The diagnostic yield of intravenous urography
Mark A. Little1,
David B. Stafford Johnson2,
John P. O'Callaghan2 and
J. Joseph Walshe1
1 Departments of Nephrology and
2 Diagnostic Radiology, Beaumont Hospital, Dublin, Ireland
Correspondence and offprint requests to:
Professor Joseph Walshe, Consultant Nephrologist, Beaumont Hospital, Dublin 9, Ireland.
 |
Abstract
|
---|
Background. Intravenous urography (IVU) is considered an integral imaging component of the nephro-urological work-up in a wide array of clinical settings. At our institution there is an open-access policy with regard to requesting IVU studies.
Methods. In a prospective, blinded observational study we undertook to assess the diagnostic yield of IVU with respect to the source of referral (i.e. Urology, Nephrology, GP, A & E, other speciality) and the presenting features, such as renal colic, haematuria, bladder outflow obstruction, recurrent urinary tract infection (UTI) etc. Two hundred consecutive patients were evaluated.
Results. Overall, 23% of tests were positive. There was a highly significant difference in diagnostic yield between the groups (P<0.001 for both referral source and test indication). A positive result was most likely after referral by a kidney specialist (37.1%) and when the test indication was renal colic (42%) or haematuria (32%). The yield was <15% in all other circumstances, with 94.9% and 92.1% of GP- and other hospital speciality-initiated IVUs being negative. When investigating recurrent UTI, 91.7% of tests were negative and 86.2% were negative when the indication was bladder outflow obstruction.
Conclusions. It is suggested that an open access policy for IVU is not justified, especially when cost and the risk associated with contrast media and radiation exposure are taken into account. Our study supports the abandonment of routine IVU in the investigation of UTI and bladder outflow obstruction.
Keywords: bladder outflow obstruction; cancer; colic; diagnosis; haematuria; intravenous urogram; urinary tract infection
 |
Introduction
|
---|
Intravenous urography (IVU) has been considered an integral component of the nephro-urological work-up since its introduction by Swick in 1929 [1]. It is, however, associated with significant disadvantages in terms of cost and toxicity. The emergence of newer, cheaper, and less invasive techniques has challenged IVU as the procedure of choice in the investigation of recurrent urinary tract infection (UTI), haematuria, and suspected stone disease [24]. There is evidence to support the use of ultrasonography in place of IVU in a wide array of clinical settings [28]. Despite this, IVU remains the primary urinary tract imaging technique at many medical centres.
In this study we undertook to examine prospectively, and in a blinded fashion, the diagnostic yield in an unselected cohort of patients referred for IVU in a large teaching hospital and to question whether access to this investigation should be limited.
 |
Subjects and methods
|
---|
Two hundred consecutive patients referred for IVU over a 6-month period were included in the study. All IVUs were performed at Beaumont Hospital, site of the national kidney centre. An open access policy exists with respect to IVU, with referrals coming from the nephro-urological units, other specialities, the accident and emergency (A&E) department, and community-based family doctors. Patients were classified according to the referral source and the presenting complaint. IVU was performed using a standard technique. We did a full-length control film, an immediate tomogram, a 5-min spot view of the kidneys, a full-length radiograph of the abdomen after release of compression, and a full-length post-micturition film. The contrast agent used was Iopamidol 300 for all examinations. Supplementary oblique, compression, tomographic, or delayed films were performed at the discretion of the radiologist. All examinations were performed and interpreted by two radiologists (D.S.J, J.O'C), both of whom were blinded to the referral source and test indication. There were 114 females (57%) and 86 males (43%) with a mean age of 56 years (range 1785). Details of referral source and presenting complaint are summarized in Table 1
. Over half of the patients were referred by a kidney specialist (n=105, 52.5%). The most frequent indications were renal colic and recurrent UTI, together accounting for 126 patients (63%) (Table 2
). Rare miscellaneous clinical presentations included hypertension, suspected renal trauma, and non-specific symptoms, such as weight loss and lethargy. Results were recorded as `positive' if the examination revealed an abnormality deemed relevant in the clinical context and `negative' if the study was normal or demonstrated an incidental finding unrelated to the presenting complaint, e.g. simple renal cyst. Test positivity was correlated with the referral source and presenting complaint. Statistical analysis was performed using the
2 test and confidence intervals for odds ratio values were calculated using Miettinin's test-based approach.
