Abdominal Pain

Abdominal pain is pain that is felt in the abdomen. The abdomen is an anatomical area that is bounded by the lower margin of the ribs and diaphragm above, the pelvic bone (pubic ramus) below, and the flanks on each side. Although abdominal pain can arise from the tissues of the abdominal wall that surround the abdominal cavity (such as the skin and abdominal wall muscles), the term abdominal pain generally is used to describe pain originating from organs within the abdominal cavity. Organs of the abdomen include the stomach, small intestine, colon, liver, gallbladder, spleen, and pancreas.

Occasionally, pain may be felt in the abdomen even though it is arising from organs that are close to, but not within, the abdominal cavity. For example, conditions of the lower lungs, the kidneys, and the uterus or ovaries can cause abdominal pain. On the other hand, it also is possible for pain from organs within the abdomen to be felt outside of the abdomen. For example, the pain of pancreatic inflammation may be felt in the back. These latter types of pain are called "referred" pain because the pain does not originate in the location that it is felt. Rather, the cause of the pain is located away from where it is felt.

What causes abdominal pain?

Abdominal pain is caused by inflammation (for example, appendicitis, diverticulitis,colitis ), by stretching or distention of an organ (for example, obstruction of the intestine, blockage of a bile duct by gallstones, swelling of the liver with hepatitis), or by loss of the supply of blood to an organ (for example, ischemic colitis).

To complicate matters, however, abdominal pain also can occur without inflammation, distention or loss of blood supply. An important example of this latter type of pain is the irritable bowel syndrome (IBS). It is not clear what causes the abdominal pain in IBS, but it is believed to be due either to abnormal contractions of the intestinal muscles (for example, spasm) or abnormally sensitive nerves within the intestines that give rise to painful sensations inappropriately (visceral hyper-sensitivity). These latter types of pain are often referred to as functional pain because no recognizable (visible) causes for the pain have been found - at least not yet.

How is the cause of abdominal pain diagnosed?

Doctors determine the cause of abdominal pain by relying on:

1. characteristics of the pain,
   
2. findings on physical examination,
   
3. laboratory, radiological, and endoscopic testing, and
   
4. surgery.

Characteristics of the pain

The following information, obtained by taking a patient's history, is important in helping doctors determine the cause of pain:

• The way the pain begins. For example, abdominal pain that comes on suddenly suggests a sudden event, for example, the interruption of the supply of blood to the colon (ischemia) or obstruction of the bile duct by a gallstone (biliary colic).

• The location of the pain.
  
  • Appendicitis typically causes pain in the right lower abdomen, the usual location of the appendix.
    
  • Diverticulitis typically causes pain in the left lower abdomen where most colonic diverticuli are located.
    
  • Pain from the gallbladder (biliary colic or cholecystitis) typically is felt in the right upper abdomen where the gallbladder is located.

• The pattern of the pain.
  
  • Obstruction of the intestine initially causes waves of crampy abdominal pain due to contractions of the intestinal muscles and distention of the intestine.
    
  • True cramp-like pain suggests vigorous contractions of the intestines.
    
  • Obstruction of the bile ducts by gallstones typically causes steady (constant) upper abdominal pain that lasts between 30 minutes and several hours.
    
  • Acute pancreatitis typically causes severe, unrelenting, steady pain in the upper abdomen and upper back. The pain of acute appendicitis initially may start near the umbilicus, but as the inflammation progresses, the pain moves to the right lower abdomen. The character of pain may change over time. For example, obstruction of the bile ducts sometimes progresses to inflammation of the gallbladder with or without infection (acute cholecystitis). When this happens, the characteristics of the pain change to those of inflammatory pain. (See below.)

• The duration of the pain.
  
  • The pain of IBS typically waxes and wanes over months or years and may last for decades.
    
  • Biliary colic lasts no more than several hours.
    
  • The pain of pancreatitis lasts one or more days.
    
