European Journal of Radiologv, 11 (1990)
87-90
Elsevier
87
EURRAD
00083
Ultrasonic diagnosis of ureteral calculi in patients with acute flank pain A. Aslaksen
and J.H. G6thlin
Department of Diagnostic Radiology, Haukeland
(Received
12 March 1990; accepted
Key words: Kidney, urography;
University Hospital, Bergen, Norwa_v
after revision 9 May 1990)
Kidney, ultrasound
study; Ureter, calculi; Hydronephrosis
Abstract
The diagnostic value ofultrasonography (US) and intravenous urography has been compared patients with severe acute flank pain of less than 72 hours’ duration. Ultrasonography was real-time transducer. Ureteral calculi were considered the final diagnoses in 46 patients, hydronephrosis. Ureteral calculi were correctly diagnosed by US in 17 patients (sensitivity is included as a positive sign of ureteral calculus, a correct diagnosis was suggested by US to be a valuable method in patients with previous contrast media reactions, but recommend renal colic is clinically suspected.
Introduction Intravenous urography (IVU) has been a standard investigative method in patients with acute flank pain for more than 50 years [ 121. The method has continuously been developed and refined with improved film-screen combinations, nephrotomography and more comfortable contrast media [4]. However, intravenous urography still carries a risk of contrast media reactions, uses ionizing radiation and is an expensive examination [ 35,141. Reports comparing IVU and ultrasonography (US) in patients with suspected renal and ureteral calculi reflected different experiences describing varying sensitivity and specificity in the detection of hydronephrosis and calculi [ 2,6,7,9, lo]. The present study was performed in a group of patients referred for IVU because of acute flank pain to assess the diagnostic value of US versus IVU in detecting and correctly localizing ureteral calculi, and, when there were multiple calculi, assess the correct number, and finally to determine the degree of obstruction. It Address for reprints: Diagnostic Radiology, Bergen, Norway. 0720-04SX/9O/rSO3.500
Aslak Aslaksen M.D., Department of Haukeland University Hospital, N-5021
1990 Elsevier
Science Publishers
in a prospective study comprising 123 consecutive performed transabdominally with a 5 MHz sector of which 35 with and 11 without accompanying 37%). If hydronephrosis with or without calculus in 34 patients (sensitivity 74%). We consider US urography as the standard imaging method when
was also intended to consider the economic consequences of replacing IVU with US as the initial radiologic examination in the same patient group. Material and Methods Patients From 1 September 1987 until 31 August 1988 all patients referred for IVU to the Department of Diagnostic Radiology were also examined with realtime US of the kidney and urinary tract. A total of 46 women and 77 men, median age 47 years (range 15-84) with acute unilateral flank pain of less than 72 hours’ duration, were included in the study. Two patients were excluded: one patient refused urography. A ruptured ovarian cyst with free peritoneal fluid was diagnosed by US in a young woman who was referred for gynecological examination without IVU. The final material thus consists of 121 patients. Urography IVU was routinely performed with a 35 x 43 cm film covering the kidneys and the bladder followed by 5-min (24 x 30 cm) and 15 min postinjection films (35 x 43 cm). Further radiograms were obtained in cases of impaired renal function due to ureteral obstruc-
B.V. (Biomedical
Division)
88
tion [ 41. Metrizoate (440 mg I/ml) 50 ml was utilized in 111 patients, iohexol (300 mg I/ml) 50 ml in 8 patients and ioxaglate (320 mg I/ml) in 2 patients. The IVU definitions of hydronephrosis were: (1) Mild: subtle distension of the fornices to frank distension of calices but the papillae still easily identified. (2) Moderate: calices ballooned outward and papillae barely visible. (3) Severe: marked hydronephrosis with a saclike collecting system [ 11. The urograms were interpreted as part of the normal routine in our department by one consultant in the Section of Uroradiology. The original descriptions have been used for comparison of results. Ultrasonography
