A patient with bowel obstruction is being evaluated for definitive management. Which situation most strongly supports surgical intervention?

A. Functional ileus without ischemia
B. Partial obstruction improving clinically
C. Mechanical obstruction or infarction
D. Mild bloating after meals

C. Mechanical obstruction or infarction

Which combination of findings is most characteristic of intestinal obstruction?

A. Tenesmus, jaundice, melena
B. Vomiting, constipation, distention
C. Diarrhea, fever, hematemesis
D. Steatorrhea, urgency, flatulence

B. Vomiting, constipation, distention

Which group of conditions accounts for the large majority of mechanical intestinal obstructions?

A. Hernias, adhesions, intussusception, volvulus
B. Diverticulosis, angiodysplasia, hemorrhoids, fissures
C. Appendicitis, pancreatitis, hepatitis, cholangitis
D. Ulcers, polyps, fistulas, strictures

A. Hernias, adhesions, intussusception, volvulus

Imaging confirms a mechanical bowel obstruction. Which statement best explains why the small intestine is most commonly involved?

A. It has thinner serosa
B. It has narrower lumen
C. It has weaker peristalsis
D. It has poorer blood supply

B. It has narrower lumen

A 54-year-old man develops a reducible groin bulge after heavy lifting. Which structure defines the protruding sac in a typical hernia?

A. Mucosal diverticular outpouching
B. Serosa-lined peritoneal pouch
C. Fibrotic mesenteric band
D. Submucosal vascular malformation

B. Serosa-lined peritoneal pouch

Acquired abdominal hernias most commonly occur at which sites?

A. Inguinal, femoral, umbilical, scars
B. Jejunal, ileal, colonic, rectal
C. Splenic, hepatic, renal, pelvic
D. Duodenal, cecal, sigmoid, anal

A. Inguinal, femoral, umbilical, scars

Hernias are the most frequent cause of intestinal obstruction in which setting?

A. In children only
B. In the United States
C. Worldwide
D. In postoperative patients

C. Worldwide

Obstruction from a hernia most often results from:

A. Mucosal ulceration
B. Visceral protrusion
C. Arterial embolization
D. Lymphatic fibrosis

B. Visceral protrusion

Which entrapped structure is most commonly involved in a hernia causing bowel obstruction?

A. Appendix
B. Stomach
C. Small bowel loop
D. Pancreatic tail

C. Small bowel loop

A painful inguinal hernia becomes nonreducible and tender. Pressure at the neck first impairs venous drainage, causing edema and stasis, followed by permanent trapping and then vascular compromise. Which sequence is most accurate?

A. Infarction → strangulation → incarceration
B. Strangulation → edema → reduction
C. Incarceration → strangulation → infarction
D. Edema → infarction → reduction

C. Incarceration → strangulation → infarction

A 46-year-old woman with prior pelvic surgery presents with crampy abdominal pain and vomiting. Fibrous bands are suspected to be tethering bowel loops to the abdominal wall. Which process most likely led to this obstruction?

A. Adhesion formation
B. Volvulus development
C. Mucosal intussusception
D. Arterial thrombosis

A. Adhesion formation

Which clinical history most strongly predisposes to intra-abdominal adhesions?

A. Peptic ulcer disease
B. Surgical procedure
C. Lactose intolerance
D. Hemorrhoids

B. Surgical procedure

Fibrous bridges formed by adhesions may create closed loops through which bowel can slide and become trapped. This complication is best termed:

A. Strangulation
B. External prolapse
C. Internal herniation
D. Transmural infarction

C. Internal herniation

A 70-year-old patient presents with acute abdominal distention, obstipation, severe pain, and signs of bowel ischemia. Imaging suggests twisting of bowel around its mesenteric attachment. Which diagnosis is most likely?

A. Intussusception
B. Volvulus
C. Adhesion
D. Hernia

B. Volvulus

The pathophysiology of volvulus most directly causes:

A. Secretory and osmotic loss
B. Mucosal and lymphatic failure
C. Luminal and vascular compromise
D. Serosal and neural inflammation

C. Luminal and vascular compromise

Volvulus most commonly occurs in which location?

A. Sigmoid colon
B. Jejunum
C. Stomach
D. Transverse colon

A. Sigmoid colon

A 2-year-old child develops episodic abdominal pain and vomiting. Imaging suggests that one bowel segment has invaginated into the immediately distal segment after a wave of peristalsis. Which diagnosis is most likely?

A. Volvulus
B. Intussusception
C. Adhesion
D. Incarcerated hernia

B. Intussusception

Intussusception is best defined as:

A. Twisting around mesentery
B. Fibrous loop entrapment
C. Telescoping into distal bowel
D. Protrusion through abdominal wall

C. Telescoping into distal bowel

Once the bowel segment becomes trapped in intussusception, ongoing peristalsis typically causes it to:

A. Retract spontaneously
B. Pull mesentery along
C. Perforate immediately
D. Untwist at the base

B. Pull mesentery along

If untreated, intussusception may progress to:

A. Fistula and pseudomembranes
B. Dysentery, malabsorption, infarction
C. Obstruction, vessel compression, infarction
D. Ascites, jaundice, varices

C. Obstruction, vessel compression, infarction

In idiopathic intussusception in infants and young children, which intervention can be both diagnostic and therapeutic?

A. Colonoscopy
B. Contrast enema
C. Exploratory laparotomy
D. Nasogastric decompression

B. Contrast enema

The majority of the gastrointestinal tract is primarily supplied by which set of arteries?

