Pathology of Pregnancy Flashcards
What structures are included in the placenta?
Placental disc, unbilical cord, extraplacental membranes
What are the two surfaces of the placenta?
- Fetal side: covered by amnion and chorion
- Maternal surface: The decidua
What is the decidua?
Border betwixt the fetal tissue and the uterus
What is the villus?
Placenta’s functional unit of exchange
What are the inner, middle, and outer layer of the villus?
- Inner: Cytotrophoblast (Langhans cells)
- Middle: Intermediate Trophoblast
- Syncytiotrophoblast
What are Hofbauer cells?
Embryonal macrophages
What is the major secretion of the trophoblasts?
hCG
What is the fetal-placental weight ratio?
1 g placenta can oxygenate 7 grams of fetal tissue
What is the name of the condition when the placenta implants at the lower portion of the uterus and covers the internal os?
Placenta previa
What is ectopic pregnancy?
Placenta implants outside the uterine cavity
What is the term for an umbilical cord that inserts at the margin of the placental disk?
Marginal insertion
What is a velamentous insertion of the umbilical cord?
Umbilical insertion into the membranes
What is a life-threatening complication of velamentous insertion?
Vasa previa: Membranous blood vessels of the cord cover the cervical os. These vessels are easily ruptured and can cause life-threatening hemorrhage
Acute chorioamnionitis. What is this condition characterized by?
Neutrophils in the amnion and chorion
What is the order of inflammatory responses betwixt the mother and fetus?
Maternal inflammatory response occurs first, and if the infection persists the fetal inflammatory response will occur
Describe the inflammatory processes in the fetal inflammatory response to chorioamnionitis.
- Acute funisitis - neutrophil migration into muscular walls of the umbilical vessels
- Acute chorionic vasculitis - neutrophil migration into the large fetal vessels at the placental surface
What are the major risks of chorioamnionitis to the mother and infant?
- Mother: Postpartum endometriosis and pelvic sepsis w/ venous thrombosis
- Fetus: Neuro disease, stillbirth, neonatal sepsis and death
By what mechanism does villitis typically arise?
Results from transplacental passage of organisms usually from the maternal circulation (hematogenously)
Acute villitis. What is the most important consequence of acute villitis?
Establishment of an inflammatory focus that infects the fetus secondarily
What is villitis of unknown etiology?
Cause of chronic placental infsufficiency in which no infectious agent is found
What is the cause of fetal thrombotic vasculopathy?
Clotting in placental vessels
Avascular villi. What was the cause of this condition?
Villous capillaries have been replaced by fibrous tissue as a result of a chronic thrombus in a larger upstream stem villus
What is a “cushion defect”?
If a large chorionic vessel is thrombosed, thrombus can attach to and later be incorporated into the vessel wall
What is abruptio placentae?
Placental lining has separated from the uterus
What can abruptio placentae cause?
Retroplacental Hematoma
What is the outcome of retroplacental hematoma?
Depends on the size of hematoma
What does rupture of a chorionic villous blood vessel result in?
Causes blood to accumulate in the placenta and to form an intervillous thrombus/hematoma
What is placenta accreta? What is it caused by?
Abnormal adherence of the placenta to the uterus; Caused by failure to form decidua.
In this image, the chorionic villi are in contact with the underlying muscle
Placenta accreta is classified based on the depth of invasion of the villi into the myometrium. What are the 3 classifications?
- Placenta accreta: attachment of villi to the surface of the uterine wall w/o further invasion
- Placenta increta: Villi invading the underlying myometrium
- Placenta percreta: Villi penetrating the full thickness of the uterine wall
What is the most common presenting sign of a patient with placenta accreta?
Third trimester bleeding
What is a possible major consequence of placenta accreta?
Post-partum hemorrhage
What is chronic uteroplacental malperfusion an important cause of?
Perinatal morbidity and mortality
What causes villous hypoplasia?
Decreased maternal bloodflow to the placenta especially due to disease of the spiral arterioles
Villous Hypoplasia. What are the characteristic uscopic features?
Chronic ischemia with small shrunken villi with stromal fibrosis and clumped trophoblasts
What can increased perivillous fibrin result in?
Placental insufficiency
What is massive perivillous fibrin deposition?
Placental fibrion deposition and transmural villous necrosis from the maternal (decidual) to fetal (chorionic) surface
What is maternal floor infarction?
Fibrin deposit throughout the lower half of the placenta including the decidua
What are the two most frequent causes of placental infarction?
Hemorrhage b/w the base of placenta and uterine wall and occlusion/thrombosis of the uterine spiral artery
Chorioangiosis. What is chorioangiosis?
Abnormally increased chorionic vessels due to chronic fetal hypoxia
What do increased syncytial knots indicate?
Chronic uteroplacental malperfusion
What are the two subtypes of Intrauterine growth restriction?
Symmetric and asymmetric
From what is asymmetric intrauterine growth restriction usually caused?
Chronic uteroplacental insufficiency
What is another name for Asymmetric IUGR?
“Head sparing IUGR”
What is the most important prevetable cause of asymmetric IUGR?
Maternal cigarette smoking
What is Dx of Asymmetric IUGR?
Ponderal Index of
What is another name for spontaneous abortion?
Miscarriage
What is the definition of spontaneous abortion?
