A 30-year-old female complains of epigastric pain radiating to the right shoulder after vomiting French fries. Pain worsens with deep inspiration. Suspect:

• A. Irritable bowel syndrome
• B. Peptic ulcer
• C. Renal calculi
• D. Cholecystitis

Answer: (D)

A biliary process is most likely. Pain in the upper right quadrant that starts after eating fatty foods and then radiates to the right shoulder is classic for gallbladder irritation. The right shoulder referral arises because the gallbladder’s inflammation irritates the diaphragmatic pleura via the phrenic nerve (C3–C5), producing shoulder pain. The fact that deep inspiration worsens the pain fits diaphragmatic irritation, which is common with acute cholecystitis or biliary colic.

Irritable bowel syndrome usually causes diffuse, crampy abdominal pain without a specific right shoulder radiation or postprandial pattern. Peptic ulcer disease can cause epigastric pain and may radiate, but it more commonly has a different pattern and is not characteristically worsened by deep breaths or triggered specifically by fatty meals in the right upper quadrant. Renal calculi cause intense flank or groin pain with possible hematuria, not typically right shoulder pain after a fatty meal.

So the combination of post-meal right upper quadrant pain with radiation to the right shoulder and inspiration-triggered worsening points most strongly to gallbladder inflammation (cholecystitis).