Placenta Flashcards
what is the gross appearance of normal mature placenta?
single, round to ovoid, disk-shaped organ w/o an accessory lobe
what are the main components of placenta?
umbilical cord
membranes (amnion & chorion)
villous parenchyma
maternal decidual tissues
what are the 2 placenta surfaces and its gross appearance?
- fetal surface = bluish gray, shiny, and translucent w/ no opacity or usual discoloration
- maternal surface = dark red, divided into cotyledons w/ no missing cotyledons
how many blood vessels are in the umbilical cord?
2 arteries
1 vein
w/o true knot, hemorrhage or thrombosis
what is the gross appearance of amnion & chorion membranes?
gray, shiny and translucent
absence of inflammation in the membranes or green meconium staining
what part of the placenta makes up the bulk of the whole structure?
villous parenchyma
what are the 2 types of trophoblast cells?
Synctiotrophoblast cells = outer layer
Cytotrophoblast cells = inner layer
what is the histo appearance of villi of the placenta during the 1st trim?
relatively large w/ few stromal BVs
whta is the histo appearance of villi of the placenta during the midtrimester?
villi becomes smaller and cytotrophoblasts become less evident
what is the histo appearnce of villi during term?
placental villi becomes smaller with abundant stromal capillaries
Trophoblast lining appears flat
Synctiotrophoblast = prominent synctial knots
What are the diff lesions of the villous parenchyma?
Hydropic placenta
Placental infarcts
Wht are the characteristicsof hydropic placenta?
Extreme pallor due to fetal anemia
Villous edema
Immature chorionic villi
Large and thick placentas with coarse cotyledons and villous structures
What is the gross & histo morphology of hydropic placenta?
GROSS
- enlarged & pale placenta due to edema & anemia
- placental weight is greater than expected
HISTO
- chorionic villi shows diffuse enlargement w/ villous stromal edema
- INC # of Hofbauer cells, nucleated RBCs
What are placental macrophages?
Hofbauer cells
What do placental infarcts represent?
Area of villous coagulative necrosis
What are affected of placental infarcts?
- Ischemia in the placental parenchyma
- Intrauterine growth retardation
Where are placental infarcts located, color in the early andlate stage?
Location: maternal placental surface, square shaped
Color:
- Early, recent/acute infarcts: dark red hemorrhagic or dark brown due to deposit
- Late, old infarcts: pale & anemic due to deposits of scar & fibrou tissue
What is the histo appearance of placental infarcts?
Ghost outlines of dead, necrotic chorionic villi (coagulative necrosis)
Early infarcts: villous congesion & collapse w/ loss of intervillous space
Late infarcts: fibrin deposition in intervillous space
What are the most common sites of placental implantation?
Uterine fundus
Anterior wall & posterior wall
Where are the diff abnormal implantation?
Ectopic pregnancy
Placenta previa
Placecnta accreta
What are the 2 hormones responsible for implantation of the endometrium?
Estrogen & Progesterone
Where are the normal sites of placental attachment?
- placenta is attached to uterine corpus superolateraly
- Decidua basalis between placenta proper & uterine endometrium
What causes placenta accreta?
Scarring, infection or instrumentation —> placenta attached to the myometrium w/o intervening decidualized endometrium —> deficient decidualization @ implantation site
What is the effect of placenta accreta during labor>
Inability of placenta to normally be spontaneously be separated during 3rd phase of normal delivery
What are the 3 types of placenta accreta?
- Placenta Accreta vera = most common
- villi implants on myometrial surface w/o intervening decidua
- Placenta Increta
- penetration of villou tissue into parts of the myometrium or villi extend into the myometrium - Placenta percreta
- villi penetrate the entire myometrial thickness and through the uterine serosa
Where is the location of placenta accreta?
Uterus
Lower uterine segment
Cervix
What are complications from placenta accreta & tx?
Life threatining postpartum hemorrhage
Uterine atony
Massive peripartum hemorrhage
Tx: removal of uterus
What are the gross appearance of placenta increta & placenta percreta
Placenta Increta
- demo directly infiltrating the myometrium w/o intervening decidual plate
Placenta percreta
- placenta invaded the full thickness of the lower myometrial wall, penetrating the seros
What is the microscopic appeearance of placenta accreta?
Chorionic interdifitate directly with the uterine myometrium w/o an intervening decidual plate
Where is placenta implanted in Placenta previa?
Lower uterine segment, partially/completely occluding the internal os
What is the presentation of Placenta previa?
