Thoracentesis, also called thoracocentesis is a procedure in which a needle is inserted into the pleural space between the lungs and the chest wall to remove pleural fluid.
Thoracentesis can be used for diagnostic as well as therapeutic purposes.
Therapeutic thoracentesis is used to remove larger amounts of pleural fluid to alleviate dyspnea and to prevent ongoing inflammation and fibrosis.
Indications of Thoracentesis
A diagnostic thoracocentesis is performed if the cause of the pleural effusion is not clear or the effusion does not respond to therapy as expected by diagnosis.
Small sized pleural effusions do not require thoracentesis. It is not required in underlying congestive heart failure (especially bilateral effusions) or by recent thoracic or abdominal surgery.
There are no absolute contraindications for thoracentesis. Relative contraindications include the following:
- Uncorrected bleeding diathesis
- Chest wall cellulitis at the site of puncture
- Small volume of fluid (< 1 cm thickness on a lateral decubitus film
- Mechanical ventilation [increases risk of complications],
- Skin disease over the proposed puncture site
The throacentesis is usually done using a thoracentesis device which typically consists of an 8-French catheter over an 18-gauge, 7.5-in. needle with a 3-way stopcock and, ideally, a self-sealing valve
The procedure is done under local anesthesia but, mild sedation may also be added. The local anesthetic agent should infiltrate skin, subcutaneous tissue, rib periosteum, intercostal muscle, and parietal pleura.
The puncture site is initially chosen is based on the chest radiograph and located 1-2 rib interspaces below the level of dullness to percussion on physical examination.
Ultrasonography or chest CT scanning can be used to guide needle placement.
Alert and cooperative are most comfortable in a seated position, leaning slightly forward and resting the head on the arms or hands or on a pillow placed on an adjustable bedside table.
This position facilitates access to the posterior axillary space, which is the most dependent part of the thorax.
Unstable patients and those who are unable to sit up may be approached in the supine position for the procedure.
The patient is moved to the extreme side of the bed, the ipsilateral hand is placed behind the head, and a towel roll is placed under the contralateral shoulder. This measure facilitates dependent drainage
Site of the Puncture
The largest pocket of fluid superficial to the lung is approached. Traditionally, this is between the seventh and ninth rib spaces and between the posterior axillary line and the midline. Bedside ultrasonography can confirm the optimal puncture site, which is then marked.
Ultrasonography can increase the likelihood of obtaining pleural fluid and reduced the complications of the procedure.
After the site is disinfected with chlorhexidine (preferred now over povidone/iodine) solution and sterile drapes are placed.
Local anesthetic is infiltrated, slowly going deep till pleural fluid. Needle with larger bore may be used if required.
Confirm the correct location for thoracentesis by aspirating pleural fluid before introducing larger-bore thoracentesis needles or catheters.
Insertion of device or catheter and drainage of effusion
- Skin should be nicked with a No. 11 scalpel blade
- The thoracentesis device is advanced over the superior aspect of the rib until pleural fluid is obtained [ The neurovascular bundle is located at the inferior border of the rib and should be avoided.]
- Most commercial devices have a marker at 5 cm which indicates the entry to the hemithorax is usually entered, and the needle need not need be advanced any further.The 5-cm mark should be the level of the skin.
- The catheter is then fed over the needle introducer and fed all the way to the hub.
- The pleural effusion is drained with either a syringe pump or a vacuum bottle,until the desired volume has been removed for symptomatic relief or diagnostic analysis (
- The catheter or needle is carefully removed, and the wound is dressed.
A minimum of 20 mL would be enough for basic analysis and culture. Most of the diagnostic procedures remove less than 100 mL of fluid.
For therapeautic purposes, only moderate amounts of pleural fluid should be removed to avoid reexpansion pulmonary edema and to avoid causing a pneumothorax. Removal of 400-500 mL of pleural fluid is often sufficient to shortness of breath.
The maximum recommended limit is 1000-1500 mL in a single thoracentesis procedure.
Monitoring pleural pressure with a manometer is helpful.
The onset of chest pressure or pain during the removal of fluid indicates a lung that is not freely expanding, and the procedure should be stopped immediately to avoid re-expansion pulmonary edema [pulmonary edema in the setting of rapid expansion of a collapsed lung.]
Cough frequently occurs during removal of fluid, and this is not an indication to stop the procedure, unless the cough is causing the patient discomfort.
Complications of thoracentesis
Pneumothorax complicates approximately 6% of thoracenteses
- Pain at the puncture site
- Reexpansion pulmonary edema
- Malignant seeding of the thoracentesis tract
- Adverse reactions to anesthetics
- Laceration of the liver or spleen
- Diaphragmatic injury
- Tumor seeding
Minor complications include the following:
- Dry tap
- Subcutaneous hematoma/seroma
- Vasovagal syncope
- Duncan DR, Morgenthaler TI, Ryu JH, Daniels CE. Reducing iatrogenic risk in thoracentesis: establishing best practice via experiential training in a zero-risk environment. Chest. 2009 May. 135(5):1315-20.
- Schildhouse R, Lai A, Barsuk JH, Mourad M, Chopra V. Safe and Effective Bedside Thoracentesis: A Review of the Evidence for Practicing Clinicians. J Hosp Med. 2017 Apr. 12 (4):266-276.