Functional Abdominal Pain

Functional abdominal pain is mentioned in the higher syllabus for abdominal pain, and not the core syllabus. It is common in children, and some resources suggest it has a non-organic cause in most cases - some don't. Either way, a cause is difficult to elucidate, with a cause identified in <10%. It is important to consider physical and psychological factors. Functional abdominal syndrome is abdominal pain for 25% of the time, with other symptoms.
Apley's law: the further a recurrent abdominal pain is from the umbilicus, the more likely it is to be organic.

40% of 7 year olds have at least one episode of abdominal pain, with peaks in incidence at 5 and 10 years old.

Recurrent pain:  more common in girls than boys
                           more common in children whose parents have GI problems
                           obesity
                           Winter

3 of more episodes of abdominal pain in three months, that affects daily activities. 

Pain not associated with eating, loss of daily functioning, no other disorder

Causes

There is no clear idea what causes recurrent abdominal pain. The biophysical model of disease suggests it's a response to biological factors, family and school interactions, family environment and critical life events. 

It is thought, by Rome III, there are three main categories of functional abdominal pain:

Duodenal Ulcers

Abdominal Migraine

Irritable Bowel Syndrome

Duodenal Ulcers or Functional Dyspepsia: 

Consider in epigastric pain that causes night time waking. Treat by giving PPIs. Test for and treat H Pylori. If symptoms do not respond, then get an endoscopy - if the endoscopy is normal, consider functional dyspepsia.

Irritable Bowel Syndrome

Intestinal dysmotility. Family history is common, and the infection may follow a GI infection. You normally get abdominal pain that is worse before defecation - and relieved by defacation. It can be helpeful to say to children that sometimes the insides of the intestine become so sensitive that some children can feel the food going round the bends. 

Peppermint oil may be helpful. 

Avoiding sorbitol can be helpful, and increasing intake of oats and linseed can help. 

Abdominal Migraine

Abdominal migraine is associated with travel sickness. This may be associated with a headache, but in some children the abdominal pain predominates. The pain is normally midline associated with vomiting and pallor. There is normally a history of migraine. 

Pizotifen may be helpful. 

Management

Make sure you differentiate between serious and dangerous diagnoses. Serious is a disruption to schooling and life. Dangerous is life threatening. 

- Urine culture and microscopy

- FBC, ESR, CRP, LFTs, U&E, Coeliac

- Stool microsccopy 

- Abdominal USS to exclude gall stones and PUJ obstruction

- Pain and life event diary

Red Flags

Unexplained fever

Weight loss and poor growth

Joint problems, rashes

Vomiting

Pain causing waking, referred to back or shoulders

Urinary symptoms, perianal disease, PR blood 

Age under 5 

References
http://learning.bmj.com/learning/module-intro/functional-recurrent-abdominal-pain-children-assessment-management.html?moduleId=10017102&searchTerm=%E2%80%9Cabdominal%E2%80%9D&page=1&locale=en_GB

http://gut.bmj.com/content/45/suppl_2/II43.full

http://www.bmj.com/content/325/7366/701?sso=

http://gut.bmj.com/content/45/suppl_2/II60.full 

http://bestpractice.bmj.com/best-practice/monograph/787/diagnosis/differential-diagnosis.html

http://www.amazon.co.uk/Illustrated-Textbook-Paediatrics-STUDENTCONSULT-Online/dp/0723435650