Thoracentesis
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Pleural effusions are a frequent problem encountered in pulmonary medicine. Some common causes of pleural effusion include chest infection, heart failure, liver failure, malignancy, and autoimmune diseases such as rheumatoid arthritis, to name a few. Often drainage of this fluid is required for both diagnostic and therapeutic purposes, which is called thoracentesis. For this procedure, we use a Safe-T-Centesis kit to place a temporary catheter in the pleural space and manually drain the fluid, which can then be sent to the lab for further testing, including cell counts, glucose, pH, protein levels, cytology, and bacterial cultures. Based on these results, we can determine if the effusion is exudative or transudative, which helps guide further management. In this case, our patient has a recurrent left-sided exudative effusion of unknown cause with underlying history of colon cancer, and malignant effusion is a concern, and we performed both diagnostic and therapeutic ultrasound-guided thoracentesis.
Pleural effusion; thoracentesis; Safe-T-Centesis; exudative; transudative.
Pleural effusion, which is the accumulation of fluid in the pleural space, is a very common problem we manage in pulmonary medicine with a broad range of etiologies. It is reported that there are up to 1.5 million cases of pleural effusion each year in the United States.1 It is often necessary to drain this fluid for diagnostic purposes, but also for therapeutic benefit as well.
Thoracentesis is a very common bedside procedure that is utilized to drain pleural fluid. In simplest terms, a catheter over a needle is inserted through the chest wall into the pleural space. With the assistance of ultrasound, we can safely identify the pleural effusion as well as surrounding structures, including the lung, diaphragm, and pleura. Thus, the safety of thoracentesis has been improved, and the risk of complications including bleeding and pneumothorax are reduced significantly.
Prior to performing a thoracentesis, it is important to take a thorough history as well review of laboratory values and extensive review of the patient’s medication list, most importantly looking for any blood thinners a patient may be on. When taking a patient’s history, it is important to try and figure out what could potentially be causing the pleural effusion. For example, you want to explore for heart, kidney, or liver issues, prior or active cancer history, signs/symptoms of infection, and/or autoimmune symptoms. It is imperative to have an accurate and thorough history as this will help guide what testing you will perform on the pleural fluid. When reviewing the patient’s medication list, you want to look particularly for anticoagulants or antiplatelet medications, as being on these medications will increase the patient’s risk of bleeding. While it is not an absolute contraindication to performing thoracentesis if the patient is on anticoagulants/antiplatelet medications, the risks and benefits of interrupting medication and/or the need for bridging therapy before the procedure should be discussed with the patient. For those with a high thrombotic risk (eg, cardiac stents), the discussion may need to include other relevant specialty teams. However, a meta-analysis published in Chest 2021 showed that overall bleeding risk and mortality was not shown to be increased in patients with uncorrected coagulopathy, either due to underlying disease or medications.2 When reviewing a patient’s laboratory data, it is important to look at patient’s total platelet count and INR. Ideally you would like platelets >50,000 and INR within normal range. However, as stated above, bleeding risk with uncorrected coagulopathy is not significantly increased, and if the procedure is emergent, it should not be delayed and be performed after discussion with the patient about the possibility of increased bleeding, albeit low.
On the physical exam, it is important to first make sure the patient has stable hemodynamics, including blood pressure, oxygen saturation, heart rate, and respiratory rate. You want to make sure the patient has a stable blood pressure prior to performing a thoracentesis, as the removal of a significant amount of fluid can temporarily cause the blood pressure to drop. You will then want to examine the patient’s back and make sure there are no open wounds or other skin abnormalities that might interfere with where you plan to perform the procedure. An important portion of your physical exam will include performing a bedside ultrasound of the lung and pleural space to get a better look at the fluid collection and decide where to safely perform the thoracentesis. We will review the other relevant imaging in the next section.
