In patients with no alarm symptoms, the Rome criteria have a positive predictive value of approximately 98%, with additional diagnostic tests providing a yield of 2% or less.105 When needed, the exclusion of an organic condition can be accomplished by utilizing inexpensive, non-invasive and easily available diagnostic tests such as complete blood cell count, erythrocyte sedimentation rate, chemistry panel, liver and thyroid function studies, urine analysis and stool examination for blood, ova and parasites. Need for other diagnostic tests should be based on history and physical examination findings. The physician should avoid the lure of having to 'rule out' an organic disease at all cost. Performing multiple tests may provide results that often are unrelated to the presenting symptom or have no clinical relevance (such as a mildly elevated sedimentation rate). Repeating tests to confirm the serendipitous findings may further increase anxiety and undermine the clinical diagnosis of functional bowel disorder. One could use time as the physician's ally, assuring the patient that no test is necessary at this point but if further symptoms present or the current symptom worsens the physician will not hesitate to proceed with further work-up.
Hamm et al80 studied 1452 patients with an established diagnosis of IBS and found that screening tests showed a low incidence of thyroid dysfunction, ova and parasite infestation, or colonic pathology. The authors concluded that limited detection rates, added costs and the inconvenience of these tests made the routine use of endoscopy, radiography, thyroid function tests, fecal ova and parasite determination and the lactose hydrogen breath test questionable in the diagnostic evaluation of established IBS patients. In accordance with these results, Tolliver et al106 performed fecal ova and parasite determinations in 196 patients with a possible diagnosis of IBS, and found no evidence of infection in any of them. In the same study, complete blood cell count, sedimentation rate, serum chemistries, thyroid profile and urinal-ysis were normal or yielded no useful clinical information.
A study designed to investigate the prevalence of elevated antiendomysial antibody titers in children with recurrent abdominal pain compared with healthy children found no association between abdominal pain and celiac disease.107 The study showed that 1% of patients in each group had positive celiac disease antibodies. An adult investigation studied serum antibody testing for celiac disease in patients with IBS symptoms and a control group, followed by upper endoscopy in positive cases. The study revealed that 4.6% of patients in the group with possible IBS had positive antibodies in comparison with 0.67% in the control group, suggesting that testing for celiac disease may be one of the few cost-effective evaluations in patients with IBS.108
A study investigating the presence of gastro-esophageal reflux in children with recurrent abdominal pain concluded that pathological gastroesophageal reflux is a frequent finding in such children.109 Treatment of gastroesophageal reflux in this group of patients resulted in resolution or improvement of abdominal pain in 71% of cases. Another study evaluating findings on endoscopic examinations in 62 Indonesian children with recurrent abdominal pain revealed pathological abnormalities including esophagitis, erosions and duodenitis in 50% of the patients.110 In the absence of peptic ulcers, it is unclear how much these pathological findings contribute to the patients' symptoms. Endoscopy and biopsy performed in children evaluated for dyspepsia demonstrated that most children did not have significant mucosal disease. Inflammation without evidence of peptic ulceration was found in 38% of the patients with H. pylori being identified in only five cases.111 Follow-up at 6 months to 2 years revealed that most subjects improved, regardless of the cause of dyspepsia.
The diagnostic yield of a sonographic examination of the abdomen in children presenting with func tional bowel disorders seems to be extremely low. Yip et al, in a retrospective evaluation of 644 ultrasound studies performed in children with the diagnosis of recurrent abdominal pain found abnormalities in only ten children, concluding that only children who have abdominal pain with atypical clinical features should receive sonographic screening.112 In another study, the evaluation of 57 patients with chronic abdominal pain by abdominal and/or pelvic sonography revealed only one case of ovarian cyst that later resolved sponta-neously.113 Stordal et al114 studied 44 children with recurrent abdominal pain without finding any abnormalities on ultrasound that could be related to the symptoms.
The diagnostic yield of esophageal pH monitoring in children presenting with chronic abdominal pain is controversial. A study of 44 children presenting with recurrent abdominal pain demonstrated gastroesophageal reflux in 25% of cases.114 No studies have compared outcomes between children who had pH monitoring studies and those who did not. The inconvenience associated with this test and its cost preclude its use at least in the initial evaluation of chronic abdominal pain.
This test is often used to diagnose lactose intolerance in patients with functional bowel disorders, but the cause-effect relationship between lactose intolerance and symptoms has been questioned.81 Lactose intolerance is discussed in more detail in a previous section of this chapter.
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