What is the next step in managing a patient with lower bilateral abdominal pain and back pain, who recently completed fluoroquinolone (antibiotic) therapy for H. pylori, has a normal urine dipstick, no groin pain, swelling, or lump, and normal liver function tests (LFTs), with no clear connection between the abdominal and back pain?

Next Steps in Management

The next step is a thorough physical examination focusing on abdominal wall musculoskeletal structures, followed by consideration of CT abdomen/pelvis if examination suggests intra-abdominal pathology or if musculoskeletal causes are excluded. Plain X-ray has limited utility in this clinical scenario and should not be the initial imaging modality.

Clinical Context and Differential Diagnosis

Your patient presents with lower bilateral abdominal pain and seemingly unrelated back pain following recent fluoroquinolone therapy for H. pylori. The normal urine dipstick effectively excludes urinary tract infection, and the absence of gastrointestinal symptoms (no constipation, diarrhea, nausea, or vomiting) makes active gastroenteritis or H. pylori treatment failure less likely 1.

Critical Consideration: Fluoroquinolone-Associated Complications

Fluoroquinolones carry significant musculoskeletal risks that must be considered in your differential diagnosis. While Achilles tendon rupture is the most recognized complication, fluoroquinolones can cause widespread musculoskeletal pain and tendinopathy 2. The bilateral nature of the abdominal pain and concurrent back pain could represent:

• Abdominal wall musculoskeletal pain (myofascial pain, rectus abdominis strain)
• Fluoroquinolone-induced musculoskeletal symptoms affecting abdominal and paraspinal muscles 2
• Intra-abdominal pathology (less likely given symptom pattern but not excluded)

Specific Physical Examination Findings to Assess

Perform a focused examination looking for these specific findings:

• Carnett's sign: Increased pain with abdominal wall tensing (patient lifts head/shoulders while supine) indicates abdominal wall musculoskeletal origin rather than visceral pathology 3
• Point tenderness: Localized tenderness over rectus abdominis, oblique muscles, or trigger points suggests myofascial pain 3
• Absence of peritoneal signs: No rebound tenderness, guarding, or rigidity helps exclude acute intra-abdominal pathology 3
• Bilateral lower quadrant palpation: Assess for masses, organomegaly, or hernias 3
• Spinal examination: Assess for paraspinal tenderness, range of motion limitations, and whether spinal movements reproduce abdominal pain 3

Why X-ray is NOT the Appropriate Next Step

Plain abdominal X-ray has extremely limited diagnostic value in this clinical scenario because:

• It cannot visualize soft tissue pathology (musculoskeletal structures, solid organs, or most inflammatory processes)
• It is primarily useful for detecting bowel obstruction, perforation (free air), or radiopaque stones—none of which are suggested by this clinical presentation 3
• The absence of constipation, distension, or obstructive symptoms makes bowel pathology unlikely

Appropriate Imaging Algorithm

If physical examination suggests intra-abdominal pathology or fails to identify a clear musculoskeletal cause:

• CT abdomen/pelvis with IV contrast is the gold standard for evaluating unexplained abdominal pain when visceral pathology is suspected 3
• CT can identify appendicitis, diverticulitis, inflammatory bowel disease complications, masses, or gynecologic pathology (in female patients) 3

If physical examination clearly identifies musculoskeletal origin (positive Carnett's sign, reproducible trigger points):

• No imaging is initially required 3
• Consider trial of conservative management with NSAIDs (if not contraindicated post-H. pylori treatment), physical therapy, and reassessment 3

H. Pylori Treatment Considerations

Given recent fluoroquinolone therapy for H. pylori, several points warrant attention:

• Fluoroquinolone resistance is increasing globally (11-30% primary resistance), and treatment failure rates are significant when resistance is present 1
• Eradication confirmation is mandatory: Test for eradication success at least 4 weeks after completion of therapy using urea breath test or monoclonal stool antigen test, with PPI discontinued at least 2 weeks before testing 4
• The absence of GI symptoms does not confirm successful eradication 1

Red Flags Requiring Urgent Evaluation

Immediately escalate care if any of these develop:

• Fever, tachycardia, or hemodynamic instability
• Development of peritoneal signs (rebound, guarding, rigidity)
• Severe, worsening, or migratory pain
• New onset nausea, vomiting, or inability to tolerate oral intake
• Syncope or presyncope

Common Pitfalls to Avoid

• Do not assume pain is H. pylori-related without confirming active infection or treatment failure 1
• Do not overlook musculoskeletal causes: Abdominal wall pain is frequently misdiagnosed as visceral pathology, leading to unnecessary testing 3
• Do not ignore fluoroquinolone adverse effects: These medications can cause debilitating musculoskeletal complications even in otherwise healthy patients 2
• Do not order plain X-rays reflexively: They rarely change management in undifferentiated abdominal pain without obstructive symptoms 3