To evaluate for a pleural effusion, generally a chest radiograph and ultrasound are a good place to start. While a chest radiograph will generally tell you if an effusion is present, the ultrasound will better identify both the size and echogenicity of the effusion, such as if it is a simple or complex appearing fluid collection. It has been shown that ultrasound is not only the safest way to identify pleural effusion (reduces exposure to radiation), but also a study done in 2011 showed 100% sensitivity, specificity, and diagnostic accuracy for thoracic ultrasound identifying a pleural effusion.3 CT imaging of the chest is not required prior to a thoracentesis, although it is very likely you will have this to review as well prior to the procedure.
None.
Before offering the thoracentesis procedure, safety, indication, contraindication and preparation need to be evaluated.
Common indications for thoracentesis are to diagnose new or of uncertain etiology equal or more than 1 cm in size or unclear unilateral effusion as well as relief of symptoms with large pleural effusions. There is no absolute contraindication for thoracentesis. Common relative contraindications include bleeding disorders, uncorrected anticoagulation, cellulitis or wound at the thoracentesis puncture site, inability to cooperate or inexperienced operator. If concern for empyema and hemothorax, other pleural procedures such as chest tube is preferred than thoracentesis.3
Once confirmed thoracentesis is an appropriate procedure, informed consent must be taken and clearly documented including risk and benefits. There are no large studies to define bleeding risk related to thoracentesis. General rule is that holding the anticoagulants and antiplatelets in an elective procedure will likely reduce the bleeding risk.
In the video the procedure is performed “at the bedside” but ideally, when feasible the procedure should be undertaken in a clean, dedicated procedure room.
The procedure will begin with proper positioning of the patient. There are 2 positions a patient can be in for this procedure. The ideal position will be to have the patient sit with legs hanging over the side of the bed, with arm rest on the table and feet on the floor/chair. If the patient is unable to sit, lateral decubitus position with extended arm position is also acceptable.
Once the patient is in the proper position, the procedure site is confirmed using ultrasound probe with either abdominal probe or cardiac probe. The usual site is the posterolateral back at least 6–8 cm away from the spine, one to two intercostal spaces below the fluid but above the diaphragm. The needle entry site should be just above the rib to avoid injury to intercostal neurovascular structures. While there is no defined optimal size of a fluid collection, generally it is recommended that collection be at least 1 cm in size to ensure avoidance of surrounding structures.4
Once the site is marked and after time-out, sterilize the skin using chlorhexidine or other sterile solution and drape the skin under sterile condition. Safe-T-Centesis kit includes 10 cc of 1% lidocaine solution in a glass container with various needle sizes. To prevent glass shards from entering your syringe, recommend to use a filtered needle to draw the lidocaine. Switch to a 25-guage needle to make a subcutaneous wheel. It is important to make sure your patient is properly locally anesthetized prior to draining the pleural fluid as it will be quite painful for your patient if they are not. Once the top layer of skin is numb, switch to a 22-gauge needle perpendicular to the skin and inject lidocaine along the track with applying suction when you advance and give 1–2 cc of lidocaine every 3–5 mm depth. Once you reach the pleural space, you should get fluid drawn back into your syringe, and that is how you will know you are in the pleural space. As you remove the needle, it is important to not instill more lidocaine as you withdraw as this could introduce air and possibly infection (if the pleural fluid is infected) into the skin which could lead to complications. In certain patient populations such as large body habitus, it is sometimes needed to use the longer needle such as spinal needle or using the thoracentesis catheter itself depending on the experience level of the operator.
Once the skin is properly numbed, make a small 3–5-mm skin nick with the scalpel. The catheter is slowly advanced through the skin nick, just above the rib while aspirating. Once the fluid return is observed, it is recommended to advance another 3–5 mm. Then, without moving the introducer needle, advance the catheter over the needle until hubbed. Attach the catheter to the drainage bag for fluid removal. Prior to fluid removal, it is important to educate patients on what to expect during the procedure. Coughing is an expected symptom with thoracentesis because as the lung re-expands this induces coughing. You should tell them if they develop chest pain or tightness to alert you right away as this could be a sign of lung entrapment or re-expansion pulmonary edema. Generally, we start by using our 50-cc syringe to draw up samples to be sent off for testing. You will continue to drain the fluid until 1) patient develops significant chest pain, tightness, or shortness of breath (as this could indicate re-expansion pulmonary edema), 2) drainage slows down indicating all the fluid has been removed, or 3) generally up to 1.5–2 L depend on patient’s tolerance.
