In a 29-year-old patient who recently had gastroenteritis and now presents with persistent abdominal fullness, what is the appropriate assessment and management?

Post-Gastroenteritis Abdominal Fullness: Assessment and Management

This 29-year-old patient likely has post-infectious functional gastrointestinal symptoms, most commonly post-infectious irritable bowel syndrome (PI-IBS) or post-infectious functional dyspepsia (PI-FD), which develop in 10-26% of patients following acute gastroenteritis and require symptomatic management rather than further antimicrobial therapy. 1

Initial Assessment Priority

Rule out persistent infection or complications first:

• Check for alarm features including fever, severe pain, bloody stools, significant weight loss, or signs of dehydration that would indicate ongoing infection requiring further workup 1
• Obtain basic laboratory tests including complete blood count, CRP, and stool studies only if symptoms suggest persistent infection (fever, bloody diarrhea, severe systemic symptoms) 1
• For isolated abdominal fullness without alarm features, extensive testing is not indicated as the acute infectious phase has resolved 1

Understanding Post-Infectious Symptoms

Post-infectious functional symptoms are extremely common:

• PI-IBS develops in 10.1% of patients at 12 months following infectious enteritis, with a 4.2-fold increased risk compared to uninfected individuals 1
• PI-FD (characterized by postprandial fullness) occurs in 9-26% of patients after gastroenteritis, with similar prevalence to PI-IBS 1
• Overlapping PI-IBS and PI-FD occurs in 13-44% of affected patients, meaning abdominal fullness may coexist with altered bowel habits 1

Pathophysiology Explanation

The abdominal fullness results from post-infectious changes:

• Persistent low-grade inflammation, altered gut microbiota, visceral hypersensitivity, and abnormal gut motility following the initial infection 1
• These changes can persist for months to years after the acute infection resolves 1
• Bacterial gastroenteritis causes greater mucosal damage than viral, explaining higher rates of post-infectious symptoms 1

Management Algorithm

Step 1: Reassurance and Education

Provide clear explanation that:

• Symptoms are a recognized complication of gastroenteritis, not ongoing infection 1
• No antibiotics are needed for post-infectious functional symptoms 1
• Symptoms typically improve over time, though may persist for months 1

Step 2: Dietary Modifications

Address abdominal fullness specifically:

• Small, frequent meals rather than large meals to reduce postprandial fullness 2
• Avoid gas-producing foods (legumes, cruciferous vegetables, carbonated beverages) that worsen bloating 2
• Consider trial of low-FODMAP diet if symptoms are severe, as food intolerances commonly develop post-infection 2

Step 3: Pharmacologic Management

For persistent abdominal fullness:

• Prokinetic agents may help if delayed gastric emptying contributes to fullness symptoms 2
• Antispasmodics can reduce visceral hypersensitivity if cramping accompanies fullness 1
• Neuromodulators (low-dose tricyclic antidepressants) for refractory symptoms affecting quality of life 1

Step 4: When to Investigate Further

Obtain additional workup if:

• Symptoms persist beyond 4 weeks without improvement 1
• New alarm features develop (weight loss >5%, fever, bloody stools, severe pain) 1
• Consider fecal calprotectin if uncertainty exists about ongoing inflammation versus functional symptoms 1
• Imaging or endoscopy only if alarm features present or diagnostic uncertainty after 4-6 weeks 1

Critical Pitfalls to Avoid

Do not prescribe antibiotics for post-infectious functional symptoms - the infection has resolved and antimicrobials will not improve functional symptoms and may worsen dysbiosis 1

Do not order extensive testing immediately - in a young patient without alarm features, post-infectious functional symptoms are the most likely diagnosis and testing adds cost without benefit 1

Do not dismiss symptoms as "just IBS" - validate the patient's experience, explain the pathophysiology, and provide a structured treatment plan 1

Do not overlook lactose intolerance - this commonly develops post-gastroenteritis and can cause bloating and fullness; consider a 2-week lactose elimination trial 3

Expected Timeline

Natural history of post-infectious symptoms:

• Most patients show gradual improvement over 6-12 months 1
• Younger age may predict longer symptom duration 1
• Severity of initial infection correlates with likelihood of persistent symptoms 1