Evaluation and Treatment of Colonic Symptoms

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Key points

  • Most acute diarrhea is infectious, with empiric antibiotics reserved for patients with high fever, blood diarrhea, or other worrisome features.

  • Irritable bowel syndrome (IBS) and functional diarrhea are the most common causes of chronic diarrhea.

  • In chronic diarrhea, fecal calprotectin may help differentiate IBS from an inflammatory disorder.

  • Determine if constipation is due to a defecatory disorder by history (excessive straining, need for perineal pressure, and/or manual disimpaction) because

Diarrhea

In the past, the definition of diarrhea relied on increased stool weight (>200–300 g/d) and increased frequency of stools (>3/day). However, most definitions now focus on loose or watery stool consistency and urgency because these are most consistent with patient self-reports of diarrhea.1 Probably the best description is that the stool takes the shape of the container in which it is collected. Diarrhea is considered acute if duration is less than 2 weeks, persistent if 2 to 4 weeks, and

Epidemiology

In the United States, there are more than 300 million cases of diarrhea per year. However, accurate estimates of incidence are difficult because most patients do not present for evaluation. In addition, the yield of stool culture has been quite low, with historically only 1.5% to 5.8% returning a positive result.4 Most cases of acute diarrhea are due to infection, including viruses (norovirus or rotavirus), bacteria (Staphylococcus, Salmonella, Shigella, Campylobacter, Escherichia coli, and C

Diagnostic tests

In the immune-competent patient who presents in the first 2 to 3 days with acute diarrhea and no worrisome symptoms, no specific diagnostic testing is indicated. Evidence of a more inflammatory or invasive infection includes fever, severe abdominal pain, and blood and/or pus in the stool. If any of these are present, diagnostic testing is indicated. In addition, patients who are immunocompromised, elderly, generally unwell, or having severe symptoms are candidates for testing.

Supportive

In severe diarrhea, the initial priority should be to assure adequate hydration. In the United States, this is often done intravenously. However, because most patients with diarrhea can tolerate oral intake, oral rehydration is possible with products such as Pedialyte (which has half the sugar and more than twice the sodium of Gatorade). Although the data are mixed, minimizing dairy intake given possible transient lactase deficiency is reasonable. Otherwise, a regular diet should be maintained

Traveler’s diarrhea

For patients who travel to resource-poor regions, the incidence of traveler’s diarrhea is 20% to 60%.11 For acute diarrhea in the traveler, bacterial pathogens are usually the cause. E coli (enterotoxigenic and enteroaggregative) is most commonly identified. In travelers with acute diarrhea, empiric antibiotic treatment for 3 to 5 days, usually with a quinolone, is recommended. For travelers with persistent diarrhea, Giardia, Entamoeba, Strongyloides, and Schistosoma should be considered.12

Food-borne diarrhea

For food-borne illness, development of symptoms within 6 to 24 hours is most likely due to preformed toxin, as seen in Staphylococcus, Bacillus, and Clostridium perfringens. In addition, vomiting is frequently present as an initial symptom given upper gastrointestinal involvement. Typically, these patients only require supportive care.

Watery diarrhea

Most watery diarrhea is due to viral gastroenteritis, such as norovirus or rotavirus. However, because there are no specific treatments, care is supportive. Diagnostic testing is not indicated unless there is either epidemiologic concern or history is inconclusive.

Inflammatory diarrhea

Bloody diarrhea, fever, and abdominal pain are concerning for an invasive infection such as Shigella, Salmonella, Campylobacter, C difficile, or Yersinia. However, bloody diarrhea without fever is particularly worrisome for enterohemorrhagic E coli (including serotype 0157:H7). It is important to identify this variant of E coli because antibiotics should be avoided and the chance of developing hemolytic uremic syndrome is significant—up to 10% according to the World Health Organization.

Chronic diarrhea

Chronic diarrhea is defined as the presence of loose stools with or without increased stool frequency for at least 4 weeks. As the definition has varied significantly, best estimates are that roughly 3% to 5% of the population suffers from chronic diarrhea. In these patients, the differential diagnosis is much longer than for those with an acute onset.13 In addition, initially it is important to determine exactly what the patient means by “diarrhea” because the term can be used in describing

Diagnostic tests

In patients with chronic diarrhea, it is reasonable to check a complete blood count (to evaluate for anemia and leukocytosis) and electrolytes. In appropriate situations, other testing may include autoantibodies for celiac disease, thyroid function, and protein levels. Although frequently checked, systemic inflammatory markers, such as erythrocyte sedimentation rate and C-reactive protein, have limited data in the diagnostic work-up of chronic diarrhea. If a likely diagnosis is not immediately

Osmotic

There are only a few disorders that are consistently osmotic and make evaluation straightforward. Use of fecal osmotic gap is rarely necessary. If history is compatible, the physician can try eliminating lactose from the diet. If there is continued clinical concern for lactose intolerance, hydrogen breath testing can be performed. Otherwise, the most likely diagnosis is intentional or accidental ingestion of an osmotically active agent (or a mixed disorder). Some patients ingest a significant

IBS or Functional Diarrhea

IBS is characterized by the presence of abdominal pain or discomfort in the setting of irregular bowel function. Functional diarrhea describes frequent loose stool but without the associated abdominal pain or other symptoms. Mucus is a common complaint. Features making IBS less likely include bloody or nocturnal diarrhea and weight loss. Testing on patients with IBS can show abnormal hydrogen and some patients respond to rifaximin, which suggests alteration in bacterial distribution.18, 19