US was performed by one physician (AA) with a real-time scanner with a 5 MHz sector phased-array transducer [ 151. All the examinations were recorded on video tape, both for economical reasons and because it gives an opportunity to review the dynamic examination. The patients were examined in supine and oblique positions, preferably with a well-distended urinary bladder, which, however, was not always achievable. Assessment of hydronephrosis by US was done by measuring the maximal calyx diameter: no hydronephrosis O-5 mm, mild hydronephrosis 6-10 mm, moderate hydronephrosis 11-15 mm, severe hydronephrosis > 16 mm diameter [ 131. Calculi detected by US were defined as hyperechoic foci with acoustic shadows. Suspected calculi with a diameter of 2 mm and less were not reported as positive, since they were not considered certain. The IVU results were routinely reported to the referring clinician, but the US results only when a positive finding differing from the IVU was disclosed, since only these US results could have impact on patient monitoring. The US investigator and the radiologist reporting the urograms had access to the same information given by the referring clinician. Each examination was performed on the same day without knowledge of the result of the other. Urography was considered reference method and ultrasonography was compared against it. The results of the two methods were compared after both were completed. After the study had been completed plain radiographs were reviewed in order to evaluate whether the combination of plain radiographs and US might increase the sensitivity as compared with US alone. The detection of calculi at plain radiographs were reported as definitely, equivocal and not visible.
TABLE 1 The urographic (IVU) and ultrasonographic ureteral calculi in 46 patients
(US) appearance
of
Diagnosis
IVU
us
Hydronephrosis and calculus Hydronephrosis and calculus detected after revision Hydronephrosis only Calculus without hydronephrosis Calculus and non-opacification of kidney Normal (no sign of hydronephrosis or calculus)
31 3 11 1 -
16 18 1 11
Total
46
46
Results Of the 46 ureteral calculi diagnosed, 42 were localized in the distal, 3 in the middle and 1 in the proximal third of the ureter. In 3 patients with hydronephrosis at IVU, calculi were suggested at US. Revision of the radiograms in these three patients showed distal calculi (Table 1). Ureteral calculi were suggested by US in 19 patients, including 2 cases with distal ureteral calculi without hydronephrosis in whom no signs of obstruction or calculi were detected at IVU (sensitivity 37 %, specificity 97%). In one of the patients control urography performed 1 month later was normal, while it was impossible to trace the other patient for follow-up. US detected 16 of the 34-calculi with associated hydronephrosis, 15 of which were lodged in the distal third of the ureter and one in the proximal. Of the 12 calculi without hydronephrosis, US detected one (Tables 1 and 2). Unilateral hydronephrosis was detected by IVU in 34 patients while US detected 33, and suggested mild hydronephrosis in a further 4. Three of these were considered non-hydronephrotic with no sign of obstruction at IVU and in the remaining patient IVU showed a ‘standing ureter’, suggesting a released calculus. All
TABLE 2 Correlation between ultrasonography and urography in detecting ureteral calculi in 121 patients referred for acute flank pain Ultrasonography
Urography
Calculus No calculus *Two false-positive
calculi.
Calculus
No calculus
14 29
5* 73
89
TABLE 3 Correlation
between ultrasonography
and urography in detecting hydronephrosis
Ultrasonography
and/or calculi in 121 patients referred for acute flank pain
Urography ___--
Calculus and/or hydronephrosis No calculus nor hydronephrosis
Calculus and/or hydronephrosis
No calculus nor hydronephrosis
35 11
6* 69 -___--
*Four hydronephroses
and two calculi considered
false-positive
(see text).
