Abdominal pain is one of the most common medical complaints of childhood.  There is an extensive number of both direct and indirect causes.  Some are completely harmless and others are life-threatening.  Most often, the associated symptoms point to the true cause of the pain.  Abdominal pain without vomiting, diarrhea, fever, x-ray changes or abnormal laboratory work is most likely to be benign.  This "functional" pain is often centered over the belly button and pressing on the belly does not worsen the pain.  Many non-gastrointestinal problems can cause abdominal pain, such as: pneumonia, urinary tract infection, gallstones or pancreatitis.

What causes abdominal pain?

The list of causes of abdominal pain are extensive.  Pain in the abdomen is not well localized, that is... pain under the belly button (for example) may be from the appendix which lives in the right lower abdomen.  This makes it more difficult to determine the source.  Children respond differently to abdominal pain.  Some children tolerate significant pain before telling their parents.  For others, anxiety, excitement and fear can cause disabling pain.  It is important to consider the age of the child, how long the symptoms have been occurring, the character of the pain, what makes it better or worse, and what other symptoms are present.

Why is abdominal pain difficult to evaluate in children?

The history and physical exam is the key to evaluating abdominal pain in children.  Infants may present with vague symptoms such as poor feeding, irritability and sleepiness.  Toddler's often can't describe their symptoms well.  When a toddler is asked where the pain is located, they often point to the entire belly or to the middle (at the belly button) regardless of the cause or location of the pain.  Young children may also have difficulty telling the difference between pain, nausea, or general malaise.

What are the most common causes of abdominal pain in kids?

The most common medical cause is gastroenteritis (often with vomiting and diarrhea).

The most common surgical cause is appendicitis.  This is also the most common surgical emergency in children.

How important is the location of the pain?

Abdominal pain in the middle of the belly or "all over" is less likely to be a surgical problem.  Below are some causes of abdominal pain that are often (but not always) located in a specific area of the abdomen.

Mid-upper abdomen (epigastric area)

• Esophagitis
• Gastritis
• Stomach ulcer
• Duodenal ulcer
• Pancreatitis
• Stomach or esophagus irritation due to medications

Right upper abdomen

• Gallstones (cholelithiasis)
• Gallbladder irritation (cholecystitis)
• Gallbladder dysfunction
• Inflammation of the liver or around the liver (hepatitis or peri-hepatitis)
• Right lower pneumonia
• Urinary tract infection
• Kidney stones

Left upper abdomen

• Right lower pneumonia
• Urinary tract infection
• Kidney stones
• Constipation

Right lower abdomen

• Gastroenteritis
• Appendicitis
• Crohn's disease
• Ovarian or testicular torsion
• Intussuception

Left lower abdomen

• Constipation
• Gastroenteritis
• Colitis (inflammation of the colon)
• Ovarian or testicular torsion

What are some major causes of abdominal pain?

Gastroenteritis - This is a typical "stomach bug."  In children, the 3 common symptoms of gastroenteritis are: 1. vomiting, 2. diarrhea, and 3. abdominal pain.  Fever may or may not be present.  Gastroenteritis is most often caused by a virus and the major treatment involves fluids and rest.  The major risk to children with gastroentertitis is dehydration.  Most cases of gastroenteritis (especially when caused by a virus) will resolve within a few days.

Constipation - This is a very common cause of recurrent abdominal pain in children.  Even if a child is passing stool daily, a back-up of stool my cause intermittent crampy discomfort.

Peptic ulcer disease - irritation in the stomach and duodenum (the first part of the small intestines) can cause pain.  The pain is usually centered high in the abdomen and is made better by eating and antacids.  Endoscopy (EGD - esophagogastroduodenoscopy) is the best test to determine the severity and cause of this problem.

Pancreatitis - severe intermittent pain in the middle or left upper part of the abdomen.  The pain may radiate to the back and is worse after eating fatty foods.  This can be diagnosed with a blood test (amylase and lipase levels) and/or imaging.  A CT scan is the best test to identify pancreas inflammation.  An ultrasound can help determine if there is a gallstone blocking both the pancreatic and bile ducts.

Urinary tract infection - pain may occur in the lower middle abdomen.  If the infection has spread to the kidneys, pain may also occur in the back.  Adults frequently have pain with urination, blood in the urine, cloudy urine or smelly urine.  Children often have mild or no symptoms.  Fever may be the only symptom in young children.  Urinalysis is the best initial test.

