Biopsy and Drainage · IR Playbook

Image-Guided Thoracentesis and Pleural Drainage (-)

Image-guided thoracentesis removes pleural fluid for diagnosis or symptom relief, while pleural drainage places a catheter for continuous evacuation. Thoracic ultrasound improves target selection and reduces pneumothorax and inadvertent organ injury.

Indications

Diagnostic sampling of an unexplained pleural effusion
Therapeutic drainage of a symptomatic pleural effusion
Continuous drainage of pleural infection, empyema or a recurrent or loculated pleural collection

Relative contraindications

No safe ultrasound-accessible window
Local infection at the proposed entry site
Uncorrected clinically important bleeding risk or anticoagulation
Uncooperative patient unable to remain still

Equipment

Ultrasound machine with curvilinear or phased-array probe, sterile cover and gel
Sterile preparation set, drapes, gloves and dressing
1% lidocaine with 21–25G infiltration needle
21G, approximately 40 mm needle and 50–60 mL syringe for diagnostic aspiration
6–8 Fr catheter-over-needle aspiration set with three-way stopcock and drainage tubing
8–14 Fr locking pigtail drainage catheter set with compatible guidewire and dilators
Closed drainage bag or underwater-seal system, holding suture and securement dressing

Procedure steps

Position the patient sitting, semirecumbent or lateral decubitus according to the collection. Scan in the final procedural position and select the safest fluid pocket.
Confirm the side and map the skin-to-fluid depth, diaphragm, lung and adjacent organs. Choose a lateral puncture immediately above the rib.
Perform a time-out, prepare a sterile field and infiltrate 1% lidocaine from skin to parietal pleura. Aspirate while advancing; failure to obtain fluid at the expected depth requires repeat ultrasound rather than blind advancement.
Advance the aspiration needle or catheter along the planned tract, using real-time ultrasound when the window is small or loculated. Confirm free aspiration of pleural fluid and advance the flexible catheter while withdrawing the needle.
Collect approximately 50 mL for diagnostic testing and distribute it promptly into the required biochemistry, microbiology, cytology and blood-gas containers according to the clinical question.
For one-time therapeutic thoracentesis, connect the catheter to a three-way stopcock and drain slowly by manual aspiration or gravity. Avoid vacuum bottles and wall suction; stop at 1.5 L or earlier if chest pain, tightness, persistent cough or worsening breathlessness develops.
When continuous drainage is required, pass the compatible guidewire through the access needle or catheter and confirm that it advances freely within the pleural collection. Remove the access needle while maintaining wire position.
Make a small skin incision and dilate sequentially over the wire. Do not advance a sharp dilator more than 1 cm beyond the parietal pleura.
Advance an 8–14 Fr locking pigtail catheter over the wire, ensuring that every side hole lies within the pleural cavity. Remove the wire, form the pigtail and confirm free aspiration.
Connect the catheter to a closed drainage system, secure it with a holding suture and apply a sterile dressing. Prescribe the drainage rate and document catheter size, fixation depth, fluid appearance and postprocedure plan.

Complications

Pneumothorax
Haemorrhage or haemothorax
Re-expansion pulmonary oedema
Pain or vasovagal reaction
Drain blockage, displacement or infection

Exam pearls

No safe ultrasound window means no blind thoracentesis.
Use a flexible catheter rather than a rigid needle for therapeutic aspiration exceeding 60 mL.
Small-bore drains of 14 Fr or less are suitable for initial drainage of most pleural infections.
Never advance the Seldinger dilator deeply into the pleural cavity.

Viva questions

Why must ultrasound be used before pleural fluid aspiration?: It confirms the side, identifies a safe fluid pocket and maps the diaphragm, lung and adjacent organs, reducing pneumothorax and inadvertent organ puncture.
How should therapeutic thoracentesis be drained?: Drain slowly through a flexible catheter using manual syringe aspiration or gravity. Avoid vacuum bottles or wall suction and generally remove no more than 1.5 L in one attempt.
Why is the puncture made immediately above the rib?: The main intercostal neurovascular bundle lies along the inferior rib margin; entering above the rib reduces the risk of vascular or nerve injury.