A. Celiac, SMA, IMA
B. Renal, iliac, lumbar
C. Gastric, splenic, hepatic
D. Portal, caval, azygos

A. Celiac, SMA, IMA

A pathology specimen shows necrosis limited to the mucosa and not extending beyond the muscularis mucosae. This is best classified as:

A. Mural infarction
B. Transmural infarction
C. Mucosal infarction
D. Serosal infarction

C. Mucosal infarction

Infarction involving the mucosa and submucosa is best termed:

A. Mural infarction
B. Mucosal infarction
C. Transmural infarction
D. Mesenteric strangulation

A. Mural infarction

Necrosis involving all layers of the intestinal wall, from the mucosa to the serosa.

A. Mucosal infarction
B. Mural infarction
C. Transmural infarction
D. Focal serosal necrosis

C. Transmural infarction

The most important risk factor for mesenteric arterial thrombosis is:

A. Chronic pancreatitis
B. Severe atherosclerosis
C. Portal hypertension
D. Diverticulosis

B. Severe atherosclerosis

Obstructive emboli causing acute intestinal ischemia most commonly arise from:

A. Hepatic veins and splenic cysts
B. Iliac plaques and varices
C. Aortic atheromas or mural thrombi
D. Mesenteric nodes and lymphatics

C. Aortic atheromas or mural thrombi

A 76-year-old woman develops abrupt cramping left lower abdominal pain, urgency to defecate, and bloody diarrhea. Which diagnosis is most likely?

A. Acute colonic ischemia
B. Secretory diarrhea
C. Small bowel volvulus
D. Malabsorptive enteropathy

A. Acute colonic ischemia

Which portion of the GI tract is the most common site of ischemia?

A. Stomach
B. Colon
C. Esophagus
D. Jejunum

B. Colon

Which pair of sites are classic GI watershed zones?

A. Cecum and ascending colon
B. Duodenum and jejunum
C. Splenic flexure and rectosigmoid
D. Ileum and transverse colon

C. Splenic flexure and rectosigmoid

A bowel specimen shows a sharply demarcated segment of intensely congested, dusky purple-red intestine involving all wall layers. Which mechanism is most likely?

A. Chronic venous congestion
B. Acute arterial obstruction
C. Lymphatic occlusion
D. Osmotic fluid loss

B. Acute arterial obstruction

In acute colonic ischemia, which finding most strongly suggests need for surgery?

A. Guarding on examination
B. Steatorrhea after meals
C. Intermittent bloating only
D. Fasting improves symptoms

A. Guarding on examination

Right-sided ischemic colitis is more severe primarily because it involves bowel supplied by the:

A. Inferior mesenteric artery
B. Celiac trunk
C. Superior mesenteric artery
D. Internal iliac artery

C. Superior mesenteric artery

Which statement about colonic ischemia is most accurate?

A. Usually diffuse and continuous
B. Most common in young men
C. Lesions are patchy, segmental
D. Right-sided disease is milder

C. Lesions are patchy, segmental

A premature neonate develops abdominal distention and feeding intolerance, and imaging plus surgery reveal full-thickness bowel wall necrosis involving both small and large intestine. Which diagnosis is most likely?

A. Angiodysplasia
B. Necrotizing enterocolitis
C. Exudative colitis
D. Dysentery

B. Necrotizing enterocolitis

The most severe bowel injury in necrotizing enterocolitis is:

A. Mucosal edema
B. Villous blunting
C. Transmural necrosis
D. Serosal fibrosis

C. Transmural necrosis

An older adult presents with intermittent lower GI bleeding. Colonoscopy shows malformed mucosal and submucosal vessels in the cecum. Which diagnosis best fits?

A. Volvulus
B. Angiodysplasia
C. Dysentery
D. Intussusception

B. Angiodysplasia

A patient develops chronic bulky, frothy, greasy, yellow stool after an allogeneic hematopoietic stem cell transplant. Which condition could directly explain the malabsorption?

A. Graft-versus-host disease
B. Right-sided ischemia
C. Necrotizing enterocolitis
D. Angiodysplasia

A. Graft-versus-host disease

A patient has painful, bloody, small-volume diarrhea with tenesmus. Which term best describes this syndrome?

A. Exudative diarrhea
B. Secretory diarrhea
C. Dysentery
D. Osmotic diarrhea

C. Dysentery

A hospitalized patient has watery diarrhea with isotonic stool losses that continue even when oral intake is stopped. Which diarrhea type is most likely?

A. Malabsorptive
B. Secretory
C. Exudative
D. Osmotic

B. Secretory

A young adult with lactase deficiency develops diarrhea after dairy intake, and symptoms improve completely during fasting. Which diarrhea mechanism is most likely?

A. Secretory
B. Exudative
C. Malabsorptive
D. Osmotic

D. Osmotic

_____ diarrhea follows generalized failure of nutrient absorption, is associated with steaorrhea and is relieved by fasting

A. Secretory
B. Exudative
C. Malabsorptive
D. Osmotic

C. Malabsorptive

_____ diarrhea is due to inflammatory disease characterized by purulent, bloody stools than continue during fasting

A. Secretory
B. Exudative
C. Malabsorptive
D. Osmotic

B. Exudative

A 24-year-old woman develops chronic diarrhea, bloating, and weight loss after eating wheat-containing foods. Small-bowel biopsy suggests immune-mediated enteropathy. Which diagnosis is most likely?

