterus
  • Placenta _____: Chorionic villi attach to myometrium without muscular invasion
  • Placenta _____ is further extension of the chorionic villi into the myometrium
  • Placenta _____ is penetration of the chorionic villi through the uterus
31

increta

trophoblastic

High

Placental Invasion:

  • Placenta ____ results from underdeveloped decidualization of endometrium
  • The association of placenta previa reflects the thin, poorly formed deciduas of the lower uterine segment that offers little resistance to deeper invasion by the trophoblast
  • Previous cesarean scar permits _____ invasion.
  • ____ maternal mortality and morbidity associated with placenta increta/percreta
32

Circumvallate/circummarginate

Circumvallate/Circummarginate Placenta:

  • _______/________ placenta is attachment of placental membranes to fetal surface of placenta rather than to underlying villous placental margin