ED evaluation and management of pleural effusions: One size doesn’t fit all

Authors: Nihanth (Sunny) Peta, MD, MS (EM Resident Physician) and Jacob Avila, MD (EM Ultrasound Director), University of Kentucky, Department of Emergency Medicine // Reviewed by: Tim Montrief, MD (@EMinMiami); Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)


A 31-year-old female presents to the Emergency Department (ED) with abdominal pain. She was recently admitted for multiple intra-abdominal abscesses, as well as a left-sided pleural effusion, and discharged with a two intra-abdominal JP drains. She arrives today, just days after being discharged, noting that when she woke up this morning, she had excruciating suprapubic pain, nausea, and then emesis. She also notes that her left abdominal drain has not had any output and seems to have some sort of air leak. Vital signs upon presentation reveals a blood pressure of 140/100 mm Hg, heart rate of 122 beats per minute, 33 respirations per minute, SpO2 of 87% on room air, and Temperature 99.3oF. Physical exam reveals a young female in moderate distress with shallow respirations, diminished left sided lung sounds, and an abdomen that is diffusely tender to palpation. Computed Tomography (CT) scan of the abdomen reveals unchanged size of intraabdominal fluid collection and a partial small bowel obstruction. The chest x-ray (CXR) is shown below in figure 1.

Each lung is enclosed in a cavity that is encased by the pleura, shown in figure 2 above. The pleura is a serous membrane that surrounds each lung and is made up of two layers. The visceral pleura is superficial to the lung and directly covers the lung and extends into the different lung fissures. The parietal pleura is the outer layer and attaches to the mediastinum, chest wall, and diaphragm inferiorly. The lung’s visceral pleural is separated from the parietal pleura by the pleural space. This pleural space is a “relative vacuum” that holds a very small amount of lubricating pleural fluid to aid in the movement of the two different pleural surfaces during normal respirations.1 That small amount of fluid is maintained by hydrostatic and oncotic pressures. However, a disturbance in either type of pressure, causing a change in the permeability of either pleural membrane, can lead to an effusion.


Etiologies and Risk Factors

At least 1.5 million cases of pleural effusions are seen in the United States each year.2 From a single-centered study in Egypt, the most common causes of these effusions, as seen in figure 3 below, are due to congestive heart failure, pneumonia, and malignancies.16 In patients with pneumonia and pleural effusions, the mortality rates can reach 11% within a 30 day period.17 Patients who develop a malignant pleural effusion have an average survival time of less than 1 year.3

Pleural effusions have a wide array of etiologies. To determine the type of effusion present, Light’s criteria can be used to help differentiate the two major categories of effusions. It states that the pleural effusion is likely an exudate if any of the following criteria are met:

  • The pleural fluid-to-serum total protein ratio is greater than 0.5
  • The pleural fluid-to-serum lactate dehydrogenase ratio is greater than 0.6
  • The pleural fluid LDH level is greater than 2/3 of the upper limit of normal for serum LDH

Exudative pleural effusions, seen in infections (pneumonia, Tuberculosis), malignancy, abdominal disorders, and chylothorax, are usually due to inflammation of the pleura or a disruption in its lymphatic drainage mechanisms.

Transudative pleural effusions, seen in congestive heart failure (CHF), cirrhosis, nephrotic syndrome, pulmonary emboli, and pericardial pathologies, are usually due to ultra-filtrated plasma that is pushed out of the pleura.


Presentation, Evaluation, and Diagnostic workup

A thorough history and physical exam can help in establishing the cause of a patient’s pleural effusion. Patients will often present with dyspnea, cough, chest pain, or fevers. The most common and sensitive physical examination findings, seen in table 1 below, can include diminished breath sounds, asymmetrical chest expansion, decreased vocal fremitus, and dullness to percussion.23 Along with decreased vocal fremitus (vibration felt on the patient’s thorax during vocalization) and asymmetrical chest expansion, dullness to percussion and a delayed time to full expansion on the side of the effusion are the most reliable physical exam findings seen in pleural effusions.8,9 The most specific (99%) physical exam finding is a pleural friction rub, although it is not sensitive (5.3%).23 Physical examination findings for pleural effusions are widely variable and depend on the size of the effusion.