A. Environmental enteropathy
B. Celiac disease
C. Autoimmune enteropathy
D. Crohn disease

B. Celiac disease

In celiac disease, gliadin peptides presented by HLA-DQ2/DQ8 primarily activate which immune cell?

A. CD8+ T cells
B. Plasma cells
C. CD4+ T cells
D. Neutrophils

C. CD4+ T cells

Celiac disease most commonly involves which regions of the GI tract?

A. Duodenum and jejunum
B. Ileum and cecum
C. Stomach and duodenum
D. Colon and rectum

A. Duodenum and jejunum

The malabsorption in celiac disease is most directly caused by:

A. Pancreatic enzyme deficiency
B. Ileal bile salt loss
C. Lymphatic obstruction
D. Loss of brush border

D. Loss of brush border

The most sensitive serologic test for celiac disease is measurement of IgA antibodies against:

A. Endomysium
B. Tissue transglutaminase
C. Gliadin peptidase
D. Deamidated gluten

B. Tissue transglutaminase

The most common malignancy associated with celiac disease is:

A. Colonic adenocarcinoma
B. Gastric lymphoma
C. Enteropathy-associated T-cell lymphoma
D. Pancreatic adenocarcinoma

C. Enteropathy-associated T-cell lymphoma

Environmental enteropathy is most strongly associated with:

A. Gluten ingestion
B. Poor sanitation
C. Autoantibody formation
D. Mesenteric ischemia

B. Poor sanitation

A young boy has severe persistent diarrhea and multiple autoimmune disorders. Family history suggests an inherited syndrome. Which pattern best fits autoimmune enteropathy?

A. Autosomal dominant
B. Mitochondrial
C. Autosomal recessive
D. X-linked

D. X-linked

The severe familial form of autoimmune enteropathy caused by FOXP3 mutation is called:

A. IPEX
B. MEN1
C. Lynch syndrome
D. Wiskott-Aldrich

A. IPEX

FOXP3 mutations in IPEX most directly impair the function of:

A. B lymphocytes
B. Macrophages
C. Regulatory T cells
D. NK cells

C. Regulatory T cells

Abetalipoproteinemia is best described as an inherited inability to:

A. Absorb gluten peptides
B. Hydrolyze brush-border sugars
C. Produce pancreatic lipase
D. Secrete triglyceride-rich lipoproteins

D. Secrete triglyceride-rich lipoproteins

A peripheral smear in a patient with abetalipoproteinemia would most likely show:

A. Schistocytes
B. Acanthocytes
C. Spherocytes
D. Target cells

B. Acanthocytes

A 29-year-old patient has chronic abdominal pain and diarrhea. Endoscopy shows inflamed bowel separated by normal intervening mucosa. Which diagnosis is most likely?

A. Ulcerative colitis
B. Ischemic colitis
C. Crohn disease
D. Microscopic colitis

C. Crohn disease

Which feature best distinguishes Crohn disease from ulcerative colitis?

A. Transmural inflammation
B. Rectal involvement
C. Toxic megacolon risk
D. Mucosal ulceration only

A. Transmural inflammation

A patient with inflammatory bowel disease develops enteroenteric fistulas and bowel wall fibrosis. Which diagnosis best fits?

A. Ulcerative colitis
B. Infectious colitis
C. Pseudomembranous colitis
D. Crohn disease

D. Crohn disease

Which distribution is most typical of ulcerative colitis?

A. Any GI segment
B. Colon and rectum
C. Small bowel only
D. Stomach and duodenum

B. Colon and rectum

Histology from an inflamed bowel segment shows noncaseating granulomas and transmural inflammation. Which disorder is most likely?

A. Crohn disease
B. Ulcerative colitis
C. Ischemic colitis
D. Diverticulitis

A. Crohn disease

A patient with longstanding inflammatory bowel disease develops severe colonic dilation and systemic toxicity. Which disease is classically associated with this complication?

A. Crohn disease
B. Celiac disease
C. Angiodysplasia
D. Ulcerative colitis

D. Ulcerative colitis

Which gross feature is classically associated with Crohn disease?

A. Continuous rectosigmoid disease
B. Diffuse pseudopolyposis
C. Creeping fat
D. Superficial mucosal erosion

C. Creeping fat

Ulcerative colitis is typically confined to which bowel layers?

A. Muscularis and serosa
B. Mucosa and superficial submucosa
C. Full bowel wall thickness
D. Subserosa and mesentery

B. Mucosa and superficial submucosa

A patient with Crohn disease develops recurrent obstructive symptoms from fibrosing bowel narrowing. Which treatment is often required?

A. Surgical resection
B. Total colectomy
C. Air enema reduction
D. Anticoagulation

A. Surgical resection

A patient with severe ulcerative colitis undergoes total colectomy. What is the expected effect on the intestinal disease?

A. Disease shifts to ileum
B. Fistulas continue
C. Skip lesions persist
D. Intestinal disease is cured

D. Intestinal disease is cured

A 61-year-old woman has months of chronic nonbloody watery diarrhea. Colon imaging is normal, but biopsy shows inflammatory colitis. Which diagnosis is most likely?

A. Ulcerative colitis
B. Microscopic colitis
C. Crohn disease
D. Ischemic colitis

B. Microscopic colitis

Which feature best characterizes microscopic colitis?