If a patient develops persistent cough, dyspnea or chest pressure, stop drainage and evaluate for pulmonary edema. If the air bubbles were aspirated with symptoms of hypotension, hypoxia, or chest pain, stop drainage and evaluate for pneumothorax. If the patient develops hypotension especially in the older population, likely due to vasovagal syncope, stop the procedure immediately and call for help to stabilize vital signs. Upon completion of aspiration, ask the patient to hum or breathe out while removing the catheter and apply bandage.
Complications of thoracentesis procedure includes pneumothorax, hemothorax, post procedure pain, re-expansion pulmonary edema, vasovagal syncope, injury to nearby structures including diaphragm, liver, spleen, heart, and major blood vessels. Generally recommend to obtain a postprocedure CXR to rule out the complications. Any anticoagulants held for the procedure can be safely re-started the following day.
All pleural fluid needs to be sent for cell count/differential, LDH, total protein, gram stain, culture (aerobic and anaerobic), cytology, glucose, pH. Same day serum total protein and LDH is needed to calculate Light’s criteria. Additional labs can be sent upon clinical questionnaires.
- Sterile tray, sterile drape, skin antiseptic solution (e.g. chlorhexidine), lidocaine, sterile dressing, sterile gloves, catheter for drainage, introducer needle, scalpel, drainage tubing, collection bag.
- Local anesthetic, usually lidocaine 1–2% solution (should be included in the kit but make sure to double check).
- Several different gauge needles (18 gauge for drawing up lidocaine, 22 or 25 for administration).
- Several syringes ranging from 5 mL to 60 mL (smaller for lidocaine, larger for fluid removal).
- Aerobic and anaerobic blood culture bottles, clear specimen cup.
The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.
Citations
- Jany B, Welte T. Pleural effusion in adults-etiology, diagnosis, and treatment. Dtsch Arztebl Int. 2019 May 24;116(21):377-386. doi:10.3238/arztebl.2019.0377.
- Fong C, Tan CWC, Tan DKY, See KC. Safety of thoracentesis and tube thoracostomy in patients with uncorrected coagulopathy: a systematic review and meta-analysis. Chest. 2021 Nov;160(5):1875-1889. doi:10.1016/j.chest.2021.04.036.
- Rachelle Asciak, Eihab O Bedawi , Rahul Bhatnagar, et al. British Thoracic Society Clinical Statement on pleural procedures. Thorax. 2023;78(suppl 3):43–68. doi:10.1136/thorax-2022-219371.
- Xirouchaki N, Magkanas E, Vaporidi K, et al. Lung ultrasound in critically ill patients: comparison with bedside chest radiography. Intensive Care Med. 2011 Sep;37(9):1488-93. doi:10.1007/s00134-011-2317-y.
