Gastroenterology — MCQs

Gastroenterology Indian Medical PG Practice Questions and MCQs

Question 331: What is the standard citrate content in Oral Rehydration Solution (ORS) in millimoles per liter?

A. 30
B. 20
C. 10 (Correct Answer)
D. 40

Explanation: ***10*** - The **standard citrate content** in Oral Rehydration Solution (ORS), as per WHO guidelines, is **10 mmol/L**. - WHO ORS (2006 formulation) contains trisodium citrate dihydrate at 2.9 g/L, providing 10 mmol/L of citrate. - Citrate serves as a **bicarbonate precursor**, helping to correct metabolic acidosis often associated with dehydration. *20* - This value is **higher than the recommended** citrate concentration for standard ORS formulations. - Excessive citrate could potentially lead to **unwanted side effects** or alter the solution's osmolarity. *30* - This concentration is **significantly above** the standard citrate content in ORS when expressed in mmol/L. - Note: 10 mmol/L of trivalent citrate equals 30 mEq/L, but WHO guidelines express citrate in mmol/L, not mEq/L. *40* - This represents an **extremely high** citrate concentration for ORS. - Such a high level would be **detrimental** and is not used in standard oral rehydration therapy.

Question 332: Which of the following statements is true regarding Hirschsprung's disease?

A. The rectum is the most common site affected. (Correct Answer)
B. The aganglionic segment is dilated, not contracted.
C. Barium enema is the gold standard for definitive diagnosis.
D. Calcification is a typical feature of this disorder.

Explanation: ***The rectum is the most common site affected.*** - Hirschsprung's disease is a **congenital aganglionic megacolon**, where a segment of the colon lacks parasympathetic ganglia. - The **rectum** is almost always involved (nearly 100% of cases), with involvement extending proximally to varying degrees. - Most commonly affects the **rectosigmoid region** (75-80% of cases). *The aganglionic segment is dilated, not contracted.* - The aganglionic segment is typically **constricted** and **non-peristaltic**, leading to functional obstruction. - The bowel proximal to the aganglionic segment becomes **dilated** due to stool accumulation. - This creates the characteristic **transition zone** seen on imaging. *Barium enema is the gold standard for definitive diagnosis.* - While **barium enema** can show a transition zone and dilated proximal bowel, it is NOT the gold standard. - The **gold standard** for definitive diagnosis is **rectal biopsy** demonstrating absence of ganglion cells and presence of hypertrophied nerve trunks. - Barium enema is a useful diagnostic tool but not definitive on its own. *Calcification is a typical feature of this disorder.* - **Calcification** is not a feature of Hirschsprung's disease. - The pathology involves the **absence of ganglion cells** in the myenteric (Auerbach's) and submucosal (Meissner's) plexuses, not calcific deposits.

Question 333: Congenital megacolon develops secondary to failure of which?

A. Failure of enteric neurogenesis
B. Failure of external anal sphincter relaxation
C. Failure of migration of vagal neural crest cells to the gut (Correct Answer)
D. Failure of the defecation reflex development

Explanation: ***Failure of migration of vagal neural crest cells to the gut*** - **Congenital megacolon**, also known as **Hirschsprung disease**, results from the **failure of neural crest cells** to migrate completely during embryonic development. - These neural crest cells usually form the **submucosal (Meissner's) and myenteric (Auerbach's) plexuses** in the colon, which are essential for normal bowel motility. *Failure of enteric neurogenesis* - While ultimately leading to a lack of enteric nerves, this option is less specific. The primary defect is a failure of **migration** of the precursor cells (neural crest cells), rather than a failure of the neurogenesis process itself once the cells are in place. - **Enteric neurogenesis** usually occurs from neural crest cells that have successfully migrated to the gut wall. *Failure of external anal sphincter relaxation* - This description typically refers to conditions like **anismus** or pelvic floor dyssynergia, which are acquired disorders of defecation, not a congenital malformation like megacolon. - **Hirschsprung disease** involves the internal anal sphincter (which is aganglionic), not primarily the external anal sphincter. *Failure of the defecation reflex development* - The **defecation reflex** relies on intact enteric nervous system and extrinsic nerves. Dysfunction of this reflex in Hirschsprung disease is a consequence of the underlying aganglionosis. - This option describes a symptom or consequence rather than the fundamental embryonic defect.

Question 334: Which of the following conditions is most commonly associated with childhood cholelithiasis?

