Paracentesis: are you stabbing in the dark?
Had a few problematic ascitic taps recently in our place – so I thought I would have a look at the evidence around paracentesis, what is new and what works. There are a few medical “rules” out there for this procedure, but are they supported by the data?
Click to see my review of each of these questions:
Oh, and using an US is cool – you get great pics, practice you FAST technique with real collections to find.
- Do a scout scan to identify the deepest pocket of fluid and where the organs are that you want to miss- liver, spleen, bowel…
- Pick a spot – I don’t mind if it is left or right, as long as it is clear on the US
- Roll the patient with a pillow under one buttock (procedure side-down) and leave them for 15 minutes
- Rescan to confirm you have a clear space, measure the depth to the peritoneum and the depth of fluid beyond that.
- Prep / aseptic technique. Inject some local with adren. into your spot and infiltrate to the peritoneum
- I use a suprapubic catheter kit, but a central line or dedicated kit is fine
- Put the probe anteriorly, insert the needle lateral to the probe in plane so you can watch the tip. In you go
- Drain as much as you think / need. Send your samples. Leave the drain in if you want to remove big volumes
- Monitor the patient for circulatory failure, and use albumin – especially for the sicker patient / big volume taps.
Well – there is not much evidence – certainly I could find no positive evidence – studies which demonstrated an increased rate of bleeding with coagulopathy for this paracentesis. There are a few studies and reviews which came to the conclusion that there was no significantly increased bleeding risk. For example this retrospective case review series of 600 chest and abdo taps from Transfusion 2003; and this literature review in Transfusion 2005.
This series from Pache & Bilodeau Alimentary Pharmacology and Therapeutics 2005 looked at nearly 5000 taps and found the rate of bleeding was 0.2%, and death was rare – 0.016%. They note that these outcomes occurred in the patients with the most severe liver disease. So maybe the patient’s predisposition is the problem rather than the procedure?
Now I am sure if you accidentally stab the patient in the liver, IVC or inferior hypogastric artery they will bleed – but being coagulopathic is probably not the issue here! Sure it makes the resuscitation a bit trickier, but it is not the cause! I think this is one of those medical myths where we all see or hear about a bad outcome, somebody retrospectively looks at the INR and blames it for the bleed – retrospectoscopic bias!
Probably my boss should have used an US to guide him, rather than blame the intern if he hit something bleedy!
Once again, the complications of circulatory dysfunction and hepatorenal syndrome are associated with the more severe / decompensated end of the spectrum of liver disease. So tread carefully in the patient with advanced disease, renal impairment and poor cardiac function at the outset.
OK, that is paracentesis in a page or so. Let me know if you have any other pearls
Casey
Great post! This is still one of my less favourite procedures (due to fear mainly based on over-estimating the risk in bloated, coagulopathic patients and due to mobile bowel that seems to want to impale itself on the needle, even under U/S guidance…), it’s nice to see a succinct summary of the evidence a few practical pearls.
Cheers
Casey! Nice post man. Great review of paracentesis with US. I remember when I learn how to test for a fluid wave in med school. As soon as I learned US I forgot about fluid waves. I wouldn’t dream of doing this procedure without US. Talk about “do no harm.”
The only pearl I would add is to put color flow on the ant abd wall. Nice trick to make sure you don’t lacerate the epigastric artery or vein on your way in. I’ve seen a couple cases of that. I also like to watch the needle go I. Maybe not necessary- but it makes me warm and fuzzy.
Thanks Mike (from US Podcast – the hard working one)
Yes, using the US to ‘miss’ those vessels on the anterior wall.
It is uncommon to hit one, surgeons put in lap ports all the time and manage to miss – but here the stakes are a bit higher. – the patient is already sick and usually coagulopathic!
We had one incident of hitting a reasonable-sized vessel ( it had a name even) which was very unpleasant for all concerned. It would seem to be a harmless move to map out your target area a bit.
Casey
Great post. This site is fast becoming THE repository for us time-pressed rural docs. I wonder if you’ve thought of adding short vimeo or youtube clips for the ‘how to do it’ section? This is one of those procedures that even the first-timer can do relatively safely…and a video to jog the memory re: kit is worth a thousand words.
Anyhow, good stuff. So glad I’ve invested in USS for use in my practice
I use ultrasound for all therapeutic taps. However, where it is really useful is to guide a diagnsotic tap in some-one with only a small amount of ascites. On a slightly differne topic, I would be curious to know how many people have tried ultrasound to find the landmarks for a lumbar puncture in a patient big enough to have their own gravitational field. The literature makes it seem simple and effective but my experience has been mixed – there have been times when it has been a big help and times when it hasn’t helped at all. Any thoughts?
Well, I’ve had to dig out the USS a few times for epidurals on the BMI > 40 people on labour ward
Can be useful
Again, this is an area where a few youtube videos can be real useful…