Dyspnea is the most common symptom associated with a pleural effusion. While most patients with a pleural effusion will have shortness of breath, up to 17% of patients presenting with shortness of breath will have a pleural effusion.7 If the patient also has a cough, it will often be nonproductive.18 If the patient’s cough is purulent or their sputum contains blood, consider an underlying infection or traumatic lesion. Chest pain can indicate irritation of the pleura, and you may need to consider exudative etiologies such as malignancies or infection.10 Extrapulmonary physical exam findings, such as distended neck veins and lower extremity edema, may indicate the patient’s effusion is due to CHF. However, edema may also be due to a nephrotic pathology. Ascites with edema and dyspnea suggests an underlying hepatic pathology.

Although a history and physical examination will assist in the initial evaluation of the patient, further imaging is typically needed for further evaluation.9 Imaging modalities such as X-ray, Ultrasound, and CT scan will be the ultimate diagnostic modalities.

If you suspect a pleural effusion, a chest x-ray can confirm the diagnosis. This is the simplest method used to evaluate a patient with difficulty breathing and physical exam findings pertinent to pleural effusion. Depending on the size of the pleural effusion, CXR specificity approaches 89%, while sensitivity for large pleural effusions approaches 92%.24 However, unless there is at least 175mL of fluid in the pleural space, you may not be able to see it on an anterior-posterior CXR.19

If you suspect an effusion but the initial X-ray is negative, then obtain further confirmatory imaging studies.25 If the entire hemithorax looks like a “white-out” on CXR, look for mediastinal shift, as the patient may need a prompt thoracentesis for relief of symptoms. This presentation, known as a tension hydrothorax, occurs due to an increase in intrathoracic pressure causing a decrease in diastolic filling and subsequently a decrease in cardiac output.20 The mediastinal shift in this scenario will be away from the side of the effusion (Figure 4 below). If the shift is toward the side of the effusion, consider occult obstructive pathologies or damage to the lung parenchyma.11

In most modern EDs, the ultrasound can be used to distinguish between an effusion and pneumonia; it can save you valuable time in a busy department. Probe placement just above the diaphragm, posteriorly and laterally (Figure 5 below), can help visualize fluid as small in volume as 5 ml.12 Transudative effusions often appear as anechoic fluid (lack of echoes; appears black in Figure 6 below) on ultrasound, while exudative effusions often present with varying echogenicities.13 In addition to clarifying the type of effusion you may be dealing with, the ultrasound can also be used as a guide for a thoracentesis, if needed.

Ultrasound has near 100% sensitivity for effusions greater than 100 mL in volume.13 Another huge benefit of the ultrasound, in addition to being rapidly available in most EDs, is the lack of radiation exposure.

If the initial CXR or the more sensitive ultrasound does not help in identifying the reason your patient is in the ED, use the gold standard tool, a spiral CT chest, to further evaluate the source of the patient’s symptoms. CT scans will be able to determine the type of fluid the patient may have and in addition, help visualize the lung parenchyma, mediastinum, vasculature, and any other sources for the effusion. On a CT scan, malignant effusions can be differentiated from non-malignant effusions. Characteristics such as pleural thickening or mediastinal pleural involvement suggest a malignant source of the effusion.15

So now you’ve confirmed that there is some sort of fluid in your patients’ pleural space. What now?


Management and Disposition

Patients who come to the ED and are with a pleural effusion will either require hospital admission or may be discharged. Patients with a known pleural effusion presenting with complaints unrelated to the effusion may be discharged home after ensuring they have appropriate follow up. Patients with a new pleural effusion or a pleural effusion causing hemodynamic instability require admission to the hospital. The treatment for a pleural effusion will depend on its etiology.26 As with any patient who presents to the ED, start with airway, breathing, and circulation. If the patient presents with respiratory distress due to a newly diagnosed pleural effusion, admission to the hospital is warranted for further evaluation. That patient may also require a therapeutic and diagnostic thoracentesis in the ED. If you suspect a parapneumonic effusion (whether it is uncomplicated, complicated, or an empyema), initiate the appropriate antibiotics (including anaerobic coverage).26 Patients with complicated effusions or an empyema will also need a tube thoracostomy for drainage of pus.27 Once you’ve decided your patient requires a thoracentesis, what next? Indications for a thoracentesis in the ED include an unstable patient or new effusions (>10mm).11 Performing a thoracentesis under ultrasound guidance decreases complications such as bleeding, pneumothorax, and dry taps. Literature suggests that ultrasound guided thoracentesis has a 0.97% rate of pneumothorax, whereas the rate of pneumothorax was 8.89% when ultrasound is not used for thoracentesis.14



