Diarrhea Diagnosis

  • Diagnosis

    Diarrhea is a condition characterized by frequent, loose, watery stools. Mild cases typically last three to seven days, and resolve without treatment. The average adult experiences four episodes of diarrhea a year. Infants and children may also develop diarrhea; in the U.S., most children have had 7 to 15 episodes of diarrhea by the time they reach 5 years of age. Chronic diarrhea is recurrent, or lasts for more than three weeks, and usually requires medical attention.

    Diarrhea occurs when your body's ability to absorb liquid from digested food particles is disrupted. In patients with diarrhea, loss of water and electrolytes may result in dehydration, which is a major concern. The most important treatment for simple cases of diarrhea is to prevent dehydration, and to rehydrate if you have already become dehydrated.

    Worldwide, diarrhea is one of the greatest threats to the lives and health of children. More than one billion cases occur each year, and three to five million children die of diarrheal infections. Although deaths from diarrhea are rare in the U.S. and other developed countries, the condition is responsible for several million visits to doctor's offices and numerous hospital stays each year.

    Diarrhea is sometimes called "stomach flu" or gastroenteritis. Diarrhea may be accompanied by vomiting. It may occur in clusters among schools, neighborhoods, or families because the infection spreads through close contact. These mini-epidemics usually clear up quickly.

    People of all ages are vulnerable to traveler's diarrhea. When you travel, particularly to developing countries, a variety of new organisms are introduced into your system. Some of these organisms may be infectious, and may cause diarrhea. Traveler's diarrhea is most common in areas that have contaminated water supplies, poor sewage systems, and inadequate techniques of food handling or preparation.

    Although patients recognize diarrhea mainly by the frequency of loose stools, doctors may define it as a significant increase in the weight of stool passed in a single day. In medical terms, diarrhea is defined as more than 200 g (or 200 mL) of stool over a 24-hour period in persons consuming a typical Western diet. Your doctor may use this definition when making a diagnosis. However, he or she will also take into account your explanation of your symptoms.

    Several agents can cause diarrhea, including viral, bacterial, or parasitic infections resulting from consuming contaminated food or water. You can also pick up an infectious agent through personal contact with an infected person. Common bacterial causes of infection include Salmonella species, Shigella species, Escherichia coli, and Campylobacter jejuni. Because only a few bacteria are needed to cause Shigella infections, they spread easily in day care centers, institutions, and families. E. coli bacteria can cause diarrhea by attacking the intestinal wall or by producing toxins that block the ability of the intestine to absorb water and electrolytes. Some of the toxins produced by bacteria may even make the intestine secrete water and electrolytes instead of absorbing them. A serious form of E. coli has caused recent nation-wide food outbreaks, leading to several deaths.

    Several viruses, including rotavirus or the Norwalk virus, can lead to diarrhea. These viruses damage the mucous membrane that lines your intestines, and disrupt fluid absorption. Rotavirus is a common cause of diarrhea in U.S. children. In fact, most children in the U.S. have had a rotavirus infection by the time they are four or five years old, although they may not necessarily have shown symptoms. Rotavirus tends to spread in such settings as daycare centers. In adults, the Norwalk virus is more commonly the cause of diarrhea. The Norwalk virus can be found in drinking water, or in food such as contaminated shellfish. Norwalk virus has been known to lead to outbreaks on cruise ships. Other viruses that may trigger diarrhea include cytomegalovirus, herpes simplex virus, and viral hepatitis.

    Parasites that enter the body and invade the digestive system can cause diarrhea. The most likely "bugs" are Giardia lamblia, Entamoeba histolytica, and Cryptosporidium species. In the U.S., Giardia infection is the most common parasitic cause of diarrhea. Giardia spreads through contaminated water supplies, and can be passed among children in day-care centers.

    Enterotoxigenic E. coli, an organism that is part of the E. coli species of bacteria, is the most common cause of traveler's diarrhea. Shigella species and many other pathogens also cause this disease among travelers from industrialized countries. Rotavirus, the Norwalk virus, other viruses, and such parasites as Giardia species and Entamoeba histolytica, are responsible for some cases. There is no evidence that jet lag, change in altitude, or fatigue contribute to traveler's diarrhea.

    The inability to digest certain food substances, such as lactose (the form of sugar found in dairy products), wheat, or other grains, can also cause diarrhea; chronic diarrhea can be caused by food allergies or food additives, such as sorbitol and fructose.