Cite this article
Yu Maw Htwe, MD. Thoracentesis. J Med Insight. 2025;2025(486). https://doi.org/10.24296/jomi/486Procedure Outline
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Transcription
CHAPTER 1
Hey, everyone. My name's Alex Lopez. I am a fifth year pulmonary critical care fellow, here at Penn State Hershey. What I'm gonna tell you all about today is a thoracentesis that we're about to do bedside. So this patient, she is a 54-year-old female. She's been having a recurrent left-sided effusion. And so in order you send that fluid off for testing, we're gonna perform a thoracentesis today. So in general, this is a bedside procedure that we do pretty regularly in pulmonology. Like I said, we do it at the bedside. There's a couple different positions the patient can be in. They can be sitting on the edge of the bed with their head forward, leaning on pillows, or if they're not able to do that, they can also be laying down in the lateral decubitus position. We ultrasound the area, so we know exactly how much fluid we have, and where we're going. We sterilize the area very well before we proceed with any procedure. I'm wearing sterile gloves. There's a sterile drape. The main thing is lidocaine. That's the most painful part of the procedure for the patient. We numb up the skin area very well, and then numb up the track until we reach the pleural space. Once we have done that, we have a catheter. It's a Safe-T-Centesis catheter with a blunt end. So when you're going into that pleural space, if you do hit any lung, it shouldn't puncture the lung. So before you insert the catheter, after you've numbed up the area, you wanna make a very small skin nick. There's a scalpel in your tray that you'll see here in a little bit, during the video. You make a very small skin nick. You insert the catheter into that space, and you withdraw your needle. Once you're in the space, you draw out the fluid, only about 50 milliliters at a time. The lung doesn't like to get much more than that. That negative pressure can be very painful for the patient. Once your catheter is in place, there's a two liter bag that comes in the kit. The connector to the bag, the long end goes towards the bag. The short end goes to the patient, and you withdraw the fluid through that because it's a one way valve. So you can withdraw the fluid out and it goes directly into the bag, not back into the patient. 'cause you wouldn't wanna introduce air into that pleural space. Once you've drained all the fluid, generally no more than two liters at a time, any more than that it can be very painful for the patient. You can also get something called re-expansion, pulmonary edema. So that's the fluid shift, and it causes fluid to go into the lungs themselves. So we don't generally take off more than two liters at a time. Once the catheter's moved to the space, as you're pulling the catheter out, you should ask the patient to hum. That creates some negative pressure as you're pulling that catheter out to prevent air from getting trapped in the subcutaneous space. And that can cause subcutaneous emphysema. That can be uncomfortable for the patient afterwards as well. You put a bandage over the area. Generally we recommend keeping that on for at least 24 hours after the procedure. Patients can shower and bathe as they please. After a thoracentesis, it's recommended you get a chest x-ray to look for one to make sure the fluid that you just drained is gone, and look for any residual fluid. And also to look for a pneumothorax, which is one of the known complications of a thoracentesis. Generally it happens about 1 to 2% of the time. So a very rare complication, but does happen. So you wanna get a chest x-ray afterwards. All the fluid gets sent off for testing. So we test for cell counts, we culture the fluid to look for bacterias, funguses, anything like that. And then we also send it off for cytology to look for cancer cells. Because there's a lot of different reason this fluid could be there. And so one of the reasons we drain it often is to send it for testing and figure out why it's there.
CHAPTER 2
Just identifying the best spot here. So that looks pretty good. So we have a good distance here. We have the diaphragm right here, coming in and out is collapsed lung right there. And this is all your pleural fluid right here. So that's about four centimeters of fluid or so. So that's a pretty good spot. Okay. So I like that there. Then you wanna mark your spot, so you're just gonna feel a marker on your back here. Okay? Okay. Just gonna reconfirm you like that spot. We got a fluid back there, okay? Okay.
CHAPTER 3
So our kit here. This is a sterile kit behind you. So, I'm just opening this up on the side of the bed here. I'm just putting on my gloves and then I'll talk you through everything I'm doing. Okay? Okay. So this is our bag that we'll eventually put our fluid into. Are there no ChloraPreps? Oh, there's one. Okay. All right. I'm gonna start with cleaning up the area here. And so this is a a sterile procedure, and that everything on the skin is sterile. I'm wearing sterile gloves. And we'll put a sterile drape on here soon. Okay. You wanna give yourself a much bigger area than you think you'll use. And so this is our drape here. It's got a big sticky. So this is the spot that we'll put over and then it has a sticky at the top to keep it from slipping. Okay. And then just to give yourself some more working room here, I tend to put this at the bottom as well. And I'll use these little stickies just to keep it together here. Okay. Have some more sterile working place here.