Expulsion of a conceptus before the 20th week of gestation
What are dizygotic twins?
Fertilization of two separate ova resulting in genetically different twins
What are monozygotic twins?
Early division of a signle fertilized ovum resulting in genetically identical twins of the same sex
What is the name of the condition in which monozygous twins do not separate?
Conjoint fetuses w/i a monoamniotic, monochorionic placenta
What are two complications of pregnancy that result in maternal death?
- ARDS
- DIC
What is preeclampsia? Eclampsi?
HTN, Proteinuria, Edema; Preeclampsia + seizures
What is believed to be the basis of preeclampsia?
Faulty remodeling of uterine spiral arteries that supply the placenta with oxygenated maternal blood
Describe the pathogenesis of acute atherosis.
Spiral arteries escape invasion by trophoblastic tissue and never dilate. these arteries commonly show fibrionoid ncerosis, clusters of lipid-rich macrophages and perivascular infiltrate of monoculcear cells
What is the central pathogenetic abnormality in preeclampsia?
Placental ischemia
What vascular changes that normally occur in pregnancy do not occur in preeclampsia?
Vessels still reactive to vasoconstrictors
Describe the general pathogenesis leading to preeclampsia
- Inadequate cytotrophoblastic invasion of maternal spiral arteries
- Placental ischemia
- Generalized endothelial cell injury
- Reduced renal BF, Increased VR, Increased arterial pressure, Enhanced pressor response (HTN, Proteinuria, Edema)
- Preeclampsia
What is a pathologic change in the mother that is always seen in (pre)eclampsia?
Maternal kidneys always shown glomerular change
What abnormalities are seen in the majority of women dying from preeclampsia?
Liver abnormalities
What is HELLP syndrome?
Potentially fatal condition of pregnant women and infants in the third trimester
Hemolytic anemia, elevated liver enzymes and low platelet count
What is believed to be the cause of amniotic fluid embolism?
Amniotic fluid, fetal squamous cells, hair and other amniotic material enter te maternal circulation through the uterine veins in the devidual bed at the base of the placenta
What is considered the distinctive feature of amniotic fluid embolism?
Fetal squamous epithelial cells in both alveolar capillaries or in larger blood vessels
What is gestational diabetes?
Pregnanat woman without previous diabetes develops abnormally high blood glucose levels
What is the hallmark of gestational diabetes?
Resistance to maternal insulin
Describe the pathogenesis and consequences of gestational diabetes
- Pregnancy hormones/factors interfere w/ insulin binding resulting in hyperglycemia
- Glucose crosses the placenta and fetus increases output of insulin
- Insulin stimulates growth leading to large fetal size (Macrosomia)
What is acute fatty liver pregnancy?
Rare life-threatening condition of pregnancy caused by disordered metabolism of fatty acids by maternal mitochondria
What enzyme is deficient in acute fatty liver of pregnancy?
Mitochondrial enzyme long chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD)
What is Dx of Acute fatty liver of pregnancy?
Liver biopsy showing characteristic uvesicular fat droplets in the cytoplasm of enlarged hepatocytes w/ central nuclei
What is the leading avoidable cause of morbidity and mortalty in pregnant women and their infants?
SMOKING
What are the two main factors that contribute to morbidity and mortality of the fetus in smokers?
- Carbon Monoxide: Decreases fetal O2
- Nicotine: Potent vasoconstrictor of uterus and placenta
What is gestational trophoblastic disease?
Spectrum of disorders with abnormal trophoblast proliferation and maturation
What is a hydatidiform mole?
A placenta with grossly swollen chorionic villi, resembling bunches of graphes, and showing varying degrees of trophoblastic proliferation
How does a hydatidiform mole form?
Complete moles result from fertilization of an empty ovum that lacks functional maternal DNA
Complete hydatidiform mole. What is the most common type?
Haploid (23,X)
How are complete hydatidiform moles typically monitored? What is the most serious complication?
Serum hCG levels are monitored; Development of choriocarcinoma
What is a partial hydatidiform mole? How is it formed?
A mole with three sets of chromosomes, 1 from the mother and 2 sets from the father (normal ovum fertilized by either 2 sperm or 1 sperm that did not successfully undergo meiosis)
How is a partial hydatidiform mole histo different than a complete?
- Contain two types of chorionic villi
- Normal villi
- Hydropically swollen villi
Trophoblastic proliferation is focal and less pronounced than in complete mole
What is an invasive hydatidiform mole?
A mole that penetrates the underlying myometrium
What is the typical histo of invasive hydatidiform moles?
Trophoblastic proliferation
From what is gestational choriocarcinoma derived?
Fetal trophoblasts
Choriocarcinoma. What are the typical histo findings?
Malignant cytotrophoblasts, and syncytiotrophoblasts
A tumor contains villous structures but seem cancerous. Dx?
HYDATIDIFORM MOLE. Tumors containing any villous structures, EVEN IF METASTATIC, are considered hydatidiform moles and NOT choriocarcinoma
What is the typical presentation of a patient with choriocarcinoma? How is it monitored?
Abnormal uterine bleeding; Monitor hCG levels
What distinguishes placental site trophoblastic tumor from choriocarcinoma?
Monomorphic trophoblastic proliferation unlike the dimorphic patter of trophoblast in choriocarcinoma