  • A diagnostic thoracentesis can be performed in patients with new pleural effusions or in patients with known but worsening pleural effusions.
  • A therapeutic thoracentesis should be performed in unstable patients, patients with complicated parapneumonic effusions, or in patients with empyemas.
  • Listen to your patients during the thoracentesis; if they complain of chest discomfort or worsening dyspnea… stop the procedure.



  • Typically, you should not drain more than 1 liter of fluid. Draining more than 1 liter of fluid can cause re-expansion pulmonary edema (patient becomes unstable and has frothy sputum).21
  • Your patient develops a cough during the thoracentesis. Should you be worried? Not really. This cough is probably a sign of physiologic lung re-expansion or pleural irritation from the tube.22


Case conclusion: The patient was promptly placed on supplemental oxygen, pain was controlled with fentanyl, and a liter bolus of LR was administered. Empiric antibiotics were started for a possible empyema or parapneumonic effusion. Further chart review upon re-presentation to the ED showed that the patient had a recent hemothorax and underwent multiple IR procedures (shown in Figure 7 below). Diagnostic and therapeutic thoracentesis was performed in the ED with the general surgery team managing the intra-abdominal drain complications. The patient improved clinically and was admitted to the general surgery service for further treatment.


Take Home Points

  1. There are a lot of causes for pleural effusions, but CHF is the most common precipitant seen in patients with bilateral pleural effusions. Malignancy is the most common cause of unilateral pleural effusions.[4]
  2. You may not be able see a pleural effusion on a CXR unless there is at least 175mL of fluid present.[5]
  3. If the effusion’s fluid is > 1.5cm in thickness (from parietal to visceral pleura) and covers at least 3 rib spaces, then it may be safe to tap.
  4. A great guide on thoracentesis, using ultrasound, can be found here: http://www.emdocs.net/ultrasound-guided-thoracentesis/
  5. Use an ultrasound to locate the effusion and decrease the risk of bleeding complications and pneumothorax.[6]
  6. Patients with parapneumonic effusions or hemodynamic instability will need prompt initiation of antibiotics and a tube thoracostomy.


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References / Further Reading

