GI development US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for GI development. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
GI development US Medical PG Question 1: A 7-month-old boy is brought to the ED by his mother because of abdominal pain. Two weeks ago, she noticed he had a fever and looser stools, but both resolved after a few days. One week ago, he began to experience periodic episodes during which he would curl up into a ball, scream, and cry. The episodes lasted a few minutes, and were occasionally followed by vomiting. Between events, he was completely normal. She says the episodes have become more frequent over time, and this morning, she noticed blood in his diaper. In the ED, his vitals are within normal ranges, and his physical exam is normal. After confirming the diagnosis with an abdominal ultrasound, what is the next step in management?
- A. Supportive care
- B. Broad-spectrum antibiotics
- C. Air contrast enema (Correct Answer)
- D. Abdominal laparotomy
- E. Abdominal CT scan
GI development Explanation: ***Air contrast enema***
- An **air contrast enema** is both diagnostic and therapeutic for **intussusception**, which is strongly suggested by the patient's symptoms (colicky abdominal pain, drawing legs to chest, currant jelly stools).
- It uses air pressure to **reduce the intussusception**, avoiding surgery if successful and the bowel is not compromised.
*Supportive care*
- While supportive care (IV fluids, pain control) is important, it does not address the underlying mechanical issue of **intussusception** and would not resolve the condition.
- Delaying definitive treatment for intussusception can lead to **bowel ischemia, necrosis, and perforation**, which are life-threatening.
*Broad-spectrum antibiotics*
- Antibiotics are not the primary treatment for **intussusception**, as it is a mechanical obstruction, not typically a primary infection.
- They might be considered if there are signs of **perforation or peritonitis**, but the immediate goal is reduction.
*Abdominal laparotomy*
- An **abdominal laparotomy** is a surgical intervention reserved for cases where **non-operative reduction** (like an air enema) fails or if there are signs of **bowel perforation or gangrene**.
- It is not the *first-line* next step after diagnosis, especially if non-invasive options remain viable.
*Abdominal CT scan*
- An **abdominal CT scan** can diagnose intussusception but is typically not the preferred initial imaging because it involves **radiation exposure** and **does not offer therapeutic benefit**, unlike an air contrast enema.
- Abdominal ultrasound is usually sufficient for diagnosis and safer for pediatric patients.
GI development US Medical PG Question 2: A 13-year-old girl presents to an orthopedic surgeon for evaluation of a spinal curvature that was discovered during a school screening. She has otherwise been healthy and does not take any medications. On presentation, she is found to have significant asymmetry of her back and is sent for a spine radiograph. The radiograph reveals a unilateral rib attached to the left transverse process of the C7 vertebrae. Abnormal expression of which of the following genes is most likely responsible for this finding?
- A. WNT7
- B. FGF
- C. Homeobox (Correct Answer)
- D. PAX
- E. Sonic hedgehog
GI development Explanation: ***Homeobox***
- **Homeobox genes (HOX genes)** play a crucial role in specifying the identity of vertebral segments along the **craniocaudal axis** during embryonic development.
- An abnormal expression of these genes can lead to **skeletal malformations**, such as the formation of a **cervical rib**, by altering the segmental identity of the C7 vertebra.
*WNT7*
- **WNT7 genes** are involved in limb patterning and have a role in the formation of the **dorsoventral axis** of the limb and kidney development.
- They are not primarily associated with vertebral segmentation or the formation of cervical ribs.
*FGF*
- **Fibroblast growth factor (FGF) genes** are essential for various processes, including limb development, neurogenesis, and angiogenesis.
- While they are involved in numerous developmental pathways, they are not the primary genes responsible for specifying vertebral identity and thus cervical rib formation.
*PAX*
- **PAX genes** are a family of transcription factors critical for organ development, especially of the eye, brain, and kidney.
- While important for development, they are not directly implicated in the specification of vertebral segments or the pathogenesis of cervical ribs.
*Sonic hedgehog*
- **Sonic hedgehog (SHH)** signaling is a key pathway in embryonic development, particularly for pattern formation in the neural tube, limbs, and facial structures.
- While crucial for body axis development and segmentation, **HOX genes** have a more direct role in determining the specific identity of vertebral segments and causing cervical ribs.
GI development US Medical PG Question 3: A research team is studying certain congenital anomalies of the respiratory tract. The method consists of marking a certain germinal layer with an isotope, following its development stages in chicken embryos, and finally analyzing the specimen. A given specimen of tissue is presented in the exhibit. Which of the following germinal structures most likely gave rise to the epithelial lining of this specimen?
- A. Ectoderm
- B. Neural crest
- C. Mesoderm
- D. Endoderm (Correct Answer)
- E. Surface ectoderm
GI development Explanation: ***Endoderm***
- The **epithelial lining** of the entire respiratory tract, including the larynx, trachea, bronchi, and lungs, is derived from the **endoderm**.
- The **laryngotracheal groove** develops from the ventral wall of the primitive foregut, which is endodermal in origin, further differentiating into the respiratory tree.
*Ectoderm*
- The **ectoderm** primarily forms the epidermis, hair, nails, and the nervous system (brain and spinal cord).
- It does not contribute to the internal epithelial lining of the respiratory tract.
*Neural crest*
- **Neural crest cells** contribute to a wide variety of structures, including components of the peripheral nervous system, head mesenchyme, and melanocytes.