A. Bloody diarrhea with masses
B. Transmural granulomatous inflammation
C. Continuous rectal ulceration
D. Normal radiology despite diarrhea

D. Normal radiology despite diarrhea

A colon biopsy shows a dense subepithelial collagen band, increased intraepithelial lymphocytes, and mixed lamina propria inflammation. Which diagnosis is most likely?

A. Lymphocytic colitis
B. GVHD colitis
C. Collagenous colitis
D. Ulcerative colitis

C. Collagenous colitis

Which histologic feature helps distinguish lymphocytic colitis from collagenous colitis?

A. Transmural fissures
B. Normal collagen thickness
C. Granuloma formation
D. Pseudomembrane formation

B. Normal collagen thickness

Lymphocytic colitis has a strong association with:

A. Celiac and autoimmune disease
B. Diverticulosis and hemorrhoids
C. Angiodysplasia and volvulus
D. NEC and intussusception

A. Celiac and autoimmune disease

A patient develops diarrhea after allogeneic hematopoietic stem cell transplantation. The stool is initially watery and later becomes bloody. Which diagnosis is most likely?

A. Microscopic colitis
B. Collagenous colitis
C. Lymphocytic colitis
D. Intestinal graft-versus-host disease

D. Intestinal graft-versus-host disease

The most common histologic finding in intestinal graft-versus-host disease is:

A. Dense subepithelial fibrosis
B. Transmural necrosis
C. Crypt epithelial apoptosis
D. Noncaseating granulomas

C. Crypt epithelial apoptosis

A 68-year-old patient undergoing screening colonoscopy is found to have multiple saclike mucosal outpouchings in the colon that are acquired rather than congenital. These lesions are best classified as:

A. True diverticula
B. Adenomatous polyps
C. Pseudodiverticula
D. Vascular ectasias

C. Pseudodiverticula

The pathogenesis of diverticular disease is most closely related to:

A. Elevated intraluminal pressure
B. Transmural granulomatous inflammation
C. Mucosal ischemic necrosis
D. Defective enteric innervation

A. Elevated intraluminal pressure

Which dietary pattern most promotes progression of diverticular disease?

A. High-protein diet
B. High-fat diet
C. Lactose-free diet
D. Low-fiber diet

D. Low-fiber diet

Which statement about diverticular disease is most accurate?

A. Usually presents with obstruction
B. Most patients are asymptomatic
C. Has high malignant potential
D. Usually involves true diverticula

B. Most patients are asymptomatic

A small left-sided colonic polyp is found on routine colonoscopy. Histology shows a benign epithelial proliferation without dysplasia. Which lesion is most likely?

A. Hyperplastic polyp
B. Inflammatory fibroid polyp
C. Tubular adenoma
D. Hamartomatous polyp

A. Hyperplastic polyp

Which feature best distinguishes a hyperplastic polyp from an adenomatous lesion?

A. More common in rectum
B. Causes mucus discharge
C. No malignant potential
D. Associated with fistulas

C. No malignant potential

Hyperplastic polyps are most commonly found in the:

A. Cecum
B. Jejunum
C. Transverse colon
D. Left colon

D. Left colon

A patient presents with rectal bleeding and mucus discharge. Endoscopy shows an inflammatory lesion on the anterior rectal wall. Which diagnosis best fits?

A. Hyperplastic polyp
B. Solitary rectal ulcer syndrome pattern
C. Diverticular disease
D. Villous adenoma

B. Solitary rectal ulcer syndrome pattern

Which symptom pair is most characteristic of the inflammatory polyp/solitary rectal ulcer syndrome pattern?

A. Hematemesis and melena
B. Rectal bleeding and mucus
C. Steatorrhea and bloating
D. Obstipation and vomiting

B. Rectal bleeding and mucus

A 4-year-old child presents with intermittent painless rectal bleeding. Colonoscopy reveals a solitary rectal polyp composed of disorganized but mature tissue elements. Which diagnosis is most likely?

A. Hyperplastic polyp
B. Tubular adenoma
C. Juvenile polyp
D. Inflammatory pseudopolyp

C. Juvenile polyp

Juvenile polyps are best classified as:

A. Hamartomatous polyps
B. Neoplastic adenomas
C. Inflammatory lesions
D. Vascular malformations

A. Hamartomatous polyps

Which presentation is most typical of a juvenile polyp?

A. Watery secretory diarrhea
B. Small bowel obstruction
C. Mucocutaneous pigmentation
D. Rectal bleeding

D. Rectal bleeding

Juvenile polyps most often arise in the:

A. Jejunum
B. Rectum
C. Cecum
D. Duodenum

B. Rectum

A child has multiple hamartomatous colorectal polyps and a family history of similar lesions. Which syndrome should raise concern for future colonic adenocarcinoma?

A. Lynch syndrome
B. FAP
C. Juvenile polyposis syndrome
D. Cowden syndrome

C. Juvenile polyposis syndrome

Juvenile polyposis syndrome is often associated with mutation in:

A. SMAD4
B. APC
C. KRAS
D. MLH1

A. SMAD4

The major long-term malignancy risk in juvenile polyposis syndrome is:

A. Gastric lymphoma
B. Pancreatic carcinoma
C. Small bowel carcinoid
D. Colonic adenocarcinoma

D. Colonic adenocarcinoma

A teenager with dark pigmented macules on the lips is found to have multiple hamartomatous polyps throughout the GI tract. Which syndrome is most likely?

