Clinical manifestations and diagnosis

Functional: The symptoms of functional recurrent abdominal pain are nonspecific and may show an improvement during weekends, and school vacations.

Although the occurrence of nocturnal pain is considered an important indicator of an organic cause, children with functional pain may awaken during the night with symptoms. Functional abdominal pain is periumbilical and very difficult for the child to characterize. The child can be distracted from the pain. The child is well between episodes with normal physical examination and growth parameters. The family may reinforce the symptoms by demonstrating excessive concern. Despite concerns about psychosocial factors, many children with functional abdominal pain appear to be well adjusted and from well adapted families.

A wide range of potential organic causes must be considered before establishing a diagnosis of functional pain.

Lactose intolerance: Lactose intolerance is so common that the finding may be coincidental. In genetically programmed individuals lactase begins to decrease gradually at 4-6 years of age. If milk drinking continues at a constant rate, the entire amount of lactose ingested may not be hydrolyzed. The lactose spills into the distal small bowel and colon where it is fermented by bacteria and gases - hydrogen and carbon-di-oxide are produced. This causes intestinal dilation and pain. This may be the sole symptom. As the syndrome progresses, diarrhoea results from the osmotic effect of unabsorbed sugar. Diagnosis of lactose intolerance from lab tests is difficult, because tests are sensitive and over diagnosis is common. Dietary restriction is the easiest way to establish lactose intolerance. The child should be given lactose free diet for 2 weeks. If the pain subsides the diagnosis can be suspected. However it should be confirmed by giving the child lactose again and observing exacerbation of symptoms. After the diagnosis is established the parents can be counselled and low lactose dairy products should be reintroduced as tolerated.

Constipation: The child with simple constipation frequently complains of abdominal pain. Unless the physician specifically asks about the frequency of bowel movements the diagnosis may go unsuspected for a long time. Rectal examination is helpful in establishing the diagnosis but a trial of a mild stimulant may be necessary to establish the cause.

Musculoskeletal pain : Pain arising from strained abdominal muscle or chronic myositis is quiet frequent as school aged children frequently engage in competitive sports. The pain is described as sharp or knife like and may be triggered by various activities or body position. It is usually located at the insertion of the rectus or oblique muscles into the costal margin or iliac crest. If the abdominal muscles are tightened during physical examination and if pain is still reproduced by palpation then the origin undoubtedly is musculoskeletal.

Intestinal parasites (Giardiasis) may cause only abdominal pain, so stool should be examined for ova and parasites as part of evaluation in all children.

PUD (Peptic Ulcer Disease) : A small proportion of children with recurrent abdominal pain which typically radiates to the back may suffer from PUD. A strong family history or the presence of iron deficiency anaemia or occult blood in stools should indicate upper gastro intestinal endoscopy. Evaluation for H.pylori gastritis and treatment is reserved for children with epigastric pain suggestive of peptic disease.

Inflammatory Bowel Disease (IBD) : This disease does not present with pain alone but if the location and characteristics are suggestive this diagnosis should be considered. ESR may be normal in 50% of children with IBD.

Abdominal migraine : It may cause episodic abdominal pain in children in the absence of headache. These episodes are associated with nausea with or without vomiting. Transient diarrhoea is less common. The episodes can last for hours and end when child falls asleep and awakes feeling improved. A strong family history of migraine headache, is suggestive enough.

Lab studies may be unnecessary if the history and physical examination clearly leads to the diagnosis of functional abdominal pain. Reasonable screening studies are:
a. Complete blood count (CBC)
b. Erythrocyte sedimentation rate (ESR)
c. Stool for ova and cysts
d. Urine analysis
e. USG abdomen for kidney, gall bladder and pancreas and USG pelvis for lower abdominal pain. Upper gastro intestinal x-ray series for suspected disorder of stomach or small intestines.
f. UGI endoscopy for peptic ulcer disease.
g. H.pylori antibody test
h.Laparoscopy may identify structural anomalies inflammatory lesions and adhesions. (With ESR abnormal look for inflammation, infection and neoplastic diseases).