A. Total parenteral nutrition (TPN)
B. Sickle cell disease
C. Hereditary spherocytosis (Correct Answer)
D. Cystic fibrosis

Explanation: ***Hereditary spherocytosis*** - This condition leads to chronic **hemolysis** due to defective red blood cell membranes, causing premature destruction of red blood cells. - The increased breakdown of red blood cells results in elevated levels of **unconjugated bilirubin**, which is then excreted into bile, increasing the risk of **pigment gallstones** and cholelithiasis. *Sickle cell disease* - While sickle cell disease is a hemolytic condition that can cause **cholelithiasis** due to chronic hemolysis, it is generally less common in childhood compared to hereditary spherocytosis. - Sickle cell disease more frequently presents with **vaso-occlusive crises** and other complications like acute chest syndrome or dactylitis. *Total parenteral nutrition (TPN)* - TPN can lead to cholelithiasis, but this is due to **biliary stasis** and sludge formation from prolonged lack of oral intake, rather than hemolysis. - It's a risk factor for gallstones, but it is not a hemolytic condition itself. *Cystic fibrosis* - Patients with cystic fibrosis are at an increased risk of gallstones, primarily due to **abnormal bile composition** and mucin hypersecretion, which can lead to biliary sludge and stone formation. - Cholelithiasis in cystic fibrosis is not typically linked to a **hemolytic process**.

Question 335: What is the most common surgical cause of abdominal pain in children?

A. Porphyria
B. Worm colic
C. Lead poisoning
D. Appendicitis (Correct Answer)

Explanation: ***Appendicitis*** - **Appendicitis** is the most common surgical emergency in children, presenting with abdominal pain that often localizes to the right lower quadrant. - The pain is typically initially periumbilical, then migrates to the **right lower quadrant**, and may be accompanied by fever, nausea, vomiting, and anorexia. *Porphyria* - **Porphyria** is a rare metabolic disorder that can cause severe abdominal pain, but it is not a surgical condition and is not the most common cause of abdominal pain in children. - Abdominal pain in porphyria is often accompanied by neurological and psychiatric symptoms, which are distinct from the presentation of appendicitis. *Worm colic* - **Worm colic**, or intestinal obstruction due to a large burden of parasitic worms, can cause abdominal pain but is less common in developed countries and is not typically a surgical emergency requiring immediate intervention in the same way appendicitis is. - Diagnosis is usually made by identifying parasites in stool samples, and treatment involves anthelmintic medications rather than surgery. *Lead poisoning* - **Lead poisoning** can cause abdominal pain, often referred to as "lead colic," along with other systemic symptoms such as constipation, neurological issues, and anemia. - It is a medical condition managed with chelation therapy and environmental remediation, not a surgical cause of abdominal pain.

Question 336: Which of the following statements is not true regarding hypertrophic pyloric stenosis?

A. Usually presents between 2 - 8 weeks
B. Dilated stomach with significant gas (Correct Answer)
C. Common in males
D. Ultrasound is the investigation of choice for diagnosis.

Explanation: ***Dilated stomach with significant gas*** - This statement is **not true** as described because while the stomach may be dilated in **hypertrophic pyloric stenosis**, the key radiographic finding is a **gas-filled stomach with absent or minimal gas distally** in the bowel. - The phrase "significant gas" is misleading because the characteristic finding is actually **gastric distention with gas** but **lack of gas beyond the pyloric obstruction**. - On imaging, you see a **dilated, fluid-filled stomach** (often described as the "caterpillar sign" on ultrasound) with minimal air in the duodenum and distal bowel, not "significant gas" throughout. *Ultrasound is the investigation of choice for diagnosis* - **Ultrasound** is indeed the gold standard for diagnosing hypertrophic pyloric stenosis, offering a non-invasive and accurate way to measure **pyloric muscle thickness** and length. - Typical ultrasound findings include a **pyloric muscle thickness** greater than 3 mm and a pyloric channel length greater than 14-16 mm. - The "target sign" or "doughnut sign" on transverse view is pathognomonic. *Usually presents between 2 - 8 weeks* - Hypertrophic pyloric stenosis commonly manifests between **2 and 8 weeks** of life, with peak incidence around 3-5 weeks. - This presentation typically follows a period of normal feeding before the characteristic **projectile, non-bilious vomiting** begins. - It can occur as early as 1 week or as late as 5 months, though this is less common. *Common in males* - The condition has a clear **male predominance**, with a male-to-female ratio of approximately **4:1**. - It is also more common in **first-born males** and has a genetic predisposition, with higher incidence in families where a parent or sibling was affected.

Question 337: In which condition does maximum sodium loss occur in a child?