A. Juvenile polyposis syndrome
B. Peutz-Jeghers syndrome
C. Cronkhite-Canada syndrome
D. Serrated polyposis syndrome

B. Peutz-Jeghers syndrome

In Peutz-Jeghers syndrome, hamartomatous polyps most often involve the:

A. Small intestine
B. Rectum
C. Esophagus
D. Appendix

A. Small intestine

Which gene is characteristically mutated in Peutz-Jeghers syndrome?

A. SMAD4
B. TP53
C. STK11
D. BRAF

C. STK11

A screening colonoscopy identifies a neoplastic colonic polyp with epithelial atypia. Which histologic feature is the defining hallmark of an adenoma?

A. Mucin depletion
B. Dysplasia
C. Granulomas
D. Fibrosis

B. Dysplasia

Which statement about colonic adenomas is most accurate?

A. They are usually inflammatory
B. They lack malignant significance
C. They are mainly hamartomatous
D. They are most common neoplastic polyps

D. They are most common neoplastic polyps

Most colorectal adenocarcinomas arise from which precursor lesion?

A. Adenoma
B. Hyperplastic polyp
C. Juvenile polyp
D. Inflammatory polyp

A. Adenoma

A 1-cm pedunculated polyp is removed from the sigmoid colon. Histology shows crowded tubular glands without villous architecture. Which diagnosis is most likely?

A. Villous adenoma
B. Sessile serrated adenoma
C. Tubular adenoma
D. Tubulovillous adenoma

C. Tubular adenoma

Which gross pattern is most typical of a villous adenoma?

A. Small and pedunculated
B. Flat with granulomas
C. Tiny and left-sided
D. Large and sessile

D. Large and sessile

A broad-based colonic adenoma causes chronic mucous stool losses with hypokalemia. Which lesion best fits?

A. Tubular adenoma
B. Villous adenoma
C. Juvenile polyp
D. Hyperplastic polyp

B. Villous adenoma

Which microscopic feature best characterizes a villous adenoma?

A. Covered by villi
B. Serrated crypt bases
C. Dense collagen band
D. Cystic dilated glands

A. Covered by villi

A polyp demonstrates both tubular glands and villous projections on histology. Which diagnosis is most appropriate?

A. Tubular adenoma
B. Villous adenoma
C. Tubulovillous adenoma
D. Serrated hyperplastic polyp

C. Tubulovillous adenoma

A right-sided colonic polyp is found to have premalignant potential despite lacking classic cytologic dysplasia. Which lesion is most likely?

A. Juvenile polyp
B. Sessile serrated adenoma
C. Inflammatory polyp
D. Solitary rectal ulcer

B. Sessile serrated adenoma

Which feature most strongly supports sessile serrated adenoma rather than tubular adenoma?

A. Pedunculated architecture
B. Protein secretion
C. Right-sided location
D. Pure villous surface

C. Right-sided location

A colonic polyp shows dysplastic glands that have penetrated through the basement membrane but remain confined to the lamina propria. Which diagnosis is most appropriate?

A. Invasive adenocarcinoma
B. High-grade dysplasia
C. Intramucosal carcinoma
D. Sessile serrated adenoma

C. Intramucosal carcinoma

Intramucosal carcinoma is defined by extension of dysplastic epithelium into the:

A. Lamina propria or muscularis mucosae
B. Muscularis propria and serosa
C. Submucosa and mesentery
D. Pericolic fat and nodes

A. Lamina propria or muscularis mucosae

Why does intramucosal carcinoma have little to no metastatic potential?

A. It remains cytologically bland
B. It lacks gland formation
C. It cannot breach basement membrane
D. It is confined to mucosa

D. It is confined to mucosa

What is the usual treatment for intramucosal carcinoma arising in a polyp?

A. Chemoradiation
B. Polypectomy alone
C. Segmental colectomy
D. Immunotherapy

B. Polypectomy alone

Familial adenomatous polyposis is best described as which syndrome?

A. APC-associated adenomatous polyposis
B. Mismatch repair deficiency syndrome
C. Hamartomatous polyposis syndrome
D. Biallelic MYH serrated syndrome

A. APC-associated adenomatous polyposis

Which finding is required for diagnosis of classic familial adenomatous polyposis?

A. At least 10 polyps
B. Rectal cancer before age 30
C. Biallelic APC mutation only
D. At least 100 polyps

D. At least 100 polyps

Colorectal adenocarcinoma develops in ____% of untreated FAP patients

100

The standard preventive treatment for classic familial adenomatous polyposis is:

A. Annual polypectomy
B. Endoscopic ablation
C. Prophylactic colectomy
D. Small-bowel resection

C. Prophylactic colectomy

After colectomy for FAP, which medication class can reduce polyps in the residual rectum?

A. NSAIDs
B. Antimetabolites
C. Corticosteroids
D. Bile acid binders

A. NSAIDs

MYH-associated polyposis is caused by:

A. Monoallelic APC deletion
B. Somatic KRAS mutation
C. Germline STK11 mutation
D. Biallelic MYH mutation

D. Biallelic MYH mutation

Compared with classic FAP, MYH-associated polyposis typically shows:

A. Greater rectal involvement
B. Fewer polyps
C. Earlier colectomy need
D. Obligatory APC loss

B. Fewer polyps

Lynch syndrome is most strongly associated with which underlying defect?