  • The pain of acid-related diseases - gastroesophageal reflux disease (GERD) or duodenal ulcers - typically show periodicity, that is, a period of weeks or months during which the pain is worse followed by periods of weeks or months during which the pain is better.
    
  • Functional pain may show this same pattern of periodicity.

• What makes the pain worse. Pain due to inflammation (appendicitis, diverticulitis, cholecystitis, pancreatitis) typically is aggravated by sneezing, coughing or any jarring motion. Patients with inflammation as the cause of their pain prefer to lie still.

• What relieves the pain.
  
  • The pain of IBS and constipation often is relieved temporarily by bowel movements and may be  associated with changes in bowel habit.
    
  • Pain due to obstruction of the stomach or upper small intestine may be relieved temporarily by vomiting which reduces the distention that is caused by the obstruction.
    
  • Eating or taking antacids may temporarily relieve the pain of ulcers of the stomach or duodenum because both food and antacids neutralize (counter) the acid that is responsible for irritating the ulcers and causing the pain.
    
  • Pain that awakens patients from sleep is more likely to be due to non-functional causes.

• Associated signs and symptoms.
  
  • The presence of fever suggests inflammation.
    
  • Diarrhea or rectal bleeding suggests an intestinal cause of the pain.
    
  • The presence of fever and diarrhea suggest inflammation of the intestines that may be infectious or non-infectious (ulcerative colitis or Crohn's disease).

  • Physical examination

    Examining the patient will provide the doctor with additional clues to the cause of abdominal pain. The doctor will determine:
    1. The presence of sounds coming from the intestines that occur when there is obstruction of the intestines,
       
    2. The presence of signs of inflammation (by special maneuvers during the examination),
       
    3. The location of any tenderness
       
    4. The presence of a mass within the abdomen that suggests a tumor, enlarged organ, or abscess (a collection of infected pus)
       
    5. The presence of blood in the stool that may signify an intestinal problem such as an ulcer, colon cancer, colitis, or ischemia.
    For example:
    • Finding tenderness and signs of inflammation in the left lower abdomen often means thatdiverticulitis is present, while finding a tender (inflamed) mass in the same area may mean that the inflammation has progressed and that an abscess has formed.
      
    • Finding tenderness and signs of inflammation in the right lower abdomenoften means that appendicitis is present, while finding a tender mass in the same area may mean that appendiceal inflammation has progressed and that an abscess has formed.
      
    • Inflammation in the right lower abdomen, with or without a mass, also may be found in Crohn's disease. (Crohn's disease most commonly affects the last part of the small intestine, usually located in the right lower abdomen.)
      
    • A mass without signs of inflammation may mean that a cancer is present.

    Exams and tests

    While the history and physical examination are vitally important in determining the cause of abdominal pain, testing often is necessary to determine the cause.
    Laboratory tests. Laboratory tests such as the complete blood count (CBC), liver enzymes, pancreatic enzymes (amylase and lipase), and urinalysis are frequently performed in the evaluation of abdominal pain.
    • An elevated white count suggests inflammation or infection (as with appendicitis, pancreatitis, diverticulitis, or colitis).
      
    • Amylase and lipase (enzymes produced by the pancreas) commonly are elevated in pancreatitis.
      
    • Liver enzymes may be elevated with gallstone attacks.
      
    • Blood in the urine suggests kidney stones.
      
    • When there is diarrhea, white blood cells in the stool suggest intestinal inflammation.
    Plain X-rays of the abdomen. Plain X-rays of the abdomen also are referred to as a KUB (because they include the kidney, ureter, and bladder). The KUB may show enlarged loops of intestines filled with copious amounts of fluid and air when there is intestinal obstruction. Patients with a perforated ulcer may have air escape from the stomach into the abdominal cavity. The escaped air often can be seen on a KUB on the underside of the diaphragm. Sometimes a KUB may reveal a calcified kidney stone that has passed into the ureter and resulted in referred abdominal pain or calcifications in the pancreas that suggests chronic pancreatitis.
    Radiographic studies.
    • Abdominal ultrasound is useful in diagnosing gallstones, cholecystitis appendicitis, or ruptured ovarian cysts as the cause of the pain.
      
