Anatomy and Pathology of the Placenta 3

Question 1

What are some common abnromalities of implantation?

Answer 1

• Placenta previa
  
  • placenta implants very low in uterus
  • covers internal os
  • cervical dilation at the time of labor can cause severe bleeding and potentially fetal and/or maternal death
• Ectopic pregnancy
  
  • implantation outside of the uterus
  • most common location is the fallopian tube
• Placenta accreta
  
  • ​placenta grows into myometrial smooth msucle
  • due to defective endometrium
    
    • previous C-section or prior endometrial curettage increases risk
  • key feature is perivillous fibrinoid, which is implantation directly upon myometrium without intervening decidua
• Placenta increta
  
  • ​invasion deeper into the myometrium
• Placenta percreta
  
  • full-thickness invasion into the myometrium

Question 2

List the abnormalities of the uteroplacental vasculature that can occur.

Answer 2

• Placental abruption
• Preeclampsia
• Acute atherosis
• Maternal vascular underperfusion

Question 3

List the vascular abnormalities of the fetoplacental vasculature that can occur.

Answer 3

• Thrombosis
• Significant obstruction in larger vessels
• Fetal thrombotic vasculopathy (FTV)

Question 4

What is placental abruption?

Answer 4

• Rupture of a retroplacental (decidual) blood vessel
  
  • often related to maternal hypertension
• Abruption occurs when a large hematoma occurs
  
  • causes separation of the placental from blood supply
  • fetal death is the consequence

Question 5

What is pre-eclampsia? What is the clinical presentation? What is the pathology?

Answer 5

• Narrowing or thrombosis of retroplacental (decidual) blood vessels is commonly seen
  
  • causes ischemia and often placental infarts
• Numerous placental infarcts will compromise the delivery of oxygena nd nutrients to the fetus
  
  • results in fetal growth restriction or fetal death
• Classic vascular lesion is acute atherosis
• Overall pathologic changes referred to as maternal vascular underperfusion
• Clinical peresentation
  
  • hypertension
  • edema
  • proteinuria
  • symptoms cease after delivery
• Pathology
  
  • decidual vasculopathy - abnormal decidual vessels
    
    • fibrinoid necrosis of vessel walls
    • atherosis/mural foam cells
  • multiple infarcts
  • abruption

Question 6

What is fetal thrombotic vasculopathy (FTV)? What are some common causes?

Answer 6

• Term used to describe lesions of the fetoplacental vasculature
  
  • Clinical associations
    
    • preeclampsia
    • intrauterine growth restriction
    • intrauterine fetal demise
    • neonatal seizures
    • amputation necrosis
• Common causes:
  
  • Stasis
    
    • cord compression - hypercoiling, velamentous umbilical cord insersion, true knot, cord entanglement
    • right heart failure
    • polycythemia
  • Hypercoagulability
    
    • thrombophilic disorders, acquired or genetic
  • Vascular damage
    
    • infection
    • meconium

Question 7

What are some “downstream” effects of significant obstruction of larger fetal vessels?

Answer 7

• Chorionic villous vasculature is lost
  
  • villi known as avascular villi
  • considered evidence of upstream fetal vascular thrombosis
• Maternal supply is maintained and trophoblastic layers persist

Question 8

What are some common umbilical cord pathologies?

Answer 8

• Length < 35 cm is short and > 70 cm is long
• Coiling/strictures
  
  • normal coiling is 1-3 coils/10cm
• Knots
• Velamentous insertion
• Single umbilical artery
• Meconium-associated myonecrosis

Question 9

What are the fetal outcomes associated with placental pathology?

Answer 9

• Normal
• Preterm delivery
• Fetal growth restriction
• Neurological injury
• Infection
• Death/stillbirth
• Others
  
  • syndromes
  • tumors
  • gestational trophoblastic disease
  • hydrops