  1. Noppen M. Normal volume and cellular contents of pleural fluid. Curr Opin Pulm Med. 2001 Jul. 7(4):180-2.
  2. Sahn SA. The value of pleural fluid analysis. Am J Med Sci. 2008 Jan. 335(1):7-15.
  3. Burrows CM, Mathews WC, Colt HG. Predicting survival in patients with recurrent symptomatic malignant pleural effusions: an assessment of the prognostic values of physiologic, morphologic, and quality of life measures of extent of disease. Chest. 2000 Jan. 117(1):73-8.
  4. Quereshi NR, Rahman NM, Gleeson FV. Thoracic ultrasound in the diagnosis of malignant pleural effusion. Thorax. 64(2):139-43. 2009.
  5. Grimberg A, Shigueoka DC, Atallah AN, Ajzen S, Iared W. Diagnostic accuracy of sonography for pleural effusion: systematic review. São Paulo medical journal = Revista paulista de medicina. 128(2):90-5. 2010.
  6. Jones PW, Moyers JP, Rogers JT, Rodriguez RM, Lee YC, Light RW. Ultrasound guided thoracentesis: is it a safer method? Chest. 123(2):418-23. 2003.
  7. Atkinson P, Milne J, Loubani O, Verheul G. The V-line: a sonographic aid for the confirmation of pleural fluid. Critical ultrasound journal. 4(1):19. 2012.
  8. Wong CL, Holroyd-Leduc J, Straus SE. Does this patient have a pleural effusion? JAMA. 2009 Jan 21. 301(3):309-17.
  9. Kalantri S, Joshi R, Lokhande T, Singh A, Morgan M, Colford JM Jr, et al. Accuracy and reliability of physical signs in the diagnosis of pleural effusion. Respir Med. 2007 Mar. 101(3):431-8.
  10. Froudarakis ME. Diagnostic work-up of pleural effusions. Respiration. 2008. 75(1):4-13.
  11. Adler, E. H., & Blok, B. K. (2014). Thoracentesis. In J. R. Roberts, C. B. Custalow, T. W. Thomsen, & J. R. Hedges (Eds.), Roberts and Hedges’ Clinical Procedures in Emergency Medicine (6th ed.). Philadelphia: Elsevier/Saunders.
  12. Irwin, Z., & Cook, J. O. (2016). Advances in Point-of-Care Thoracic Ultrasound. Emergency Medicine Clinics of North America. 34(1), 151-157.
  13. Soni NJ, Franco R, Velez MI, Schnobrich D, Dancel R, Restrepo MI, et al. Ultrasound in the diagnosis and management of pleural effusions. J Hosp Med. 2015 Dec. 10 (12):811-6.
  14. Cavanna L, Mordenti P, Bertè R. Ultrasound guidance reduces pneumothorax rate and improves safety of thoracentesis in malignant pleural effusion: report on 445 consecutive patients with advanced cancer. World journal of surgical oncology. 12:139. 2014.
  15. Hallifax RJ, Talwar A, Wrightson JM, Edey A, Gleeson FV. State-of-the-art: Radiological investigation of pleural disease. Respir Med. 2017 Mar. 124:88-99.
  16. Diaz-guzman E, Dweik RA. Diagnosis and management of pleural effusions: a practical approach. Compr Ther. 2007;33(4):237-46.
  17. DeBiasi EM, Pisani MA, Murphy TE, et al. Mortality among patients with pleural effusion undergoing thoracentesis. Eur Respir J. 2015;46(2):495–502. doi:10.1183/09031936.00217114
  18. Na M. J. (2014). Diagnostic tools of pleural effusion. Tuberculosis and respiratory diseases, 76(5), 199–210. doi:10.4046/trd.2014.76.5.199
  19. Yu H. (2011). Management of pleural effusion, empyema, and lung abscess. Seminars in interventional radiology,28(1), 75–86. doi:10.1055/s-0031-1273942
  20. Vinck EE, Garzón JC, Peterson T, Villarreal R, Cabrera L, Van den eijnden L. Tension hydrothorax: Emergency decompression of a pleural cause of cardiac tamponade. Am J Emerg Med. 2018;36(8):1524.e1-1524.e4.
  21. Verhagen M, van Buijtenen JM, Geeraedts LM Jr. Reexpansion pulmonary edema after chest drainage for pneumothorax: A case report and literature overview. Respir Med Case Rep. 2014;14:10–12. Published 2014 Nov 26. doi:10.1016/j.rmcr.2014.10.002
  22. Feller-kopman D, Berkowitz D, Boiselle P, Ernst A. Large-volume thoracentesis and the risk of reexpansion pulmonary edema. Ann Thorac Surg. 2007;84(5):1656-61.
  23. Wong CL, et al. Does this patient have a pleural effusion?  JAMA. 2009;301(3):309–317
  24. Kitazono, M.T., Lau, C.T., Parada, A., Renjen, P., & Miller, W.T. (2010). Differentiation of pleural effusions from parenchymal opacities: accuracy of bedside chest radiography. AJR. American journal of roentgenology, 194 2, 407-12 .
  25. Lichtenstein D, et al. Comparative diagnostic performances of auscultation, chest radiography, and lung ultrasonography in acute respiratory distress syndrome.  Anesthesiology. 2004;100(1):9–15.
  26. Karkhanis VS, Joshi JM. Pleural effusion: diagnosis, treatment, and management. Open Access Emerg Med. 2012;4:31–52. Published 2012 Jun 22. doi:10.2147/OAEM.S29942
  27. Colice GL, Curtis A, Deslauriers J, et al. Medical and surgical treatment of parapneumonic effusions: an evidence based guideline. Chest. 2000;118:1158–1171.

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