Module 9: 2nd and 3rd trimester normal anatomy: placenta and cord Flashcards
What is the placenta classified as an organ that does that? 5
- Provides nutrients to the fetus
- Transfer of oxygen
- Removal of fetal waste
- Temperature regulation
- Excretion of hormones (hCG)
What is some of the waste removed by the placenta? 3
- Urea
- Uric acid
- Bilirubin
By 12 weeks gestation how many distinct components of the placenta is recognizable? 2
Two
1. Fetal portion: chorion frondosum
2. Maternal portion: decidua basalis
The fetal and maternal portion of the placenta are held together how?
By anchoring of stem villi at the cytotrophoblast shell
From top to bottom what does the red arrows point to?
- Chorion frondosum
- Decidua basilis
What does the syncytiotrophoblast do?
Create the large intervillous space in the decidua basalis (lacune)
The remaining portions of the decidua basalis are called what?
Placental septa.
The placental septa are divided into what?
Compartments called Cotyledon
What is the functional unit of the placenta?
Cotyledon
Each cotyledon consists of what?
Several stem villi
There are how many cotyledons in a placenta?
about 20
What does the red arrow point to?
Placenta septa
What is the maternal circulation like?
Spiral arterioles shoot blood around the chorionic villi
What is fetal circulation like?
From umbilical arteries to chorionic villi back to umbilical veins to baby
What does this image show?
Left goes towards baby and the right goes towards mom
What is the functions of the placenta? 6
- Respiration
- Nutrition
- Excretion
- Protection
- Storage
- Hormonal production
What is the respiration function of the placenta? 3
- Oxygen in the maternal blood diffuses across the placental membrane into the fetal blood by simple diffusion
- CO2 dioxide also passes readily in the opposite direction
- The placenta, therefore acts as a the lungs of the fetus
What kind of nutrients from the material blood makes it through the membrane into the fetus? 6
Nutrients from maternal blood through the placental membrane into the fetal blood such as,
1. Water
2. inorganic salts
3. Carbs
4. Fats
5. Proteins
6. Vitamins
How does excretion functions of the placenta work? Where is waste excreted?
- waste products cross the placental membrane from the fetal blood and enter the maternal blood
- They are excreted by the mother’s kidneys
How does the placenta protect the baby? Is there blood mixture between mom and baby?
- Most microorganisms do not cross the placental membrane
- There is no appreciable mixture of maternal and fetal blood
The placental membrane is sometimes referred to as what, however they don’t protect against what? 2
Placental barrier but it does not protect the fetus from many damaging agents such as
1. Drugs, poisons, carbon monoxides
2. Certain viruses (Rebella)
Once in a fetus, substances can cause what? What are these known as?
Congenital malformations, these are known as teratogens
What is the storage function of the placenta? What is stored? 5
Nutrients are stored in the placenta and area released into fetal circulation as required. Some things stored are:
1. Carbs
2. Proteins
3. Calcium
4. Iron
Where are hormones produced in the placenta? What is produced? 5
Production of the following hormones by the syncytiotrophoblasts
1. HCG
2. Estrogen
3. Progesterone
4. Human chorionic somatomammotropin (HPL human placental lactogen)
What is the sonographic appearance of the placenta around 10-12 weeks? What is present along the basal plate and in the septa?
- Diffuse granular echo pattern, apparent as early as 10-12 weeks (texture is produced by the echoes from the villi)
- Draining veins are present along the entire basal plate and in the septa
In terms of the sonographic appearance, the basic texture does not change with gestational age except for what?
The deposition of calcium
Placental calcifications are present in what amount? And when?
> 50% of placentas after 33 weeks
Calcium deposits are found primarily where? Where might they be found?
- The basal plate and septa
- May be seen in the subchorionic and perivillous space
Amount of calcification is increased in patients with what? 3
- IUGR
- Hypertension
- Smoking
What does this image demonstrate?
The early sonographic appearance of the placenta
What does this image demonstrate?
Normal placenta
What does these images demonstrate?
