Embryo Questions

Question 1

1. A baby is born with symptoms typical of Pierre Robin syndrome with a smaller than normal mandible (micrognathia), a posteriorly placed tongue, and a failure of the secondary palate to close. Which of the following structures is most likely involved in the defective development? (entrapment of the mandible by the clavicle)

Answer 1

Answer: Pharyngeal Arch 1 (failure of neural crest cells to migrate)
hypoplasia of the mandible causing posterior position of the tongue→prevents palate from closing→risk of tongue falling backwards

Question 2

2. A 26 yo woman comes to the clinic for a pre-natal checkup in her second trimester. Ultrasound showed reduced amniotic fluid (oligohydramnios). Further investigation by MRI showed compression of the limbs and face (such as in Potter’s syndrome), a lung-head ratio of 1.4), and bilateral renal agenesis. A thoracic deformity associated with all these findings is:

Answer 2

Answer: Pulmonary Hypoplasia
Secondary pulmonary hypoplasia –from compression of the lateral thoracic spaces… (the uterus compresses the thorax during development leading to reduced lung volume though bronchi and alveoli are still present.

Question 3

3. Concerned parents brought their 6 yo son to the clinic, because he had an abnormal spray pattern during urination and on further examination they also noticed he had a downward curvature of the penis called chordee. The doctor told them that their son has hypospadias that could easily be fixed with surgery. Hypospadias, the most common birth defect in male genitalia, is due to which of the following?

Answer 3

Answer: Failure of the urethral folds to fuse at the midline
Improper androgen levels lead to failure of fusion of ventral urethral folds on glans, shaft, or scrotum
Glans=ectoderm
Mesoderm=Shaft

Question 4

4. All of the following statements regarding tracheoesophageal fistulas (TEF) are true EXCEPT:

Answer 4

a. Most common is proximal pouch (EA) with distal TEF
b. Symptoms: unable to swallow, constant regurgitation, excessive saliva and mucous in nose and mouth, abdominal distention during crying, pneumonitis, Distal TEF will have gas in bowel. Inability to pass catheter into stomach.

c. Causes: 1:3000, abnormal connection between trachea and esophagus, improper division of foregut by tracheoesophageal septum,
d. VACTERL associated symptoms (Vertebral, Anal atresia, cardiac-most common, Tracheoesophageal fistula, EA, renal, limb defects), Polyhydramnios and small fetal stomach bubble (poor predictor),
e. Treatment: Surgery (thorascopic approach safest), anastomotic leaking, 90% survival

During Esophageal Atresia ends in to a blind pouch rather than stomach (EA) Tracheoesophageal septum drifts too far dorsally EA, hypertrophic pyloric stenosis

Question 5

5. A 4-day old male newborn presents to the ER with constipation and a distended abdomen. His mother tells the medical team that he has not had a bowel movement since birth. The ER resident orders an abdominal radiograph and it shows a distended colon. A second abdominal radiograph is ordered following a barium enema and it shows a funnel-like narrowing of the distal colon consistent with Hirschsprung’s Disease. Which of the following is associated with this condition?

Answer 5

• Answer: Lack of neural crest cell migration to colon
• Constipation/fecal retention
• Lack of passage of myconium within 48 hours after birth in a newborn
• Greenish/brown emesis
• Histopathology (definitive) and an abdominal radiograph with Barium contrast

Question 6

6. All of the following are common features of DiGeorge syndrome EXCEPT: (aka congenital thymic aplasia)

Answer 6

• Answer:
• Cardiac Abnormalities
• Abnormal Facies
• Thymic Aplasia
• Cleft Palate
• Hypocalcemia/Hypoparathyroidism
• REMEMEBER: CATCH-22 (On chromosome 22)

Question 7

7. A medical student is attending rounds in the Neonatal ICU. One of the infants was born with a malformation of the coronary sinus. From which embryonic structure does the coronary sinus develop?

Answer 7

Answer: Sinus Venosus

Question 8

8. A 32 yo woman comes to the ER after her third consecutive spontaneous abortion. Two years ago she gave birth to a child delivered prematurely and born with craniofacial deformations that were suspected to be due to restricted intrauterine growth. When she expressed the desire to conceive again, her physician suggested a pelvic MRI in an effort to determine the cause for her recurrent spontaneous abortions. The MRI revealed that she has a bicornuate uterus, which is caused by:

Answer 8

Answer: incomplete fusion of the Mullerian or paramesonephric ducts of the female during embryological development
Linked to Hox A10, A11, A13

Question 9

9. A 7 yo girl with monosomy X (Turner Syndrome) presents with recurrent urinary tract infections due to abnormally positioned kidneys, fused at the lower poles (i.e. horseshoe kidney). Which artery prevented complete ascent of her kidneys during development?”

