The Clinical Significance of the Various Descriptions of Vomitus

• Undigested food → esophageal issue (e.g., pharyngeal pouch or achalasia). Note: this is not really vomiting, but regurgitation, which is much less forceful and does not come from the stomach (and therefore not associated with nausea!)
• Non-bilious, with partially digested food →
  • Gastric outlet obstruction (e.g., from peptic ulcer disease or malignancy, or from pyloric stenosis)
  • GastroparesisVomiting
• Bilious (green) → small bowel obstruction distal to the hepatopancreatic ampulla (of Vater)
• Coffee ground emesis → dark brown and granular → blood altered by stomach acids → suggests a slowed or stopped gastric or duodenal bleed.
• Red blood (= hematemesis) → suggests variceal or arterial bleed → need urgent upper endoscopy
• Feculent (brown & foul-smelling) =  bacterial overgrowth, distal small bowel or colonic obstruction
• Fecal → gastrocolonic fistula or coprophagia

Reference

• Oxford Cases in Medicine & Surgery (2010)