Kidney stones - severe crampy pain that does not improve with changes in position.  Pain is not affected by eating or movement. Pain may occur in the back and radiate to the groin area.  There may be tenderness when your doctor taps on your mid-back area.  Urinalysis looks for blood in the urine and infection.  Ultrasound is often helpful.  Occasionally your doctor may order other imaging tests such as a CT scan to look for kidney stones.

Appendicitis - usually starts as a dull, achy pain around the belly button.  The pain moves to the right lower abdomen over a few hours.  Your child may feel sick and won't want to eat.  Fever is sometimes present.  Movement makes the pain worse.  Pain worsens over a few hours or days and vomiting may develop.  If not treated quickly, appendicitis may cause the appendix to rupture which can make your child very ill.  Appendicitis is diagnosed based mostly on the physical exam. Blood tests may show a high white blood cell count.  Imaging studies may show the inflamed appendix.

Gallbladder inflammation or gallstones - usually involves right upper abdominal pain.  Fever and jaundice (yellow skin color) may be present.  Pain is often worse with eating.  An ultrasound of the gallbladder is typically the most helpful study.

Menstrual pain - pain is worse during the menstrual period.  NSAIDs (i.e., ibuprophen) are helpful.

Pelvic inflammatory disease - pain is worse in the lower mid abdomen.  A pelvic exam may show inflammation and pelvic fluid can be tested for bacteria.

Functional abdominal pain - all tests are normal.  Pain is all over the abdomen and made worse by stress and anxiety.  May be associated with diarrhea or constipation (or both) and gets better temporarily after having a bowel movement.  Eating makes the pain worse and causes an urgent need to have a bowel movement in some.  Irritable bowel syndrome (IBS) is an example of a functional intestinal disorder.

Lactose intolerance - pain is all over the abdomen and is often associated with some of the following: bloating, gas, diarrhea, nausea and vomiting.  Pain is gone in the mornings but gets worse during the day after eating lactose-containing food.  Pain improves with removal of lactose (i.e., milk and cheese) from the diet.  Lactase enzyme can be taken orally to alleviate the effects of lactose.  A breath test is available to diagnose lactose intolerance however this test is time consuming and expensive.

Inflammatory bowel disease - usually associated with weight loss, diarrhea, blood in the stools.  Symptoms often occur for months prior to diagnosis.  Blood tests reveal inflammation.  Imaging tests reveal thickened inflamed bowel walls.  Endoscopy may reveal ulcerations in the colon or other parts of the gastrointestinal tract.

Esophagitis - inflammation in the esophagus is often associated with gastroesophageal reflux (GER).

Abdominal migraine - diffuse intermittent abdominal pain.  Often the child or the child's family have severe migraine headaches.  All tests are normal.  

Anxiety, excitement or depression - many emotional states get the gastrointestinal tract moving!  Often the abdominal pain may be caused by another reason, but anxiety about future pain makes the pain worse!  

What are some serious causes?

• Gastroenteritis (especially if dehydration is present)
• Stomach ulcer
• Pancreatitis
• Choledocholithiasis (a gallstone blocking the bile duct)
• Appendicitis
• Urolithiasis (kidney stone)
• Intussusception
• Intestinal obstruction
• Trauma
• Incarcerated (stuck) hernia
• Abscess
• Sepsis

Red Flags (seek medical care immediately)

• Severe or persistent symptoms
• High fever
• Unable to drink fluids
• Ill-appearing child
• Blood in the stool, urine or vomited material
• Belly tenderness (pressing on the belly makes the pain worse)
• Jaundice (yellow skin color)
• Vomiting with a yellow or green color

Acute or chronic?

How long has your child had the pain?  Does it wake your child from sleep?  These and other questions are important for assessing abdominal pain.  Acute abdominal pain (pain that started a few hours or days ago) is more likely to represent a surgical problem.  Chronic abdominal pain is less likely to be serious unless there are other symptoms such as weight loss, blood in the stool, etc.

What tests need to be done?

This depends on the entire clinical picture.  Tests may include blood tests, urinalysis, ultrasound, x-ray, or computed tomography (a CT or "cat" scan). 

How is abdominal pain treated?

The treatment depends on the cause of the pain.  Most cases of mild, isolated abdominal pain resolve without treatment.

References:

1. Leung, A.K.C., Sigalet, D.L., Acute Abdominal Pain in Children, Am Fam Physician. 2003 Jun 1;67(11):2321-2327.
2. Ross A., LeLeiko, N.S., Acute Abdominal Pain, Pediatr. Rev., Apr 2010; 31: 135 - 144.
3. Vissers RJ.  Pitfalls in appendicitis. Emerg Med Clin North Am - 01-FEB-2010; 28(1): 103-18, viii