I’m starting to have a better understanding of the difference between 1st, 2nd, and 3rd spacing. But I’m still a little confused about how Ascites could be 3rd spacing. I thought that the fluid in third-spacing couldn’t be removed, but I know that ascites can be aspirated to get rid of it.
That’s a great point, and I’m so happy when I get questions like this because it means that you’re really thinking about the information, and not just expecting it to be spoon-fed to you. Keep thinking like this and you’re on track to start thinking like a nurse!
It IS true that 3rd spacing is trapped fluid, and you’ll commonly hear that it “can’t be removed.” But let’s talk about what the really means in ascites. (And refer to my last post on Ascites and Third-spacing to get more detailed definitions for each type of fluid spacing.)
When we say that the fluid seen in 3rd spacing “can’t be removed,” what we really mean is that the body would have a tough time getting that fluid back into normal circulation all by itself. Ascites is a perfect example of this because once fluid is in the peritoneal cavity, it usually stays there! The body is just not usually very good at getting it back out.
That’s why a patient with ascites will usually have to undergo a medical intervention like aspiration to get the fluid out of the peritoneal cavity. However, since aspiration is an external, medical intervention, that still means that ascites should be classified as 3rd spacing.
In the future, if you are not sure whether a particular fluid imbalance is 3rd spacing or not, just ask yourself: “Can the body get that fluid back into circulation by itself, or will the patient probably need a medical intervention?” If they need a medical intervention, then it’s most likely 3rd spacing.

Nicole Whitworth is the founder of Your Nursing Tutor. She has a BSN and an MA in Clinical Psychology, and has been a professional nursing tutor for over 12+ years. Nicole specializes in getting nursing students through school confidently and calmly so that everything finally “clicks”. She is also the creator of the Silver Bullet Study System, an easy-to-follow study method that automatically trains your brain to become a nurse at the same time that you study for your normal nursing classes.