    Diarrhea can be caused by a reaction to medication. Many medications can cause diarrhea, but antibiotics, some blood pressure medications, chemotherapy drugs, and antacids containing magnesium are the most common. Other medications that may cause diarrhea include digitalis (used to treat heart disease), diuretics (used to treat high blood pressure and edema), cholesterol-lowering agents, lithium (used to treat bipolar disorder), theophylline (used to treat respiratory disorders, especially asthma), thyroid hormone, and colchicine (used to treat gout). Chronic diarrhea is most likely to be caused by antibiotics, drugs for high blood pressure, and cancer medications.

    A range of diseases can also lead to diarrhea. Intestinal diseases such as inflammatory bowel disease (including ulcerative colitis or Crohn's disease) or celiac disease (the inability to digest wheat and sometimes other grains), are one category. Diseases that affect the body's glands (the endocrine system) can also cause diarrhea. Some examples are thyroid disease, diabetes, adrenal disease, and Zollinger-Ellison syndrome, a tumor of the pancreas that causes ulcers in the upper gastrointestinal tract. Diseases that interfere with intestinal function, such as irritable bowel syndrome, can also cause diarrhea. Acute and chronic diarrhea may be side effects of HIV infection or AIDS. People who recently received an organ transplant may be at higher risk for diarrhea.

    Several surgical procedures can cause diarrhea because they affect the movement of food through the digestive system. If part of your intestine has been removed, you may develop short-bowel syndrome. In this syndrome, the shorter intestine is unable to absorb all of the food you eat. Gallbladder and stomach surgery can also cause diarrhea.

    Possible causes of diarrhea include such toxins as insecticides, psychedelic mushrooms, arsenic, and overuse of alcohol or caffeine.

    The causes of acute and chronic diarrhea cannot always be identified. If the problem clears up in a few days, it is usually not necessary for you or your provider to search extensively for its source. Acute diarrhea can progress to chronic diarrhea if improperly treated.

    When you have diarrhea, you have loose, liquid stools, an urgent need to use the bathroom, and increased frequency of bowel movements Table 01. You may experience abdominal cramps or pain, rectal pain, bloating, gas, nausea, or vomiting. You may have leakage of stool between bowel movements. You may develop a fever or have blood or flecks of mucus in the stool. If diarrhea persists for more than a few days, as in cases of chronic diarrhea, you may lose your appetite and lose weight. Symptoms appear within 4 to 48 hours after exposure to contaminated food or water, and are most severe during the first 24 hours.

    Table 1.   Symptom Checklist

    Loose, liquid stools
    Increased frequency of defecation
    Urgent need to defecate
    Bloating, gas
    Abdominal pain or cramps
    Nausea, vomiting
    Fever
    Blood or mucus in the stool
    Loss of appetite, weight loss

    If you lose too much liquid from your body because of diarrhea and vomiting, you may become dehydrated. Signs of dehydration include dry mouth, excessive thirst, dry eyes, and infrequent urination. Dehydration is the most serious consequence of diarrhea. Addressing dehydration is the most important aspect of treatment.

    The symptoms of acute diarrhea in infants include loose stools that occur more than once after each feeding.

    Older children may have watery, loose stools; fever; abdominal cramps; nausea and vomiting; loss of appetite; weight loss; and dehydration.

    Infants and children can become dehydrated quickly, often within a matter of several hours. Look for such symptoms as lack of tears when your baby cries, sunken eyes, wrinkled skin, and fewer than six wet diapers per day. In older children, you may notice dry mouth, increased thirst, sunken eyes, crying without tears, infrequent urination, pale or dry skin, and irritability. Older children and adults who are dehydrated may feel weak or dizzy with a racing pulse. Feeling dizzy when going from lying down to sitting up or standing is a strong clue that a person has become dehydrated.

    Although diarrhea is usually thought to be a minor problem, some of the bacteria that can cause it may spread into the bloodstream and cause symptoms in organs other than the intestines. Salmonella species is of particular concern. Salmonella bacteria can cause infections in the bones, joints, brain, membranes covering the brain, and other sites.

    The symptoms of traveler's diarrhea are the same as those of diarrhea contracted at home: frequent, loose bowel movements; abdominal cramps; nausea; bloating; fever; and listlessness. Although traveler's diarrhea usually occurs the first week you are away from home, it may occur at any time while you are abroad or after you return. The condition lasts an average of three or four days. You may experience more than one attack during a lengthy trip.

    The signs of chronic diarrhea are usually similar to those of acute diarrhea; the distinction lies in the duration of the condition. Chronic diarrhea is usually described as lasting at least two to four weeks, while acute diarrhea normally clears up in a few days. However, in some cases, the course of chronic diarrhea may vary. Diarrhea associated with irritable bowel syndrome usually occurs only during the day, and may alternate with constipation. In addition, stress or anxiety may aggravate the symptoms.