A. APC inactivation
B. STK11 mutation
C. FOXP3 mutation
D. Mismatch repair defect

D. Mismatch repair defect

Which statement about Lynch syndrome-associated colon cancer is most accurate?

A. Usually arises in rectum
B. Typically left-sided
C. Often cecal only
D. Tends to be right-sided

D. Tends to be right-sided

Lynch syndrome is associated with colorectal cancer and:

A. No extracolonic cancers
B. Only gastric lymphoma
C. Several extracolonic cancers
D. Only endometrial cancer

C. Several extracolonic cancers

Which statement about colorectal adenocarcinoma is correct?

A. Rare GI malignancy
B. Usually metastatic at diagnosis
C. Arises only from adenomas
D. Most common GI malignancy

D. Most common GI malignancy

Colorectal adenocarcinoma develops through which two major molecular pathways?

A. STK11 and FOXP3
B. APC and microsatellite instability
C. KRAS and TGF-β only
D. SMAD4 and MYH

B. APC and microsatellite instability

A right-sided colon cancer is most likely to present with:

A. Iron deficiency anemia
B. Early obstruction
C. Severe tenesmus
D. Mucus discharge

A. Iron deficiency anemia

A patient with colon cancer has occult blood loss, crampy abdominal pain, and altered bowel habits. Which tumor location is most likely?

A. Transverse colon
B. Right colon
C. Left colon
D. Cecum

C. Left colon

Which factors are most important in determining prognosis in colorectal adenocarcinoma?

A. Tumor size and grade
B. KRAS and BRAF status
C. Site and gross pattern
D. Invasion depth and nodal spread

D. Invasion depth and nodal spread

The most common site of metastasis from colorectal adenocarcinoma is the:

A. Liver
B. Lung
C. Brain
D. Bone

A. Liver

A 48-year-old patient presents with painful rectal bleeding that worsens with defecation. Which underlying mechanism most directly explains hemorrhoid formation?

A. Mucosal autoimmune injury
B. Elevated venous pressure
C. Arterial embolic occlusion
D. Crypt epithelial apoptosis

B. Elevated venous pressure

Which presentation is most characteristic of hemorrhoids?

A. Pain and rectal bleeding
B. Steatorrhea and bloating
C. Dysphagia and odynophagia
D. Hematemesis and melena

A. Pain and rectal bleeding

Hemorrhoids are classified anatomically as:

A. Mucosal or transmural
B. Pedunculated or sessile
C. Acute or chronic
D. Internal or external

D. Internal or external

Acute appendicitis is most often initiated by:

A. Villous mucin secretion
B. Autoimmune epithelial injury
C. Luminal obstruction
D. Mesenteric arterial embolus

C. Luminal obstruction

The key early pathogenic event in acute appendicitis is:

A. Reduced lymphatic drainage only
B. Increased intraluminal pressure
C. Transmural granuloma formation
D. Mucosal collagen deposition

B. Increased intraluminal pressure

In acute appendicitis, rising intraluminal pressure most directly compromises:

A. Venous outflow
B. Bile secretion
C. Arterial inflow only
D. Lymphocyte trafficking

A. Venous outflow

Which histologic finding establishes the diagnosis of acute appendicitis?

A. Submucosal fibrosis
B. Serosal hemorrhage
C. Muscularis propria neutrophils
D. Crypt abscesses only

C. Muscularis propria neutrophils

Appendiceal neuroendocrine tumor. Which statement is most accurate?

A. Usually highly aggressive
B. Most often poorly differentiated
C. Rare among appendiceal tumors
D. Usually benign

D. Usually benign

The most common tumor of the appendix is:

A. Mucinous cystadenoma
B. Adenocarcinoma
C. Neuroendocrine tumor
D. Gastrointestinal stromal tumor

C. Neuroendocrine tumor

Appendiceal neuroendocrine tumors are usually:

A. Infiltrative and high grade
B. Well differentiated
C. Associated with dysentery
D. Derived from mucinous epithelium

B. Well differentiated

A surgeon removes a dilated appendix distended by accumulated mucin. Which diagnosis best fits this gross description?

A. Appendiceal mucocele
B. Acute appendicitis
C. Juvenile polyp
D. Villous adenoma

A. Appendiceal mucocele

An appendiceal mucocele may reflect either simple obstruction or:

A. Ischemic infarction
B. Neuroendocrine hyperplasia
C. Mucinous neoplasm
D. Crohn disease

C. Mucinous neoplasm

A patient with progressive abdominal distention undergoes surgery, and the peritoneal cavity is found to be filled with tenacious, semisolid mucin. Which diagnosis is most likely?

A. Sterile peritonitis
B. Sclerosing retroperitonitis
C. Pseudomyxoma peritonei
D. Peritoneal mesothelioma

C. Pseudomyxoma peritonei

A patient develops chemical inflammation of the peritoneum after leakage of bile during abdominal injury. Which diagnosis best fits?

A. Pseudomyxoma peritonei
B. Sterile peritonitis
C. Sclerosing retroperitonitis
D. Peritoneal mesothelioma

B. Sterile peritonitis

Also known as idiopathic retroperitoneal fibrosis or Ormond disease, is characterized by dense fibrosis that may extend to involve the mesentery:

A. Peritoneal mesothelioma
B. Sterile peritonitis
C. Pseudomyxoma peritonei
D. Sclerosing retroperitonitis

D. Sclerosing retroperitonitis

A patient has fibroinflammatory retroperitoneal disease suspected to be part of a systemic immune-mediated process. Which association is most likely?

