What could be causing a fluttering sensation under my ribs in the upper right quadrant?

Fluttering Sensation Under Right Ribs: Differential Diagnosis and Evaluation

A fluttering sensation under the ribs in the upper right quadrant is most commonly a benign musculoskeletal condition called slipping rib syndrome, but requires systematic evaluation to exclude serious biliary, hepatic, or other intra-abdominal pathology.

Initial Clinical Assessment

The key distinguishing features to elicit include:

• Character of sensation: True "fluttering" or intermittent clicking/popping suggests musculoskeletal origin (slipping rib syndrome), while constant dull pain suggests visceral pathology 1
• Reproducibility with palpation: Firm, systematic palpation of the costal margin that reproduces the exact sensation is diagnostic of slipping rib syndrome 1
• Aggravating factors: Pain worsened by upper-extremity activities, coughing, laughing, or leaning over strongly suggests slipping rib syndrome 2, 3
• Associated symptoms: Fever, elevated white blood cell count, nausea, vomiting, or anorexia suggest acute cholecystitis and require urgent imaging 4

Most Likely Diagnosis: Slipping Rib Syndrome

Slipping rib syndrome is an underdiagnosed condition affecting ribs 8-10, where defects in costal cartilage cause hypermobility, impinging intercostal nerves and creating intermittent pain or fluttering sensations 2, 3.

Clinical Features:

• Accounts for approximately 3% of general medical/gastroenterology referrals 1
• Predominantly affects women (70% of cases) with mean age 48 years 1
• Characterized by three features: pain in lower chest/upper abdomen, tender spot on costal margin, and reproduction of pain with pressure 1
• Often misdiagnosed, leading to extensive unnecessary investigations and even non-curative cholecystectomies 1

Diagnostic Approach:

• Clinical diagnosis is sufficient: The hooking maneuver (pulling the anterior rib margin forward) reproduces symptoms 2, 3
• Dynamic ultrasound can confirm diagnosis in difficult cases by identifying cartilage abnormalities and soft tissue swelling 2
• No laboratory or imaging studies are required if classic features are present 1

When to Suspect Serious Pathology

Ultrasound of the abdomen is the mandatory first-line imaging study if any concerning features are present 4.

Red Flags Requiring Imaging:

• Fever or elevated white blood cell count 4
• Positive Murphy sign (pain with deep palpation under right costal margin during inspiration) 4
• Constant, severe pain rather than intermittent fluttering 5
• Jaundice or elevated liver enzymes 6
• History of recent cholecystectomy 6

Imaging Algorithm:

For suspected biliary disease:

• First-line: Abdominal ultrasound with 96% accuracy for gallstones and ability to assess for acute cholecystitis 4
• Second-line if ultrasound negative/equivocal: MRCP with sensitivity 85-100% and specificity 90% for choledocholithiasis 4, 6
• CT abdomen with contrast may be appropriate if ultrasound is inconclusive, though less sensitive than MRCP for biliary pathology 4

Treatment Approach

For Slipping Rib Syndrome:

• Reassurance and education that this is a benign, safe diagnosis requiring no investigation 1
• NSAIDs and physical therapy as first-line treatment 2
• Intercostal nerve blocks for persistent symptoms 2, 3
• Surgical resection of slipping rib cartilages for refractory cases, with good pain relief outcomes 3

Important Caveat:

Despite firm diagnosis of slipping rib syndrome, 33% of patients are re-referred to hospital by their general practitioners, leading to repeated negative investigations 1. Strong documentation and patient education are essential to prevent unnecessary testing.

Non-Biliary Causes to Consider

If musculoskeletal and biliary causes are excluded:

• Hepatic pathology: Liver masses with capsular involvement can cause RUQ sensations 4
• Pancreatic inflammation: Though typically left-sided, pancreatic pathology can occasionally present with RUQ symptoms 7
• Referred pain: From lung, pleura, or other abdominal/pelvic structures 4

The American College of Radiology emphasizes that RUQ pain is nonspecific, and systematic evaluation is required to avoid missing serious pathology while preventing overinvestigation of benign conditions 4.