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renal_colic

renal colic

introduction

  • renal colic is one of the most common presentations to the ED and mainly affects those in the 3rd to 5th decades of life - see urolithiasis for pathogenesis, risk factors and types of stones.
  • red flags
    • single kidney - patient will go into ARF if obstructed - urgent CT KUB to confirm
    • concurrent UTI - requires emergent nephrostomy within hours to drain proximal ureter to avoid severe sepsis
    • forniceal rupture on CT KUB - regarded as a urologic emergency but most can be managed conservatively as inpatient; these occur when sudden complete obstruction occurs and usual reduction in urine production has not yet occurred to avoid excessive pressures within the kidney collecting system
    • misdiagnosis

diagnosis

  • clinical picture:
    • it should be suspected in all patients presenting in severe flank pain radiating to groin, particularly if they are rolling around (makes peritonism and sciatica less likely), diaphoretic but afebrile (fever suggests acute pyelonephritis or cholecystitis).
    • in the older patient in particular, ensure there is no evidence of life threatening conditions such as abdominal aortic aneurysm (AAA)
  • microhaematuria
    • the presence of microhaematuria without nitrites or significant leukocytes is further suggestive but its absence does not exclude renal colic
      • Xafis et al. BMJ vol 25 (10), Oct 2008 pp 640-644:
        • presence of microhaematuria in CT +ve urolithiasis in non-pregnant patients without ureteral stents:
          • sensitivity 67%, specificity 58%, PPV 86%, NPV 31%
  • renal USS:
    • not commonly performed for Dx of renal colic unless CT KUB C/I (eg. pregnancy) or undesirable (children, young adults)
      • Xafis et al. BMJ vol 25 (10), Oct 2008 pp 640-644:
        • ureteric stones are difficult to see on USS but pelvicalyceal dilatation (hydronephrosis) has 81% sensitivity and 37% specificity for urolithiasis in acute flank pain, which rises to 88% sensitivity and 85% specificity if microhaematuria is also present (Seitz et al).
  • CT KUB
    • non-contrast CT scan is the current acute gold standard for the diagnosis of urolithiasis
    • it may be negative if the stone has been passed prior to CT scan being done.
  • plain abdominal KUB Xray
    • no longer used in routine diagnosis of renal colic
    • has a place in the follow up of larger stones to allow monitoring of their passage or lack of passage rather than using higher radiation repeat CT scanning.

ED Mx of suspected acute renal colic

  • timely and appropriate pain management (see also pain, analgesia and analgesics)
  • clinical history and examination to exclude other potential serious conditions such as abdominal aortic aneurysm (AAA) - see back pain for general approach to undifferentiated back pain
  • iv fluids
  • baseline FBE, U&E, Ca, uric acid, CRP (+HCG if fertile female)
  • urinalysis
  • observation until pain settles and patient is sufficiently comfortable on oral analgesics to manage at home
  • if pain is not settling, or the diagnosis is uncertain, or plan for urology OP follow up, then consider:
    • renal USS if pregnant or paediatric
    • otherwise, CT KUB if no C/I
  • indications for plain non-contrast CT KUB
    • fever and possible obstructed kidney
    • solitary kidney with renal colic
    • diagnosis is unclear (consider other Ix such as renal USS in younger patients or pregnancy to avoid radiation doses where possible - as a last resort, low dose CT scan may be used in pregnancy if benefits outweigh risks)
    • pain not settling - confirm stone size and position
  • if evidence of infection (eg. low grade fever), contact urology ASAP for possible emergency drainage of infected kidney - usually via emergency US guided urostomy (these patients often need HDU admit after procedure as high risk of bacteraemia shower)
    • Mx as for severe urosepsis with iv gentamicin + amoxicillin if no C/I
    • add coagulation studies, blood cultures and urine cultures prior to antibiotics
  • if impaired renal function (not just mildly raised CRN due to dehydration), single kidney, large stone (>7mm), or failure for pain to be adequately controlled, then contact urology for consideration for admission and surgical intervention, or at least early follow up.
  • if referring to urology stone clinic OP for follow up, ensure:
    • a CT KUB has been done for this episode of stone (a recent CT KUB is fine), and if a stone is present, then a plain Xray KUB to assist in follow up
  • role of alpha adrenergic blockers to hasten stone expulsion is controversial:
    • 2014 metaanalysis of trials showed that alpha blockers hasten stone passage by average of 3 days 1)
    • 2016 metanalysis showed tamsulosin was only of benefit in stones 5-10mm 2)
renal_colic.txt · Last modified: 2018/05/28 17:16 (external edit)