A. Gastric juice
B. Non cholera Diarrhoea
C. Ileal fluid
D. Cholera (Correct Answer)

Explanation: ***Cholera*** - **Cholera** causes **massive losses of isotonic fluid** with stool volumes reaching up to **1 liter per hour** in severe cases - The **cholera toxin** activates intestinal epithelial cell secretion, producing characteristic "rice-water stool" with sodium concentration of **90-140 mEq/L** (nearly isotonic to plasma) - Results in severe losses of **sodium, chloride, bicarbonate, and potassium**, leading to profound dehydration and electrolyte imbalances - Represents the **maximum acute sodium loss** among all pediatric gastrointestinal conditions *Gastric juice* - Loss of gastric juice (e.g., from severe vomiting or pyloric stenosis) primarily depletes **hydrogen ions and chloride**, causing **metabolic alkalosis** - Gastric fluid has **relatively low sodium concentration** (~60 mEq/L), much less than cholera stool - While clinically significant, sodium loss is not the predominant electrolyte disturbance *Ileal fluid* - Ileal fluid has moderate sodium concentration (100-140 mEq/L), similar to cholera - However, **volume of loss is typically much less** than in acute cholera - Seen in conditions like high-output ileostomy or short bowel syndrome - Losses occur more **gradually** rather than the acute, massive depletion in cholera *Non cholera Diarrhoea* - Most non-cholera diarrheal illnesses (viral, bacterial) cause **less severe fluid losses** - The fluid is often more **hypotonic** (lower sodium concentration per unit volume) - Total sodium depletion is typically **less profound** than cholera, though still clinically significant

Question 338: What is the most common electrolyte disturbance observed in children with severe viral enteritis?

A. Isotonic dehydration with Acidosis (Correct Answer)
B. Isotonic dehydration with Alkalosis
C. Hypotonic dehydration with Acidosis
D. Hypotonic dehydration with Alkalosis

Explanation: ***Isotonic dehydration with Acidosis*** - This is the **most common** electrolyte disturbance in severe viral enteritis due to equal loss of water and electrolytes, leading to **isotonic dehydration** (serum sodium 130-150 mEq/L). - **Metabolic acidosis** frequently accompanies severe diarrhea as the intestine loses significant amounts of bicarbonate in stool. - Accounts for approximately **70-80%** of dehydration cases in acute gastroenteritis. *Isotonic dehydration with Alkalosis* - While isotonic dehydration is common, **alkalosis** is rare in severe viral enteritis. - Diarrhea typically causes **bicarbonate loss**, leading to acidosis, not alkalosis. - Alkalosis would only occur with predominant vomiting without diarrhea (uncommon in viral enteritis). *Hypotonic dehydration with Acidosis* - **Hypotonic dehydration** (more water loss than electrolytes) is less common, occurring in only **10-15%** of cases. - Usually results from inappropriate fluid replacement with hypotonic solutions or specific electrolyte-losing conditions. - While acidosis can be present, the primary dehydration type in typical viral enteritis is isotonic, not hypotonic. *Hypotonic dehydration with Alkalosis* - **Hypotonic dehydration** is uncommon, and **alkalosis** is very rare in severe viral enteritis. - Severe diarrhea almost invariably causes metabolic **acidosis** due to bicarbonate loss, making this combination extremely unlikely.

Question 339: What is the duration that defines persistent diarrhea in infants?

A. Less than 14 days
B. 14 days or more (Correct Answer)
C. More than 14 days but less than 21 days
D. More than 21 days

Explanation: ***14 days or more*** - According to the World Health Organization (WHO) definition, **persistent diarrhea** is any diarrheal episode lasting for **14 days or longer**. - This duration signifies a more severe and prolonged condition, requiring different management strategies than acute diarrhea. *Less than 14 days* - Diarrhea lasting **less than 14 days** is typically classified as **acute diarrhea**. - Acute diarrhea is generally self-limiting and often caused by different pathogens and mechanisms compared to persistent diarrhea. *More than 14 days but less than 21 days* - While this period falls within the definition of **persistent diarrhea**, it is not the complete and most accurate definition. - The definition encompasses **any duration equal to or greater than 14 days**. *More than 21 days* - Diarrhea lasting **more than 21 days** is a severe form of persistent diarrhea and may be termed **chronic diarrhea** by some, but the general definition of persistent diarrhea starts at 14 days. - While concerning, it is not the initial threshold for defining persistent diarrhea.

Practice by Chapter

Gastroesophageal Reflux

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Peptic Ulcer Disease

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Inflammatory Bowel Disease

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Celiac Disease

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Malabsorption Syndromes

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Acute and Chronic Diarrhea

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Constipation and Encopresis

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Gastrointestinal Bleeding

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Intestinal Obstruction

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Liver Diseases in Children

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Pancreatic Disorders

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Pediatric Nutritional Support

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