Home » Notes » Fundamentals of Nursing » Thoracentesis


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By Matt Vera BSN, R.N.

Thoracentesis, also known as pleural fluid analysis, is a procedure in which a needle is inserted through the back of the chest wall into the pleural space (a space that exists between the two lungs and the anterior chest wall) to remove fluid or air. Pleural fluid analysis is the microscopic and chemical lab analysis of the fluid obtained during thoracentesis.

Thoracentesis may be performed for diagnostic and/or therapeutic reasons. The diagnostic use of a thoracentesis involves pleural fluid analysis to distinguish between exudate, which may result from inflammatory or malignant conditions, and transudate, which may result from failure of organ systems that affect fluid balance in the body. This analysis aids in determining the cause of the abnormality.


1. Position patient in the sitting position with arms and head resting supported on a bedside adjustable table.
If unable to sit, the patient should lie at the edge of the bed on the affected side with the ipsilateral (same side) arm over the head and the midaxillary line accessible for the insertion of the needle. Elevating the head of the bed to 30 degrees may help.

2. The usual site for insertion of the thoracentesis needle is the posterolateral aspect of the back over the diaphragm, but under the fluid level.
Confirm site by counting the ribs based on chest x-ray and percussing out the fluid level. Mark the top of the dullness by washable ink mark or indenting the skin.

3. Select the thoracentesis site in an interspace below the point of dullness to percussion in the mid posterior line (posterior insertion) or mid axillary line (lateral insertion).

4. Sterile technique should be used including gloves, betadine prep and drapes.

5. Anesthetize the skin over the insertion site with 1% lidocaine using the 5 cc syringe with 25 or 27-gauge needle. Next anesthetize the superior surface of the rib and the pleura. The needle is inserted over the top of rib (superior margin) to avoid the intercostals nerves and blood vessels that run on the underside of the rib (the intercostals nerve and the blood supply are located near the inferior margin). As the needle is inserted, aspirate back on the syringe to check for pleural fluid. Once fluid returns, note the depth of the needle and mark it with a hemostat. This gives an approximate depth for insertion of the angiocatheter or thoracentesis needle. Remove the anesthetizing needle.

6.Use a hemostat to measure the same depth on the thoracentesis needle or angiocath as the first needle. While exerting steady pressure on the patient’s back with the nondominant hand, use a hemostat to measure the 15- to 18- gauge thoracentesis needle to the same depth as the first needle. While exerting steady pressure on the patient’s back with the nondominant hand, insert the needle through the anesthetized area with the thoracentesis needle. Advance the needle until it encounters the superior aspect of the rib. Continue advancing the needle over the top of the rib and through the pleura, maintaining constant gentle suction on the syringe. Make sure you march over the top of the rib to avoid the neurovascular bundle that runs below the rib.

7.Attach the three way stopcock and tubing, and aspirate the amount needed. Turn the stopcock and evacuate the fluid through the tubing.

8.Remove the necessary amount of pleural fluid (usually 100 mL for diagnostic studies), but generally not remove more than 1500 mL of fluid at any one time because of increased risk of pleural edema or hypotension. A pneumothorax from needle laceration of the visceral pleura is more likely to occur if an effusion is completely drained.

9. When draining of fluid is completed, have the patient take a deep breath and hum, and gently remove the needle. This maneuver increases intrathoracic pressure and decreases the chance of pneumothorax. Cover the insertion site with a sterile occlusive dressing.

Thoracentesis Nursing Considerations

Before the Procedure

  • Check the doctor’s order.
  • Identify the client.
  • Asked patient to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if something is not clear.
  • Explain and emphasize the importance of the procedure.
  • Inform that she will be experiencing mild pain on the site where the needle was pricked
  • Inform the client that the procedure takes only few minutes, depending primarily on the time it takes for fluid to drain from the pleural cavity.
  • Inform the client not to cough while the needle is inserted in order to avoid puncturing the lung
  • Explain when and where the procedure will occur and who will be present.
  • Explain the procedure to the patient and SO, reinforcing what the physician has previously explained to the patient/SO
  • The patient may have a diagnostic procedure, such as a chest x-ray, chest fluoroscopy, ultrasound, or CT scan, performed prior to the procedure to assist the physician in identifying the specific location of the fluid in the chest that is to be removed.
  • The patient may receive a sedative prior to the procedure to help the patient relax.
  • Asked the patient to remove any clothing, jewelry, or other objects that may interfere with the procedure.
  • The area around the puncture site may be shaved.
  • Vital signs (heart rate, blood pressure, breathing rate, and oxygen level) are to be monitored before the procedure.

During the Procedure

  • Support the client verbally and describe the steps of the procedure as needed.
  • Vital signs (heart rate, blood pressure, breathing rate, and oxygen level) are to be monitored during the procedure.
  • The patient may receive supplemental oxygen as needed, through a face mask or nasal cannula (tube).
  • Observe the client for signs of distress, such as dyspnea, pallor, and coughing
  • Place the patient in a sitting position with arms raised and resting on an overbed table. This position aids in spreading out the spaces between the ribs for needle insertion. If the patient is unable to sit, the patient may be placed in a side-lying position on the edge of the bed on unaffected side.
  • The skin at the puncture site will be cleansed with an antiseptic solution.
  • The patient will receive a local anesthetic at the site where the thoracentesis is to be performed.
  • Don’t remove more than 1000 ml of fluid from the pleural cavity within first 30 minutes.
  • Place a small sterile dressing over the site of the puncture.

After the Procedure

  • Observe changes in the client’s cough, sputum, respiratory depth, and breath sounds, and note complaints of chest pain.
  • Position the client appropriately
  • Some agency protocols recommend that the  client lie on the unaffected side with the head of the bed elevated 30 degrees for at least 30 minutes because this position facilitates expansion of the affected lung and eases respirations
  • Position the patient in a side-lying position with the unaffected side down for an hour or longer.
  • Include date and time performed; the primary care provider’s name; the amount, color, and clarity of fluid drained; and nursing assessments and interventions provided.
  • Transport the specimens to the laboratory.
  • The dressing over the puncture site will be monitored for bleeding or other drainage.
  • Monitor patient’s blood pressure, pulse, and breathing until are stable.
  • Document all relevant information.

Possible Nursing Diagnoses:

Here are some possible nursing diagnoses for a patient post-thoracentesis (you may also check on the nursing care plans for Pleural Effusion)
  • Ineffective Breathing Pattern RT Decreased Lung Volume Capacity
  • Impaired Gas Exchange RT Alveolar Capillary Membrane Changes
  • Impaired Skin Integrity RT Mechanical Factors Secondary to Thoracentesis and CTT Insertion
  • Acute Pain rt surgical incision, chest tube sites, and immobility
  • Impaired physical mobility
  • Activity Intolerance
Matt Vera, a registered nurse since 2009, leverages his experiences as a former student struggling with complex nursing topics to help aspiring nurses as a full-time writer and editor for Nurseslabs, simplifying the learning process, breaking down complicated subjects, and finding innovative ways to assist students in reaching their full potential as future healthcare providers.

4 thoughts on “Thoracentesis”

  1. Hi Matt,
    This is a great reference and step by step notes on this procedure that is challenging to find info on.
    I was wondering if your recommendation/practice is to have the nurse with the patient during the WHOLE process? Or does the nurse assess the patient before and after?
    All the best,
    Nurse Liz

    • Hi Riwa, So glad to hear you’re finding it helpful, especially during your second year of GNM! 🎉 Nursing school can be intense, right? Out of curiosity, what’s been the most challenging topic for you so far? Maybe I can whip up some more content around that!


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