    • Computerized tomography (CT) of the abdomen is useful in diagnosing pancreatitis, pancreatic cancer, appendicitis, and diverticulitis, as well as in diagnosing abscesses in the abdomen. Special CT scans of the abdominal blood vessels can detect diseases of the arteries that block the flow of blood to the abdominal organs.
      
    • Magnetic resonance imaging (MRI) is useful in diagnosing many of the same conditions as CT tomography.
      
    • Barium X-rays of the stomach and the intestines (upper gastrointestinal series or UGI with a small bowel follow-through) can be helpful in diagnosing ulcers, inflammation, and blockage in the intestines.
      
    • Computerized tomography (CT) of the small intestine can be helpful in diagnosing diseases in the small bowel such as Crohn's disease.
      
    • Capsule enteroscopy, a small camera the size of a pill swallowed by the patient, can take pictures of the entire small bowel and transmit the pictures onto a portable receiver. The small bowel images can be downloaded from the receiver onto a computer to be inspected by a doctor later. Capsule enteroscopy can be helpful in diagnosing Crohn's disease, small bowel tumors, and bleeding lesions not seen on x-rays or CT scans.
    Endoscopic procedures.
    • Esophagogastroduodenoscopy or EGD is useful for detecting ulcers, gastritis (inflammation of the stomach), or stomach cancer.
    • Colonoscopy or flexible sigmoidoscopy is useful for diagnosing infectious colitis, ulcerative colitis, or colon cancer.
      
    • Endoscopic ultrasound (EUS) is useful for diagnosing pancreatic cancer or gallstones if the standard ultrasound or CT or MRI scans fail to detect them.
      
    • Balloon enteroscopy, the newest technique allows endoscopes to be passed through the mouth or anus and into the small intestine where small intestinal causes of abdominal pain or bleeding can be diagnosed, biopsied, and treated.

    • Special problem in irritable bowel syndrome (IBS) of diagnosing the cause of abdominal pain

      As previously discussed, the pain ofirritable bowel syndrome is due either to abnormal intestinal muscle contractions or visceral hypersensitivity. Generally, abnormal muscle contractions and visceral hypersensitivity are much more difficult to diagnose than other diseases causing abdominal pain, particularly since there are no typical abnormalities on physical examination or the usual diagnostic tests. The diagnosis is based on the history (typical symptoms) and the absence of other causes of abdominal pain.

      Why can diagnosis of the cause of abdominal pain be difficult?

      Modern advances in technology have greatly improved the accuracy, speed, and ease of establishing the cause of abdominal pain, but significant challenges remain. There are many reasons why diagnosing the cause of abdominal pain can be difficult. They are:
      • Symptoms may be atypical. For example, the pain of appendicitis sometimes is located in the right upper abdomen, and the pain of diverticulitis is on the right side. Elderly patients and patients taking corticosteroids may have little or no pain and tenderness when there is inflammation, for example, with cholecystitis or diverticulitis. This occurs because corticosteroids reduce the inflammation.
      • Tests are not always abnormal.
        
        • Ultrasound examinations can miss gallstones, particularly small ones.
          
        • CT scans may fail to show pancreatic cancer, particularly small ones.
          
        • The KUB can miss the signs of intestinal obstruction or stomach perforation.
          
        • Ultrasounds and CT scans may fail to demonstrate appendicitis or even abscesses, particularly if the abscesses are small.
          
        • The CBC and other blood tests may be normal despite severe infection or inflammation, particularly in patients receiving corticosteroids.
      • Diseases can mimic one another.
        
        • IBS symptoms can mimic bowel obstruction, cancer, ulcer, gallbladder attacks, or even appendicitis.
          
        • Crohn's disease can mimic appendicitis.
          
