Gastroenterology Practice Questions

Q: What is the most common cause of epidural abscess?

Staphylococcus. **Explanation:** The most common cause of a spinal epidural abscess (SEA) is **Staphylococcus aureus**, accounting for approximately **60-90%** of all cases [2]. This is primarily due to the organism's high virulence and its prevalence on the skin, allowing it to enter the epidural space via hematogenous spread (from skin/soft tissue infections or IV drug use) or direct inoculation (during spinal surgery or epidural anesthesia) [2]. **Analysis of Options:** * **A. Staphylococcus (Correct):** *S. aureus* is the leading pathogen. Coagulase-negative Staphylococci (e.g., *S. epidermidis*) are also frequently isolated, especially in cases involving spinal hardware or recent procedures [2]. * **B. Streptococcus:** These are the second most common aerobic organisms but occur significantly less frequently than Staphylococci [1]. * **C. Gram-negative bacilli:** Organisms like *E. coli* or *Pseudomonas* are typically seen only in specific contexts, such as urinary tract infections, IV drug use, or following abdominal/pelvic procedures. * **D. Microaerophilic anaerobic streptococci:** These are rare causes, usually associated with a contiguous spread from a pharyngeal or dental source [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Fever, spinal pain (localized), and neurological deficits (though the full triad is present in only <15% of patients). * **Risk Factors:** Diabetes mellitus (most common), IV drug use, chronic kidney disease, and recent spinal instrumentation. * **Gold Standard Investigation:** **MRI with gadolinium contrast** is the imaging modality of choice. * **Management:** Emergency surgical decompression and drainage combined with long-term antibiotics is the standard of care to prevent permanent neurological damage.

Q: Majority of patients with HNPCC have mutations in which gene?

MSH2. Hereditary Non-Polyposis Colorectal Cancer (HNPCC), also known as **Lynch Syndrome**, is an autosomal dominant condition caused by germline mutations in **DNA Mismatch Repair (MMR) genes** [1]. These genes are responsible for correcting errors (mismatches) that occur during DNA replication [1]. When these genes are defective, it leads to **Microsatellite Instability (MSI)** and an increased risk of colorectal and extra-colonic cancers [1]. **Why MSH2 is the correct answer:** While several MMR genes are implicated, **MSH2** and **MLH1** are the most frequently mutated, accounting for approximately 90% of all HNPCC cases [1]. Among these, **MSH2** is generally considered the most common (approx. 50-60%), followed closely by MLH1 (approx. 30-35%). **Analysis of Incorrect Options:** * **MSH1:** This is a common distractor; the actual gene is **MLH1**. There is no "MSH1" gene involved in Lynch Syndrome. * **MSH3:** While MSH3 is an MMR gene, mutations in this gene are rare in HNPCC and do not account for the majority of cases. * **MSH4:** This gene is involved in meiotic recombination rather than the mismatch repair pathway associated with Lynch Syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Amsterdam II Criteria:** Used for clinical diagnosis (3-2-1 rule: 3 relatives, 2 generations, 1 diagnosed before age 50) [2]. * **Associated Cancers:** Endometrial cancer (most common extra-colonic), ovarian, gastric, and small bowel cancers. * **Tumor Location:** Predominantly occurs in the **proximal/right colon** (cecum to splenic flexure). * **Pathology:** Often shows "Crohn’s-like" lymphoid reaction and signet ring cells.

Q: Skip lesions are characteristic findings in which of the following conditions?

Crohn's disease. Explanation: **Crohn's Disease (Correct Answer):** Skip lesions are a hallmark pathological feature of Crohn's disease. This term refers to the **discontinuous** nature of the inflammation, where segments of diseased bowel are separated by areas of normal-appearing mucosa [1]. This occurs because Crohn's disease is a transmural inflammatory process that can affect any part of the gastrointestinal tract (from mouth to anus), though it most commonly involves the terminal ileum and cecum. **Analysis of Incorrect Options:** * **Ulcerative Colitis:** Unlike Crohn's, inflammation in UC is **continuous** and starts from the rectum, extending proximally [1]. It is limited to the mucosa and submucosa and does not skip segments [1]. * **Typhoid:** Characterized by inflammation of Peyer's patches in the terminal ileum, leading to longitudinal ulcers along the long axis of the bowel. It does not present with the "skip" pattern seen in IBD. * **Tuberculosis (Intestinal):** Typically involves the ileocecal region. While it can cause multiple strictures, the classic description involves transverse ulcers and "confluent" granulomas, rather than the specific skip lesion pattern of Crohn's. **High-Yield Clinical Pearls for NEET-PG:** * **Transmural Involvement:** Crohn’s affects all layers; UC is superficial (mucosa/submucosa) [1]. * **Cobblestone Appearance:** In Crohn's, deep longitudinal and transverse ulcers with intervening edematous mucosa create a "cobblestone" look. * **String Sign of Kantor:** A radiological finding in Crohn's due to terminal ileal narrowing [2]. * **Granulomas:** Non-caseating granulomas are pathognomonic for Crohn's (found in ~40-60% of cases). * **Creeping Fat:** Mesenteric fat wrapping around the bowel is highly suggestive of Crohn's.

Q: Which metabolic disorder can lead to acute pancreatitis?

