Fetal/Placental Pathology Flashcards
Describe how a blastocyst implants into the endometrium around days 8-9 post-fertilization?
It is likely that some adhesion molecules are essential for blastocyst attachment to the endometrium. Once the trophoblastic shell has attached, marked changes occur on its surface and invasion is accomplished by dissociation and ingestion of endometrial cells.
So at approx 14 days from fertilization, the chorion extends its CT into the developing villi, the umbilical cord begins to develop from embryonic mesoderm, and the amnion fills with fluid, and then the embryo herniates into the amniotic cavity
With continued expansion of the embryonic cavity, the surface of the ovum becomes attenuated, the peripheral villi atrophy (with partial decidua necrosis), and the future placental “membranes” form.
What do placental ‘membranes’, that outline the uterine cavity where the fetus will develop, consist of?
These consist of decidua on the outside, hyalinized villi and trophoblasts in the middle, and the chorion (and amnion) on the inside.
What does the placenta develop from?
The placenta is a fetomaternal organ that has two components:
A fetal part that develops from the chorionic sac, the outermost fetal membrane
A maternal part that is derived from the endometrium
There is a placental membrane that acts as a location between the fetus and mother where blood and nutrients can be exchanges (villi)
What genes regulate placental development?
Homeobox genes ( HLX and DLX3 ) expressed in the trophoblast and its blood vessels
How does maternal blood enter the intervillous space?
from the spiral endometrial arteries in the decidua basalis
Describe the development of the urachus?
During the third week of development, the allantois protrudes into the area of the urogenital sinus.
Between the 5th and 7th week of development, the allantois will become the urachus, a duct between the bladder and the yolk sac. A patent allantois can result in urachal cyst.
What is symmetric growth restriction?
placental abnormalities/disruptions leading to all organ systems being similarly affected
What are some causes of symmetric growth restriction?
Chromosomal disorders, congenital anomalies, and congenital infections.
What types of infections fall can cause symmetric growth restriction?
•TORCH group of infections
toxoplasmosis,
other viruses and bacteria, such as syphilis.
rubella,
cytomegalovirus,
herpesvirus,
T or F. asymmetric growth restriction spares the brain and is caused by a down-regulation of growth in the latter half of gestation due to placental disruptions
T.
What are some common sources of Uteroplacental insufficiency that can cause asymmetric growth restriction?
- umbilical-placental vascular anomalies (such as single umbilical artery, abnormal cord insertion, placental hemangioma),
- placental abruption,
- placenta previa,
- placental thrombosis and infarction,
- placental infection , or
- multiple gestations.
Third trimester loss is usually due to what?
placental insufficiency, whereas earlier losses are more likely due to chromosomal abnormalities
Asymmetric etal growth restriction may also be due to maternal abnormalities or illnesses, not just placenta disruptions. Name some.
maternal conditions that result in decreased placental blood flow, including:
•Vascular diseases, such as preeclampsia (toxemia of pregnancy) and chronic hypertension
What is a spontaneous abortion defined as?
(aka miscarriage)- this is loss of a pregnancy before 20 weeks of gestation, whereas loss of pregnancy after 20 weeks is called a stillbirth
Again, most early SABs are due to chromosomal abnormalities, while the majorty of third trimester stillbirths are due to placental insufficiency. What causes the majority of pregnancy loss in the second trimester?
maternal or fetal anatomical abnormalities and ascending infection
What are some things included in ‘fetal or maternal structural abnormalities’ that commonly cause abortion in the second trimester?
- Maternal endocrine factors , including luteal-phase defect, poorly controlled diabetes, and other uncorrected endocrine disorders.
- Physical defects of the uterus , such as submucosal leiomyomas, uterine polyps, or uterine malformations, may prevent or disrupt implantation
- Systemic disorders affecting the maternal vasculature , such as antiphospholipid antibody syndrome, coagulopathies, and hypertension
Infections are a common cause of fetal morbidity and mortality in the second trimester. What is one of the more common infections?
Infections can either be ascending (more common) or blood-bourne. A particularly common blood-bourne fetal infection arises from Listeriosis infection, in which Listeria spp. from food (delis, unpasteurized drinks, sushi) enters from the GI and passes through the placenta
How does Listeria affect a fetus? What about the mother?
Listeriosis is a rare disease that causes mild maternal illness, but can be devastating to the fetus. Listeria’s obligate intracellular nature make it a difficult infection to diagnose and treat
It can also cause severe disease in the neonate, including death
What is this?