A. STK11-related syndrome
B. APC-associated polyposis
C. IgG4-related disease
D. HLA-B27 arthritis

C. IgG4-related disease

Which lesion is a primary malignant tumor of the peritoneal lining?

A. Peritoneal mesothelioma
B. Pseudomyxoma peritonei
C. Sclerosing retroperitonitis
D. Sterile peritonitis

A. Peritoneal mesothelioma

A patient develops profuse watery diarrhea after exposure to contaminated water. The responsible organism produces diarrhea primarily by which mechanism?

A. Mucosal invasion with ulceration
B. Enterocyte apoptosis and sloughing
C. cAMP-mediated chloride secretion
D. Villous destruction with malabsorption

C. cAMP-mediated chloride secretion

Cholera toxin most directly causes intestinal fluid loss by activating:

A. CFTR-dependent chloride secretion
B. Sodium-glucose cotransport inhibition
C. Crypt macrophage apoptosis
D. Mesenteric vascular thrombosis

A. CFTR-dependent chloride secretion

A traveler presents with massive painless watery diarrhea and severe dehydration. The stool is described as gray-white flecks in liquid. Which description is classic?

A. Currant-jelly stool
B. Rice-water stool
C. Greasy bulky stool
D. Bloody mucoid stool

B. Rice-water stool

Which organism is a common bacterial enteric pathogen and is strongly associated with both reactive arthritis and Guillain-Barré syndrome?

A. Vibrio cholerae
B. Shigella dysenteriae
C. Campylobacter jejuni
D. Clostridioides difficile

C. Campylobacter jejuni

Which postinfectious extraintestinal complication is classically associated with Campylobacter jejuni?

A. Toxic megacolon
B. Enteropathy-associated lymphoma
C. Reactive arthritis
D. Pseudomyxoma peritonei

C. Reactive arthritis

A febrile patient has painful bloody diarrhea after ingesting contaminated food. These are gram-negative unencapsulated, nonmotile, facultative anaerobes that belong to the Enterobacteriaceae family and are closely related to enteroinvasive E. coli:

A. Cholera
B. Campylobacter enteritis
C. Microscopic colitis
D. Shigellosis

D. Shigellosis

Shigellosis most characteristically involves which intestinal regions?

A. Duodenum and jejunum
B. Cecum and ascending colon
C. Ileum and left colon
D. Rectum

C. Ileum and left colon

Which management approach is most appropriate for shigellosis?

A. Antidiarrheals to limit fluid loss
B. Surgery for transmural necrosis
C. Steroids for immune suppression
D. Antibiotics; avoid antidiarrheals

D. Antibiotics; avoid antidiarrheals

A 23-year-old patient develops fever and abdominal symptoms after eating undercooked poultry and eggs. Which source most strongly supports salmonellosis?

A. Contaminated meat, poultry, eggs, milk
B. Unwashed shellfish from seawater
C. Unpasteurized fruit juice only
D. Contaminated canned vegetables only

A. Contaminated meat, poultry, eggs, milk

A patient with enteric fever has ileal lymphoid hyperplasia on pathology. Enlargement of which structure is classically associated with typhoid fever?

A. Crypt abscesses
B. Peyer patches
C. Brunner glands
D. Paneth cell nests

B. Peyer patches

A febrile traveler is suspected of having typhoid fever. Which skin finding, if present, would support the diagnosis?

A. Erythema nodosum
B. Target lesions
C. Rose spots
D. Spider angiomas

C. Rose spots

During the febrile phase of typhoid fever, which diagnostic study is most likely to be positive?

A. Blood cultures
B. Stool ova exam
C. Sweat chloride test
D. Fecal elastase assay

A. Blood cultures

A patient develops enterocolitis after consuming pork and raw milk during the winter. Which organism is most strongly suggested by this epidemiologic pattern?

A. Shigella sonnei
B. Yersinia enterocolitica
C. Vibrio cholerae
D. Campylobacter jejuni

B. Yersinia enterocolitica

Which exposure pattern is most classically associated with Yersinia infection?

A. Shellfish and seawater
B. Daycare fecal spread
C. Poultry and eggs
D. Pork, raw milk, water

D. Pork, raw milk, water

Yersinia most directly initiates intestinal invasion by targeting which specialized epithelial cell?

A. M cell
B. Goblet cell
C. Paneth cell
D. Enterocyte

A. M cell

Yersinia adhesins promote host cell attachment by binding to:

A. E-cadherin
B. ICAM-1
C. β1-integrins
D. Selectins

C. β1-integrins

Which statement about E. coli is most accurate?

A. Gram-positive cocci
B. Acid-fast bacilli
C. Anaerobic spirochetes
D. Gram-negative bacilli

D. Gram-negative bacilli

The heat-labile toxin of ETEC causes diarrhea by increasing intracellular:

A. cAMP
B. cGMP
C. IP3
D. DAG

A. cAMP

ETEC heat-stable toxins resemble guanylin and stimulate which pathway?

A. Adenylate cyclase, increased cAMP
B. Phospholipase C, increased IP3
C. Guanylate cyclase, increased cGMP
D. Tyrosine kinase, increased MAPK

C. Guanylate cyclase, increased cGMP

The pathogenesis of Clostridioides difficile colitis most often begins with:

A. Viral invasion of enterocytes
B. Antibiotic disruption of microbiota
C. Mesenteric arterial thrombosis
D. Autoimmune crypt destruction

B. Antibiotic disruption of microbiota

Which gross or endoscopic finding is classically associated with Clostridioides difficile colitis?

