Gastroenterology — MCQs

Gastroenterology Indian Medical PG Practice Questions and MCQs

Question 211: Congenital hypertrophic pyloric stenosis usually presents?

A. Within 2 days after birth
B. Around 1 week after birth
C. Around 2 weeks after birth (Correct Answer)
D. Around 2 months after birth

Explanation: **Explanation:** **Congenital Hypertrophic Pyloric Stenosis (CHPS)** is characterized by hypertrophy and hyperplasia of the muscular layers of the pylorus, leading to a functional gastric outlet obstruction. 1. **Why Option C is Correct:** While the name implies it is "congenital," the clinical symptoms are rarely present at birth. The hypertrophy develops progressively over the first few weeks of life. The classic presentation occurs between **3 to 6 weeks of age** (averaging around 3 weeks). However, symptoms often begin as mild spitting up around **2 weeks of age**, which then progresses to the characteristic forceful, non-bilious projectile vomiting. 2. **Why Other Options are Incorrect:** * **Option A & B:** At 2 days or 1 week, the pyloric muscle has typically not thickened enough to cause a complete or significant obstruction. Vomiting in the first 24–48 hours is more suggestive of intestinal atresia or malrotation. * **Option D:** While CHPS can occasionally present late, it is rare for the initial presentation to occur as late as 2 months. Most cases are diagnosed and surgically corrected well before this timeframe. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Projectile non-bilious vomiting, palpable "olive-shaped" mass in the epigastrium, and visible gastric peristalsis (left to right). * **Metabolic Profile:** Hypochloremic, hypokalemic metabolic alkalosis with paradoxical aciduria (crucial for exams). * **Diagnosis:** Ultrasound is the investigation of choice (Pyloric muscle thickness >4mm or length >14mm). * **Management:** Initial step is fluid resuscitation (Normal Saline); definitive treatment is **Ramstedt’s Pyloromyotomy**.

Question 212: Which of the following is NOT seen in lactose intolerance?

A. Reducing substances present in stools
B. Alkaline urine (Correct Answer)
C. Acidic stool
D. Lactase enzyme deficiency

Explanation: **Explanation:** Lactose intolerance occurs due to a deficiency of the **lactase enzyme** (Option D) in the brush border of the small intestine. When lactose is not hydrolyzed into glucose and galactose, it remains in the intestinal lumen, acting as an osmotic agent that draws water in, leading to osmotic diarrhea. **Why "Alkaline Urine" is the correct answer:** In lactose intolerance, the unabsorbed lactose reaches the colon, where bacteria ferment it into **Short-Chain Fatty Acids (SCFAs)** (like lactic, acetic, and propionic acid) and gases ($H_2, CO_2$). These acids are absorbed into the bloodstream, leading to a mild **metabolic acidosis**. Consequently, the kidneys compensate by excreting excess hydrogen ions, resulting in **acidic urine**, not alkaline urine. **Analysis of other options:** * **Acidic Stool (Option C):** The bacterial fermentation of lactose produces lactic acid and other SCFAs, which significantly lowers the stool pH (typically **< 5.5**). * **Reducing Substances in Stool (Option A):** Lactose is a reducing sugar. Since it remains unabsorbed, it can be detected in the stool using Benedict’s reagent or Clinitest tablets. * **Lactase Enzyme Deficiency (Option B):** This is the primary pathophysiology, whether congenital, primary (developmental), or secondary (post-gastroenteritis). **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Hydrogen Breath Test (increased $H_2$ due to bacterial fermentation). * **Stool pH:** Characteristically < 5.5. * **Clinical Presentation:** Explosive, watery diarrhea, abdominal distension, and perianal excoriation (due to acidic stools). * **Secondary Lactose Intolerance:** Most commonly occurs after a viral rotavirus infection due to sloughing of the villi tips where lactase is located.

Question 213: Which of the following statements about Alagille syndrome is FALSE?

A. Complete absence of bile ducts
B. Normal liver
C. Mutations in Jagged 1 gene
D. No risk of hepatocellular carcinoma (Correct Answer)

Explanation: ### Explanation **Alagille Syndrome (Syndromic Bile Duct Paucity)** is an autosomal dominant multisystem disorder primarily caused by mutations in the **JAG1 gene** (94%) or **NOTCH2 gene**, affecting the Notch signaling pathway. **Why Option D is the Correct Answer (The False Statement):** Contrary to the statement, patients with Alagille syndrome **do have an increased risk** of developing **Hepatocellular Carcinoma (HCC)**. While the risk is lower compared to conditions like Tyrosinemia, chronic cholestasis and cirrhosis in these patients can lead to malignant transformation, necessitating periodic screening with alpha-fetoprotein (AFP) and ultrasound. **Analysis of Other Options:** * **Option A (Complete absence of bile ducts):** This is a characteristic histological feature known as **ductopenia** (bile duct paucity). The ratio of interlobular bile ducts to portal tracts is significantly reduced (<0.4). * **Option B (Normal liver):** This is technically **incorrect** in a clinical sense (as the liver is cholestatic), but in the context of this specific question's construction, it refers to the fact that the liver parenchyma may initially appear normal outside of the portal tract paucity, or it is a distractor highlighting that the primary defect is biliary, not hepatocytic. *Note: In many standard MCQ formats, the "most false" statement is the clinical risk of HCC.* * **Option C (Mutations in Jagged 1 gene):** This is a true statement. JAG1 mutations on chromosome 20p12 are the hallmark of the disease. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Pentad:** 1. **Liver:** Chronic cholestasis (Bile duct paucity). 2. **Heart:** Peripheral Pulmonary Artery Stenosis (most common). 3. **Eyes:** Posterior embryotoxon. 4. **Skeletal:** Butterfly vertebrae (clefting of thoracic vertebrae). 5. **Facies:** "Triangular facies" (prominent forehead, deep-set eyes, pointed chin). * **Diagnosis:** Requires histological proof of bile duct paucity plus three of the five clinical features. * **Pruritus:** Often severe and out of proportion to the jaundice.

Question 214: What is the commonest cause of vomiting in a one-month-old infant?

A. Pyloric stenosis
B. Cardiac chalasia
C. Aerophagy (Correct Answer)
D. Gastro–esophageal reflux

Explanation: **Explanation:** **Correct Answer: C. Aerophagy** **Medical Concept:** Aerophagy, or the swallowing of air during feeding, is the **most common** cause of vomiting (specifically physiological spitting up) in early infancy. It occurs due to improper feeding techniques, such as a poor latch during breastfeeding or using a bottle nipple with an incorrect flow rate. The swallowed air distends the stomach, and as the infant attempts to belch, a small amount of milk is regurgitated. It is a benign, self-limiting condition that improves with proper burping and feeding posture. **Analysis of Incorrect Options:** * **A. Pyloric Stenosis:** While a classic cause of vomiting in this age group (typically 3–6 weeks), it presents with **non-bilious, projectile vomiting** and is far less frequent than simple aerophagy. * **B. Cardiac Chalasia:** This refers to the transient relaxation of the lower esophageal sphincter (LES). While it causes "spitting up," it is considered a component of the spectrum of GERD rather than the most common overall cause. * **C. Gastro-esophageal Reflux (GER):** Physiological GER is very common in infants (often called "happy spitters"); however, aerophagy remains the more frequent underlying mechanical trigger for vomiting episodes in the general neonatal and early infancy population. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of vomiting in infants:** Aerophagy. * **Most common surgical cause of vomiting (3–6 weeks):** Hypertrophic Pyloric Stenosis (HPS). * **Metabolic abnormality in HPS:** Hypochloremic, hypokalemic metabolic alkalosis with paradoxical aciduria. * **Management of Aerophagy:** Frequent burping, ensuring the nipple is full of milk during bottle feeding, and upright positioning after feeds.

Question 215: A neonate is diagnosed with Bell's stage I necrotizing enterocolitis (NEC). What is the initial management of choice?

A. Laparotomy and proceed
B. Insertion of bilateral pelvic drains
C. Conservative management with IV fluids and antibiotics (Correct Answer)
D. Initial conservative management and laparotomy after 24 hours

Explanation: **Explanation:** Necrotizing Enterocolitis (NEC) is a life-threatening gastrointestinal emergency in neonates, primarily affecting preterm infants. Management is strictly guided by the **Modified Bell’s Staging Criteria**, which categorizes the severity of the disease. **Why Option C is Correct:** Bell’s Stage I (Suspected NEC) is characterized by non-specific systemic signs (lethargy, temperature instability) and mild gastrointestinal symptoms (abdominal distension, occult blood in stools). At this stage, the bowel wall is intact without perforation or necrosis. The standard of care is **conservative management**, which includes: 1. **Bowel rest:** Making the infant NPO (Nil Per Oral). 2. **Gastric decompression:** Using a nasogastric tube. 3. **Medical therapy:** Intravenous fluids and broad-spectrum antibiotics. Most Stage I and Stage II (Pneumatosis intestinalis) cases respond well to this medical regimen. **Why Other Options are Incorrect:** * **Options A & D:** Surgical intervention (Laparotomy) is reserved for **Bell’s Stage IIIb**, where there is evidence of intestinal perforation (Pneumoperitoneum). Operating on Stage I is premature and carries high morbidity. * **Option B:** Peritoneal drainage (often unilateral) is an alternative to laparotomy specifically in extremely low birth weight (ELBW) infants who are too unstable for surgery, not for early-stage NEC. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic X-ray finding:** Pneumatosis intestinalis (gas in the bowel wall) defines Stage II. * **Absolute indication for surgery:** Pneumoperitoneum (Football sign on X-ray). * **Most common site:** Terminal ileum and proximal colon. * **Risk Factors:** Prematurity (most common), formula feeding, and intestinal ischemia.

Question 216: True about the concentration of Oral Rehydration Solution is:

A. Sodium 70 mEq/lit
B. Potassium 20 mEq/lit (Correct Answer)
C. Bicarbonate 80 mEq/lit
D. Chloride 30 mEq/lit

Explanation: The question focuses on the composition of the **WHO Reduced Osmolarity ORS**, which has been the standard recommendation since 2002 to reduce the need for unscheduled IV fluids and decrease stool output. ### Why Option B is Correct The concentration of **Potassium in ORS is 20 mEq/L**. Potassium is added as Potassium Chloride to replace the significant fecal losses of potassium during diarrhea, thereby preventing hypokalemia and associated complications like paralytic ileus and muscle weakness. ### Why Other Options are Incorrect * **A. Sodium (75 mEq/L):** In the reduced osmolarity formula, the Sodium concentration is **75 mEq/L**, not 70. The older "Standard ORS" had 90 mEq/L, but 75 mEq/L is now preferred to avoid hypernatremia. * **C. Bicarbonate (None):** Modern ORS uses **Trisodium Citrate (10 mmol/L)** instead of Bicarbonate. Citrate is more stable in tropical climates and is converted to bicarbonate in the body to correct acidosis. * **D. Chloride (65 mEq/L):** The chloride concentration in reduced osmolarity ORS is **65 mEq/L**, not 30. ### High-Yield Facts for NEET-PG To master ORS-related questions, remember the **"75-65-20-10-75"** rule for Reduced Osmolarity ORS: 1. **Sodium:** 75 mEq/L 2. **Chloride:** 65 mEq/L 3. **Potassium:** 20 mEq/L 4. **Citrate:** 10 mmol/L 5. **Glucose:** 75 mmol/L 6. **Total Osmolarity:** **245 mOsm/L** (Standard ORS was 311 mOsm/L). **Clinical Pearl:** The glucose-to-sodium ratio is kept at **1:1** to optimize the SGLT-1 (Sodium-Glucose Luminal Transporter) mechanism in the small intestine, which facilitates the coupled absorption of sodium and water even during secretory diarrhea.

Question 217: Which marker is used for the early diagnosis of Hirschsprung disease?

A. Acetylcholinesterase (Correct Answer)
B. Adrenaline
C. Vasoactive intestinal peptide (VIP)
D. None of the above

Explanation: **Explanation:** **Hirschsprung Disease (HD)** is characterized by the congenital absence of ganglion cells in the submucosal (Meissner) and myenteric (Auerbach) plexuses. In the absence of these inhibitory neurons, there is a compensatory **hypertrophy and proliferation of cholinergic nerve fibers** in the affected segment. 1. **Why Acetylcholinesterase (AChE) is correct:** The hypertrophied extrinsic nerve fibers in the aganglionic segment produce high levels of the enzyme **Acetylcholinesterase**. On a rectal suction biopsy, histochemical staining for AChE shows a characteristic increase in coarse, darkly staining nerve fibers in the muscularis mucosae and lamina propria. This is a highly sensitive and specific marker used for early diagnosis, especially when traditional H&E staining for ganglion cells is inconclusive in neonates. 2. **Why other options are incorrect:** * **Adrenaline:** While the autonomic nervous system is involved, adrenaline is not a diagnostic marker for HD. The pathology primarily involves the parasympathetic (cholinergic) system. * **Vasoactive Intestinal Peptide (VIP):** VIP is an inhibitory neurotransmitter. In HD, VIP-containing nerve fibers are actually **decreased or absent** in the aganglionic segment, making it a poor marker for positive identification compared to the proliferation of AChE. **Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Rectal Suction Biopsy (demonstrating absence of ganglion cells and presence of hypertrophied nerve bundles). * **Initial Screening:** Contrast Enema (shows a "transition zone" between the dilated proximal colon and narrow distal segment). * **Anorectal Manometry:** Shows **failure of the Rectoanal Inhibitory Reflex (RAIR)**—the internal sphincter fails to relax upon rectal distension. * **Associated Condition:** Strongly associated with **Down Syndrome** (Trisomy 21).

Question 218: What is the recommended concentration of glucose in Oral Rehydration Solution (ORS)?

A. 200 mmol/L
B. 105 mmol/L
C. 110 mmol/L
D. None of the above (Correct Answer)

Explanation: The correct answer is **None of the above** because the standard concentration of glucose in the current WHO-recommended Low Osmolarity ORS is **75 mmol/L**. ### **Medical Concept: The SGLT-1 Mechanism** The efficacy of ORS relies on the **sodium-glucose cotransporter-1 (SGLT-1)** in the small intestine. Glucose facilitates the absorption of sodium and water even during secretory diarrhea. However, the concentration must be precise: if glucose levels are too high, it creates an osmotic effect in the lumen, worsening diarrhea (osmotic diarrhea). ### **Analysis of Options** * **A (200 mmol/L):** This is excessively high and would cause severe osmotic diarrhea and hypernatremia. * **B (105 mmol/L):** This was the glucose concentration in the **"Old" WHO ORS** (Standard ORS) used prior to 2002. It is no longer the recommended standard. * **C (110 mmol/L):** This is an incorrect value and does not correspond to any standard ORS formulation. ### **High-Yield Facts for NEET-PG** The **Low Osmolarity ORS** (current standard) has a total osmolarity of **245 mOsm/L**. Memorizing the specific composition is essential for the exam: | Component | Concentration (mmol/L) | | :--- | :--- | | **Sodium** | 75 | | **Glucose** | **75** | | **Chloride** | 65 | | **Potassium** | 20 | | **Citrate** | 10 | **Clinical Pearls:** 1. **Sodium-to-Glucose Ratio:** In the current formula, the ratio is **1:1**, which is optimal for water absorption. 2. **Reduced Osmolarity Benefits:** Compared to the old formula (311 mOsm/L), the 245 mOsm/L formula reduces stool output, vomiting, and the need for unscheduled IV fluids. 3. **ReSoMal:** For children with **Severe Acute Malnutrition (SAM)**, a different formula called ReSoMal is used, which has lower sodium (45 mmol/L) and higher potassium (40 mmol/L).

Question 219: Which of the following is a cause of liver cirrhosis in childhood?

A. Alpha-1 antitrypsin deficiency (Correct Answer)
B. Coeliac disease
C. Phenylketonuria
D. Cow's milk intolerance

Explanation: **Explanation:** **Alpha-1 Antitrypsin (A1AT) Deficiency** is the most common genetic cause of liver disease in children. The underlying pathophysiology involves a point mutation (most commonly the **PiZZ genotype**) that leads to the misfolding of the A1AT protein within the endoplasmic reticulum of hepatocytes. These misfolded proteins cannot be secreted into the blood, leading to their accumulation in the liver, which triggers inflammation, hepatocyte death, and eventually **cirrhosis**. On histology, this is classically seen as **PAS-positive, diastase-resistant globules**. **Why the other options are incorrect:** * **Coeliac Disease:** This is an immune-mediated enteropathy triggered by gluten. While it can cause a mild elevation in transaminases (coeliac hepatitis), it does not typically progress to cirrhosis. * **Phenylketonuria (PKU):** This is a metabolic disorder caused by a deficiency of phenylalanine hydroxylase. It primarily affects neurological development (intellectual disability, seizures) and does not cause structural liver damage or cirrhosis. * **Cow’s Milk Intolerance:** This is an immunological reaction to milk proteins, manifesting as proctocolitis or enteropathy (diarrhea, vomiting, or occult blood in stools). It has no association with hepatic fibrosis. **Clinical Pearls for NEET-PG:** * **Most common cause** of neonatal cholestasis (after biliary atresia): A1AT deficiency. * **Diagnosis:** Low serum levels of A1AT and protease inhibitor (Pi) typing. * **Extra-hepatic manifestation:** Panacinar emphysema (usually seen in adults, exacerbated by smoking). * **Other metabolic causes of childhood cirrhosis:** Wilson disease, Galactosemia, and Hereditary Tyrosinemia type 1.

Question 220: Which of the following statements is true about the new WHO oral rehydration solution (ORS) formula?

A. It has a sodium ion concentration of 75 mM/L.
B. Its glucose concentration is 75 mM/L.
C. Its total osmolarity is 245 mOsm/L.
D. All of the above. (Correct Answer)

Explanation: The correct answer is **D. All of the above.** ### **Explanation** The World Health Organization (WHO) and UNICEF transitioned from the standard high-osmolarity ORS to the **Reduced Osmolarity ORS** in 2004. This change was implemented to reduce the risk of hypernatremia and to decrease the need for unscheduled intravenous fluids, stool output, and the incidence of vomiting in children with non-cholera diarrhea. 1. **Sodium Concentration (75 mM/L):** The sodium content was reduced from 90 mEq/L to 75 mEq/L. This lower concentration is safer for children, as it prevents the osmotic pull of water into the gut lumen, thereby reducing stool volume. 2. **Glucose Concentration (75 mM/L):** Glucose is essential for the co-transport of sodium across the intestinal epithelium via the SGLT-1 transporter. A 1:1 molar ratio of sodium to glucose is maintained for optimal absorption. 3. **Total Osmolarity (245 mOsm/L):** The total osmolarity was reduced from 311 mOsm/L to 245 mOsm/L. This "hypotonic" solution ensures faster water absorption and prevents osmotic diarrhea. ### **Composition of New WHO ORS (High-Yield Table)** | Component | Concentration (mmol/L) | | :--- | :--- | | **Sodium** | 75 | | **Chloride** | 65 | | **Glucose (Anhydrous)** | 75 | | **Potassium** | 20 | | **Citrate** | 10 | | **Total Osmolarity** | **245 mOsm/L** | ### **Clinical Pearls for NEET-PG** * **Trisodium Citrate** is used instead of Bicarbonate because it increases the shelf life of the ORS packet. * **Zinc Supplementation:** Should be given alongside ORS (20 mg/day for 10–14 days; 10 mg/day for infants <6 months) to reduce the duration and severity of diarrhea. * **ReSoMal:** A special ORS used for children with **Severe Acute Malnutrition (SAM)**; it has lower sodium (45 mmol/L) and higher potassium (40 mmol/L).

Practice by Chapter

Gastroesophageal Reflux

Practice Questions

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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