Introduction

Top Abstract Introduction Methods Results Discussion Conclusions References

Ultrasonography, with or without plain abdominal radiography, has now largely replaced intravenous urography for the investigation of urinary tract infection in women and children.^1-11 Because men have a much lower incidence of urinary tract infection and a higher incidence of stone disease, intravenous urography remains the conventional investigation because underlying anatomical abnormalities may be detected. ^{12 13} Intravenous urography involves the use of ionising radiation and contrast media, the health risks of which are well documented with quantifiable morbidity and mortality. ^{14 15} Ultrasonography is cheaper and quicker than intravenous urography but depends more on the skill of the operator.⁵

We carried out a prospective study to establish whether abdominal radiography with ultrasonography can detect as many important abnormalities as intravenous urography in men presenting with proved urinary tract infection.

	Methods

Top Abstract Introduction Methods Results Discussion Conclusions References

From January 1995 to December 1996 we investigated 114 men who presented consecutively to the departments of urology and nephrology with proved urinary tract infection. Complete data were obtained on 100 patients. Ultrasonography and intravenous urography were performed on separate days and by different radiologists. The results of the first investigation, usually intravenous urography, were not known at the time of the second investigation.

For each patient we compared the results of ultrasonography alone, ultrasonography with plain radiography, and intravenous urography. We divided the urinary tract into the upper tract (defined as the kidneys and ureters) and the lower tract (bladder, prostate, and urethra). After the radiological assessments we saw and examined patients in the department of urology. Subsequent investigations included additional measurements of flow rates, cystoscopy, urodynamic assessment, and transrectal ultrasonography, when appropriate. Clinical diagnosis was on the basis of history, examination, and these investigations.

	Results

Top Abstract Introduction Methods Results Discussion Conclusions References

The mean (range) age of participants was 54 (18-88) years. Fifty three had had only one single infection, and 47 had more than one documented episode. We assessed 62 men with cystoscopy and four with full urodynamic investigation. We assessed flow rates in 90. Nine patients underwent transrectal ultrasonography. Of these, three underwent biopsy, and two were found to have prostate cancer. Table 1 summarises the results and compares the two radiological techniques. Fifty three patients had a detectable abnormality considered to be clinically significant. All important abnormalities detected by intravenous urography were also detected by ultrasonography or abdominal radiography.

Ultrasonography detected hydronephrosis in eight patients. In one case intravenous urography showed that the collecting system was within normal limits. Ultrasonography alone missed five out of six cases of urinary tract stones, but all were detected with the addition of plain radiography. In two cases ultrasonography misdiagnosed stones that were not detected by plain radiography or intravenous urography. In one case plain radiography misdiagnosed a stone not seen on intravenous urography. Although ultrasonography missed a bladder stone, this patient had been catheterised and the bladder was therefore empty. Three small, scarred kidneys were found by both methods. In one man ultrasonography misdiagnosed one kidney as small and scarred that was subsequently shown to be normal on intravenous urography.

Both methods identified a pelvic kidney. Ultrasonography failed to detect ureteric dilatation in three men. Two of these, however, had dilatation secondary to ureteric stones that were seen on the plain radiograph, the other had associated hydronephrosis secondary to chronic retention that was seen on ultrasonography. Intravenous urography identified two patients with non-functioning kidneys. Ultrasonography showed that these kidneys were small and scarred.

Ultrasonography detected a poorly emptying bladder in 34 patients compared with 26 detected with intravenous urography. Ultrasonography alone missed one bladder diverticulum. Table 2 shows the ability of abdominal radiography and ultrasonography to detect abnormalities seen on intravenous urography.

	Discussion

Top Abstract Introduction Methods Results Discussion Conclusions References

We have shown in this series that plain radiography with ultrasonography of the renal tract will detect most clinically important abnormalities that would normally be shown on intravenous urography. Patients with urinary tract infection are investigated to discover any underlying disease process which, if treated, will prevent or reduce further infections. In our study over half of the men with proved urinary tract infection had some abnormality.