Microscopic colitis

Microscopic colitis is an increasingly recognized cause of chronic diarrhea, especially in older adults. Because diagnosis requires colonic biopsy in the setting of normal-appearing mucosa, it is a challenging and likely underreported diagnosis. Biopsy can show lymphocytic and/or collagenous infiltration, although there are newer reports of both eosinophilic and mast cell populations. The typical presentation is diffuse watery diarrhea, occasionally severe. Associated medications include

Inflammatory Bowel Disease

One of the challenges is determining when colonoscopy is indicated to rule out inflammatory bowel disease (IBD) versus irritable bowel syndrome. Fecal calprotectin may aid in this decision. In a meta-analysis of subjects referred for colonoscopy for suspected IBD, calprotectin had a sensitivity of 93% and specificity of 96% in diagnosing IBD. A subsequent study, in which 41% of subjects had histologically confirmed inflammation, sensitivity and specificity were 75% and 88%, respectively.17 In a

Celiac Disease

Although not specifically outlined in the 1999 American Gastroenterological Association (AGA) guidelines, testing for celiac disease should be performed if the diagnosis is not immediately obvious. This is especially true if there is weight loss, steatorrhea, bloating, anemia, abnormal liver enzymes, or bone loss. Both IgA antiendomysial and IgA antitissue transglutaminase have excellent sensitivity in patients with abdominal symptoms (sensitivity 89%–90%, specificity 98%–99%). Gliadin

Diarrhea summary

Important considerations for diarrhea include:

  • 1.

    Chronic diarrhea can be due to a large number of underlying diagnoses but irritable bowel or functional disorders are the most common

  • 2.

    History and examination help determine osmotic, secretory, inflammatory, or malabsorptive causes

  • 3.

    Testing with fecal calprotectin may help differentiate inflammatory from noninflammatory causes

  • 4.

    Treatment of chronic diarrhea is driven by diagnosis (Figs. 1 and 2)

Constipation

Chronic constipation is characterized by infrequent and/or difficult bowel movements that persist for at least 3 months.27 Associated symptoms can include hard or firm stool, incomplete evacuation, bloating, and abdominal discomfort. Although many studies and guidelines use fewer than three bowel movements per week as a criterion, this applies to a marked minority of patients who consider themselves constipated. As many as 50% of patients who report constipation actually have a daily bowel

Defecatory disorders

The initial goal of history, examination, and basic testing is to identify concerning symptoms as well as relevant medical or pharmacologic issues. After that, it is important to determine if there is a defecatory disorder in which evacuation is the primary problem. Normal defecation requires relaxation of the puborectalis muscles, pelvic floor descent, abdominal wall muscle contraction, and, finally, relaxation of the anal sphincter.31 Issues with any of these actions can lead to difficulty

Laxatives

The mainstay of treatment over the years has been laxatives. Laxatives are either osmotic (polyethylene glycol, lactulose, and magnesium) or stimulatory (bisacodyl, senna, and cascara). Pooled data on osmotic laxatives reveal a significant effect with only 38% failing to improve compared with 69% for placebo, resulting in an NNT of 3.35 In direct comparisons, polyethylene glycol has been found to be more effective than lactulose in improving stool frequency and form, relief of abdominal pain,

Secretagogues

There are two relatively new agents approved for use in patients with chronic constipation. Linaclotide is a peptide that stimulates cyclic guanosine monophosphate through the guanylate cyclase receptor. This results in chloride-rich fluid secretion into the intestinal lumen. Subjects with chronic constipation (average of 0.3 complete spontaneous bowel movements per week) were studied for 12 weeks with daily linaclotide or placebo. A return to normal bowel function (at least 3 complete

Prokinetics

Cisapride and tegaserod, 5-HT4 agonists used for constipation, have been removed from the US market due to concerns of excess cardiovascular events and QT prolongation. Prucalopride, a more selective 5-HT4 agent, is now available in Canada and Europe but has not been approved for use in the United States. In a meta-analysis, the NNT was 6 to return to normal bowel function. Thus far, there has been no significant effect on QT length or increase in adverse cardiovascular events.35

Others

Probiotics may have a benefit in patients with functional constipation, with data suggesting improvement in defecation frequency and stool consistency.39 There are no convincing data on the efficacy of stool softeners such as docusate, although there may be a role in patients with hard stools.

Surgical treatment

If slow transit constipation is documented, and a patient fails an aggressive trial of fiber, laxatives, and prokinetics, total colectomy is an option. Obviously, this needs to have been very carefully considered.

Summary

Important considerations for constipation include:

  • 1.

    Initial evaluation should evaluate for fecal incontinence, fecal impaction, medication side effects, concerning symptoms, underlying medical or metabolic issues and irritable bowel syndrome

  • 2.

    History and examination should be used to determine if a defecatory disorder is most likely

    • a.

      If defecatory disorder is likely, testing with balloon expulsion or anal manometry can be considered and, if confirmed, treatment with biofeedback (if testing not

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  • Cited by (6)

    • Management of constipation in older adults

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      Citation Excerpt :

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    • Post-acute and long term geriatric care clinical advisor. Volume II

      2016, Post-Acute and Long Term Geriatric Care Clinical Advisor. Volume II

    Disclosures: None.

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