Paracentesis: are you stabbing in the dark?

Ultrasound has many advantages in this procedure – reduces the rate of failed taps, the number of “unecessary” taps for dry belly and I find it really helps to map out the best place, the depth and location of your needle. I would never do another one blind after doing a lot under US-guidance.  This retrospective case review series from the Journ of Med Economics 2012 showed benefits alround to using US guidance.  There was decrease in adverse events, infection and a drop in the budget costs associated with these outcomes.

Oh, and using an US is cool – you get great pics, practice you FAST technique with real collections to find.

here is how I do it – no evidence, just experience….

1. Do a scout scan to identify the deepest pocket of fluid and where the organs are that you want to miss- liver, spleen, bowel…
2. Pick a spot – I don’t mind if it is left or right, as long as it is clear on the US
3. Roll the patient with a pillow under one buttock (procedure side-down) and leave them for 15 minutes
4. Rescan to confirm you have a clear space, measure the depth to the peritoneum and the depth of fluid beyond that.
5. Prep / aseptic technique.  Inject some local with adren. into your spot and infiltrate to the peritoneum
6. I use a suprapubic catheter kit, but a central line or dedicated kit is fine
7. Put the probe anteriorly, insert the needle lateral to the probe in plane so you can watch the tip.  In you go
8. Drain as much as you think / need. Send your samples.  Leave the drain in if you want to remove big volumes
9. Monitor the patient for circulatory failure, and use albumin – especially for the sicker patient / big volume taps.

I remember being an intern on the Gastro unit, and being growled at by the boss because the INR wasn’t done on a patient due to have a belly tap. OK, I might have been an imperfect intern – but was my boss justified in worrying about an increased INR when doing a tap?

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!

Traditionally patients undergoing big paracentesis volumes were given IV albumin infusion to prevent post-tap circulatory collapse, hyponatremia etc.  Over the last few years a few other strategies have been suggetsed and used –  in 2011 there was a meta-analysis in Hepatology – this showed that IV albumin was generally the best bet for circulatory dysfunction and hyponatremia.  There was also a small mortality benefit – so it seems like a reasonable thing to do.  The previous Cochrane reviews on the topic in 1998 and 2002 showed no benefit, a trend towards increased mortality – so it is interesting that the latest review comes to a new conclusion.

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.