What is functional abdominal pain?

Functional abdominal pain is classified as a functional gastrointestinal disorder (FGIDs). Functional abdominal pain is the most common condition seen by pediatric gastroenterologists. Diagnosis may be made in children who have abdominal pain for two months or greater, a normal physical exam performed by their healthcare provider, and the absence of infection, inflammation or anatomic irregularities of the gastrointestinal (GI) tract. Your child’s gastroenterologist will carefully exam and evaluate your child for these other disorders.

Causes of functional abdominal pain

Functional abdominal pain is thought to be caused by the input from overly sensitive nerves of the GI tract muscles and nerves that are processing these signals in the brain. We call this our “brain-gut axis.” In functional abdominal pain and other functional gastrointestinal disorders, there is a heightened sensitivity to the normal function of the gastrointestinal tract.

Daily functions of the GI tract, like stretching and pushing food down after we eat, may feel more painful due to these sensitive nerves. Any periods of stress, anxiety and depression can worsen these symptoms because of the close interaction between the brain and the GI tract.

Functional abdominal pain is not caused by an anatomic, biochemical, inflammatory or infectious abnormalities.

Signs and symptoms of functional abdominal pain

The pain associated with functional abdominal pain is real. The pain can be chronic or recurrent. The pain is usually felt between the chest and the pelvis, most commonly concentrating in the middle, near the belly button. The pain can come and go, or it can be continuous. It can also be made worse by esophageal reflux, constipation, food intolerance, medication side effects, viral or bacterial infections, stress and anxiety.

Overlap diagnoses of functional abdominal pain

Other disorders that may be associated with functional abdominal pain include:

• Functional dyspepsia
• Irritable bowel syndrome (IBS)
• Abdominal migraine
• Functional constipation
• Anxiety disorders
• Depressive disorders

Testing and diagnosis of functional abdominal pain

Your healthcare provider will obtain a detailed history of the pain and perform a physical exam. In functional abdominal pain, physical exam is normal and the child is growing well. Screening tests may be performed to screen for other conditions causing pain. Extensive testing, including endoscopy is usually performed only if basic screening lab results do not fit the diagnosis of functional abdominal pain. If physical exam and screening tests are unremarkable, then a diagnosis of functional abdominal pain may be made.

Testing may include:

• Blood tests. These tests are done to evaluate whether your child is anemic, has an infection, or has an illness caused by inflammation, irritation or autoimmune factors.
• Urine analysis and culture. These are done to help assess for urinary tract infections.
• Stool sample. This sample is taken to check for bacteria and parasites that may cause diarrhea.
• Stool samples for occult blood. Occult blood cannot be seen and is only detected by a special solution that turns blue when coming into contact with blood. It suggests an inflammatory source in the gastrointestinal tract.
• Abdominal ultrasound. A diagnostic imaging technique which creates images from the rebound of high-frequency sound waves in the internal organs. Used to evaluate for potential disorders of the kidneys, liver, pancreas and gallbladder.