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Clinical Case 035: to frolic with renal colic

68 yo man presents with a 3 day history of pain in the right iliac fossa.  This pain is classic for renal colic – comes on suddenly, gets really bad quick, pulses away for half an hour or so then goes away – leaving a dull ache in its place.  Some “dark urine” noted by the patient.  No fevers, no dysuria, no GI symptoms.

PMHx: type 2 DM – diet only,  overweight,  meat-eater, no gout,  no family history of urolithiasis, no surgical history

Physical exam – not much to find: non-tender abdomen, no loin tenderness, Obs all normal (pain has disappeared)

Urinalysis:   here we get to the first clinical question –

Acually – not as good as I always thought – surely if the UA is clean – there cannot be a stone right? Well wrong. Two recent studies by Xafis (Emerg Med Journ, 2008) and Kim (J. Korean Soc of EM, 2011) both came up with similar numbers.

The sensitivity, specificity , + predictive and  – predictive values for microscopic haematuria (vs. CT) were:  67%, 58%, 86% and 31% in the Swiss study.   Then 89.4%, 41.1, 88.9%, and 42.1% in the Korean study.

So I don’t think you can conclusively say Yeah or Nay based on a urinalysis

So we often need to do some tests to work out the answer: IS THERE A STONE?

This is an area of radiology that has evolved over the past 5 years.  The old-school IVP and plain film KUBs have pretty much gone by the wayside.

In WA Health we have access to the “Imaging Pathways” resource which I find quite useful in deciding what to do next.  For suspected renal colic the pathway looks like this (Click) – basically a low-dose, non-contrast CT KUB is your first step in pretty much everybody unless pregnant or you think they might have a AAA!

The combination of a plain film KUB with an US is not to be sneezed at I think.  This Spanish study (European Radiol, 2004) showed that whilst CT was more accurate than US + KUB, US was good at picking the stones that were likley to require intervention (usually the big, high ones). So if a stone passes in the night and doesn’t show on US – does it matter?  Maybe not – but that is a discussion you need to have with your patient, are they (and you) comfortable with this degree of diagnostic uncertainty?

So what next – you diagnose a stone. It is 4 mm, in the lower ureter – so it should pass, in theory.  What can you offer this patient to make them experience les pain and pass it quicker? This paper by Daniel Spernat and John Kourambas (BJUI, Nov 2011) has just been released online.  It goes through all the therapies and evidence nicely – so read it yourself – it is not too long.

  • Drink lots of water – urine output to be >2 L/day
  • Citrate – works by inhibiting crystal formation / binding calcium.  Take potassium citrate – it helps in other ways too…
  • Avoid lots of animal protein and salt – well that is just good all round health advice!
  • Calcium – you need to eat it for your bones etc, but avoid excess.
  • Thiazide diuretics – decrease stones, but you should take citrate with it to avoid hypocitraturia…
  • Allopurinol:  decreases gout stones, but also oxalate stones – they form around gout.
  • Sodium bicarb – alkalinser of urine, but it has a lot of sodium (bad) – so use K-citrate instead.
  • Alpha blockers – “medical expulsion therapy” is used for distal ureteric stones.  Tamsulosin seems to be the most efficacious. Though only slightly better than placebo – Study thanks Andy
  • Ca-channel blocker (nifedipine) work, but not as good as alpha-blockers
  • NSAIDs are good for pain relief and decrease ureteric pressure – but no difference in passage rates – oh, and watch that renal function if using these!

This cool table summarises it all in a nutshell:

Table 2.  First-line agents in routine use
Uric acid stone prevention Potassium citrate
Calcium stone prevention with hypercalciuria UroPhos-K
Cystine stone prevention D penicillamine or alpha mercaptopropionylglycine
Uric acid stone dissolution Potassium citrate
Medical expulsion therapy Alpha blockers
Struvite stones Surgical treatment is first-line therapy

  1. the diagnosis of renal stone disease is a bit like the diagnosis of anaemia – there are a lot of causes out there (in there), and the diagnosis should probably trigger a search of the common aetiologies – I send off a few bloods (FBP, UEcr, uric acid, Calcium..)and try and catch a stone for analysis if I can.
  2. Beware the patient with a fever, septic looking or who has lots of white cells and nitrites in the UA with the blood – they are at risk of an infection and possible urosepsis – so treat them early!