    Eating contaminated food or drinking contaminated water is a primary risk factor for diarrhea caused by infectious agents. This risk is higher in nonindustrialized countries, although contamination can occur anywhere. You may develop an infection while camping or backpacking if you drink impure water from a stream or lake. You can also pick up an infection from improperly cooked food or food that has become contaminated after cooking. Such contamination can occur no matter where the food is prepared.

    Traveler's diarrhea occurs mainly in areas with contaminated water supplies, poor sewage systems, and inadequate techniques or supplies for food preparation. High-risk destinations include most of the developing countries of Central America, Africa, the Middle East, and Asia. Intermediate-risk locales include most of the southern European countries and a few Caribbean islands. The U.S., Canada, Northern Europe, Australia, New Zealand, and several Caribbean islands are considered low-risk destinations.

    Children are at higher risk due to their poor personal hygiene and close contact with others in such settings as day-care centers; families are also at risk because of infections that children may bring home.

    Most cases of diarrhea resolve within a few days, and it is usually not necessary for you to consult your doctor for a formal diagnosis. However, you should contact your doctor if diarrhea lasts for more than three days. You should also contact your doctor if you experience severe pain in the abdomen or rectum; have a fever of 102°F (39°C) or higher; notice blood, mucus, or worms in your stool; or have symptoms of dehydration. Recurrent episodes of diarrhea in adults or children also warrant a consultation with your provider.

    Contact a doctor if your child's diarrhea is accompanied by a high fever (more than 102°F or 39°C), vomiting, severe abdominal pain, or stools that contain blood or mucus. Call the doctor immediately if you see signs of dehydration. Always contact your doctor if diarrhea lasts for more than a few hours in a child younger than six months of age. Also seek advice if a child younger than three years of age has diarrhea for more than one day. For older children, call the doctor if acute diarrhea is accompanied by dehydration, bloody or slimy stools, a temperature higher than 101°F, no urination in the past eight hours, or stomach pains that last for more than two hours.

    When a doctor's visit is necessary, the doctor or other health care provider will obtain a medical history and perform a physical examination. If you are a parent with a sick child, the doctor will ask you about your child's medical history and other relevant factors, such as enrollment in a day-care program or preschool. The physical examination is likely to include rectal and abdominal exams. If you have diarrhea, the doctor will try to determine the cause by asking you about your eating habits, medication use, recent travel, exposure to poor sanitary conditions, and contact with others who may have shown symptoms of diarrhea. The doctor will also want to know the characteristics of your diarrhea, such as whether there is blood or a large amount of mucus in the stool, whether you have experienced abdominal or rectal pain or severe cramping, and the color and consistency of the stool. You will also be asked when the diarrhea began and the number and volume of stools each day. The time of day that the loose stools occur can also help the doctor identify the cause. Nocturnal diarrhea is common in diabetic patients, for example, but uncommon in patients with irritable bowel syndrome. The doctor may also inquire about factors that aggravate diarrhea, such as stress or specific foods. In addition, the doctor may want to know about recent surgeries and injuries, and whether you are experiencing fever or chills.

    The doctor may perform or order several diagnostic tests. A stool culture may be taken and sent to a laboratory, where technicians will look for bacteria, parasites, or other signs of disease or infection. The doctor may order blood tests to learn whether you have certain diseases that may cause diarrhea. An elevated sedimentation rate can indicate an infection or inflammation, and the presence of certain antibodies may point to celiac disease. Patients with Crohn's disease may have a low red blood cell count or hemoglobin, which could indicate intestinal bleeding, or a high white blood cell count, which could indicate an inflammation. Because thyroid disorders can cause diarrhea, tests of thyroid-stimulating hormone and other thyroid hormones may be necessary.

    If more information is needed to diagnose the cause of your diarrhea, your doctor may order several tests that will be performed after your initial appointment. The doctor may test for food intolerance or allergies. You will be asked to avoid certain foods, such as milk products, carbohydrates, or wheat, to see if the diarrhea responds to the change in your diet. You may also be asked to undergo sigmoidoscopy or colonoscopy. During sigmoidoscopy, the doctor uses a special flexible tube to look at the inside of the rectum and the lower part of the large bowel (colon). A colonoscopy is a similar procedure that provides an image of the entire large bowel.