 |
Results
|
---|
Of the 200 IVU studies performed, 46 (23%) were positive and 154 (77%) were negative. The abnormalities recorded are summarized in Table 3
. Renal or ureteric calculi were present in 37 cases (80.4% of positive results). No adverse reactions occurred during the study period. The correlation of test result with referral source and presenting complaint are summarized in Tables 4 and 5
. The difference in IVU yield between the groups was highly significant (P<0.001 for both referral source and test indication). With nephrology and urology referral respectively, 37.5 and 37.1% of the tests were positive. On the other hand, 94.9% of GP-initiated IVUs were negative, as were 92.1% of IVUs ordered by other hospital specialities. When the test indication was renal colic, 42.4% of IVUs were positive and with haematuria 31.8% were positive, but the yield was <15% in all other circumstances. When investigating recurrent UTI and bladder outflow obstruction respectively, 91 and 86.2% of tests were negative.
The odds ratio of an IVU being positive (Figure 1
) were 4.44 (95% CI, 1.9410.15) and 2.16 (95% CI, 0.627.4) for urology and nephrology referral respectively. This contrasts with odds ratio values of 0.14 (95% CI, 0.030.63) after GP referral, 0.24 (95% CI, 0.070.87) after referral by non-renal hospital speciality, and 0.39 (95% CI, 0.071.96) after referral from the A&E department. The corresponding odds ratio values when the IVU was performed for renal colic, haematuria, bladder outflow obstruction, and recurrent UTI were 4.75 (95% CI, 2.588.75), 1.66 (95% CI, 0.614.5), 0.49 (95% CI, 0.141.67) and 0.22 (95% CI, 0.080.62) respectively (Figure 2
).

View larger version (15K):
[in this window]
[in a new window]
|
Fig. 1. Odds ratio plot for probability of test positivity according to referral source (univariate analysis). Error bars indicate 95% confidence intervals.
|
|

View larger version (14K):
[in this window]
[in a new window]
|
Fig. 2. Odds ratio plot for test positivity according to presenting complaint (univariate analysis). Error bars indicate 95% confidence intervals.
|
|
 |
Discussion
|
---|
This study shows that in an unselected group of 200 patients the overall diagnostic yield was only 23%. The yield was heavily dependent on the source of referral for IVU. After urology referral the odds ratio of the test being positive was 4.44, as compared to 0.14 after GP referral and 0.24 after referral by a non-nephro-urological speciality. This contrasts sharply with the findings from a similar prospective study of 235 patients by Collie et al. [9] who reported an overall diagnostic yield of 37.4%. However, the demographic make-up differed markedly from that in our study, with 59% of their population being male and 67% having been referred for surveillance after resection of a transitional-cell carcinoma. Carcinoma made up 15.9% of positive findings in their study as compared to 2.2% in ours. In addition, Collie found no difference with respect to source of referral with a 30.6% diagnostic yield after GP referral, or test indication with a positive result in 31% of patients investigated for UTI. The dramatic difference when compared to the corresponding values of 5.1 and 8.3% in our study must be related to differing thresholds for referral for IVU between the two medical communities. Perhaps the level of access to IVU afforded to the GPs in Collie's study was less than that in ours or that all potential IVU studies were discussed with the radiology department before proceeding. In addition, because of the nature of our study, we did not control for age, sex, or test urgency (elective vs emergency) and it is possible that these variables were confounding.
The indications for IVU have been systematically challenged over the past 10 years, with a significant body of evidence now supporting the withdrawal of IVU as a screening test in patients with recurrent UTI and bladder outflow obstruction [4,7,1012]. In addition, several studies have looked at alternatives in the investigation of renal colic and haematuria, with various combinations of urinalysis, plain X-ray of kidneys, ureters, and bladder (KUB), ultrasound and helical CT scanning being proposed as viable, cost-effective options [2,3,5,6,8,1315]. Despite these studies, IVU maintains its position over ultrasonography in many centres and is still considered the gold standard test in the imaging of the pelvicalyceal system and in the diagnosis of upper renal tract transitional-cell carcinoma and reflux nephropathy. In our study, 44.5% of IVUs performed were for recurrent UTI or bladder outflow obstruction and, in support of previous studies, the yield was unacceptably low (8.3 and 13.8% respectively). In a large retrospective analysis, Newhouse et al.[11] found significant abnormalities in 1.4% of 1000 women investigated for recurrent UTI, a value that is unlikely to be different from the general population. In a smaller study by Fair et al. [12] there were nine abnormalities among 164 patients, none of which affected management. A prospective direct comparison of IVU vs KUB plus ultrasonography in 94 women with UTI, performed by McNicholas et al. [4], found that more useful information was derived from KUB+ultrasonography because of the ability to scan the pelvis at the same lime. In the absence of a history of UTI in childhood or renal insufficiency, the risks of IVU in this setting outweigh the benefits. IVU has traditionally been used to investigate UTI in the hope of identifying a correctable congenital pathology or reflux nephropathy. However, it is now appreciated that virtually all renal damage arising from reflux occurs in early life and that further infections in adulthood generally do not cause additional damage. Hypertension, azotaemia, infection in childhood, and urinary sediment abnormalities are more predictive of reflux nephropathy in adults than the occurrence of infection. Therefore, IVU has a place in investigation of UTI only in very selected cases, such as those with associated colic or haematuria.
The case against IVU in the investigation of bladder outflow obstruction (BOO) is equally strong. Mushlin and Thornbury [10] reviewed 2640 IVUs performed in the investigation of BOO; our results support their findings of a 20% abnormal IVU rate. A dilated upper tract was the commonest finding (5.3%), although this never influenced surgery (and perhaps merely served to delay it). The incidence of malignancy was 0.45%, a value similar to the general population, the majority of which would be detected by pre-operative cystoscopy.
The diagnostic yield after referral for haematuria (31.8%) and renal colic (42.4%) supports the utility of IVU in this setting. What remains unclear is whether ultrasonography with or without KUB is a more cost-effective approach with equivalent accuracy. This issue was addressed in a prospective study by Lewis-Jones et al. [16] in which the results from ultrasonography/KUB or IVU were identical in 81.4%. Additional information was provided in 12.5% of ultrasonography/KUB studies and 6.1% of IVU studies. Given that the cost of ultrasonography plus KUB is between 25 and 50% that of IVU [17], they concluded that IVU should be replaced in this setting. With respect to renal colic specifically, it appears that there remains quite a strong argument to retain the IVU as the investigation of choice when an initial ultrasonography plus KUB is negative, especially in centres without ready access to helical CT. False negatives occur with ultrasonography in the case of ureteric stones and when the upper tract has not yet become dilated. This fact has been illustrated by Juul et al. [5] in a series of 102 patients with suspected ureteric colic; 6% of cases of acute post-renal obstruction were missed by ultrasonography (all of these had `white kidney' on IVU) and IVU demonstrated 40 ureteric calculi as compared to 18 with ultrasonography. Similar findings were reported by Andreson and Wegner [18], with ultrasonography failing to detect 24% of ureteric calculi, and Yilmaz et al. [3], who reported a sensitivity of 19% and specificity of 97% with ultrasonography. The latter study evaluated emergency helical CT scanning in the investigation of renal colic, and found sensitivity and specificity of 94 and 97% respectively. The utility of non-contrast helical CT in the evaluation of renal colic has been emphasized by several recent North American [1921], European [22] and Australian [23] studies. Given the speed with which it can be performed, this modality is replacing IVU in many centres. However, in many institutions, such as ours, access to CT scanning is restricted to problematic cases because of limited resources. In these circumstances, IVU may be used following a negative ultrasonography plus KUB, especially when there is associated haematuria. It should be emphasized that IVU is most likely to demonstrate obstruction when the test is performed while the patient is experiencing pain, particularly in cases of non-stone urinary obstruction such as intermittent pelviureteric junction obstruction.
When haematuria is not accompanied by flank pain, the main pathology to exclude is renal-tract cancer. After the urine has been examined for red cell dysmorphism and red cell casts to exclude renal parenchymal disease, IVU has a role in subsequent diagnostic algorithms. This was supported by the reasonable diagnostic yield with respect to haematuria in our study (31.8%), although we found very few cancers (0.5% of all IVUs performed). However, whether IVU should be the initial investigation in patients with haematuria is debatable. Using previously published values for sensitivity and specificity in patients with microscopic haematuria, Corwin and Silverstein [8] found that algorithms beginning with IVU did not add accuracy while increasing both costs and patient morbidity. They concluded that the initial investigation should be cystoscopy for patients >40 years or ultrasonography for patients below 40 years and that IVU should not be used as a first line investigation when investigating painless microscopic haematuria.
When considering the potential yield of IVU in a particular setting, the large radiation dose of IVU, particularly when compared to ultrasonography plus KUB, must be taken into consideration. In a prospective study looking at the radiation dosearea product in 205 patients, Muller et al. [24] calculated the average dose as 1017 cGy/m2 with a mean of 3.7 films. With more films, the dose rises to 3000 cGy/m2. When compared to nuclear imaging, such as DMSA technetium scintigraphy, the radiation dose from IVU is twice as great in all but children under 1 year old [25]. However, the dose from IVU has been quantified as less than 1/3 that of helical CT [26], a fact that will become more important as the use of CT to investigate renal colic and haematuria expands.
We conclude that our study supports the withdrawal of routine IVU in the investigation of recurrent UTI and bladder outflow obstruction. We also suggest that access to IVU be restricted to in-hospital referral from either the urology or nephrology services. Access to emergency IVU for patients presenting acutely with renal colic in the A&E department would be reasonable if ultrasonography is negative and helical CT is not readily available.
 |
References
|
---|
-
Swick M. The discovery of intravenous urography: historical and developmental aspects of the urographic media and their role in other diagnostic and therapeutic areas. Bull NY Acad Med 1966; 42: 128151[ISI][Medline]
-
Spencer J, Lindsell D, Mastorakou I. Ultrasonography compared with intravenous urography in the investigation of adults with haematuria. Br Med J 1990; 310: 10741076[Free Full Text]
-
Yilmaz S, Sindel T, Arslan G et al. Renal colic: comparison of spiral CT, US and IVU in the detection of ureteral calculi. Eur Radiol 1998; 8: 212217[ISI][Medline]
-
McNicholas MM, Griffin JF, Cantwell DF. Ultrasound of the pelvis and renal tract combined with a plain film of abdomen in young women with urinary tract infection: can it replace intravenous urography? Br J Radiol 1991; 64: 221224[Abstract]
-
Juul N, Brons J, Torp-Pederson S, Fredfeldt K-E. Ultrasound versus intravenous urography in the initial evaluation of patients with suspected obstructing urinary calculi. Scand J Urol Nephrol [Suppl] 1991; 137: 4547[Medline]
-
Hendreson SO, Hoffner RJ, Aragona JL, Groth DE, Esekogwu VI, Chan D. Bedside emergency department ultrasonography plus radiography of the kidneys, ureters and bladder vs intravenous pyelography in the evaluation of suspected ureteral colic. Acad Emerg Med 1998; 5: 666671[Abstract]
-
Butler MR, Donnelly B, Komaranchat A. Intravenous urography in evaluation of acute urinary retention. Urology 1978; 12: 464466[Medline]
-
Corwin HL, Silverstein MD. The diagnosis of neoplasia in patients with asymptomatic microscopic hematuria: a decision analysis. J Urol 1988; 139: 10021006[ISI][Medline]
-
Collie DA, Paul AB, Wild SR. The diagnostic yield of intravenous urography: a demographic study. Br J Urol 1994; 73: 603606[ISI][Medline]
-
Mushlin AI, Thornbury JR. Intravenous pyelography: the case against its routine use. Ann Intern Med 1989; 111: 5870[ISI][Medline]
-
Newhouse JH, Rhea JT, Murphy RX, Pfister RC. Yield of screening urography in young women with urinary tract infection. Urol Radiol 1982; 4:187190[ISI][Medline]
-
Fair WR, McClellan BL, Jost RG. Are excretory urograms necessary in the evaluation of women with urinary tract infection? J Urol 1979; 121: 313315[ISI][Medline]
-
Aslaksen A, Gadeholt G, Gothlin JH. Ultrasonography versus intravenous pyelography in the evaluation of patients with microscopic haematuria. Br J Urol 1990; 66:144147[ISI][Medline]
-
Tasso SR, Shields CP, Rosenberg CR, Sixsmith DM, Pang DS. Effectiveness of selective use of intraveous pyelography in patients presenting to the emergency department with ureteral colic. Acad Emerg Med 1997; 4: 78084[Abstract]
-
Ghali AM, Elmalik EM, Ibrahim AI, Abdulhameed E, el Tahir MI. Cost-effective emergency diagnosis plan for urinary stone patients presenting with ureteric colic. Eur Urol 1998; 33: 529537[ISI][Medline]
-
Lewis-Jones HG, Lamb GH, Hughes PL. Can ultrasound replace the intravenous urogram in preliminary investigation of renal tract disease? A prospective study. Br J Radiol 1989; 62: 977980[Abstract]
-
Geitung JT, Gothlin JH, Uhde A, Aslaksen A. Calculation of internal costs in a department of diagnostic radiology. Eur J Radiol 1988; 8: 181182[Medline]
-
Andreson R, Wegner HEH. Intravenous urography revisited in the age of ultrasound and computerised tomography: diagnostic yield in cases of renal colic, suspected pelvic and abdominal malignancies, suspected renal mass and acute pyelonephritis. Urol Int 1997; 58: 221226[ISI][Medline]
-
Sheley RC, Semonsen KG, Quinn SF. Helical CT in the evaluation of renal colic. Am J Emerg Med 1999; 17: 2782
-
Chen MY, Zagoria RJ. Can noncontrast helical computed tomography replace intravenous urography for evaluation of patients with acute urinary tract colic. J Emerg Med 1999; 17: 299303[ISI][Medline]
-
Miller OF et al. Prospective comparison of unenhanced spiral computed tomography and intravenous urogram in the evaluation of acute flank pain. Urology 1998; 52: 982987[ISI][Medline]
-
Thibeau JF, Sourtzis S, Bellemans MA, Vandendris M. Comparison of spiral computed tomography without contrast media and intravenous urography in the diagnosis of renal colic. Progr Urol 1999; 9: 233238
-
Niall O, Russell J, MacGregor R, Duncan H, Mullins J. A comparison of noncontrast computerised tomography with excretory urography in the assessment of acute flank pain. J Urol 1999; 161: 534537[ISI][Medline]
-
Muller M, Heicappell R, Steiner U, Merkle E, Aschoff AJ, Miller K. The average dose-area product at intravenous urography in 205 adults. Br J Radiol 1998; 71: 210212[Abstract/Free Full Text]
-
Smith T, Gordon I, Kelly JP. Comparison of radiation dose from intravenous urography and 99Tcm DMSA scintigraphy in children. Br J Radiol 1998; 71: 314319[Abstract/Free Full Text]
-
Denton ER, MacKenzie A, Greenwell T, Popert R, Rankin SC. Unenhanced helical CT for renal colicis the radiation dose justifiable? Clin Radiol 1999; 54: 444447[ISI][Medline]
Received for publication: 7. 6.99
Accepted in revised form: 15. 9.99