CHAPTER 4
Alright so, going through your kit here, you're gonna have a lot of different things. First thing I always start with is getting your lidocaine. So, generally come with about 10 cc with lidocaine. And these are glass bottles that you'll have to break. So there's a special needle in the kit that has a filter in it and keeps any glass pieces from getting in there. So you wanna take your - prevent any injury. Open it up like that. And draw back your lidocaine. Okay. One more bottle here. All right, so that's your numbing medicine. I wanna get all the air bubbles out. And I always like to start with the tiniest needle to numb up the skin. Make it as comfortable as you can. All right, so I will - I'm gonna numb her up and then I'll set up the rest of the kit here. All right, pinch and a burn, okay? Yep. So usually start - get a little skin. Pinch! Ouch. Yeah, there's the pinch there and a little bit of burn. Okay. I know. Usually create a big wheel right underneath the skin. And anytime you're going somewhere new, you wanna pull back, make sure you're not hitting any blood vessels. Okay. All right. I'm pretty generous on the skin. I'm sorry. I know that's that medicine. It burns, but once it starts kicking in, you shouldn't feel anymore. Okay? And so when you're going in, generally you wanna feel the rib above, the rib below. And you wanna try to go just above the rib below because the neurovascular bundle lies just inferior to the rib. And so you kind of wanna avoid that and avoid the arteries there. All right. You might feel some more pinching and burning. Okay? As you're going in, always pulling back as you're advancing. Okay, feeling in some rib there. All right, just a minute. Hitting rib. Okay. Okay.
CHAPTER 5
And so this here, this is your introducer needle, catheter. So you take this - this is the catheter that will stay in the patient once you get into the pleural space, and you just insert it through there and you wanna make sure that's flush up against there. So it kind of locks in right there.
CHAPTER 6
All right? You wanna make a little bit of a skin nick here, not too big. You just wanna make it easier to advance that catheter in. Usually do kind of parallel to how the ribs are kind of shaped. Okay, that should be good there.
CHAPTER 7
Ow. Okay. More lidocaine there. Ow. Okay? Okay, we're in the space. Ow. Okay? So once you're in the space, you advance just a little further and then I drop this hand here and hold this hand steady, not inserting the needle any further and just advancing the catheter over that there. And that's it, and you're in the space.
CHAPTER 8
All right. And so the way this hooks up here, so it has a one-way valve. So as you pull fluid out and you can push it into the bag, but it won't get pushed back into the patient. 'cause you don't wanna inject any air to that space. The short side goes towards the patient. And the long side goes to the bag. And then your 60-cc syringe hooks up at the other end here. And you have your stop cock. So you wanna, it tells you which direction's off. So to open up the flow, you want it pointed this way. Alright. And now we start draining the fluid. Are there any other 60-cc syringes? Do you want me to like push this one into the bag and then, or go ahead and dump it in there? All right. So these are our samples we're sending off here. All right, how you doing? Alright. Okay. So now this is just the drainage of the fluid. I can only drain about 50 milliliters at a time, any more, the lung would get unhappy. You want this one here? All right. Oh. Should be good. Yep. Okay, all right, and now we just drain the fluid. So as I'm draining the fluid, I know this is not your first one you've had done. Coughing is very normal as that lung re-expands 'cause parts of it are collapsed right now. From that fluid as it re-expand expands, it's going to, you're gonna wanna feel like you have to cough, okay? And that's totally normal and it won't mess up anything I'm doing back here. All I have in there is a plastic catheter right now, so it can't cause any damage or anything. So if you need to sit up, move around, you can. So you said they took off two liters last week? Two liters. Okay. I think it might have been just shy of that, but yeah. Okay. Close enough. Yeah. Yeah. This is the tedious part. CT scan after? Okay. Yeah. If you start having any pain like you were telling me you had before, I want you to tell me right away. Okay? Because that could be, that's your lung telling us it might have had all it can can handle in terms of drainage