First Aid for the USMLE Step 2 CS

Section 3. Minicases

Constipation/Diarrhea

Key History

Frequency, color, odor, and volume of stools; presence of mucus or flatulence; whether stools float in bowl; duration of change in bowel habits; associated symptoms (constitutional, abdominal pain, bloating, tenesmus, sense of incomplete evacuation, melena or hematochezia); thyroid disease symptoms (eg, feeling hot, palpitations, weight loss); diet (especially fiber and fluid intake); medications (including recent antibiotics); sick contacts, travel, camping, HIV risk factors; history of abdominal surgeries, diabetes, pancreatitis; alcohol and drug use; family history of colon cancer.

Key Physical Exam

Vital signs; relevant thyroid/endocrine exam; abdominal and rectal exams; ± female pelvic exam.

Presentation

Differential

Workup

■ 67 yo M presents with alternating diarrhea and constipation, decreased stool caliber, and blood in the stool for the past 8 months. He also reports unintentional weight loss. He is on a low-fiber diet and has a family history of colon cancer. His last colonoscopy was 12 years ago.

Colorectal cancer

Irritable bowel syndrome

Diverticulosis

GI parasitic infection

(ascariasis, giardiasis)

Inflammatory bowel

disease

Rectal exam, stool for occult blood

CBC

Electrolytes

AST/ALT/bilirubin/

alkaline phosphatase

Colonoscopy

Barium enema

CT—abdomen/pelvis

■ 28 yo M presents with constipation (hard stool) for the past 3 weeks. Since his mother died 2 months ago, he and his father have eaten only junk food.

Low-fiber diet

Depression

Substance abuse (eg,

heroin)

Irritable bowel syndrome

Hypothyroidism

Rectal exam

TSH

Electrolytes

Urine toxicology

CONSTIPATION/DIARRHEA (cont'd)

Presentation

Differential

Workup

■ 30 yo F presents with alternating constipation and diarrhea accompanied by abdominal pain that is relieved by defecation. She has no nausea, vomiting, weight loss, or blood in her stool.

Irritable bowel syndrome

Inflammatory bowel disease

Celiac disease

Chronic pancreatitis

GI parasitic infection (ascariasis, giardiasis) Lactose intolerance

Rectal exam, stool for occult blood CBC

Electrolytes

Colonoscopy

Stool for ova and parasitology

CT—abdomen/pelvis

■ 33 yo M presents with watery diarrhea, vomiting, and diffuse abdominal pain that began yesterday. He also reports feeling hot. Several of his coworkers are also ill.

Infectious diarrhea (gastroenteritis)—

bacterial, viral, parasitic, protozoal

Food poisoning

Rectal exam, stool for occult blood

Stool leukocytes and culture CBC

Electrolytes

CT—abdomen/pelvis

■ 40 yo F presents with watery diarrhea and abdominal cramps. Last week she was on antibiotics for a UTI.

Pseudomembranous

(Clostridium difficile) colitis

Gastroenteritis Cryptosporidiosis

Food poisoning Inflammatory bowel disease

Stool for C difficile toxin

Rectal exam, stool for occult blood

Stool leukocytes and culture CBC

Electrolytes

■ 25 yo M presents with watery diarrhea and abdominal cramps. He was recently in Mexico.

Traveler’s diarrhea

Giardiasis

Amebiasis

Food poisoning

Hepatitis A

Rectal exam

Stool leukocytes, culture,

Giardia antigen,

Entamoeba histolytica antigen

CBC

Electrolytes

AST/ALT/bilirubin/ alkaline phosphatase

Viral hepatitis serologies

■ 30 yo F presents with watery diarrhea, abdominal cramping, and bloating. Her symptoms are aggravated by milk ingestion and are relieved by fasting.

Lactose intolerance

Gastroenteritis

 

Inflammatory bowel disease

Irritable bowel syndrome Hyperthyroidism

Rectal exam

Stool leukocytes and culture

Hydrogen breath test

TSH

CONSTIPATION/DIARRHEA (cant'd)

Presentation

Differential

Workup

■ 33 yo M presents with watery diarrhea, diffuse abdominal pain, and weight loss within the past 3 weeks. He has a history of aphthous ulcers. He has not responded to antibiotics.

Crohn’s disease

Gastroenteritis

Ulcerative colitis

Celiac disease

Pseudomembranous colitis

Hyperthyroidism

Small bowel lymphoma

Carcinoid syndrome

Rectal exam, stool for occult blood

Stool leukocytes and culture

CBC

Electrolytes

Colonoscopy

CT—abdomen

TSH

Small bowel series

5-HIAA

 

Upper Gi Bleeding

Key History

Amount, duration, context (after severe vomiting, alcohol ingestion, nosebleed); associated symptoms (constitutional, nausea, abdominal pain, dyspepsia); medications (especially blood thinners, NSAIDs, and corticosteroids); history of peptic ulcer disease, liver disease, abdominal aortic aneurysm repair, easy bleeding.

Key Physical Exam

Vital signs, including orthostatics; ENT, heart, lung, abdominal, and rectal exams.

Presentation

Differential

Workup

■ 45 yo F presents with coffee-ground emesis for the past 3 days. Her stool is dark and tarry. She has a history of intermittent epigastric pain that is relieved by food and antacids.

Bleeding peptic ulcer

Gastritis

Gastric cancer

Esophageal varices

Rectal exam

CBC, type and cross

Electrolytes

AST/ALT/bilirubin/ alkaline phosphatase

INR

Upper endoscopy (including H pylori testing if ulcer is confirmed)

■ 40 yo F presents with epigastric pain and coffeeground emesis. She has a history of rheumatoid arthritis that has been treated with NSAIDs. She is an alcoholic.

Gastritis

Bleeding peptic ulcer

Gastric cancer

Esophageal varices

Mallory-Weiss tear

Rectal exam

CBC, type and cross

Electrolytes

AST/ALT/bilirubin/

alkaline phosphatase

INR

Upper endoscopy





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