What is the best course of action for a female patient with a one-month history of intermittent loose stools and abdominal pain?

Evaluation and Management of One-Month History of Intermittent Loose Stools and Abdominal Pain

Begin with targeted baseline laboratory testing including complete blood count, C-reactive protein or erythrocyte sedimentation rate, celiac serology, and fecal calprotectin, while actively screening for alarm features that would necessitate urgent investigation. 1

Initial Clinical Assessment

Detailed History Taking:

• Confirm the relationship between abdominal pain and bowel habits by asking specifically whether pain is relieved by defecation or temporally associates with changes in stool frequency or consistency 1
• Document symptom duration and onset triggers, including whether symptoms started after acute gastroenteritis, antibiotic use, or psychological stress 1
• Use the Bristol stool chart to classify predominant stool type on abnormal days; loose/watery stools >25% of the time suggests diarrhea-predominant IBS 1
• Screen for alarm features including rectal bleeding, unintentional weight loss, nocturnal symptoms that wake the patient from sleep, fever, family history of inflammatory bowel disease or colorectal cancer, and age >50 years at symptom onset 2, 1
• Assess symptom timing: IBS symptoms typically subside during sleep; waking from sleep with pain or diarrhea indicates another diagnosis should be considered 2

Physical Examination:

• Examine for abdominal tenderness, distension, and masses 3
• Look for signs of systemic disease including fever, weight loss, or pallor 1

Baseline Laboratory Testing

All patients with one month of these symptoms require:

• Complete blood count to evaluate for anemia 1, 4
• C-reactive protein or erythrocyte sedimentation rate to assess for inflammation 1
• Celiac serology (tissue transglutaminase IgA with total IgA level), as 1 in 3-4 patients with suspected diarrhea-predominant symptoms may have celiac disease 4
• Fecal calprotectin to distinguish functional from inflammatory conditions 1

Interpretation of fecal calprotectin:

• ≥250 μg/g: High suspicion for inflammatory bowel disease; perform colonoscopy 1
• 100-249 μg/g: Repeat test off NSAIDs and proton pump inhibitors; consider colonoscopy if repeat remains indeterminate or abnormal 1
• <100 μg/g: Supports functional diagnosis 1

Additional testing if indicated:

• Stool examination for ova and parasites if travel history or endemic area exposure 1
• Thyroid function tests (TSH, free T4) to exclude hypothyroidism 4
• Comprehensive metabolic panel to assess electrolyte disturbances, liver function, and kidney function 4

Diagnostic Approach Based on Test Results

If baseline investigations are normal and no alarm features exist:

• Make a positive diagnosis of IBS-D rather than continuing exhaustive testing, using Rome IV criteria: recurrent abdominal pain at least 1 day per week in the last 3 months, associated with 2 or more of: related to defecation, change in stool frequency, or change in stool form 1, 4
• Note that at one month, symptoms do not yet meet the Rome IV duration criteria (requires 3 months), but clinical suspicion should guide initial management 5
• Supportive features that strengthen the diagnosis include bloating and visible abdominal distension, abnormal stool frequency, passage of mucus, and urgency or feeling of incomplete evacuation 1

If alarm features are present:

• Rectal bleeding or blood in stool requires further investigation 2
• Fever requires immediate medical attention 2
• Severe, unrelenting abdominal pain requires immediate medical attention 2
• Persistent vomiting requires immediate medical attention 2

Initial Management Strategy

For diarrhea-predominant symptoms with normal baseline testing:

• Initiate a therapeutic trial with loperamide, which serves both diagnostic and therapeutic purposes 1
• Antispasmodics such as dicyclomine 40 mg four times daily can be used for abdominal pain relief; controlled trials showed 82% favorable response versus 55% with placebo 4
• Hyoscyamine sulfate is FDA-approved as adjunctive therapy in the treatment of irritable bowel syndrome and can be used to reduce symptoms and control visceral spasm 6

Additional management options for IBS-D:

• Ondansetron, ramosetron, or eluxadoline may be considered 2
• Tricyclic antidepressants rank first for abdominal pain relief in network meta-analyses and should be baseline therapy for chronic pain 4

Patient Education and Expectations

• Explain that IBS is characterized by chronic, recurring symptoms that typically follow a pattern of flares and remissions, with episodes lasting two to four days followed by periods of remission 2
• Discuss prognosis factors: chronic ongoing life stress is a key prognostic factor; one study found no patients with ongoing life stresses recovered over 16 months, compared with 41% recovery in those without such stresses 5, 2
• Emphasize that IBS has no cure, treatments aim to improve quality of life, and therapy will likely be necessary long-term 4
• Reassure that pain perception is real and multifactorial, involving both peripheral factors (visceral hypersensitivity) and central factors (central sensitization) 4

Follow-Up and Monitoring

If symptoms persist despite initial management:

• Consider lactose hydrogen breath test for carbohydrate malabsorption, fructose breath testing, or small bowel biopsies based on clinical judgment 1
• Avoid repetitive testing once a diagnosis of functional pain is established; refer for psychological support (cognitive behavioral therapy) associated with pharmacological options 3
• Implement cognitive behavioral therapy for associated anxiety or sleep difficulties, as these contribute to both symptoms 4

Common Pitfalls to Avoid

• Do not pursue exhaustive testing in the absence of alarm features, as this increases healthcare costs without improving outcomes 3, 7
• Do not use opioids for chronic abdominal pain management in functional disorders 8
• Do not dismiss the patient's distress; establishing an effective patient-physician relationship is a cornerstone of therapy 8
• Recognize that at one month, symptoms are still relatively acute; progressive diseases such as bowel cancer are usually diagnosed within six months of symptom onset, so continued vigilance is warranted 5