Deciduitis- acute exuate inflammation with microabscess (3-5 neutrophils collected together) formation within the decidua
What are the main ways placental infections can occur?
they can occur hematogenously or trans-placental. These are typically the TORCH infections and cause a chronic-villitis vs.
ascending from the birthing canal and these cause acute chorioamnionitis
What constitutes a fetal inflammatory response?
Inflammation of umbilical vessels (vasculitis) and cord substance (Wharton’s Jelly) (funisitis) occurs in response to infection, and constitutes the fetal inflammatory response (while choricoamnioitis is the maternal response)
•Inflammation in the umbilical vein is called what? the umbilical arteries?
phlebitis and arteritis
Established or long standing infections of the umbilical cord can cause what?
tissue necrosis and accumulation of cellular debris (necrotizing funisitis)
•Inflammation located at the periphery or surface of the umbilical cord may be the primary pattern seen. What is this called?
(peripheral funisitis)
Describe umbilical infections caused by Candida albicans
Candida is a fungal organsm that is the most common cause of acute chorioamnionitis with peripheral funisitis. Most cases are diagnosed in preterm deliveries
How would umbilica infections caused by Candida present grossly? histo?
● Gross description: well-circumscribed, pale yellow plaques scattered over the surface of the umbilical cord (top)
● Micro description: microabscesses containing yeast in subamniotic layer of umbilical cord; chorioamnionitis or necrotizing funisitis may be present (bottom)
What does this image show?
This is a chronic villitis with CMV
How commonly does CMV cause chronic villitis?
It causes about 10% of chronic villitis cases, but often these infections present with no clinical symptoms
When are fetal CMV infections most severe?
in placentas with plasmacytic villitis and inclusion bodies
Micro description: increased fetal erythroblasts with intranuclear inclusions and villous edema
Most of the time, the donor twin is smaller than the other twin at birth. The infant often has anemia, is dehydrated, and looks pale.
The recipient twin is born larger, with redness to the skin, too much blood, and a higher blood pressure. The twin that gets too much blood may develop cardiac failure because of the high blood volume.
Grossly describe amnion nodosum
Multiple yellow-tan superficial amniotic lesions, 0.2 to 0.4 cm and usually near insertion of umbilical cord
Provide a micro description of amnion nodosum
- Nodules of protuberant eosinophilic fibrinous material with entrapped squamous cells
- Associated with stratified squamous metaplasia
What is Potter sequence?
the atypical physical appearance of a fetus or neonate due to oligohydramnios experienced in the uterus. Oligohydramnios is the decrease in amniotic fluid volume sufficient to cause deformations in morphogenesis of the fetus
clubbed feet, pulmonary hypoplasia, and cranial anomalies = potters sequence
How can the placenta appear in cases of preeclampsia?
Most placentas are smaller than expected (left: normal; right: preeclampsia) and Infarcts and retroplacental hematomas are more common
There is fibrinoid necrosis of the vessel wall (strong eosinophilic staining areas). These are maternal vessels in the decidua.
What is a molar pregnancy?
also known as hydatidiform mole —this is a noncancerous (benign) tumor that develops in the uterus. A molar pregnancy starts when an egg is fertilized, but instead of a normal, viable pregnancy resulting, the placenta develops into an abnormal mass of cysts, often described as a grapelike cluster
T or F. A Complete mole occurs when an egg that has lost its female chromosomes, and as a result the genetic material is completely paternally derived
T. A partial mole occurs due to fertilization of an egg with two sperm
What is the buzzword for a complete hydatidiform mole?
‘Snowstorm”
What is this?
A partial hydatidiform mole- some villi appear normal, whereas others are swollen, avascular, and grape-like (though not as large as a complete mole).
There is minimal trophoblastic proliferation
How do gestational choricocarcinomas appear histologically?
The tumor is composed of syncytiotrophoblastic giant cells in association with cytotrophoblasts on a highly hemorrhagic background.
What is this?
Necrotizing enterocolitis (NEC).
A, entire small bowel is markedly distended with a perilously thin wall (impending perforation).
B, The congested portion of the ileum corresponds to areas of hemorrhagic infarction and transmural necrosis microscopically. Submucosal gas bubbles (pneumatosis intestinalis) can be seen in several areas (arrows).
What is fetal hydrops?
accumulation of edema fluid in the fetus during intrauterine growth.
What is this? When does it classically occur?
Fluid accumulation is particularly prominent in the soft tissues of the neck, and this condition has been termed cystic hygroma.
Cystic hygromas are characteristically seen, but not limited to, constitutional chromosomal anomalies such as 45,X karyotypes (aka Turner syndrome)