        • Infection of the right kidney can mimic acute cholecystitis.
          
        • A ruptured right ovarian cyst can mimic appendicitis; while a ruptured left ovarian cyst can mimic diverticulitis.
          
        • Kidney stones can mimic appendicitis or diverticulitis.
      • The characteristics of the pain may change. Examples discussed previously include the extension of the inflammation of pancreatitis to involve the entire abdomen and the progression of biliary colic to cholecystitis.

      • How can I help my doctor to determine the cause of my abdominal pain?

        Before the visit, prepare written lists of:
        • Medications you are currently taking, including herbs, vitamins, minerals, and food supplements.
        • Your allergies to medications, food, or pollen
        • The medications that you have tried for your abdominal pain.
        • Important medical illnesses that you have such as diabetes, heart disease, etc..
        • Previous surgeries such asappendectomy, hernia repairs, gallbladder removal, hysterectomy, etc..
        • Previous procedures such ascolonoscopy, laparoscopy, CT scan, ultrasound, upper or lower barium X-rays, etc..
        • Previous hospitalizations
        • Ill family members, particularly those who have symptoms similar to yours.
        • Family members with gastrointestinal diseases (involving the esophagus, stomach, intestines, liver, pancreas, and gallbladder).
        • Be candid with your doctor about your prior and current alcohol consumption and smoking habits, any history of chemical dependence.
        Be prepared to tell your doctor:
        • When the pain first started
        • If there were previous episodes of similar pain.
        • How frequently episodes of pain occur
        • If each episode of pain starts gradually or suddenly
        • The severity of the pain
        • What causes the pain and what makes the pain worse
        • What relieves the pain
        • The characteristics of the pain. Is the pain sharp or dull, burning or pressure like? Is the pain jabbing and fleeting, steady and unrelenting or crampy (coming and going)?
        • If the pain is associated with fever, chills, sweats, diarrhea, weight loss,constipation, rectal bleeding, loss of appetite, nausea or loss of energy?
        After the visit to the doctor, do not expect an instant cure or immediate diagnosis, and remember:
        • Multiple office visits and tests (blood tests, radiographic studies, or endoscopic procedures) are often necessary to establish the diagnosis and/or to exclude serious illnesses.
        • Doctors may start you on a medication before a firm diagnosis is made. Your response (or lack of response) to that medication sometimes may provide your doctor with valuable clues as to the cause of your abdominal pain. Therefore, it is important for you to take the medication that is prescribed.
        • Notify your doctor if your symptoms are getting worse, if medications are not working, or if you think you are having side effects from the medication.
        • Call your doctor for test results. Never assume that "the test must be fine since my doctor never called."
        • Do not self medicate (including herbs, supplements) without discussing with your doctor.
        • Even the best physician never bats 1000. Do not hesitate to openly discuss with your doctor referrals for second or third opinions if the diagnosis cannot be firmly established and the pain persists.
        • Self education is important, but make sure what you read came from credible sources.

        • Abdominal Pain At A Glance

          • Abdominal pain is pain that is felt in the abdomen.
          • Abdominal pain comes from organs within the abdomen or organs adjacent to the abdomen.
          • Abdominal pain is caused by inflammation, distention of an organ, or by loss of the blood supply to an organ. Abdominal pain in IBS may be caused by contraction of the intestinal muscles or hyper-sensitivity to normal intestinal activities.
          • The cause of abdominal pain is diagnosed on the basis of the characteristics of the pain, physical examination, and testing. Occasionally, surgery is necessary for diagnosis.
          • The diagnosis of the cause of abdominal pain is challenging because the characteristics of the pain may be atypical, tests are not always abnormal, diseases causing pain may mimic each other, and the characteristics of the pain may change over time
          Additional resources from WebMD Boots UK on Abdominal Pain
          REFERENCE: Fauci, Anthony S., et al. Harrison's Principles of Internal Medicine. 17th ed. United States: McGraw-Hill Professional, 2008.