The incompletely emptying bladder
The most common abnormality was an incompletely emptying bladder, either because of obstructed outflow, an underactive detrusor, or urethral stricture. Four out of seven patients with an underactive detrusor were diagnosed with formal urodynamic assessment. Patients with obstructed outflow were diagnosed either with urodynamics or clinically in the presence of a low urinary flow together with an incompletely emptying bladder in accordance with standard urological practice. The proportion of patients with obstruction was significantly higher in men aged over 50 years, which is predictable in view of the high prevalence of benign prostatic hypertrophy.¹⁶

The high proportion of patients who produced satisfactory measurements of flow rate was mainly due to the presence of a flow rate machine in the radiology department so that patients were confirmed to have a full bladder before micturition. The usefulness of such measurements in this group of patients has previously been emphasised by other authors, ^{13 17} but this has not been widely adopted. Our series indicates that for patients with a poorly emptying bladder a clinical diagnosis can usually be made with ultrasonography and flow rate; formal urodynamic studies are necessary in only a minority. Flow rate measurements are also helpful in the diagnosis and management of prostatitis.¹⁸ Ultrasonography has specific advantages over intravenous urography in the assessment of the lower urinary tract, including a measure of volume after micturition and size and projection of the prostate. Urologists use these features in recommending different treatments for obstruction of bladder outflow.

View larger version (24K): [in this window] [in a new window]   Proposed algorithm for investigations of men with urinary tract infection

Stones
Ultrasonography alone is not as effective as intravenous urography in the diagnosis of urinary tract stone disease, and indeed in our series five of the six cases of urinary tract stones were missed on ultrasonography alone. With the addition of plain radiography all the urinary tract stones were diagnosed, although without the additional information of precise site and degree of obstruction that intravenous urography would have shown.

If a proteus or another organism that can split urea is isolated from the urine the chance of underlying stone disease is considerably higher.¹⁹ Ultrasonography can detect stones at the vesicoureteric junction but cannot easily show the normal ureter or ureteric calculi in other positions; it can, however, show any secondary dilatation of the pelvicaliceal system. An intravenous urogram is superior in these circumstances and would therefore be the next investigation.

Upper tract dilatation and scarring
Ultrasonography misdiagnosed hydronephrosis in one patient. Dilatation, however, does not equate with obstruction, and it was only with the additional anatomical and functional information from intravenous urography that we could say that this patient's collecting system was normal. Ultrasonography wrongly diagnosed a small kidney that was subsequently shown to be normal on intravenous urography. In the two patients in whom a unilateral non-functioning kidney was seen on intravenous urography, ultrasonography also showed the kidneys to be small and scarred.

Safety
Previous authors have highlighted the added safety of ultrasonography compared with intravenous urography, ^{5 20} and certainly there is a saving in cost and time. Figures from the National Radiation Protection Board show that the radiation dose of an intravenous urographic examination is 2.5 mSv. This is equivalent to 14 months' background radiation and comes at a risk of induction of fatal cancer (in patients aged 16-69 with an average life expectancy) of 1:8000. The radiation dose of a normal plain radiograph is 0.7 mSv, which is equivalent to four months' background radiation and a risk of cancer of 1:30 000.

Incidental findings and symptoms
The importance and usefulness of incidental findings varies according to clinical presentation. In patients with right flank pain an ultrasound examination that shows gallstones may be helpful. Uncomplicated duplex collecting systems without dilatation were judged to be unimportant; if obstruction is present ultrasonography usually shows dilatation. Spinal abnormalities such as sacral agenesis may be important in younger patients with a suspected neuropathic bladder.

In 1990 Spencer et al compared use of ultrasonography with intravenous urography in men and women.²⁰ They showed the usefulness of ultrasonography and said that without the additional use of plain radiography a considerable number of abnormalities would be missed. They also found a high proportion of patients with incompletely emptying bladders, but the causes were not clear. This observation and our data should encourage the use of flow rate machines for patients presenting with urinary tract infection.

We propose the algorithm outlined in the figure for men with a proved urinary tract infection and agree that the high proportion of underlying abnormalities justifies active investigation in these patients.^21-23 Specialist referral is not indicated in younger men with normal results on ultrasonography and plain radiography who recover from the infection and regain normal flow.

	Conclusions

Top Abstract Introduction Methods Results Discussion Conclusions References

Intravenous urography remains an important investigation, particularly in the assessment of stone disease, upper tract obstruction, and any abnormalities seen on plain film and ultrasonography. In view of the hazards of ionising radiation and contrast media, however, ultrasonography, radiography, and determination of flow rate should be the initial investigations of choice in men presenting with a symptomatic and proved urinary tract infection.

	Acknowledgments

Ann Frost and Jayne Clarke typed the manuscript, and the audit department of the Lister Hospital retrieved the case records.