Answer 9

Answer: Inferior Mesenteric Artery

Question 10

1. A pregnant diabetic woman presents to the clinic for her 2nd trimester checkup. A blood test indicated high alpha-fetoprotein levels. Ultrasound examination shows midline facial malformations (e.g. fused eyes, midline cleft lip) and fetal MRI shows a lack of interhemispheric fissure development of the brain. Genetic analysis shows polymorphism in MTHFR, an enzyme of folate metabolism. These findings are consistent with which of the following neural tube disorders?

Answer 10

Answer: Holoprosencephaly: failure of prosencephalon cleavage during the 5th and 6th week
Specifically: alobar holoprosencephaly

Question 11

11. What fetal ultrasound image would reliably diagnose annular pancreas?

Answer 11

Answer: Double bubble sign (amniotic fluid in stomach+duodenum) or Hyperechogenic band (tissue visualized due to ring of pancreatic tissue

Question 12

12. A newborn presents with a large fluid filled sac in the lumbar region of the infant’s back. The sac contains parts of the lumbar spinal cord. You are unable to see light through the sac (meaning that the spinal cord is in there too). In addition, the infant seems to have Arnold-Chiari II malformation (cerebellum is actually pulled into the foramen magnum) and hydrocephaly (cerebellum is pulled downward blocking normal circulation of CSF and a build up of fluid in the subarachnoid space). Based on this information, what is your diagnosis?

Answer 12

Answer: Myelomeningocele Spina Bifida Cystica

Question 13

13. A premature infant develops progressive difficulty breathing over the first few days of life. Deficient surfactant synthesis by which of the following cell types may be contributing to the infant’s respiratory problems?

Answer 13

Answer: Type II pneumocytes

Question 14

14. Which of the following is true regarding development of the thymus?

Answer 14

Answer:
• Thymic epithelial cells (TECs) are derived from 3rd and 4th pharyngeal pouches and migrate medially and caudally into the superior mediastinum.
• After migration, neural crest cells envelope the thymus to form septa and the capsule.
• Migration and colonization of immature T-cells from bone marrow begin differentiation of cortex and medulla.
• Components of the functional thymus have multiple origins: TECs, neural crest cells, and immature T-cells from bone marrow.
• Thymic production and release of mature T-cells begin between weeks 14-16 gestation and continues after birth.

Question 15

15. A 4 yo boy is brought to your office for a chest x-ray because a few days ago he suddenly fainted when he was running around at the pre-school playground. You are told that the child had slight cyanosis when he fainted, and a chest X-ray showed a “boot shaped heart.” With this child’s most likely diagnosis, you should expect to see all of the following features EXCEPT:

Answer 15

Answer: Pulmonary Stenosis
Right Ventricular Hypertrophy
Overriding Aorta
Ventricular Septal Defect

Think PROVe for remembering

Dx: Tetralogy of Fallot – should see murmur, feeding difficulty, dec growth/development, dyspnea, clubbing of fingers and toes, tet spells, squatting
Should not see -?

Question 16

16. A female newborn presents with several anomalies, the most noticeable being a protruding intestinal sac within the umbilicus that is enclosed in amnion (this is the big difference between OMPHALOCELE and GASTRICHIS) . Her mother is 19 yo and is generally healthy. Which condition did the newborn most likely present with?

Answer 16

Answer: Omphalocele: CAUSED BY FAILURE OF MIDGUT TO RE-ENTER ABDOMEN DURING GUT ROTATION-→OCCURS AT UMBILICAL RING, BOWEL IS FUNCTIONAL, DELIVERY NORMAL DEPENDING ON SIZE, USUALLY SEE OTHER ABNORMALITIES WITH THIS DEFECT

GASTRICHIS →OCCURS USUALLY DUE TO WEAKNESS IN RIGHT ABDOMINAL WALL VIA A VASCULAR ABNORMALITY, BOWEL MAY NOT BE FUNCTIONAL, NOT ASSOCIATED WITH OTHER ABNORMALITIES, DELIVERY USUALLY NORMAL

Question 17

17. A mother takes her in 4 yo son to the pediatrician to check for an upper respiratory tract infection. During the examination, the physician detects an anterior, midline neck mass that moves when he swallows. A CT scan reveals that the mass is associated with the hyoid bone. What is the most likely diagnosis?

Answer 17

Answer: HIGHEST SUSPICION→Thyroglossal Duct Cyst (USUALLY ASYMPTOMATIC→BUT IS TROUBLESOME IN INFECTED AS IN THE ABOVE CASE)

LESSER LEVEL OF SUSPICION→Ectopic Thyroid

Question 18

18. A 28 yo patient in her 20th week of gestation comes in for her regular OB checkup. When measuring the distance from the top of the fundus to the symphysis pubis, the physician is concerned to find that the uterine size is small. The physician concludes that this is due to oligohydramnios, or low amounts of amniotic fluid. Ultrasound showed that the fetus had bilateral renal agenesis. What is the immediate cause of death?