Painless vaginal bleeding in the 2nd to 3rd trimester of pregnancy
What are risk factors of devling placenta previa?
Multiparity
Myoma
Cesarean section - main
Advanced maternal age - main
What are causes of placenta previa?
- surgery,trauma/scar
Wht are complications of placenta previa?
Fetal malpresentation
Premature rupture of the membranes
When do you grade placentas?
When placental implantation is low in the uterus
What re the gradings & locations of placenta?
Grrade I (Lateral placenta) = placenta implanted on LUS
Grade II (Marginal placenta) = edge of plaenta reaches internal Os
GradeIII (partial placenta previa) = low lying placenta partially covers the internal os
Grade IV (complete placenta previa) = low lying placenta COMPLETELY covers the internal os; CS
What is the early sepration or premature separation of the placenta?
Abruptio placenta
What are risk factors of Abruptio placenta?
Smoking
Cocaine use
Maternal age >35yo
HTN
Placental abruption in a prior pregnancy
What are conditions that could be associated with abruptio placenta?
Multiple gestation pregnnacies
Polyhydrdamnios
Preeclampsia
Sudden uterine decompression
Short umbilical cord
Traums to abdomen
What causes abruptio placenta?
Compromise of the vascular structure resulting in tearing of vascular networks
What is a severe form of concealed abruptio placenta?
Couvelaire uterus (uterine placental apoplexy)
What are the manifesations of preeclampasia & eclampsia?
HTN, edema, and proteinuria
What is the HELLP syndrome that forms complications of preeclampsia & eclampsia?
Micorangiopathic Hemolytic Anemia
Elevated Liver enzymes
Low platelet
What are aberrations of preeclampsia & eclampsia?
- Abnromal placental vasculature
2, Endonthelkial dysfunction & imabalce of angiogenic and antiangiogenic factors - Endothelial dysf and imabalnce of angiogenic and antiangiogenic factors
- Coagulation abnormalities
What enzyme is INC in preeclampsia?
Endoglin
SFitL (soluble FMS-like tyrosine kinase
What are the common sites of coagulation abnormaltiies in preecmplasmia?
Liver
Kidneys
Brain
Pitutiary glnad
What is the histo apperance of plaenta in toxemia of pregnancy?
- Acute atherosis of uterine vessels
- clear foam cells in intmia portion of arteries
- fibrinoid necrosis of the vessel wall & subendothelial macrophages
What is benign lobular of blood vessels in the placenta?
Chorangioma aka Hemangioma of the placenta
What is the microscopic appearnce of chorangioma?
Proliferation of small/medium sized vessels aside from the synctiotohphoblasts layer acros sits surface
What are the possible routes of placental infections?
Ascending infection via birth canal
Hematogenous/transplacental
What is itnervillositis, Perivillositis, & Villitis?
Villitis = inflammation within the placental chorionic villi; inflammation of the placental parenchyma
Perivillositis = inflammation surrounding the chorionic villi & reflect maternal septicemia
Intervillositis = inflammation involves the intervillous space, ascending infections
what are causes of placental intervillositis, villitis, & perivillositis?
E. coli, L. monocytogenes, Campylobacter, & Chlamydia spp.
CMV
Rubella or Toxoplasmosis (unuasual)
what is seen in CMV caused placental intervillositis villitis?
intravenous plasma cells & hemosiderin
what are diff abnormal placental shapes & lobes?
mature bilobate placenta
accessory lobe or succenturiate lobe
circummarginate & circumvallate placentas
what is a diffuse thin placenta without free membranes?
placenta membranacea
what are clin significance of Bilobate placenta?
multiparity
adv maternal age
infertility
presence of placena previa
excessive placental adhesions
first trimester bleeding
what abnormal placental shape has bilobate placenta resulting from uterine sulcal implantation?
mature bilobate placenta
what abnormal placental shape is formed if some of the capsular villus tissue fails to atrophy during devt?
accessory lobe or succenturiate lobe
accessory lobe/succemnnturiate lobes can often come what?
ifnarcted or fibrinous
what are clin signficance of accessory/succenturiate lobe?
- trauma to the vessel can produce fatal hemorrhage
- thromotic and thrombo-embolic events
- retained palcenta after the delivery
- greater assoc of accessory lobe w/ placenta previa
- INC tendency for placental infarction
what are features of normal umbilical cord?
- pearly white color
- inserted in a central or paracentral position
- whartons jelly
what are the BVs in whartons jelly?
2 arteries = carry deoxygenated blood from baby to the placenta
1 vein = carries the oxygenated blood from placenta to baby