 

 

Comments

  1. do you give ALL of those therapies? I’d heard of some of them but have never given more than
    -- plenty of fluid
    -- good analgesia

    I used to give tamsulosin but am a little bit more dubious of late

  2. Casey Parker says:

    HI Andy
    No I don’t use them all. My standard cocktail is:
    -- lots of water
    -- citrate / alkaliniser (though I think K-citrate) seems good on this reading
    -- NSAID based analgesia
    -- tamsulosin for the hypertensive middle-aged chap (ie most of them) -- used to be prazosin
    -- then it depeds on the size and site of the rock as to what next??

  3. My approach is similar. Fluids lots of fluids analgesia and Tamsulosin/

    I generally US everyone for rule out AAA and then confirmation of renal stone looking for hydronephrosis.

    As everyone who has been around I have diagnosed a renal Colic as a AAA just doing the quick AAA scan.

  4. Casey Parker says:

    Andy -- the “medical expulsion rate” for tamsulosin was up around 80%. Which seems pretty good -- in those with small (<5 mm), distal ureteric stones.

    Ray -I have not seen a AAA diagnosed as a stone. I am sure there are a few cases each year - traps for young players!! Makes you wonder - how many silent stones are there out there? Or how many innocent AAAs get operated on due to pain and a positive CT or US in the heat of the night?

  5. This trial (PMID: 21149761, one of the better ones) says no. It may still work, i know, i’m just (as usual) a little bit skeptical

    am yet to diagnose AAA as a stone but rather entertainingly I did once CT an elderly confused lady (with a known 3.5cm AAA) for palpable tender mass in her belly and it came back as urinary retention. this was before we had US but still pretty damn embarassing. Radiologist was more gracious than i deserved!

  6. For those interested in a more in depth review of urolithiasis: http://www.aafp.org/afp/2011/1201/p1234.html#afp20111201p1234-b13

    What are your thoughts on starting a metabolic evaluation in ED? (Ordering serum calcium, uric acid…).

    Cheers!

  7. Although it’s uncommon, I, like many others have confused a AAA with renal colic. It ruptured 30 mins after I had said “I’m sure this is just a stone, but the rules say I have to get a CT” (and I was young enough to follow the rules) the patient was in CT when they crashed (luckily had a good outcome). As a result I ultrasound everyone with renal colic (OK I ultrasound almost everyone anyway, but definitely this group). Even if I can’t definitely diagnose renal colic, I don’t lose sleep wondering if I missed the AAA.
    As mentioned above, the commonest thing to find is a dilated collecting system. Often it’s not enough to fulfil the criteria for hydronephrosis, but “mild dilation” or “fullness” (or whatever other vague term you like), particularly if asymmetric. The best article I know discussing the relationship between obstruction (a functional diagnosis) and hydronephrosis (an anatomical diagnosis) is
    http://onlinelibrary.wiley.com/doi/10.1046/j.1464-410X.2000.00583.x/full
    (I’d ignore the whole section on Doppler) -- also a useful reminder when dealing with patients with renal failure that a normal ultrasound doesn’t exclude obstruction (although sometimes radiologists seem to forget this).
    In answer to Pat -- we recommend for their first stone: Ca and Urate and try to catch the stone (but don’t need to redo it once it’s been checked before).

  8. Bottom line, I need to do more ultrasounds in ED….

  9. Neil Hughes says:

    Like Adrian, and many others I’m sure I too have had the dreaded crash call to x-ray (not CT -- this is the UK) for the older “renal colic” patient who was indeed a AAA. I think it’s worth emphasising that an bedside ED U/S purely to rule out AAA is definitely worth doing and doing liberally. It’s important not to be put off doing this if you are less experienced and cannot confidently comment on the bile ducts etc. Of course this is of particular relevance when we don’t have access to immediate CT direct from the ED which, unfortunately, is still the situation in much of the UK. I also encourage a check of lactate as in more elderly patients as bowel ischaemia can be a troublesome differential.

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