Maternal Lakes
When grading the placenta what is grade 0?
Homogenous, chorionic plate is straight
What is a grade 1 placenta
Scattered echogenic areas, subtle undulations
What is a grade 2 placenta?
Indentations, linear echogenic areas
What is a grade three placenta?
Indentations to the basal layers, cystic areas, shadowing calcifications (after 36 weeks)
what does this image demonstrate?
Grade 0 Placenta
what does this image demonstrate?
Chorionic plate is smooth
What does this image demonstrate?
Grade 1 Placenta: subtle chorionic plate indentations
What does this image demonstrate?
Grade 1 random echogenic areas
What does this image demonstrate?
Grade 1 (almost 2) placenta
What does this image demonstrate?
Grade 2 indentations, linear echogenic areas
What does this image demonstrate?
Grade 2 (almost 3) placenta
What does this image demonstrate?
Grade 3: indentations to basal layer
What does this image demonstrate?
Indentations to basal layer
What is the size and the shape of the placenta? How heavy is it? How thick is it?
- Flat and circular
- 500-600 grams
- thickness is around 1.5-4cm
The placenta grows how much a week?
1mm a week
What do we not include in the placenta?
Myometrium or retroplacental complex
What is placentamegaly?
When the placenta that is >4cm in thickenss
What causes placentamegaly? 7
- Maternal diabetes
- Maternal Anemia
- Hydrops
- Placental hemorrhage
- Intrauterine infection
- Partial mole
- Chromosomal abnormalities
What is a thin placenta?
<1.5cm in thickness
What causes thin placentas? 2
- Vascular deficiencies or infarctions
- Pre-eclampsia - BP increase
What might thin placenta result in? ( In terms of the fetus)
IUGR or small baby
What are symptoms of pre-eclampsia? 3
- Hypertension
- Proteinuria
- Edema
What does the umbilical cord form a connecting stalk with?
Yolk Sac
What vessels does the umbilical cord contain?
2 arteries and 1 vein
what is the vessels in the umbilical surrounded by?
Wharton jelly
What is the umbilical covered in?
Amnion
How long is the amnion?
50-100cm long
Where should the umbilical cord insert into?
Center of placenta
The umbilical vein travels in which direction? ( Cephalic or caudal)
Travels cephalad to the portal sinus in the fetus
Umbilical arteries travel how? ( Caudal or cephalic) What do they eventually become?
Caudad to become the hypogastric arteries around fetal bladder?
What is being measured here?
A fibroid
What is a single umbilical artery anomaly called? How often is this finding? What is indicated if we see this?
- Two vessel cord
- Often an isolated finding and very common
- Feal echo is indicated
What can single umbilical artery associated with? 2
- Cardiac and renal anomalies
- Chromosome abnormalities
What does this image point towards?
Single umbilical artery
What is a uncommon cord anomaly?
Cord syst which is a allantoic remnant
What are some cord anomalies? 5
- Cord cyst
- Omphalocele
- Cord prolapse
- Hematoma
- Umbilical vein thrombosis
What is this an image of?
Two umbilical arteries
What does this image demonstrate?
Single umbilical artery and how it travels
What does the red arrow point to?
Cord cyst
What does this image demonstrate?
Omphalocele
What does this image demonstrate?
Cord prolapse
What causes a hematoma in the umbilical cord, and what is the risk? 2
- Caused by trauma or wall weakness
- High risk of perinatal death
What is umbilical vein thrombus? How can this develop? What is the risk level of this?
- Occlusion of vein secondary to increased resistance or stasis
- Can develop due to umbilical vein varix or blockage
- High risk of perinatal death
What is umbilical vein varix?
Intra-abdominal focal enlargement of the umbilical vein
What may occur during umbilical vein varix? and what might it be associated with?
- Stasis may occur here and blood may clot
- Associated with a higher incidence of adverse outcomes
What does this image demonstrate?
Umbilical vein varix
What does this image demonstrate?
Umbilical vein varix
What does these images demonstrate?
Umbilical vein varix