Evaluation and Management of Chronic Diarrhea: An Algorithmic Approach

Introduction

Chronic diarrhea is one of the most common conditions facing both primary care clinicians and gastroenterologists. The differential diagnosis for this symptom is vast and overlapping. For this reason, it is important to approach the diagnosis and treatment of chronic diarrhea in a systematic fashion. Many textbooks list dozens of diagnoses that cause diarrhea and then provide lists of tests and treatments. This may leave the clinician confused about how to provide a focused, logical, and cost-effective approach to evaluation and treatment. This Clinical Update provides a sequential evaluation strategy beginning with what the patient brings to the clinician, the symptom features. From this information, an initial evaluation and treatment strategy can be developed, which, if not successful, can lead to any of several more specific pathways involving specialized tests and treatments for the less common disorders.

In this update, common presentations of chronic diarrhea will be reviewed. Then an algorithmic approach to diagnostic and treatment approaches will follow, with this information being used to more fully explore the specific features of each case.

Consider the following clinical scenarios:

• A 28-year-old woman reports several years of cramp-like lower abdominal pain, often occurring after meals, relieved with defecation, and associated with abdominal bloating, rectal urgency, and frequent loose, nonbloody, small-volume stools and mucus.
• A 72-year-old woman and mother of 5 reports a longstanding history of diarrhea (3-4 small, loose, nonbloody stools each day) but with recent worsening that has kept her at home. Physical exam is notable for perianal contact dermatitis and decreased sphincter tone.
• A 62-year-old man reports a 1-month history of bloody diarrhea associated with decreased appetite, nausea and vomiting, intermittent fever, and a 10-pound weight loss.
• A 61-year-old female healthcare worker reports a 3-month history of diarrhea (10-12 watery movements/day and night) associated with mild, diffuse abdominal discomfort and a 10-pound weight loss. A review of her previous records indicates a more longstanding history of unexplained diarrhea.
• 49-year-old woman presents with several weeks of gradual-onset diarrhea (2-5 semi-formed nonbloody stools/day that are greasy and foul-smelling) with bloating, mild fatigue, and a 5-pound weight loss. She returned 6 weeks ago from a vacation in Thailand.

All of the patients described above presented with a chief complaint of "diarrhea" lasting for 1 month or more. These cases are representative of the diarrheal syndromes most commonly encountered in primary care practice. The evaluation and treatment of diarrheal syndromes is often a multistep process that requires ruling out a wide variety of entities that must be considered in the differential diagnosis.

Often, symptoms and clinical findings overlap, despite different underlying pathophysiologic mechanisms,^[1] or are multidetermined, with more than 1 pathophysiologic process responsible for the diarrhea. This can make chronic diarrhea a challenging clinical problem.

However, most cases of chronic diarrhea can be diagnosed through careful history and physical examination and select laboratory studies. Diagnoses that remain in question, particularly infectious or inflammatory in nature, can often be made through endoscopic evaluation (usually sigmoidoscopy) with biopsy. Thus, the primary care clinician can accurately diagnose the majority of patients with chronic diarrhea. Remaining cases should be referred to a gastroenterologist for continued outpatient evaluation. Inpatient hospitalization is only rarely required for further investigation, an example of this being long-standing refractory diarrhea associated with dehydration.

This Clinical Update will first provide a review of diarrhea, with an emphasis on obtaining an accurate and thorough history and comprehensive physical examination. Other possible symptoms and clinical findings will be described in relation to associated diarrheal syndromes. Finally, case presentations will be used to more fully explore the diagnosis and management of the often difficult-to-treat clinical scenarios encountered in primary care practice.