This is a medical question of type : exams and tests 
 How to diagnose Irritable Bowel Syndrome in Children ? 
 To diagnose IBS, a health care provider will conduct a physical exam and take a complete medical history. The medical history will include questions about the childs symptoms, family members with GI disorders, recent infections, medications, and stressful events related to the onset of symptoms. IBS is diagnosed when the physical exam does not show any cause for the childs symptoms and the child meets all of the following criteria:
                
- has had symptoms at least once per week for at least 2 months  - is growing as expected  - is not showing any signs that suggest another cause for the symptoms
                
Further testing is not usually needed, though the health care provider may do a blood test to screen for other problems. Additional diagnostic tests may be needed based on the results of the screening blood test and for children who also have signs such as
                
- persistent pain in the upper right or lower right area of the abdomen  - joint pain  - pain that wakes them from sleep  - disease in the tissues around the rectum  - difficulty swallowing  - persistent vomiting  - slowed growth rate  - GI bleeding  - delayed puberty  - diarrhea at night
                
Further diagnostic tests may also be needed for children with a family history of
                
- inflammatory bowel diseaselong-lasting disorders that cause irritation and ulcers, or sores, in the GI tract  - celiac diseasean immune disease in which people cannot tolerate gluten, a protein found in wheat, rye, and barley, because it will damage the lining of their small intestine and prevent absorption of nutrients  - peptic ulcer diseasea sore in the lining of the esophagus or stomach
                
Additional diagnostic tests may include a stool test, ultrasound, and flexible sigmoidoscopy or colonoscopy.
                
Stool tests. A stool test is the analysis of a sample of stool. The health care provider will give the childs caretaker a container for catching and storing the childs stool. The sample is returned to the health care provider or a commercial facility and sent to a lab for analysis. The health care provider may also do a rectal exam, sometimes during the physical exam, to check for blood in the stool. Stool tests can show the presence of parasites or blood.
                
Ultrasound. Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. The procedure is performed in a health care providers office, outpatient center, or hospital by a specially trained technician, and the images are interpreted by a radiologista doctor who specializes in medical imaging; anesthesia is not needed. The images can show problems in the GI tract causing pain or other symptoms.
                
Flexible sigmoidoscopy or colonoscopy. The tests are similar, but a colonoscopy is used to view the rectum and entire colon, while a flexible sigmoidoscopy is used to view just the rectum and lower colon. These tests are performed at a hospital or outpatient center by a gastroenterologista doctor who specializes in digestive diseases. For both tests, a health care provider will give written bowel prep instructions to follow at home. The child may be asked to follow a clear liquid diet for 1 to 3 days before either test. The night before the test, the child may need to take a laxative. One or more enemas may also be required the night before and about 2 hours before the test.
                
In most cases, light anesthesia, and possibly pain medication, helps the child relax. For either test, the child will lie on a table while the gastroenterologist inserts a flexible tube into the anus. A small camera on the tube sends a video image of the intestinal lining to a computer screen. The test can show signs of problems in the lower GI tract.
                
The gastroenterologist may also perform a biopsy, a procedure that involves taking a piece of intestinal lining for examination with a microscope. The child will not feel the biopsy. A pathologista doctor who specializes in diagnosing diseasesexamines the tissue in a lab.
                
Cramping or bloating may occur during the first hour after the test. Full recovery is expected by the next day.