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Three Part Question

[In patients presenting to the Emergency department with features suggestive of ureteric colic,] is [spiral CT scan better than IVU] in the [detection of ureteric calculi?]

Clinical Scenario

A 45-year-old man presented to the emergency department with a history of sudden onset left-sided loin pain radiating to the left groin. Urinalysis revealed 2+ blood and nil else. Plain abdominal x ray did not reveal any radio-opaque calculus. You wonder whether a spiral computed tomography (CT) scan or intravenous urography (IVU) will be more appropriate for the further evaluation of the patient.

Search Strategy

OvidSP Medline 1966 to January week 3 2009
[{exp tomography, x ray computed/or exp tomography, spiral computed/or helical computed.mp or CT scan.mp. or CAT scan.mp. or comput$ tomography.mp.} AND {exp urography/or IVU.mp. OR exp ureteral obstruction/or exp contrast media/or exp Colic/or intravenous pyelography.mp. or intravenous urography.mp.}]. Limited to humans and the English language.

The Cochrane Library Issue 1 2009 [MeSH descriptor Tomography, X-Ray Computed explode all trees] AND [MeSH descriptor Urography explode all trees].

Search Outcome

Overall, 1081 papers were found, with only nine having direct relevance to the three-part question. One was a meta-analysis that included four of the other papers. This and the additional four papers are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Homer et al, 2001, New Zealand	228 adults 123 had CT and 105 had IVU Gold standard (spontaneous stone passage, surgical retrieval or identification on retrograde pyelography) CT vs IVU	Prospective randomised diagnostic cohort	Sensitivity	100% vs 99%	Indeterminate results considered positive in 18 patients in the IVU group. However, presence of stone confirmed in only 8 of these
			Specificity	100% vs 100%
			Detection of alternative diagnosis	27% vs 4%
Mendelson et al, 2003, Australia	200 patients 102 had CT and 98 had IVU Gold standard (documented passage of calculus, patient reporting passage of calculus or surgical intervention). CT vs IVU	Randomised diagnostic cohort	Detection of other pathologies	6 vs 10	Not controlled No follow up Retrospective
Worster et al, 2002, Canada	Four diagnostic cohort studies Non-contrast helical CT vs IVU	Meta-analysis	Pooled positive likelihood ratio	23.15 (11.53–47.23) vs 9.32 (5.23–16.61) p = 0.046
			Pooled negative likelihood ratio	0.05 (0.02–0.15) vs 0.33 (0.23–0.48) p = 0.013
Pfister et al, 2003, Switzerland	113 Patients 55 had CT 58 had IVU Gold standard (spontaneous passage, endoscopic retrieval or stone identification on retrograde pyelography) CT vs IVU	Randomised prospective trial	Sensitivity	94.1% vs 94.2%	No indication of how patients were randomly assigned Direct procedural costs in hospital perspective only analysed Both imaging modalities not applied to every patient. No details of follow up
			Specificity	85.2% vs 90.4%
			Detection of other pathologies	7% vs 5%
Wang et al, 2008, Taiwan	82 Patients All had unenhanced CT and IVU on same day Composite gold standard (endoscopic evaluation, operative findings and pathology report) CT vs IVU	Diagnostic cohort	Sensitivity	98.5% vs 59.1%	No documentation of radiation dose utilised Cost effectiveness assumed but not analysed
			Specificity	100% vs 100%
			Detection of other diagnosis	58% vs 0%

Comment(s)

Most of the papers appraised showed that spiral CT has a better sensitivity and specificity than IVU. It also takes less time to perform and is better at revealing an alternative diagnosis, which may or may not be related to the patient’s symptoms. However spiral CT appears to be more expensive (although two studies showed no significant difference in costs from the hospital perspective) and is associated with a higher radiation dose than IVU. Furthermore, IVU is able to provide an idea of the functional status of the kidneys, whereas spiral CT has the advantage of being able to detect other pathologies.

Clinical Bottom Line

Spiral CT is more effective than IVU in the detection of renal or ureteric calculi.

References

1. Homer JA, Davies-Payne DL, Peddinti BS Randomised prospective comparison of non-contrast enhanced helical CT and IVU in the diagnosis of acute ureteric colic. Australasian Radiology 2001;45:285-290
2. Mendelson RM, Arnold-Reed DE, Kuan M et al. Renal colic: A prospective evaluation of non-enhanced spiral CT versus IVU Australasian Radiology. 2003;47:22-28
3. Worster A, Preya I, Weaver B, et al. The accuracy of noncontrast helical computer tomography versus intravenous pyelography in the diagnosis of suspected urolithiasis. A meta-analysis. Emerg Med 2002;40:280–6.
4. Pfister SA, Deckart A, Laschke S, et al. Unenhanced helical CT vs intravenous urography in patients acute flank pain: accuracy and economic impact. Eur Radiol 2003;13:2513–20.
5. Wang J-H, Sha S-H, Huang S-S, et al. Prospective comparison of unenhanced spiral CT and IVU in the evaluation of acute renal colic. J Chinese Med Assoc 2008;71:30–6.