What are the steps and care for pleural effusion tapping?

Pleural Effusion Tapping: Procedure Steps and Care

Diagnostic pleural aspiration should be performed using ultrasound guidance with a fine-bore (21G) needle, and the fluid must be sent for comprehensive analysis including protein, LDH, pH, cytology, Gram stain, AAFB stain, and microbiological culture in both sterile vials and blood culture bottles. 1

Pre-Procedure Assessment

Patient Evaluation

• Perform thoracic ultrasound on every patient before any pleural procedure to assess safety, effusion size, character, and identify pleural nodularity suggesting malignancy 1
• Ultrasound guidance reduces pneumothorax risk dramatically (1.0% vs 8.9% without ultrasound) and decreases dry taps and solid organ puncture 1
• Determine if the patient is symptomatic—asymptomatic patients should not undergo therapeutic drainage 1
• Review medication history as tyrosine kinase inhibitors and other drugs commonly cause exudative effusions 1

Clinical Decision Points

• If clinical picture suggests transudate (heart failure, hypoalbuminemia, dialysis), treat the underlying cause first 1
• If ultrasound shows it is unsafe to aspirate, obtain CT scan before proceeding 1

Procedure Technique

Diagnostic Aspiration

• Use a 21-gauge fine-bore needle with a 50 ml syringe for diagnostic sampling 1
• Perform under real-time ultrasound guidance 1
• Limit fluid removal to 1-1.5 liters maximum to prevent re-expansion pulmonary edema 1
• Stop immediately if patient develops cough or chest discomfort during aspiration 1

Fluid Handling

Send pleural fluid for the following mandatory tests: 1

• Protein and LDH (to differentiate transudate vs exudate using Light's criteria if protein 25-35 g/L)
• pH measurement in all non-purulent effusions when infection suspected
• Cytology (recognizing only 60% of malignant effusions are diagnosed on first cytology)
• Gram stain and culture in sterile tube
• AAFB stain and TB culture
• Blood culture bottles to increase microbiological diagnostic yield

Fluid Appearance Documentation

• Note appearance: serous, blood-tinged, frankly bloody, or purulent 1
• Note odor: unpleasant aroma suggests anaerobic infection 1
• If turbid/milky, centrifuge—if supernatant clears, suspect empyema; if remains turbid, suspect chylothorax 1
• Obtain pleural fluid hematocrit if bloody to diagnose hemothorax 1

Post-Procedure Care

Immediate Monitoring

• Monitor for pneumothorax (most common complication, though rare with ultrasound guidance at 1%) 1
• Watch for re-expansion pulmonary edema if large volume removed 1
• Assess symptomatic response to guide further management 1

Follow-Up Based on Results

If Transudate: 1

• Treat underlying cause (heart failure, cirrhosis, hypoalbuminemia)
• No further pleural intervention unless symptoms persist

If Exudate with Unknown Etiology: 1

• Obtain contrast-enhanced CT thorax (chest/abdomen/pelvis if malignancy suspected)
• Consider pleural biopsy (ultrasound/CT-guided, closed biopsy, or thoracoscopy)
• Reconsider specific treatable diagnoses: tuberculosis, pulmonary embolism, lymphoma, IgG4 disease

If Symptomatic Malignant Effusion: 1

• Perform large-volume thoracentesis first to assess symptomatic response and lung expansion
• If expandable lung: offer either indwelling pleural catheter or chemical pleurodesis
• If non-expandable lung or failed pleurodesis: use indwelling pleural catheter

Critical Pitfalls to Avoid

• Never remove >1.5 liters in single aspiration without monitoring for symptoms 1
• Never perform therapeutic drainage on asymptomatic patients—nearly 100% recurrence without benefit 1
• Never skip ultrasound guidance—it reduces pneumothorax risk by 89% 1
• Always send fluid in blood culture bottles in addition to sterile containers to maximize microbiological yield 1
• Do not rely on single cytology—sensitivity is only 60% for malignancy 1
• Intercostal tube drainage without sclerosant has nearly 100% recurrence and is not recommended 1