Contributors: See bmj.com

	Footnotes

Funding: None.

Competing interests: None declared.

The full version of this article appears on bmj.com

	References

Top Abstract Introduction Methods Results Discussion Conclusions References

1.	Alon U, Pery M, Davidai G, Berant M. Ultrasonography in the radiologic evaluation of children with urinary tract infection. Pediatrics 1986; 78: 58-64[Abstract].
2.	Lindsell D, Moncrieff M. Comparison of ultrasound examination and intravenous urography after a urinary tract infection. Arch Dis Child 1986; 61: 81-82[Abstract].
3.	Kenda R, Kenig T, Silc M, Zupancic Z. Renal ultrasound and excretory urography in infants and young children with urinary tract infection. Pediatr Radiol 1989; 19: 299-301[Medline].
4.	Kangarloo H, Gold RH, Fine RN, Diament MJ, Boechat MI. Urinary tract infection in infants and children evaluated by ultrasound. Radiology 1985; 154: 367-373[Abstract].
5.	Lewis-Jones HG, Lamb GHR, Hughes PL. Can ultrasound replace the intravenous urogram in preliminary investigation of renal tract disease? A prospective study. Br J Radiol 1989; 62: 977-980[Abstract].
6.	Sherwood T, Whitaker RH. Initial screening of children with urinary tract infections: is plain film radiography and ultrasonography enough? BMJ 1984; 288: 827[Medline].
7.	Fair WR, McClennan BL, Jost RG. Are excretory urograms necessary in evaluating women with urinary tract infection? J Urol 1979; 121: 313-315[Medline].
8.	Engel G, Schaeffer AJ, Grayhack JT, Wendel EF. The role of excretory urography and cystoscopy in the evaluation and management of women with recurrent urinary tract infection. J Urol 1980; 123: 190-191[Medline].
9.	Fowler Jr JE, Pulaski ET. Excretory urography, cystography, and cystoscopy in the evaluation of women with urinary-tract infection: a prospective study. N Engl J Med 1981; 304: 462-465[Medline].
10.	Fairchild TN, Shuman W, Berger RE. Radiographic studies for women with recurrent urinary tract infections. J Urol 1982; 128: 344-345[Medline].
11.	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? A prospective study. Br J Radiol 1991; 64: 221-224[Abstract].
12.	Lipsky BA. Urinary tract infections in men. Epidemiology, pathophysiology, diagnosis, and treatment. Ann Intern Med 1989; 110: 138-150[Medline].
13.	Booth CM, Whiteside CG, Milroy EJ, Turner-Warwick RT. Unheralded urinary tract infection in the male. A clinical and urodynamic assessment. Br J Urol 1981; 53: 270-273[Medline].
14.	Ansell G, Bettmann MA, Kaufman JA, Wilkins RA, eds. Complications in diagnostic imaging and interventional radiology. 3rd ed. Oxford: Blackwall Science, 1996.
15.	Ionising Radiation (Medical Exposures) Regulations 2000, National Radiation Protection Board 2000. www.nrpb.org.uk (accessed Oct 2001).
16.	Garraway WM, Collins GM, Lee RJ. High prevalence of benign prostatic hypertrophy in the community. Lancet 1991; 338: 469-471[Medline].
17.	Lepor H. Benign prostatic hyperplasia. In: Walsh PC, Retik AB, Vaughan ED, Wein AJ, eds. Campbell's urology. 7th ed. Philadelphia: WB Saunders, 1998:1453-1477.
18.	Nickel JC. Prostatitis: evolving management strategies. Urol Clin North Am 1999; 26: 737-751[Medline].
19.	Pead L, Maskell R. Urinary tract infection in adult men. J Infect 1981; 3: 71-78[Medline].
20.	Maskell R. Urine microscopy and culture in the selection of patients for urinary tract investigation. Br J Urol 1989; 63: 7-10[Medline].
21.	Spencer J, Lindsell D, Mastorakou I. Ultrasonography compared with intravenous urography in investigation of urinary tract infection in adults. BMJ 1990; 301: 221-224[Medline].
22.	Huland H, Busch R, Riebel T. Renal scarring after symptomatic and asymptomatic upper urinary tract infection: a prospective study. J Urol 1982; 128: 682-685[Medline].
23.	Busch R, Huland H. Correlation of symptoms and results of direct bacterial localisation in patients with urinary tract infections. J Urol 1984; 132: 282-285[Medline].

(Accepted 4 October 2001)