A. Creeping fat
B. Pseudomembranes
C. Villous atrophy
D. Cobblestoning

B. Pseudomembranes

Which combination is a classic risk profile for Clostridioides difficile colitis?

A. Antibiotics, hospitalization, advanced age
B. Pork intake, winter season, infancy
C. Raw milk, travel, dehydration
D. Gluten exposure, HLA typing, anemia

A. Antibiotics, hospitalization, advanced age

Which diagnostic approach is preferred for suspected Clostridioides difficile colitis?

A. Routine stool culture
B. Blood culture
C. Toxin detection
D. Colon biopsy first

C. Toxin detection

A patient with confirmed Clostridioides difficile colitis requires treatment. Which regimen is appropriate based on the material provided?

A. IV ceftriaxone
B. Oral metronidazole or vancomycin
C. Oral NSAIDs
D. Air contrast enema

B. Oral metronidazole or vancomycin

Has become the most common cause of diarrhea worldwide

A. Rotavirus
B. Adenovirus
C. Norovirus
D. Campylobacter jejuni

C. Norovirus

Norovirus most commonly spreads through:

A. Tick bites only
B. Food, water, person-to-person
C. Airborne spores only
D. Sexual transmission only

B. Food, water, person-to-person

This encapsulated virus with a segmented, double-stranded RNA genome is highly prevalent and a significant cause of diarrheal deaths worldwide.

A. Rotavirus
B. Norovirus
C. CMV
D. EBV

A. Rotavirus

Pediatric diarrhea, can affect immunocompromised patients:

A. Astrovirus
B. Rotavirus
C. Cholera toxin
D. Adenovirus

D. Adenovirus

A 6-year-old child develops bloating, foul-smelling stools, and lactose intolerance after a camping trip. Which organism most likely caused decreased brush-border enzymes, including lactase?

A. Giardia lamblia
B. Cryptosporidium parvum
C. Enterobius vermicularis
D. Ascaris lumbricoides

A. Giardia lamblia

The diarrhea caused by Giardia lamblia is best classified as:

A. Exudative diarrhea
B. Dysenteric diarrhea
C. Malabsorptive diarrhea
D. Secretory diarrhea

C. Malabsorptive diarrhea

Which diagnostic test is most appropriate for suspected giardiasis based on the material provided?

A. Blood culture
B. Stool cyst immunofluorescence
C. Stool toxin assay
D. Duodenal manometry

B. Stool cyst immunofluorescence

A patient with AIDS develops profuse nonbloody watery diarrhea. The organism causes sodium malabsorption, chloride secretion, and increased intestinal permeability. Which pathogen is most likely?

A. Giardia lamblia
B. Strongyloides stercoralis
C. Cryptosporidium
D. Hookworm

C. Cryptosporidium

Which stool finding is most useful for diagnosing cryptosporidiosis?

A. Stool ova
B. Stool oocysts
C. Stool leukocytes
D. Stool ketones

B. Stool oocysts

A patient has watery diarrhea from a parasite that causes both sodium malabsorption and chloride secretion. Which infection is most likely?

A. Pinworm infection
B. Cryptosporidiosis
C. Giardiasis
D. Ascariasis

B. Cryptosporidiosis

A child develops cough, transient pulmonary symptoms, and later intestinal parasitic infection. Which helminth classically migrates through the lungs before maturing in the intestine?

A. Enterobius vermicularis
B. Hookworm
C. Ascaris lumbricoides
D. Giardia lamblia

C. Ascaris lumbricoides

Which parasite is most associated with an eosinophil-rich inflammatory reaction during tissue migration?

A. Ascaris lumbricoides
B. Cryptosporidium
C. Giardia lamblia
D. Norovirus

A. Ascaris lumbricoides

A patient remains chronically infected because larvae hatch within the intestine and repeatedly reinvade the host. Which organism has this autoinfective cycle?

A. Ascaris lumbricoides
B. Hookworm
C. Pinworm
D. Strongyloides

D. Strongyloides

Which pair of parasites both include a lung migration phase in their life cycle?

A. Giardia and pinworm
B. Ascaris and Strongyloides
C. Hookworm and pinworm
D. Giardia and Cryptosporidium

B. Ascaris and Strongyloides

A patient from a resource-limited setting has fatigue and chronic microcytic anemia. Endoscopy shows worms attached in the duodenum causing superficial erosions. Which infection is most likely?

A. Strongyloidiasis
B. Ascariasis
C. Hookworm infection
D. Pinworm infection

C. Hookworm infection

Hookworm causes chronic iron deficiency anemia primarily because the worms:

A. Induce hemolysis directly
B. Suck blood in duodenum
C. Block folate absorption
D. Destroy Peyer patches

B. Suck blood in duodenum

A child has intense nighttime perianal itching. Which parasite most likely causes this by depositing eggs on the perirectal mucosa?

A. Giardia lamblia
B. Hookworm
C. Enterobius vermicularis
D. Strongyloides

C. Enterobius vermicularis

Which transmission route is most characteristic of pinworm infection?

A. Hand-to-mouth spread
B. Tick-borne spread
C. Aerosol inhalation
D. Raw pork ingestion

A. Hand-to-mouth spread