Left upper quadrant

Splenic disease
Myocardial infarction
Dissecting aortic aneurysm
Pneumonia
Pyelonephritis
Nephrolithiasis
Pancreatitis
Hiatal hernia
Peptic ulcer disease
Mallory-Weiss tear

Epigastrium

Peptic ulcer disease
Esophagitis
Myocardial infarction
Pericarditis
Pneumonia
Pancreatitis
Cholecystitis
Perforation/obstruction

Right upper quadrant

Hepatitis
Hepatic tumor
Cholelithiasis
Cholecystitis
Cholangitis
Pyelonephritis
Nephrolithiasis
Pneumonia
Pulmonary embolism/infarction

Periumbilical

Gastroenteritis
Appendicitis
Pancreatitis
Intestinal ischemia/infarction
Intestinal obstruction

Left lower quadrant

Diverticulitis
Colon cancer
Urinary tract infection
Nephrolithiasis
Pyelonephritis
Irritable bowel syndrome
Gynecologic causes (ectopic pregnancy, pelvic inflammatory disease, mittelschmerz, ovarian cyst, fibroids, endometriosis, tumor, torsion)
Inguinal hernia
Psoas abscess

Hypogastrium

Ectopic pregnancy
Ovarian torsion
Pelvic inflammatory disease

Right lower quadrant

Same as for left lower quadrant plus

Appendicitis
Diverticulitis
Meckel’s diverticulum
Intussusception