The abdomen can be divided into four regions called quadrants. Locations and associated conditions include:
Diffuse
Peritonitis
Vascular: mesenteric ischemia, ischemic colitis, Henoch-Schonlein purpura, sickle cell disease, systemic lupus erythematosus, polyarteritis nodosa
Small bowel obstruction
Irritable bowel syndrome
Metabolic disorders: ketoacidosis, porphyria, familial Mediterranean fever, adrenal crisis
Epigastric
Heart: myocardial infarction, pericarditis
Stomach: gastritis, stomach ulcer, stomach cancer
Pancreas: pancreatitis, pancreatic cancer
Intestinal: duodenal ulcer, diverticulitis, appendicitis
Right upper quadrant
Liver: hepatomegaly, fatty liver, hepatitis, liver cancer, abscess
Gallbladder and biliary tract: inflammation, gallstones, worm infection, cholangitis
Colon: bowel obstruction, functional disorders, gas accumulation, spasm, inflammation, colon cancer
Other: pneumonia, Fitz-Hugh-Curtis syndrome
Left upper quadrant
Splenomegaly
Colon: bowel obstruction, functional disorders, gas accumulation, spasm, inflammation, colon cancer
Peri-umbilical (the area around the umbilicus, aka the belly button)
Appendicitis
Pancreatitis
Inferior myocardial infarction
Peptic ulcer
Diabetic ketoacidosis
Vascular: aortic dissection, aortic rupture
Bowel: mesenteric ischemia, Celiac disease, inflammation, intestinal spasm, functional disorders, small bowel obstruction
Lower abdominal pain
Diarrhea
Colitis
Crohns
Dysentery
Hernia
Right lower quadrant
Colon: intussusception, bowel obstruction, appendicitis (McBurneys point)
Renal: kidney stone (nephrolithiasis), pyelonephritis
Pelvic: cystitis, bladder stone, bladder cancer, pelvic inflammatory disease, pelvic pain syndrome
Gynecologic: endometriosis, intrauterine pregnancy, ectopic pregnancy, ovarian cyst, ovarian torsion, fibroid (leiomyoma), abscess, ovarian cancer, endometrial cancer
Left lower quadrant
Bowel: diverticulitis, sigmoid colon volvulus, bowel obstruction, gas accumulation, Toxic megacolon
Right low back pain
Liver: hepatomegaly
Kidney: kidney stone (nephrolithiasis), complicated urinary tract infection
Left low back pain
Spleen
Kidney: kidney stone (nephrolithiasis), complicated urinary tract infection
Low back pain
kidney pain (kidney stone, kidney cancer, hydronephrosis)
Ureteral stone pain

Pathophysiology
Abdominal pain can be referred to as visceral pain or peritoneal pain. The contents of the abdomen can be divided into the foregut, midgut, and hindgut.
Identifying other possible factors may aid in the diagnosis of the underlying cause of abdominal pain, such as recent travel, recent contact with other ill individuals, and for females, a thorough gynecologic history. Learning about the patients past medical history, focusing on any prior issues or surgical procedures. Clarifying the patients current medication regimen, including prescriptions, over-the-counter medications, and supplements. Confirming the patients drug and food allergies. Discussing with the patient any family history of disease processes, focusing on conditions that might resemble the patients current presentation. Discussing with the patient any health-related behaviors (e.g. tobacco use, alcohol consumption, drug use, and sexual activity) that might make certain diagnoses more likely. Reviewing the presence of non-abdominal symptoms (e.g., fever, chills, chest pain, shortness of breath, vaginal bleeding) that can further clarify the diagnostic picture. Using Carnetts sign to differentiate between visceral pain and pain originating in the muscles of the abdominal wall.After gathering a thorough history, one should perform a physical exam in order to identify important physical signs that might clarify the diagnosis, including a cardiovascular exam, lung exam, thorough abdominal exam, and for females, a genitourinary exam.Additional investigations that can aid diagnosis include:
Blood tests including complete blood count, basic metabolic panel, electrolytes, liver function tests, amylase, lipase, troponin I, and for females, a serum pregnancy test. Urinalysis
Imaging including chest and abdominal X-rays
ElectrocardiogramIf diagnosis remains unclear after history, examination, and basic investigations as above, then more advanced investigations may reveal a diagnosis.