Causes of Abdominal Pain – Diagnosis from Symptoms & Investigations

How to Determine a Cause of Abdominal Pain

The cause of the abdominal (stomach) pain can be determined from:

1. Pain LOCATION:

• Right upper quadrant (RUQ) pain may be from gallstones, bile ducts dysfunction, liver diseases, right kidney or ureteral disorders, or right adrenal gland
• Left upper quadrant (LUQ) pain may be from to pancreatitis or pancreatic cancer, spleen enlargement or rupture, trapped gas in the colon, left kidney or ureteral disorders, or left adrenal gland
• Upper middle abdominal pain may be from gastritis, stomach or duodenal ulcer or cancer, pancreatitis or pancreatic cancer, aortic aneurysm or dissection of abdominal aorta, lymph nodes enlargement in lymphoma, strained or injured muscles of abdominal wall
• Right lower quadrant (RLQ) pain may be from appendicitis, right colon inflammation in Crohn’s disease, right ovarian cyst or cancer or twisting, ectopic pregnancy, a stone in the right ureter, intestinal hernia.
• Left lower quadrant (LLQ) pain may be from diverticulitis, atherosclerosis of abdominal arteries, left ovarian disorder, ectopic pregnancy, a stone in the left ureter, intestinal hernia.
• Lower middle abdomen may arise from muscles of abdominal wall (stretching, injury, hypokalemia), menstruation, infection or cancer of the bladder, pelvic inflammatory disease, inflammation of urethra (mostly infection, including STDs), inflammation or cancer of the prostate, diseases of testes, epidydimis or seminal ducts.
• Abdominal pain that is hard to locate may appear in constipation or IBS.
• Diffuse abdominal pain may be from severe bloating or peritonitis.

2. Pain CHARACTERISTICS:

• Sudden onset (acute) abdominal pain.
• Prolonged or recurring (chronic) abdominal pain.
• Abdominal pain during or after the meal  may be from stomach ulcer, gastroparesis, IBS, food allergies
• Night abdominal pain may appear in duodenal ulcer or spinal disorders.
• Pain during the bowel movement may appear in constipation, diverticulitis, anal fissure, colorectal cancer or thrombosed hemorrhoids.
• Severe debilitating abdominal pain may be a symptom of bowel obstruction or perforation, cancer of any abdominal organ, appendicitis or peritonitis.
• Sharp cramping pain is usually from urinary stones in the kidney or ureter(s), or gallstones in the gallbladder or bile ducts.

3. Abdominal and other SYMPTOMS:

• Nausea
• Vomiting
• Bloating and belching (burping) may be due to H.pylori infection of the stomach or blockage of food outflow from the stomach
• Bloating and gas may be due to excessive ingestion of fibres or probiotics, or due to liver, gallbladder or pancreas disorder, fructose malabsorption, lactose intolerance, celiac or Crohn’s disease, small intestinal bacterial overgrowth (SIBO), intestinal parasites, IBS or food poisoning.
• Constipation
• Diarrhea
• Itchy skin may appear in food allergies or in blocked bile flow (cholestasis) due to liver or bile duct disorder
• Blood in the stool that arise from the stomach ulcer or cancer, or esophageal varices colors stool black, blood from small intestinal inflammation (Crohn’s disease) is dark red, and the blood from the colon (ulcerative colitis, severe food poisoning, cancer, hemorrhoids) is bright red. 

4. SIGNS, found by the doctor during physical examination (1):

• Inspection. Paleness  may appear in anemia due to iron malabsorption or in chronic bowel bleeding. Skin rash may be present in hepatitis, celiac and Crohn’s disease. Jaundice and abdominal swelling speak for liver cirrhosis. Visible lumps are usually from enlarged liver or spleen, or from intestinal hernia. Rectal mucosa may protrude out from anal canal in hemorrhoids or prolapsed rectum. Cracks and openings around the anus are usually fissures and fistulas in Crohn’s disease. Bluish discoloration around the navel or in flanks speak for intra-abdominal bleeding (in severe pancreatitis, ectopic pregnancy, or injury).
• Palpation. Abdominal wall is locally tender in gallbladder disease (in RUQ, but not always), appendicitis (in RLQ), and tender all over and rigid in peritonitis (emergency!). Enlarged liver (RUQ) is due to liver disease, congestive heart disease or lymphoma/leukemia. Enlarged spleen (LUQ) may appear in lymphoma/leukemia or in liver disease. Lumps are mostly due to abdominal or inguinal hernia or, rarely, due to benign tumors (fibroma) or cancer. 
• Percussion. By tapping with a finger on a swollen abdominal wall a doctor can distinguish among fluid (mostly in liver cirrhosis, or in malnourished children in poor countries), gas and fat. Distended bladder can be also detected this way.
• Auscultation (listening by stethoscope). Normally some sounds from usual moving of the stool and gas can be heard. Excessive sounds are heard in speeded peristalsis (usually in food poisoning) or in partial bowel obstruction. No sounds can be heard in severe constipation, in complete bowel obstruction – ileus, and after abdominal surgery.
• Digital rectal examination. A doctor can detect (with a gloved finger) a palpable mass that may represent colorectal polyp or carcinoma, inflamed prostate or prostatic cancer, pus collection (abscess, often in Crohn’s disease) or thrombosed hemorrhoids.

5. INVESTIGATIONS:

• Stool tests may reveal harmful bacteria (in food poisoning or after antibiotic treatment), intestinal parasites, blood, excessive fats (chronic pancreatitis, stones in bile duct, celiac or Crohn’s disease), sugars (in fructose malabsorption in small children), and special antibodies (in celiac or Crohn’s disease).
• Ultrasound may reveal big gallstones (> 5mm), liver and spleen enlargement, urinary stones, pancreatic cyst or cancer, aneurysm of abdominal aortar and some other disorders.
• Plain X-ray of the abdomen is usually the first investigation in severe abdominal pain. X-ray with barium swallow is regularly performed before upper endoscopy, and X-ray with barium enema is performed before colonoscopy. Big stomach or intestinal tumors, deep ulcers, strictures (intestinal narrowings) and diverticles may be revealed this way. 
• CT of the abdomen is good to show small gallstones, changes in solid abdominal organs, tumors in the abdominal cavity but is not good to show small changes in the stomach or intestinal mucosa.  
• MRI of the abdomen may be done instead of CT. Special MRI investigations of bile ducts and abdominal arteries exist.
• Upper endoscopy. Esophago-gastro-duodenoscopy (EGD) may reveal esophageal varices, inflammation or ulcers, gastritis, gastric ulcers or carcinoma, and duodenal inflammation and ulcers. With endoscopic retrograde cholangiopancreatography (ERCP) bile and pancreatic ducts can be checked.
• Lower endoscopy: Rectoscopy, sigmoidoscopy and colonoscopy may reveal changes in mucosa of the large intestine. An end part of the small intestine can be checked with colonoscopy. Biopsy and hystologic examination of obtained sample under the microscope
• Capsule endoscopy is performed when small intestinal disorders are expected. A patient swallows a small capsule with a cammera that takes photos of small intestinal mucosa that can be later evaluated with the help of the computer.

References:

1. Abdominal examination  (ncbi.nlm.nih.gov)