and I don't want you to be uncomfortable. (patient coughing) You okay? I'll pull it out slowly. We can stop at any point, okay? Can you take like a pause? We can. Yep. We can. Yep. Is it hurting? Or is it just that cough? Yeah. I'll do it very slowly. Coughing's normal. Did the cough linger after your last one? Yeah. I spent about two, three hours doing nothing but coughing. Oh. We already got probably close to a liter. Maybe halfway, maybe. I dunno. It's hard to tell when it's laying flat like that, Huh? Too hard to tell when it's laying flat like that. How much we got. Yeah. It's almost a liter. Yeah. Now I know I'm not gonna cough myself into this. We don't want that to happen. We took out I think around almost a liter. Yep. Is that what it looked like before? Yep. Yeah. Actually it looked a little lighter. Yeah, in the tubing itself it's light. That color? Yeah. There's like two drops of blood in there and that makes all the fluid look a lot bloodier than it actually is. The fluid coming out through here is pretty light. You think this time it's lighter or previous time is lighter? Other time. Okay, take your time. Last time it looked a little lighter than what's in that jar there. This time it's dark. And that can happen, because last, whenever you injured, in the procedure, it causes a little bit of bleeding. Yeah. Here, I'm gonna take a rest for a second. Okay? Do you wanna peek? Just having a peek. It's just a little peek at the fluid. There's still lots of fluid. Yeah. You got some more fluid. You can cough, and we can let you rest. Don't hold it. If you want to cough, cough it up. Got some fluid left, but we can also stop it if you can't tolerate it. We have that plus a hundred. 1200, so 1300. Is it hurting? It hurts a little when I... Take a deep breath in? When it makes me pull air in and then it hurts. Another thing that we can do is... What you do is you unhook the 50-cc syringe, if there is a positive pressure in the pool of fluid, the fluid - you see? So, which means that it is already done. So now what another thing you can do is you can kind of put it in the level and if there is a positive then you're gonna see a lot of dripping. Oh. So then you can still drain. Oh, cool, yeah. That you can do, either way, that's what I do. I didn't know that. You still have some room to drain. Do you want me to drain more or are you done? Drain. Okay. Whenever you took it off, the fluid goes back that to that. Okay. Meeting some resistance there. I think we might be close to done here. Yeah, I mean it's not - you can pull it out. Yeah, I mean I think that's, okay. I think we're done actually. I think we've gotten all the fluid we can get. Okay? Sounds good.
CHAPTER 9
So as I pull this catheter out, I want you to kind of hum for me. Okay? Kind of create some negative pressure as I'm pulling this tube out. Okay? All right. On 3, 1, 2, 3 - hmm. Good. All right. It's out. Oh, you can stop sweetie. Unless that feels good, then you can keep humming all you want. All right. The drain is out. I don't have any fluid here. Okay. And once it's done, see here it's just a very tiny skin nick and we'll just put a Band-Aid over that and then you're done. All right, I'm gonna pull this drape off here. Okay. This is like a big bandaid coming off. All right. So I should mention about this needle, it's just, we call it the Safe-T-Centesis becaue at the tip... See at the tip, if you focus on the tip, and then you see the needle tip, and there's a safety tip, so I can touch it, it won't hurt my fingers. And then when I press it, there is kind of a one-way move created. But that's why if this is good for the kind of thoracentesis to reduce the risk of a pneumothorax. All right. And then after you're done, all she has is a bandage on there. And clean up your sharps, and that's it.
CHAPTER 10
This is how we gonna check the lung's fully expanded after what's left. So, that's liver there. So that you see that over there. There is a line here, right? So this is your diaphragm here and that's liver there. Do you want me to go up here? Let's see. And that, so this is normal lung here and I'm not seeing any... Okay, so right there there's a good, good picture, right? You see the curtain? Yeah. So this curtain sign, so this is lung here you'll see the diaphragm pop in here. And this is liver. As you breathe in, the lung - can you take a deep breath in for me? The lung comes across the liver. That's called a curtain sign. So that tells the lung is nice and open. It's moving as she breathes in. And most of the fluid's gone.