Answer 18

Answer: Pulmonary Hypoplasia – causing resp failure
BILATERAL RENAL HYPERPLASIA→OLOGOHYDRAMNIOS→POTTER’S SEQUENCE→PULMONARY HYPOPLASIA→RESPIRATORY FAILURE FOLLOWING BIRTH (40% WITH BRA ARE STILLBORN

Question 19

19. Each of the following is associated with achondroplasia EXCEPT:

Answer 19

Answer: Things in red in .ppt
Spontaneous single-nucleotide substitution in FGFR3 gene
Narrow and disorganized zones of proliferation and hypertrophy of hyaline cartilage
Progressive discordance between femur length and biparietal diameter by a given gestational age ALONE is sufficient evidence upon which one can diagnose achondroplasia prenatally.
Dx. After Birth Requires Radiographic Studies
Normal life expectancy
Macrocephaly
Trident hands

Question 20

20. An infant is born at 35 weeks’ gestation (full-term is 40 weeks) with a birth weight of 4 lbs. and 6 oz. at a rural hospital. During the pregnancy, the mother had a rubella infection. Two weeks after birth, the pediatrician notices that the infant appears breathless and weighed in at 4 lbs. and 2 oz. The pediatrician performs a physical exam and orders an echocardiogram. After confirming his suspicions, he administers ibuprofen to the infant. The infant recovers completely as a result of this treatment. Which of the following defects is the infant most likely to possess?

Answer 20

Answer: Patent Ductus Arteriosus

Question 21

21. Which of the following gives rise to all structures of the kidney?

Answer 21

Answer: Intermediate Mesoderm

— intermediate mesoderm from UG ridge

Question 22

22. Failure of fusion of the septum primum and septum secundum results in which of the following?

Answer 22

Answer: Patent Foramen Ovale

-patent foramen ovale or probe patent foramen ovale?

Question 23

23. A 3 1/2 yo male presents with abdominal pain, fever, and constipation. Blood is found in his stool, with no associated pain. A radiograph exhibited a 2” process found about 2 feet proximal to the ileocecal valve. Ectopic gastric and pancreatic tissue was found in a biopsy. What would be the best diagnosis?

Answer 23

Answer: Meckel’s Diverticulum (remnant of vitelline/omphalomesenteric duct that has failed to involute during gestation)
	--- note rule of 2s
•		2% of the population affected
•	2% of cases are symptomatic
•	2 years typical age of presentation
•	2:1 male to female representation
•	2 feet proximal to the iliocecal valve
•	2 cm in diameter
•	2 inches in length
•	2 types of ectopic tissue (gastric and pancreatic)

Question 24

24. What is the recommended treatment for a tubal ectopic pregnancy?

Answer 24

Answer: Methotrexate Administration
Unilateral salpingostomy, salpingotomy, fimbrial expression
Unilateral salpingectomy with cornual resection
Exploratory laparotomy if presents with tubal rupture

Question 25

25. A 5 week old infant presents with projectile vomiting after feeding. The child was previously feeding normally. Upon examination, a small olive-like mass is palpated in the right subcostal area adjacent to the midline. Which disorder might you suspect in the infant?

Answer 25

• Answer: Infantile hypertrophic pyloric stenosis

Question 26

1. During a scheduled check-up, a healthy 35 yo woman undergoes a routine ultrasound which shows her to be pregnant with typical dizygotic twins. What type of chorion and amnion formation would be seen?

Answer 26

Answer: Diamniotic-dichorionic membrane

Question 27

27. A newborn male of East Asian descent presents to craniofacial clinic with bilateral cleft lip. His mother complains that he is having difficulty feeding. No airway obstruction is noted, and he is scheduled for a surgical cleft lip adhesion at 10 weeks. Which facial prominences fail to fuse in the formation of cleft lip? (facial prominences are tissue outgrowth derived from the neural crest and mesenchyme of the 1st pharyngeal arch)

Answer 27

Answer: It is due to the failure of fusion of the maxillary swellings and the merged medial nasal processes (aka the intermaxillary process)

Question 28

28. A 27 yo new mother brings her daughter in for her two week old visit. Ultrasonograpy during her 6th month of pregnancy showed the fetus to have unilateral multicystic dysplastic kidney disease. What is the prognosis for this infant?

Answer 28

Answer: Normal human function
–unilateral is asymptomatic
however -potential for malignant transformation to wilms tumor
-more prone to UTI in contralateral kidney
-more prone to have ureter defects in contralateral kidney

• Patient should have ultrasound every 6-12 months through childhood to ensure that kidney is disappearing as it should.
• Possible complications associated with having only one kidney apply to the patient throughout life.