- They are not involved in forming the epithelial lining of the respiratory system.
*Mesoderm*
- The **mesoderm** forms the connective tissue, cartilage, and muscle components of the respiratory tract, such as the smooth muscle and cartilage rings of the trachea and bronchi, and the visceral pleura.
- However, it does not form the epithelial lining itself.
*Surface ectoderm*
- **Surface ectoderm** specifically gives rise to the epidermis, hair, nails, and glands of the skin, as well as the oral cavity epithelium.
- It does not contribute to the internal epithelial structures of the respiratory tract.
GI development US Medical PG Question 4: A 10-month-old infant is brought in by his parents because he is vomiting and not passing stool. His parents say he has vomited multiple times over the past couple of hours, but the most recent vomit was green. The patient has no significant past medical history. On physical examination, the patient is irritable and crying. On palpation in the periumbilical region, an abdominal mass is present. Emergency laparotomy is performed, which shows a part of the patient’s intestine folded into the section adjacent to it. Which of the following is the most likely diagnosis for this patient?
- A. Pyloric stenosis
- B. Hirschsprung’s disease
- C. Duodenal atresia
- D. Intussusception (Correct Answer)
- E. Meckel’s diverticulum
GI development Explanation: ***Intussusception***
- This diagnosis is highly suggested by the classic presentation of a 10-month-old infant with **bilious vomiting**, **abdominal pain** (irritability), and an **abdominal mass** in the periumbilical region, coupled with the surgical finding of one part of the intestine telescoping into an adjacent section.
- The sudden onset of symptoms in an otherwise healthy infant, along with **green vomit** (indicating bile) and an acute abdomen, are hallmark signs of this condition.
*Pyloric stenosis*
- This condition typically presents with **non-bilious projectile vomiting** in infants usually between 3 weeks and 6 months of age, with an **olive-shaped mass** in the epigastrium.
- The patient's **bilious vomiting** and the specific finding of intestinal telescoping rule out pyloric stenosis.
*Hirschsprung’s disease*
- This condition usually presents with **failure to pass meconium** in the neonatal period or chronic constipation and abdominal distension in older infants.
- While it involves the intestine, it is a **motility disorder** due to the absence of ganglion cells, not an anatomical telescoping of bowel.
*Duodenal atresia*
- This is a congenital obstruction of the duodenum, typically diagnosed shortly after birth with **bilious vomiting** and a characteristic "**double bubble**" sign on X-ray.
- It would not involve an abdominal mass or the intussusception described.
*Meckel’s diverticulum*
- This condition is a remnant of the vitelline duct and can present with painless rectal bleeding or, less commonly, intestinal obstruction, **volvulus**, or **intussusception** if it acts as a lead point.
- While it can be a rare cause of intussusception, the question directly describes the pathophysiology of intussusception itself rather than a diverticulum causing it.
GI development US Medical PG Question 5: A 4-month-old girl is brought to the physician because she has been regurgitating and vomiting 10–15 minutes after feeding for the past 3 weeks. She is breastfed and formula-fed. She was born at 38 weeks' gestation and weighed 2966 g (6 lb 9 oz). She currently weighs 5878 g (12 lb 15 oz). She appears healthy. Vital signs are within normal limits. Examination shows a soft and nontender abdomen and no organomegaly. Which of the following is the most appropriate next best step in management?
- A. Upper endoscopy
- B. Ultrasound of the abdomen
- C. Esophageal pH monitoring
- D. Positioning therapy (Correct Answer)
- E. Pantoprazole therapy
GI development Explanation: ***Positioning therapy***
- This infant is thriving, as evidenced by her significant weight gain, despite her regurgitation and vomiting. Her examination is also benign. These features make **gastroesophageal reflux (GER)**, a physiological process, the most likely diagnosis.
- **Positioning therapy** (e.g., keeping the infant upright during and after feeds) is a first-line, conservative management strategy for GER in infants who are otherwise healthy and gaining weight well.
*Upper endoscopy*
- **Upper endoscopy** is an invasive procedure and is typically reserved for evaluating patients with suspected complicated gastroesophageal reflux disease (GERD), such as those with **poor weight gain**, **hematemesis**, or **esophagitis**, none of which are seen here.
- It would not be the initial step in a thriving infant with symptoms consistent with uncomplicated GER.
*Ultrasound of the abdomen*
- An **abdominal ultrasound** is primarily used to diagnose **pyloric stenosis** in infants, which typically presents with **projectile, non-bilious vomiting** and **poor weight gain** or weight loss, usually between 3 and 6 weeks of age.
- This infant's symptoms are different in character (regurgitation/vomiting 10-15 minutes after feeding, not projectile) and she is gaining weight well, making pyloric stenosis less likely.
*Esophageal pH monitoring*
- **Esophageal pH monitoring** is used to quantify acid reflux episodes and is typically reserved for infants with atypical symptoms, suspected **complicated GERD**, or those who have failed empirical therapy.
- It is not indicated as a primary diagnostic or management step in a healthy, thriving infant with typical GER symptoms.
*Pantoprazole therapy*
- **Proton pump inhibitors (PPIs)** like pantoprazole are used to treat **GERD** by reducing stomach acid production, especially in cases with evidence of **esophagitis** or significant symptoms impacting growth or comfort.
- Given this infant is thriving and has no signs of complications, acid-suppressing medication is not appropriate as the initial management step; conservative measures should be tried first.
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