    Good hygiene plays an important role in limiting the spread of infectious organisms that can cause diarrhea. Handle food properly, and avoid undercooked meats, raw seafood, or food left out for several hours at a picnic or buffet. Wash your hands after using the toilet, before meals, and whenever your hands are soiled. Teach your children to follow these practices, and to avoid putting objects in their mouths.

    If you travel, use common sense to reduce your risk for traveler's diarrhea. Do not use tap water, even for brushing your teeth, and don't use ice made from tap water. Boil water for at least five minutes before using it to mix baby formula. Drink bottled water or other bottled drinks only if the seal on the bottle is unbroken. Hot drinks made from boiled water, such as coffee or tea, are usually safe, as are carbonated drinks, pasteurized milk, beer, and wine. Practice good hygiene, and make sure that children traveling with you do so as well.

    Although both cooked and uncooked foods can cause problems, raw or undercooked meat and seafood and raw fruits and vegetables are most likely to trigger an attack of traveler's diarrhea. Avoid raw fruits and vegetables unless you can peel them, and skip raw, leafy vegetables, such as lettuce, which are difficult to clean. Don't eat raw or rare meat or fish. Instead, consume hot, well-cooked foods. Do not eat food that has been left to sit, since it may have become contaminated. Be cautious of unpasteurized milk and dairy products.

    You can get sick from food prepared in a private home or restaurant, but food from street vendors carries the highest risk; if you must buy food from a vendor, watch it being cooked, and then eat it immediately.

    If you are planning a trip abroad, particularly to a high-risk destination, ask your provider for advice about preventive measures. Your provider can inform you about drugs that might prevent traveler's diarrhea. Antibiotics are sometimes used, but the potential benefits must be weighed against risks, such as allergic reactions and other side effects. Discuss with your provider where you will be traveling and how long you plan to stay.

    Several years ago, a promising vaccine was developed against rotavirus, which causes more than three million cases of childhood diarrhea each year in the U.S. alone. However, in 1999, several months after the vaccine was approved by the U.S. Food and Drug Administration, its manufacturer voluntarily withdrew it from the market because of safety concerns. Reports showed that vaccinated children had a small but significant increase in risk for serious bowel obstruction. Researchers are currently investigating the problems associated with the vaccine, and are examining other ways of treating the diarrhea, vomiting, and dehydration associated with rotavirus.

  • Prevention and Screening

    Good hygiene plays an important role in limiting the spread of infectious organisms that can cause diarrhea. Handle food properly, and avoid undercooked meats, raw seafood, or food left out for several hours at a picnic or buffet. Wash your hands after using the toilet, before meals, and whenever your hands are soiled. Teach your children to follow these practices, and to avoid putting objects in their mouths.

    If you travel, use common sense to reduce your risk for traveler's diarrhea. Do not use tap water, even for brushing your teeth, and don't use ice made from tap water. Boil water for at least five minutes before using it to mix baby formula. Drink bottled water or other bottled drinks only if the seal on the bottle is unbroken. Hot drinks made from boiled water, such as coffee or tea, are usually safe, as are carbonated drinks, pasteurized milk, beer, and wine. Practice good hygiene, and make sure that children traveling with you do so as well.

    Although both cooked and uncooked foods can cause problems, raw or undercooked meat and seafood and raw fruits and vegetables are most likely to trigger an attack of traveler's diarrhea. Avoid raw fruits and vegetables unless you can peel them, and skip raw, leafy vegetables, such as lettuce, which are difficult to clean. Don't eat raw or rare meat or fish. Instead, consume hot, well-cooked foods. Do not eat food that has been left to sit, since it may have become contaminated. Be cautious of unpasteurized milk and dairy products.

    You can get sick from food prepared in a private home or restaurant, but food from street vendors carries the highest risk; if you must buy food from a vendor, watch it being cooked, and then eat it immediately.

    If you are planning a trip abroad, particularly to a high-risk destination, ask your provider for advice about preventive measures. Your provider can inform you about drugs that might prevent traveler's diarrhea. Antibiotics are sometimes used, but the potential benefits must be weighed against risks, such as allergic reactions and other side effects. Discuss with your provider where you will be traveling and how long you plan to stay.

    Several years ago, a promising vaccine was developed against rotavirus, which causes more than three million cases of childhood diarrhea each year in the U.S. alone. However, in 1999, several months after the vaccine was approved by the U.S. Food and Drug Administration, its manufacturer voluntarily withdrew it from the market because of safety concerns. Reports showed that vaccinated children had a small but significant increase in risk for serious bowel obstruction. Researchers are currently investigating the problems associated with the vaccine, and are examining other ways of treating the diarrhea, vomiting, and dehydration associated with rotavirus.

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