What is causing sharp pain on my upper left side?

Sharp Upper Left Side Pain: Differential Diagnosis and Evaluation

Sharp pain in the upper left side that worsens with inspiration and lying supine is most characteristic of acute pericarditis, not cardiac ischemia, and requires immediate ECG evaluation to distinguish between life-threatening causes. 1, 2

Key Diagnostic Characteristics

Pain Features That Point Away from Heart Attack

• Sharp, stabbing pain that increases with breathing in and lying flat strongly suggests pericarditis rather than myocardial ischemia 1, 2
• Anginal (heart attack) symptoms are typically described as pressure, heaviness, tightness, or squeezing—not sharp pain 1
• Pain that changes with body position (positional pain) is usually nonischemic, such as musculoskeletal or pericarditis 1
• Fleeting pain lasting only seconds is unlikely to be heart-related 1

Most Likely Causes in Upper Left Side

Cardiac/Pericardial:

• Acute pericarditis: Sharp, pleuritic chest pain worse with inspiration and lying supine, often with recent viral illness 1, 2
• Myocarditis: Similar presentation but typically includes fever and heart failure signs 1

Pulmonary:

• Pneumonia: Localized sharp pain, may be pleuritic, with fever and respiratory symptoms 1
• Pneumothorax: Sharp pain with inspiration, dyspnea, and absent breath sounds on affected side 1
• Pulmonary embolism: Tachycardia and dyspnea present in >90% of patients, pain with inspiration 1

Gastrointestinal:

• Splenic pathology: Diseases of the spleen can cause acute left upper quadrant pain 3
• Gastric or pancreatic conditions: Less likely with purely sharp, positional pain 3

Musculoskeletal:

• Costochondritis: Tenderness of costochondral joints on palpation 1

Immediate Evaluation Algorithm

Step 1: Assess for Emergency Conditions

• Obtain ECG within 10 minutes to identify life-threatening causes 2
• Check vital signs and oxygen saturation to exclude pulmonary embolism and pneumothorax 2
• Look for widespread saddle-shaped ST elevation with PR depression (pathognomonic for pericarditis) 2

Step 2: Characterize the Pain Precisely

• Relationship to breathing: Does it worsen with deep inspiration? (suggests pericarditis, pneumonia, pneumothorax, or pulmonary embolism) 1, 2
• Relationship to position: Does it worsen lying flat and improve sitting forward? (strongly suggests pericarditis) 1, 2
• Recent viral illness: Preceding respiratory infection supports pericarditis diagnosis 2
• Associated symptoms: Fever, dyspnea, palpitations, diaphoresis, or syncope 1

Step 3: Physical Examination Findings

• Listen for pericardial friction rub (present in only one-third of pericarditis cases, so absence doesn't exclude it) 2
• Check for unilateral decreased breath sounds (pneumothorax) 1
• Assess for costochondral joint tenderness (costochondritis) 1
• Evaluate for tachycardia and tachypnea (pulmonary embolism) 1

Step 4: Imaging Based on Clinical Suspicion

If pericarditis suspected:

• ECG is diagnostic in most cases with characteristic widespread ST elevation 2
• Echocardiography may show small effusion (present in only 60% of cases) 2
• Normal echo does not exclude pericarditis 2

If pulmonary cause suspected:

• Chest radiograph is useful to evaluate cardiac, pulmonary, and thoracic causes 1
• CT chest with contrast for suspected pulmonary embolism 1

If gastrointestinal cause suspected:

• CT abdomen with IV contrast for splenic or pancreatic pathology 3

Critical Pitfalls to Avoid

• Do not assume sharp pain cannot be cardiac—while less likely to be ischemic, pericarditis and myocarditis are serious cardiac conditions 1, 2
• Do not rely on troponin alone—elevated troponin occurs in up to 50% of pericarditis cases due to myocardial inflammation 2
• Do not dismiss based on normal initial ECG—serial ECGs should be performed if clinical suspicion remains high 1
• In women, elderly patients, and diabetics, atypical presentations including sharp pain may still represent acute coronary syndrome 1

When to Seek Emergency Care Immediately

Call 9-1-1 for immediate transport to the emergency department if experiencing: 1

• Sharp chest pain with severe shortness of breath
• Sharp chest pain with syncope or near-syncope
• Sharp chest pain with fever and severe illness
• Any chest pain with hemodynamic instability (low blood pressure, rapid heart rate)