Large Group 1: Embryology -Kuehn

Question 1

What are the 2 methods for determining fetal age? Which method relies on an assumption?

Answer 1

• clinical dating based on first day of LMP (EDD is 40 weeks)
• Embryologists Dating–> Estimated Day of Fertility. based on the assumption that fertilization took place 2 weeks after LMP (EDD is 38 weeks)

Question 2

What is the most critical trimester in embryological development?

Answer 2

1st trimester

Question 3

Using the EDF method, what is considered to be the Embryonic period?

Answer 3

weeks 2-8

Fetal period=weeks 9-38

Question 4

When will the most serious malformations occur in development?

Answer 4

weeks 3-8 when organogenesis is taking place

most embryos will not survive defects in weeks 1-2

Question 5

When does gastrulation take place?

Answer 5

week 3–> day 15

Question 6

What are potential causes of too much amniotic fluid (polyhydramnios) (AFI > 22-24)?

Answer 6

GI trouble (i.e. esophageal atresia, duodenal atresia)

inc urine production (i.e. gestational diabetes)

in utero CHF or hydrops fetalis (twin-twin transfusion, heart defects, congenital infections)

anencephaly

Question 7

What is the circulation of amniotic fluid?

Answer 7

some fluid from the amniotic membrane directly, mostly from the isotonic urine production of the kidneys

excreted through the cloaca/UG sinus to the amniotic sac

Fluid is swallowed via the esophagus –> reabsorbed in the intestines and then excreted through the kidneys (isotonic urine)

fluid also enters the placenta and umbilical veins and some is produced by the fetal lungs

Question 8

How do you measure amniotic fluid in a pregnant woman? What are the requirements for oligohydramnios and polyhydramnios?

Answer 8

US to determine AFI (amniotic fluid index) which is the sum of all 4 quadrants (after the 1st trimester)

oligohydramnios = AFI 22-24

Question 9

What are possible causes of too little amniotic fluid (oligohydramnios)?

Answer 9

GU disease (kidney agenesis/problems, Potter’s syndrome, bladder outlet obstruction)

ruptured amniotic membranes

twin-twin transfusion (donor twin will have oligohydramnios)

Question 10

What are the potential complications in a fetus with severe oligohydramnios (AFI < 5)?

Answer 10

depends on gestational age at occurrence.

umbilical cord compression–> dec HR

restriction in fetal movement–> contractures, asymmetric growth

early oligohydramnios (22-24 weeks) –> Pulmonary hypoplasia

if amniotic membrane is ruptured–> infection and umbilical cord prolapse

Question 11

What are possible complications of polyhydramnios?

Answer 11

Uterine overdistension can trigger preterm labor

Placental abruption post membrane rupture

Post partum hemorrhage

Abnormal fetal lie

Abnormal labor

Uterine rupture (if previous uterine scar, very rare)

Question 12

What can result from twinning after gastrulation?

Answer 12

conjoined twins

Question 13

What will occur if twinning takes place in the first 72 hours of fertilization (as blastomeres)?

Answer 13

dichorionic, diamniotic

Question 14

What happens if twinning takes place in the early blastocyst stage (4-8 days after fertilization)?

Answer 14

monochorionic, diamniotic twins

Question 15

What happens if twinning takes place in the late blastocyst stage (9-12 days after fertilization)?

Answer 15

monochorionic, monoamniotic twins

Question 16

When can twin-twin transfusions take place?

Answer 16

any monochorionic twin

i.e.:
monochorionic, monoamniotic

monochorionic, diamniotic

conjoined twins

Question 17

What are the differences in blood in fetal IVC and SVC?

Answer 17

IVC: carries high O2 blood from the umbilical vein —> through foramen ovale to left atrium
-blood from the ductus arteriosus

SVC: carries low O2 blood from the head and upper limb to the right atria –> right ventricle

Question 18

What happens to the blood of an infant with a persistent truncus arteriosus and associated VSD?

Answer 18

failure of the pulmonary trunk and aorta to separate–> blood is constantly mixed

Question 19

What is the only way an infant can survive with transposition of the great vessels?

Answer 19

patent ductus arteriosus

otherwise there is no mixing of blood and O2

Question 20

What are the 4 ways that Tetralogy of Fallot affects the neonate heart?

Answer 20

-pulmonary stenosis (1st)
then to compensate:
-VSD
-over-riding aorta (aorta sits right over the inter ventricular septum, collecting blood from both ventricles)
-hypertrophy of the right ventricle (may take place after birth)

(can have ASD or persistent ductus arteriosus too)

Question 21

What are some of the clinical signs of Tetralogy of Fallot?

Answer 21

• episodes of dyspnea and cyanosis
• thrill and systolic murmur
• boot-shaped heart on X-ray
• echo: VSD, pulmonary artery stenosis, overriding aorta, right ventricular hypertrophy

Question 22

You are doing an ultrasound on a pregnant woman and note that the fetus has an AFI of 30.  Which of the following  conditions is MOST likely to be present?
A. Esophageal atresia
B. Intrauterine growth restriction
C. Ruptured membranes
D. Tetralogy of Fallot
E. Renal agenesis

Answer 22

A. Esophageal atresia