Recurrent Abdominal Pain: A Practical Approach

B. Bhaskar Raju

Recurrent abdominal pain is probably the commonest form of pain complaint of children below 15 year age and probably also the commonest for which the least number of cases where specific etiology is identified. This makes it imperative that all pediatricians familiarise themselves with the causative factors and have a scientific and rational approach to the problem. A brief outline of an approach to a case of RAP is attempted below.

20-25% of children attending any pediatric out-patient clinic will complain of abdominal pain at sometime or other. Most of them do not fit into the syndrome of recurrent abdominal pain.

The criteria to label that the child is suffering from RAP is:

• at least 3 bouts of significant abdominal pain occurring over 3 months.
• the severe phase lasting at least 3 mts.
• usually in children above 3 year of age

Once history suggests the possibility of recurrent abdominal pain, it is the physician's duty to rule out

1. Acute abdomen which may have previous H/o. abdominal pain unrelated to the present pathology.
2. Malingering - where the child feels no pain at all but nevertheless complains of abdominal pain either for seeking attention or to avoid unpleasant tasks like exams, homework etc. Once a physician is convinced that he is dealing with a true case of RAP syndrome, his next job is to slot it into one of the 3 following well known causes of RAP.

• ORGANIC: (15%)
• DYSFUNCTIONAL: (75%)
• PSYCHOGENIC: (10%)

Organic Pain

More than 80% of abdominal pain from organic causes, present as acute abdominal pain, or as recurrent pains which do not fit into the pattern of RAP syndrome.

However, there are some organic causes which masquerade as RAP syndrome and may be dismissed as non-organic, unless there is a strong clinical suspicion entertained and a careful examination done to rule them out.

Some examples of organic recurrent abdominal pains which may be misdiagnosed easily as non-organic are:-

1. Sub Acute Appendicitis While controversy exists if appendicitis can be sub acute or chronic, it is well established that acute appendicitis if missed or inadequately treated can go on for a smoldering inflammation of the appendix which presents as recurrent abdominal pain. The typical RIF tenderness may be easily missed unless carefully looked for.
2. Gastritis/ Duodenitis Can be missed unless the child is subjected to an upper GI scopy.
3. Constipation This is a fairly common cause of RAP often missed since the doctor doesn't elicit the history nor are the parents usually aware of the bowel habits of the children beyond the age of 2-3 years. This is an easily treatable and curable condition which should be picked up at the first consult it self.
4. Helicobacter Pylori infection Its role in causing RAP is still controversial but enough evidence exists that RAP with significant epigastric tenderness is often due to H.pylori infection. This organic cause can be easily missed unless an endoscopy and antral biopsy is done
5. Gastroesophageal Reflux This is not an uncommon phenomenon in children and the gold standard for diagnosis being 24 hours pH monitoring, it is not surprising that the diagnosis is often missed or over /under diagnosed.
6. Pin Worms and Giardiasis
7. Malrotation
8. Hydronephrosis

There are several other organic cause like chronic pancreatitis, GB stones, PUD, etc which can also present as RAP. But all of them have distinct clinical features and specific tests for diagnosis which makes it unlikely that they will be missed in a routine work up for RAP. Hence, I am not elaborating on those causes.

Psychogenic Pain

Between 5-12% of RAP syndrome have a clearly recognizable psychiatric basis and need active psychiatric therapy. Besides abdominal pain, these children also have other behavioural disorders and a close connection to some precipitating events which make clinical diagnosis easy. These include school phobia, psychosis secondary to intra family problems and tragedies, depression, complaint modelling etc. In these situations the psychiatric component overshadows the problem of RAP.

Dysfunctional Pain

This constitutes the bulk of RAP seen in clinical practice wherein children complain of significant abdominal pain occurring over several weeks or months and clinical exam / all investigations fail to reveal an organic component. These children have normal behaviour pattern and are often quite intelligent. They do not have any significant psychiatric problems and no obvious precipitating factors besides routine stresses of childhood like exams, peer pressure, home work etc.

Pathogenesis of Dysfunctional Pain

Every body's intestines has variable number of non - propulsive spasmodic contractions whose number/amplitude is never severe enough to be felt by the individual as pain. In children with dysfunctional pain, these contraction are more severe, more sustained, more frequent and hence felt as recurrent abdominal pain. This is the somatic component of dysfunctional pain. For reasons poorly understood, these contractions are more during periods of stress explaining the increased frequency of RAP nearer exams and other routine stresses of childhood.

Dysfunctional abdominal pain is also sometimes called irritable bowel syndrome, to emphasise the role of spasmodic intestinal contraction creating the pain. However, now clear understanding exists of the connection between IBS of childhood and IBS of adults which presents as recurrent diarrhoea /constipation.

An Approach To A Case Of Rap

While clinical examination should give us a very good clue as to which of the above 3 groups of RAP we are dealing with, all RAP cases require a basic work up to rule out organic causes.

All cases require:

• Complete physical
• CBC, Urine RE, Stool Exam, Mantoux
• CXR
• LFT
• Urea / Creatinine
• S.amylase / lipase

  Most case will require:

• USG (Abdo)
• Barium swallow, meal, follow-through

  Selected cases will require :

• UGI Scopy
• Antral / Duodenal biopsy /H.pylori studies

The positive yield from scopies (which is an invasive procedure) will improve if it is restricted to children with food related pain, epigastric pain, and epigastric tenderness.

When significant pain persists (all investigations are negative) and an organic cause is still suspected it may be worthwhile to arrange for screening for:-

• Porphyria
• Henoch-Schonlein purpura
• Lead poisoning
• Meckel's screening etc.

Management

Avoid

• Antispasmodic
• Psychiatric reference
• Accusatory approach
• Supercilious attitude

Summary

Dysfunctional pain is by far the commonest cause of RAP in children. The pediatricians duty is to identify organic and psychogenic causes and treat them appropriately. Dysfunctional pain needs very little pharmacotherapy and plenty of reassurance.