Placenta Flashcards
Which hormone is secreted by the placenta?
hCG (+ many others)
What is the decidua?
Endometrium of pregnancy
Are the chorion/amnion derived from maternal or fetal tissue?
Fetal tissue
What is the function of the chorionic villi?
Chorionic villi sprout from the chorion to provide a large contact area between fetal and maternal circulations
What is the two layered epithelium of the chorion called?
Trophoblast
Do the fetal and maternal blood sources mix?
NO- not under normal circumstances
Does the umbilical vein bring oxygenated or deoxygenated blood to the fetus?
oxygenated
How does fetal blood become oxygenated?
The placenta is like the lungs for the fetal blood- the oxygenated maternal blood enters in spiral/endometrial arteries and bathes the fetal blood supply- oxygen is extracted
Spontaneous abortions (miscarriages) occur when?
Anytime before 20 weeks
What is the primary cause of a spontaneous abortion?
More than half are due to chromosomal abnormalities
Where do ectopic pregnancies usually occur?
90% occur in the fallopian tubes
10% occur in the ovary or abdominal cavity
Name 2 predisposing factors to ectopic pregnancies
Previous inflammation that led to scarring
IUDs
How will an ectopic pregnancy present?
Abdominal pain, acute abdomen
Will a monochorionic placenta produce fraternal or identical twins?
Identical
Monochorionic placentas imply monozygotic twins
What is the cause of twin-twin transfusion syndrome?
Intertwin vascular connections within the placenta
Leads to polyhydramnios in one amniotic sac, and oligohydramnios in the other amniotic sac
What is it called when the placenta attaches to the lower uterine segment or cervix?
Placenta previa
What are the consequences of placenta previa?
Serious 3rd trimester bleeding
Dilation of the cervix disrupts the placenta
What is it called when there is partial or complete absence of the decidua with adherence of placental villous tissue directly to the myometrium?
Placenta accreta
What are the consequences of placenta accreta?
Failure of placental separation –> incomplete/non-delivery of the placenta following birth.
Causes postpartum bleeding
Name 2 predisposing factors to placenta accreta
Placenta previa (60%) Previous cesarean section
What is it called when there is a premature separation of the placenta and formation of a retroplacental blood clot?
Abruptio placentae
What are the consequences of abruptio placentae?
Painful maternal bleeding
Potential fetal death due to inadequate blood supply to the fetus
What are consequences of retained placental tissue?
Postpartum hemorrhage
Infection
What is Preeclampsia-eclampsia?
Systemic syndrome characterized by widespread maternal endothelial dysfunction presenting clinically with hypertension, edema and proteinuria during pregnancy
Is preeclampsia more common with the first pregnancy or subsequent pregnancies?
First preganancy
What causes preeclampsia-eclampsia?
Not sure, but delivery of the placenta rapidly reverses the symptoms
(Coagulation abnormalities? Endothelial dysfunction and imbalance? Abnormal placental vasculature?)
How is the liver affected by preeclampsia?
Fibrin thrombi, hemorrhage, necrosis
How are the kidneys affected by preeclampsia?
Fibrin in glomeruli and capillaries
Renal cortical necrosis
How is the brain affected by preeclampsia?
hemorrhage and thrombosis
What is the triad at defines preeclampsia?
HTN, edema, proteinuria
What defines severe preeclampsia?
Preeclampsia + headaches and vision changes
What defines eclampsia?
Preeclampsia + convulsions
What is HELLP syndrome
Severe preeclampsia + hemolysis, elevated liver enzymes, and low platelets
What are some long term maternal sequelae of preeclampsia?
20% develop HTN and microalbuminuria within 7 years
2x increased heart and brain vascular disease
What is the most common route of a placental infection?
Ascending- usually bacterial, through the birth canal
Less commonly, TORCH infection through hematogenous spread
List the TORCH infections
T- Toxoplasma Gondii O-Others (Parvovirus B 19), Syphilis, TB, listeria R- Rubella C- CMV H- Herpes simplex virus, HIV
What are the symptoms of a TORCH infection?
fever, encephalitis, chorioretinitis, hepatosplenomegaly, pneumonitis, myocarditis, hemolytic anemia and vesicular or hemorrhagic skin lesions
Generally speaking, what are hydatidiform moles?
A noncancerous tumor that develops in the uterus as a result of a nonviable pregnancy
Leads to cystic swelling of the chorionic villi with trophoblastic proliferation
What is the general presentation of a hydatidiform mole?
Most women present with miscarriage, and undergo D&C based on the US/hCG findings
In complete hydatidiform moles, how many chromosomes are present? What is their origin?
46 chromosomes are present, BOTH sets are from the male origin.
What are the two ways a complete hydatidiform mole can arise?
Empty ovum penetrated by two sperm –> 46 chromosomes
Empty ovum penetrated by one sperm which duplicates such that there are now 46 chromosomes
What is the origin of the chromosomes of a partial hydatidiform mole?
Two sperms enter an ovum with 23 chromosomes already –> 69 chromosomes
What is the karyotype of partial vs complete hydatidiform moles?
Complete: 46, XX or 46, XY
Partial: Triploid
Describe the presence of villous edema in partial vs complete moles
Complete: all villi are edematous
Partial: some villi are edematous
Describe the trophoblast proliferation of partial vs complete moles
Complete: Diffuse, circumferential
Partial: Focal, slight
Describe the histologic atypia of complete vs partial moles
Complete; often present
Partial: absent
Describe the serum hCG levels in complete vs partial moles
Complete: Elevated
Partial: less elevated
Is fetal tissue present in complete moles? Partial moles?
Complete; Fetal tissue is absent
Partial: Fetal tissue is present
Describe the malignant potential of complete vs partial moles
Complete; 2.5% progress to choriocarcinomas (often fatal)
Partial: almost zero malignant potential
What defines an invasive mole?
A mole that penetrates the uterine wall- villi invade the myometrium
How are invasive hydatidiform moles treated?
Chemotherapy
Are gestational choriocarcinomas malignant or benign?
Malignant- they are rapidly invasive and widely metastatic
Gestational choriocarcinomas are neoplasms arising from which cell type?
Trophoblast derived cells
What is the treatment for choriorcarcinoma?
Surgery and chemotherapy- chemo is extremely effective
What does the chorion attach to?
The decidua
Do ovarian choriocarcinomas require fertilization?
No- they are non-gestational, and a result of extra-embryonic differentiation in malignant germ cells
What is the prognosis for ovarian choriocarcinomas?
Poor response to chemotherapy, poor prognosis
