A therapeutic trial is often appropriate, definitive, and highly cost effective when a specific diagnosis is suggested on the initial physician encounter. For example, chronic watery diarrhea, which ceases with fasting in an otherwise healthy young adult, may justify a trial of a lactose-restricted diet; bloating and diarrhea persisting since a mountain backpacking trip may warrant a trial of metronidazole for likely giardiasis; and postprandial diarrhea persisting since an ileal resection might be due to bile acid malabsorption and be treated with cholestyramine before further evaluation. Persistent symptoms require additional investigation. Certain diagnoses may be suggested on the initial encounter,. | Chapter 040. Diarrhea and Constipation Part 12 A therapeutic trial is often appropriate definitive and highly cost effective when a specific diagnosis is suggested on the initial physician encounter. For example chronic watery diarrhea which ceases with fasting in an otherwise healthy young adult may justify a trial of a lactose-restricted diet bloating and diarrhea persisting since a mountain backpacking trip may warrant a trial of metronidazole for likely giardiasis and postprandial diarrhea persisting since an ileal resection might be due to bile acid malabsorption and be treated with cholestyramine before further evaluation. Persistent symptoms require additional investigation. Certain diagnoses may be suggested on the initial encounter . idiopathic IBD however additional focused evaluations may be necessary to confirm the diagnosis and characterize the severity or extent of disease so that treatment can be best guided. Patients suspected of having IBS should be initially evaluated with flexible sigmoidoscopy with colorectal biopsies those with normal findings might be reassured and as indicated treated empirically with antispasmodics antidiarrheals bulk agents anxiolytics or antidepressants. Any patient who presents with chronic diarrhea and hematochezia should be evaluated with stool microbiologic studies and colonoscopy. In an estimated two-thirds of cases the cause for chronic diarrhea remains unclear after the initial encounter and further testing is required. Quantitative stool collection and analyses can yield important objective data that may establish a diagnosis or characterize the type of diarrhea as a triage for focused additional studies Fig. 40-3B . If stool weight is 200 g d additional stool analyses should be performed that might include electrolyte concentration pH occult blood testing leukocyte inspection or leukocyte protein assay fat quantitation and laxative screens. For secretory diarrheas watery normal osmotic gap possible .