patients with hydronephrosis detected at urography had ureteral calculi (Table 3). Of the 46 patients with calculi at IVU, 30 had definitely stone shadows at plain radiograph and 12 patients had calculi not visible at plain radiographs. In 4 patients the findings were equivocal due to bowel contents and/or phleboliths. Of the 18 patients with hydronephrosis, but no sign of calculi at US, 11 had definite calculi at plain radiographs, 5 had calculi which were not visible, and 2 had equivocal findings. Of the 11 patients without hydronephrosis nor calculi at US, the figures were 5, 4 and 1, respectively. In one patient a calculus was reported on the plain radiogram, but no obstruction was seen after injection of contrast medium, and it was assumed that the calculus had been released during the examination. One patient reported that a ureteral calculus had been released per urethram 15 min before the examination, and both methods showed normal findings. In one patient a ureteropelvic junction stenosis was suggested both with IVU and US. Discussion
The passage of a renal calculus is a common cause of acute flank pain in young and middle-aged patients. IVU has been considered necessary for detecting and assessing the degree of hydronephrosis when an obstructing calculus is present. The diagnostic accuracy of an IVU is high in patients with obstructing ureteral calculi, but recent reports have challenged the role of IVU in the initial evaluation of patients with acute flank pain, and instead proposed US [2] as it considered a sensitive method for detection of varying degrees of hydronephrosis [ 11. When using urography as reference, ultrasonography in our study detected 17/46 ureteral calculi (sensitivity 37x), which corresponds with the also low sensitivity of 50 “/:,( 17/34 cases) in the report of Kuuliala et al. [ 91. Hill et al. [ 61 reported six pelvicalyceal and 35 ureteral calculi, of which 27 were detected by sonography (sensi-
tivity 66%). The present study indicates that most ureteral calculi are located in the distal third of the ureter at the time of diagnosis, and that calculi lodged in the ureterovesical junction can readily be detected through a well-distended bladder at US [6]. However, only the distal 4 cm of the ureter can be examined reliably through a distended bladder, and calculi lodged more proximal cannot be visualized, which constitutes a problem in US imaging of patients with acute renal colic. In 2 patients US suggested distal calculi. No signs of calculus or obstruction could be revealed at IVU and they were considered false-positive. Varying definitions of hydronephrosis at US have been proposed [ 1,2,6,9,10], and the correlation between hydronephrosis and obstruction is still not fully understood [ 8,111. The definition of hydronephrosis at US in our study had a cut-off with a 6 mm dilation of a calyx [ 131. With that limit there were four false-positive hydronephroses when compared to IVU, and one unilateral hydronephrosis at IVU was described normal at us. In the present study ureteral calculi without hydronephrosis was detected in 11 of 46 patients. Kuuliala et al. [ 91 found no signs of obstruction 11 of 34 patients with ureteral calculi. No false-positive hydronephroses were detected by US in their group. Ureteral calculi without hydronephrosis pose great diagnostic challenges. If the calculus is non-obstructive, there is little risk of kidney damage. However, if there is severe obstruction without hydronephrosis, kidney damage may occur. There may be a time relationship before an obstructive renal pelvis dilates, and there may be factors interfering with the normal peristalsis of the ureter [ 111. If the detection of a unilateral hydronephrosis with or without demonstrable calculus is included as a positive sign for a ureteral calculus the sensitivity of US is 74”’ /O? compared to 37% when calculi only is required as sign. This is also comparable to Kuuliala et al. [9] who found 79”/, and 50 %. A false-negative rate of 26 y; is high in a diagnostic test, and to date neither cost,
90
radiation risk or risk of contrast media reaction can outweigh IVU as the most valuable method in this group of patients. The retrospective review of plain radiographs suggested the presence of more calculi than US alone. However, the combination of plain radiographs were not included in our initial protocol. The review suggested that the addition of this examination might raise the sensitivity of US, suggesting the localization of a calculus. However, the inclusion of plain radiographs would also increase the patient radiation dose and the workload in the radiology department. From an economic point of view, replacement of IVU by US can give considerable savings [3]. However, the still low sensitivity does not permit US to be the only or even the initial examination in all patients with acute flank pain. We consider ultrasonography as a good alternative to intravenous urography in patients with known allergy or other known risk factors to contrast media and as an adjunct to urography in revealing the true nature of an obstruction in the distal ureter. However, when considering the ultrasonographic diagnosis one should be aware of the relatively high degree of false-negative results in evaluating ureteral calculi without associated hydronephrosis. Thus intravenous urography remains the standard imaging method in evaluating clinically suspected ureteral calculi. Acknowledgements The Study was supported by grants from A/S Medirad, Oslo, Norway, and the Norwegian Cancer Society.
References 1 Ellenbogen PH, Scheible FW, Talner LB, Leopold GR. Sensitivity of grey scale ultrasound in detecting urinary tract obstruction. AJR 1978: 130; 731-733. 2 Erwin BC, Carol1 BA, Sommer FG. Renal colic: the role of ultrasound in initial evaluation. Radiology 1984: 152; 147-150. 3 Geitung JT, Gothlin JH, Uhde A, Aslaksen A. Calculation of internal costs in a department of diagnostic radiology. Eur J Radio1 1988: 9; 181-182. 4 Gdthlin JH, Afonso JM, Hoiem L. Simplifying radiological examinations: can it really be done in urography. Eur J Radio1 1986: 6; 85-88. 5 Hartman GW, Hattery RR, Witten DM, Williamson B. Mortality during excretory urography: Mayo clinic experience. AJR 1982: 139; 919-922. 6 Hill MC, Rich JI, Mardiat JG, Finder CA. Sonography vs. excretory urography in acute flank pain. AJR 1985: 144; 1235-1238. 7 Jut11N, Holm-Bentzen M, Rygaard H, Holm HH. Ultrasonographic diagnosis of renal stones. Stand J Urol Nephrol 1987: 21; 135-137. 8 Kamholtz RG, Cronan JJ, Dorfman GS. Obstruction and the minimally dilated renal collecting system: US evaluation. Radiology 1989; 170: 51-53. 9 Kuuliala IK, Niemi LK, Ala-Opas MY. Ultrasonography for diagnosis of obstructing ureteral calculus. Stand J Urol Nephrol 1988: 22; 275-277. 10 Laing FC, Jeffrey RB, Wing WW. Ultrasound versus excretory urography in evaluating acute flank pain. Radiology 1985: 154; 613-616. 11 Lyons K, Matthews P, Evans C. Obstructive uropathy without dilatation, a potential diagnostic pitfall. Br Med J 1988: 296; 1517-1518. CG, Scholl AJ, Rowntree LG. 12 Osborne ED, Sutherland Roentgenography of urinary tract during excretion of sodium iodid JAMA 1923: 80; 368-373. 13 Peake SL, Roxburgh HB, Langlois SLP. Ultrasonic assessment of hydronephrosis of pregnancy. Radiology 1983: 146; 167-170. 14 Shehadi WH. Adverse reactions to intravascularly administered contrast media: a comprehensive study based on a prospective survey. AJR 1975: 124; 145-152. 15 Weil FS, Bihr E, Rohmer P, Zeltner F. 2. Examination techniques in Weill, Bihr, Rohmer, Zeltner: Renal sonography. 2nd edn pp. 27-38, Berlin: Springer-Verlag, 1987.
87-90
Elsevier
87
EURRAD
00083
Ultrasonic diagnosis of ureteral calculi in patients with acute flank pain A. Aslaksen
and J.H. G6thlin
Department of Diagnostic Radiology, Haukeland
(Received
12 March 1990; accepted
Key words: Kidney, urography;
University Hospital, Bergen, Norwa_v
after revision 9 May 1990)
Kidney, ultrasound
study; Ureter, calculi; Hydronephrosis
Abstract
The diagnostic value ofultrasonography (US) and intravenous urography has been compared patients with severe acute flank pain of less than 72 hours’ duration. Ultrasonography was real-time transducer. Ureteral calculi were considered the final diagnoses in 46 patients, hydronephrosis. Ureteral calculi were correctly diagnosed by US in 17 patients (sensitivity is included as a positive sign of ureteral calculus, a correct diagnosis was suggested by US to be a valuable method in patients with previous contrast media reactions, but recommend renal colic is clinically suspected.
Introduction Intravenous urography (IVU) has been a standard investigative method in patients with acute flank pain for more than 50 years [ 121. The method has continuously been developed and refined with improved film-screen combinations, nephrotomography and more comfortable contrast media [4]. However, intravenous urography still carries a risk of contrast media reactions, uses ionizing radiation and is an expensive examination [ 35,141. Reports comparing IVU and ultrasonography (US) in patients with suspected renal and ureteral calculi reflected different experiences describing varying sensitivity and specificity in the detection of hydronephrosis and calculi [ 2,6,7,9, lo]. The present study was performed in a group of patients referred for IVU because of acute flank pain to assess the diagnostic value of US versus IVU in detecting and correctly localizing ureteral calculi, and, when there were multiple calculi, assess the correct number, and finally to determine the degree of obstruction. It Address for reprints: Diagnostic Radiology, Bergen, Norway. 0720-04SX/9O/rSO3.500
Aslak Aslaksen M.D., Department of Haukeland University Hospital, N-5021
1990 Elsevier
Science Publishers
in a prospective study comprising 123 consecutive performed transabdominally with a 5 MHz sector of which 35 with and 11 without accompanying 37%). If hydronephrosis with or without calculus in 34 patients (sensitivity 74%). We consider US urography as the standard imaging method when
was also intended to consider the economic consequences of replacing IVU with US as the initial radiologic examination in the same patient group. Material and Methods Patients From 1 September 1987 until 31 August 1988 all patients referred for IVU to the Department of Diagnostic Radiology were also examined with realtime US of the kidney and urinary tract. A total of 46 women and 77 men, median age 47 years (range 15-84) with acute unilateral flank pain of less than 72 hours’ duration, were included in the study. Two patients were excluded: one patient refused urography. A ruptured ovarian cyst with free peritoneal fluid was diagnosed by US in a young woman who was referred for gynecological examination without IVU. The final material thus consists of 121 patients. Urography IVU was routinely performed with a 35 x 43 cm film covering the kidneys and the bladder followed by 5-min (24 x 30 cm) and 15 min postinjection films (35 x 43 cm). Further radiograms were obtained in cases of impaired renal function due to ureteral obstruc-
B.V. (Biomedical
Division)
88
tion [ 41. Metrizoate (440 mg I/ml) 50 ml was utilized in 111 patients, iohexol (300 mg I/ml) 50 ml in 8 patients and ioxaglate (320 mg I/ml) in 2 patients. The IVU definitions of hydronephrosis were: (1) Mild: subtle distension of the fornices to frank distension of calices but the papillae still easily identified. (2) Moderate: calices ballooned outward and papillae barely visible. (3) Severe: marked hydronephrosis with a saclike collecting system [ 11. The urograms were interpreted as part of the normal routine in our department by one consultant in the Section of Uroradiology. The original descriptions have been used for comparison of results. Ultrasonography
US was performed by one physician (AA) with a real-time scanner with a 5 MHz sector phased-array transducer [ 151. All the examinations were recorded on video tape, both for economical reasons and because it gives an opportunity to review the dynamic examination. The patients were examined in supine and oblique positions, preferably with a well-distended urinary bladder, which, however, was not always achievable. Assessment of hydronephrosis by US was done by measuring the maximal calyx diameter: no hydronephrosis O-5 mm, mild hydronephrosis 6-10 mm, moderate hydronephrosis 11-15 mm, severe hydronephrosis > 16 mm diameter [ 131. Calculi detected by US were defined as hyperechoic foci with acoustic shadows. Suspected calculi with a diameter of 2 mm and less were not reported as positive, since they were not considered certain. The IVU results were routinely reported to the referring clinician, but the US results only when a positive finding differing from the IVU was disclosed, since only these US results could have impact on patient monitoring. The US investigator and the radiologist reporting the urograms had access to the same information given by the referring clinician. Each examination was performed on the same day without knowledge of the result of the other. Urography was considered reference method and ultrasonography was compared against it. The results of the two methods were compared after both were completed. After the study had been completed plain radiographs were reviewed in order to evaluate whether the combination of plain radiographs and US might increase the sensitivity as compared with US alone. The detection of calculi at plain radiographs were reported as definitely, equivocal and not visible.
TABLE 1 The urographic (IVU) and ultrasonographic ureteral calculi in 46 patients
(US) appearance
of
Diagnosis
IVU
us
Hydronephrosis and calculus Hydronephrosis and calculus detected after revision Hydronephrosis only Calculus without hydronephrosis Calculus and non-opacification of kidney Normal (no sign of hydronephrosis or calculus)
31 3 11 1 -
16 18 1 11
Total
46
46
Results Of the 46 ureteral calculi diagnosed, 42 were localized in the distal, 3 in the middle and 1 in the proximal third of the ureter. In 3 patients with hydronephrosis at IVU, calculi were suggested at US. Revision of the radiograms in these three patients showed distal calculi (Table 1). Ureteral calculi were suggested by US in 19 patients, including 2 cases with distal ureteral calculi without hydronephrosis in whom no signs of obstruction or calculi were detected at IVU (sensitivity 37 %, specificity 97%). In one of the patients control urography performed 1 month later was normal, while it was impossible to trace the other patient for follow-up. US detected 16 of the 34-calculi with associated hydronephrosis, 15 of which were lodged in the distal third of the ureter and one in the proximal. Of the 12 calculi without hydronephrosis, US detected one (Tables 1 and 2). Unilateral hydronephrosis was detected by IVU in 34 patients while US detected 33, and suggested mild hydronephrosis in a further 4. Three of these were considered non-hydronephrotic with no sign of obstruction at IVU and in the remaining patient IVU showed a ‘standing ureter’, suggesting a released calculus. All
TABLE 2 Correlation between ultrasonography and urography in detecting ureteral calculi in 121 patients referred for acute flank pain Ultrasonography
Urography
Calculus No calculus *Two false-positive
calculi.
Calculus
No calculus
14 29
5* 73
89
TABLE 3 Correlation
between ultrasonography
and urography in detecting hydronephrosis
Ultrasonography
and/or calculi in 121 patients referred for acute flank pain
Urography ___--
Calculus and/or hydronephrosis No calculus nor hydronephrosis
Calculus and/or hydronephrosis
No calculus nor hydronephrosis
35 11
6* 69 -___--
*Four hydronephroses
and two calculi considered
false-positive
(see text).
patients with hydronephrosis detected at urography had ureteral calculi (Table 3). Of the 46 patients with calculi at IVU, 30 had definitely stone shadows at plain radiograph and 12 patients had calculi not visible at plain radiographs. In 4 patients the findings were equivocal due to bowel contents and/or phleboliths. Of the 18 patients with hydronephrosis, but no sign of calculi at US, 11 had definite calculi at plain radiographs, 5 had calculi which were not visible, and 2 had equivocal findings. Of the 11 patients without hydronephrosis nor calculi at US, the figures were 5, 4 and 1, respectively. In one patient a calculus was reported on the plain radiogram, but no obstruction was seen after injection of contrast medium, and it was assumed that the calculus had been released during the examination. One patient reported that a ureteral calculus had been released per urethram 15 min before the examination, and both methods showed normal findings. In one patient a ureteropelvic junction stenosis was suggested both with IVU and US. Discussion
The passage of a renal calculus is a common cause of acute flank pain in young and middle-aged patients. IVU has been considered necessary for detecting and assessing the degree of hydronephrosis when an obstructing calculus is present. The diagnostic accuracy of an IVU is high in patients with obstructing ureteral calculi, but recent reports have challenged the role of IVU in the initial evaluation of patients with acute flank pain, and instead proposed US [2] as it considered a sensitive method for detection of varying degrees of hydronephrosis [ 11. When using urography as reference, ultrasonography in our study detected 17/46 ureteral calculi (sensitivity 37x), which corresponds with the also low sensitivity of 50 “/:,( 17/34 cases) in the report of Kuuliala et al. [ 91. Hill et al. [ 61 reported six pelvicalyceal and 35 ureteral calculi, of which 27 were detected by sonography (sensi-
tivity 66%). The present study indicates that most ureteral calculi are located in the distal third of the ureter at the time of diagnosis, and that calculi lodged in the ureterovesical junction can readily be detected through a well-distended bladder at US [6]. However, only the distal 4 cm of the ureter can be examined reliably through a distended bladder, and calculi lodged more proximal cannot be visualized, which constitutes a problem in US imaging of patients with acute renal colic. In 2 patients US suggested distal calculi. No signs of calculus or obstruction could be revealed at IVU and they were considered false-positive. Varying definitions of hydronephrosis at US have been proposed [ 1,2,6,9,10], and the correlation between hydronephrosis and obstruction is still not fully understood [ 8,111. The definition of hydronephrosis at US in our study had a cut-off with a 6 mm dilation of a calyx [ 131. With that limit there were four false-positive hydronephroses when compared to IVU, and one unilateral hydronephrosis at IVU was described normal at us. In the present study ureteral calculi without hydronephrosis was detected in 11 of 46 patients. Kuuliala et al. [ 91 found no signs of obstruction 11 of 34 patients with ureteral calculi. No false-positive hydronephroses were detected by US in their group. Ureteral calculi without hydronephrosis pose great diagnostic challenges. If the calculus is non-obstructive, there is little risk of kidney damage. However, if there is severe obstruction without hydronephrosis, kidney damage may occur. There may be a time relationship before an obstructive renal pelvis dilates, and there may be factors interfering with the normal peristalsis of the ureter [ 111. If the detection of a unilateral hydronephrosis with or without demonstrable calculus is included as a positive sign for a ureteral calculus the sensitivity of US is 74”’ /O? compared to 37% when calculi only is required as sign. This is also comparable to Kuuliala et al. [9] who found 79”/, and 50 %. A false-negative rate of 26 y; is high in a diagnostic test, and to date neither cost,
90
radiation risk or risk of contrast media reaction can outweigh IVU as the most valuable method in this group of patients. The retrospective review of plain radiographs suggested the presence of more calculi than US alone. However, the combination of plain radiographs were not included in our initial protocol. The review suggested that the addition of this examination might raise the sensitivity of US, suggesting the localization of a calculus. However, the inclusion of plain radiographs would also increase the patient radiation dose and the workload in the radiology department. From an economic point of view, replacement of IVU by US can give considerable savings [3]. However, the still low sensitivity does not permit US to be the only or even the initial examination in all patients with acute flank pain. We consider ultrasonography as a good alternative to intravenous urography in patients with known allergy or other known risk factors to contrast media and as an adjunct to urography in revealing the true nature of an obstruction in the distal ureter. However, when considering the ultrasonographic diagnosis one should be aware of the relatively high degree of false-negative results in evaluating ureteral calculi without associated hydronephrosis. Thus intravenous urography remains the standard imaging method in evaluating clinically suspected ureteral calculi. Acknowledgements The Study was supported by grants from A/S Medirad, Oslo, Norway, and the Norwegian Cancer Society.
References 1 Ellenbogen PH, Scheible FW, Talner LB, Leopold GR. Sensitivity of grey scale ultrasound in detecting urinary tract obstruction. AJR 1978: 130; 731-733. 2 Erwin BC, Carol1 BA, Sommer FG. Renal colic: the role of ultrasound in initial evaluation. Radiology 1984: 152; 147-150. 3 Geitung JT, Gothlin JH, Uhde A, Aslaksen A. Calculation of internal costs in a department of diagnostic radiology. Eur J Radio1 1988: 9; 181-182. 4 Gdthlin JH, Afonso JM, Hoiem L. Simplifying radiological examinations: can it really be done in urography. Eur J Radio1 1986: 6; 85-88. 5 Hartman GW, Hattery RR, Witten DM, Williamson B. