Small Bowel Obstruction MCQ Quiz | Small Intestine

Quiz Introduction

Welcome to the Small Bowel Obstruction (SBO) MCQ Quiz, specifically designed for MBBS students to test and reinforce their surgical knowledge. This quiz covers the essential aspects of SBO, from its most common etiologies like post-operative adhesions to its cardinal clinical features, including colicky pain and obstipation. You’ll be challenged on key diagnostic findings, such as air-fluid levels on abdominal X-rays, and the crucial role of CT scans in modern management. The questions also delve into the pathophysiology of fluid sequestration, common electrolyte imbalances, and the principles of both conservative and surgical interventions. Test your understanding of when to operate and the signs of strangulation. After submitting, you can review your score and download all questions with their correct answers in a convenient PDF format for future revision.

1. What is the most common cause of small bowel obstruction (SBO) in the developed world?

Hernias

Post-operative adhesions

Malignancy

Crohn’s disease

2. Which of the following is a cardinal feature of SBO?

Diarrhea

Colicky abdominal pain

Jaundice

Hematemesis

3. What is the characteristic radiographic finding on an erect abdominal X-ray in a patient with SBO?

Free air under the diaphragm

Multiple air-fluid levels

“Coffee bean” sign

“Lead pipe” colon

4. In a patient with SBO, which electrolyte abnormality is most commonly seen due to vomiting and third-space fluid loss?

Hyperkalemia and metabolic acidosis

Hypokalemia and metabolic alkalosis

Hypernatremia and respiratory acidosis

Hyponatremia and respiratory alkalosis

5. A “closed-loop” obstruction carries a high risk of which complication?

Intussusception

Volvulus

Strangulation and perforation

Gallstone ileus

6. Which investigation is considered the gold standard for diagnosing SBO, determining the level of obstruction, and identifying its cause and complications?

Abdominal Ultrasound

Barium follow-through

CT scan with oral and IV contrast

MRI enterography

7. The initial management of a simple, non-strangulated SBO primarily involves:

Immediate exploratory laparotomy

Nasogastric decompression and IV fluid resuscitation

Administration of broad-spectrum antibiotics only

Enema administration

8. Which clinical finding is most suggestive of bowel strangulation in a patient with SBO?

High-pitched bowel sounds

Colicky abdominal pain

Fever, tachycardia, and localized tenderness

Abdominal distension

9. Gallstone ileus is a form of SBO where a gallstone impacts most commonly in which part of the small intestine?

Duodenum

Proximal jejunum

Distal ileum

Ligament of Treitz

10. What does “obstipation” in the context of SBO refer to?

Passage of small, frequent stools

Inability to pass flatus or feces

Passage of bloody stools

Painful defecation

11. A Richter’s hernia is a specific type of hernia that can cause SBO. It is defined by:

The entire circumference of the bowel wall is incarcerated.

Only the anti-mesenteric border of the bowel wall is incarcerated.

The appendix is incarcerated within the hernia sac.

The Meckel’s diverticulum is incarcerated.

12. In proximal SBO, which symptom is most prominent?

Abdominal distension

Profuse vomiting

Constipation

Fever

13. In distal SBO, which symptom tends to appear later but is more pronounced?

Nausea

Bilious vomiting

Marked abdominal distension

Early electrolyte imbalance

14. What is the pathophysiological mechanism behind the massive fluid shifts in SBO?

Increased intestinal absorption

Decreased capillary permeability

Sequestration of fluid into the bowel lumen and wall (third-spacing)

Decreased hydrostatic pressure in the intestinal capillaries

15. The “string of pearls” sign on an abdominal X-ray is indicative of:

Large bowel obstruction

Paralytic ileus

Small bowel obstruction (fluid-filled loops with small gas bubbles)

Pneumoperitoneum

16. What is the most common cause of SBO in children under two years of age?

Adhesions

Hernias

Intussusception

Meckel’s diverticulum

17. A patient with known Crohn’s disease presents with symptoms of SBO. What is the most likely underlying cause?

Post-operative adhesion

Fibrotic stricture

Internal hernia

Gallstone ileus

18. The term “ileus” is often used interchangeably with obstruction, but paralytic ileus specifically refers to:

Mechanical blockage of the bowel lumen

Functional obstruction due to loss of peristalsis

Obstruction caused by a bezoar

Twisting of the bowel on its mesentery

19. Which of the following is an absolute indication for surgical intervention in SBO?

Failure to improve after 48 hours of conservative management

Presence of multiple air-fluid levels on X-ray

Peritonitis

Dehydration

20. A “volvulus” causing SBO is best described as:

Telescoping of one bowel segment into another

Protrusion of bowel through a fascial defect

Twisting of a loop of bowel around its mesenteric attachment

Obstruction by an intraluminal foreign body

21. On a CT scan, which finding is highly specific for a closed-loop obstruction?

Dilated proximal bowel with collapsed distal bowel

The “whirl sign” indicating mesenteric twisting

Bowel wall thickening

Pneumatosis intestinalis

22. The transition point in SBO refers to:

The point where the small bowel joins the large bowel

The change from dilated proximal bowel to collapsed distal bowel

The point where bowel sounds change from high-pitched to absent

The time when conservative management fails and surgery is indicated

23. Which of the following is NOT a typical cause of mechanical SBO?

Intraluminal (e.g., gallstone, bezoar)

Intramural (e.g., tumor, stricture)

Extrinsic (e.g., adhesions, hernia)

Metabolic (e.g., hypokalemia)

24. What is the primary purpose of nasogastric (NG) tube placement in the management of SBO?

To provide enteral nutrition

To decompress the stomach and proximal small bowel

To administer medications directly into the stomach

To monitor for gastrointestinal bleeding

25. A patient develops SBO two weeks after an abdominal surgery. What is the most likely cause?

Early post-operative adhesions

Recurrent malignancy

Paralytic ileus

Herniation through the surgical wound