Hyperparathyroidism. **Explanation:** **Hyperparathyroidism** is a well-recognized metabolic cause of acute pancreatitis [1]. The underlying mechanism is primarily driven by **hypercalcemia**. Elevated serum calcium levels lead to the activation of trypsinogen into trypsin within the pancreatic parenchyma, causing autodigestion. Additionally, high calcium levels can lead to the formation of calcium stones in the pancreatic ducts, causing obstruction and subsequent inflammation. **Analysis of Options:** * **Hyperparathyroidism (Correct):** Primary hyperparathyroidism (often due to a parathyroid adenoma) results in hypercalcemia, which is the direct trigger for pancreatitis [1]. * **Hypoparathyroidism (Incorrect):** This condition leads to *hypocalcemia*. While hypocalcemia is a common *consequence* (prognostic marker) of acute pancreatitis due to saponification of fat, it is not a cause [1]. * **Hypothyroidism & Hyperthyroidism (Incorrect):** Thyroid dysfunctions are not typically associated with acute pancreatitis. While severe hypothyroidism (myxedema) can cause slowed GI motility, it does not trigger pancreatic enzyme activation. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolic Causes:** Apart from hypercalcemia, **Hypertriglyceridemia** (typically Type I, IV, or V hyperlipoproteinemia with TG levels >1000 mg/dL) is a major metabolic cause of pancreatitis [1]. * **The "Stones" Connection:** Remember the classic pentad for primary hyperparathyroidism: *Stones (renal), Bones (osteitis fibrosa cystica), Groans (abdominal pain/pancreatitis), Thrones (polyuria), and Psychic overtones.* * **Drug-Induced:** Always remember drugs like Azathioprine, Sulfonamides, and Valproate as high-yield triggers for the exam. * **Scorpion Sting:** In the context of NEET-PG, *Tityus trinitatis* scorpion venom is a classic cause of acute pancreatitis [1].

Question 1

A 40-year-old male patient presented with slowly progressive dysphagia to both solids and liquids, regurgitation, chest pain, and weight loss for 2 months. Investigations included barium swallow, esophageal manometry, and upper GI endoscopy. Which of the following organisms has been most commonly implicated in causing this condition?

Accepted Answer

Herpes Simplex Virus 1 (HSV 1)

Answer

Herpes Simplex Virus 2 (HSV 2)

Answer

Varicella-Zoster Virus

Answer

Cytomegalovirus (CMV)

Question 2

A patient presents with pain in the left hypochondrium, vomiting, diarrhea, melena, and weight loss. What is the most likely diagnosis?

Accepted Answer

Zollinger-Ellison syndrome

Answer

Cholangitis

Answer

Enterocolitis

Answer

Amebiasis

Question 3

What is the most common cause of epidural abscess?

Accepted Answer

Staphylococcus

Answer

Streptococcus

Answer

Gram negative bacilli

Answer

Microaerophilic anaerobic streptococci

Question 4

A young patient presents with dysphagia, more for liquids than solids, and often regurgitates food at night. Radiography shows a 'rat-tailed' appearance. What is the likely diagnosis?

Accepted Answer

Achalasia cardia

Answer

Carcinoma esophagus

Answer

Zenker's diverticulum

Answer

Diffuse esophageal spasm

Question 5

Majority of patients with HNPCC have mutations in which gene?

Accepted Answer

MSH2

Answer

MSH1

Answer

MSH3

Answer

MSH4

Question 6

Skip lesions are characteristic findings in which of the following conditions?

Accepted Answer

Crohn's disease

Answer

Ulcerative colitis

Answer

Typhoid

Answer

Tuberculosis

Question 7

A 35-year-old patient presented with 2 episodes of hematemesis. On examination, his pulse rate is 100/min with a BP of 90/60 mm Hg. Per abdominal examination shows spleen palpable 3 cm below the costal margin. Which of the following is true about this patient?

Accepted Answer

The increased portal vein pressure should be lowered with octreotide

Answer

Elevated CRP and low C3

Answer

Most common site of bleeding is the first part of the duodenum

Answer

Urgent elective intubation of the patient

Question 8

Which metabolic disorder can lead to acute pancreatitis?

Accepted Answer

Hyperparathyroidism

Answer

Hypoparathyroidism

Answer

Hypothyroidism

Answer

Hyperthyroidism

Question 9

A 58-year-old man with cirrhosis complains of worsening fatigue and confusion over the past 5 days. He also reports that over the past 48 hours he has had a declining urinary output. On examination, he is gaunt and jaundiced. He has tense ascites and a liver span of 7 cm in the midclavicular line. Lab results reveal a WBC 4600/mm3, Hb 9.4 g/dL, and PCB 29%. BUN of 34 mg/dL and a creatinine of 3.1 mg/dL. A urinary Na <10 mEq/L. What is the most appropriate treatment for his elevated BUN and creatinine?

Accepted Answer

Liver transplantation

Answer

Large volume paracentesis

Answer

Hemodialysis

Answer

Mesocaval shunt

Question 10

A 45-year-old male presents with weakness. He is a chronic alcoholic and has hepatomegaly and icterus. His blood tests show elevated transaminases, and USG reveals fatty liver. Which of the following substances may be responsible for his liver condition?

Accepted Answer

All of the above

Answer

Orotic acid

Answer

Pyridoxine and pantothenic acid deficiency

Answer

Alcohol

Gastroenterology — MCQs

Gastroenterology — MCQs

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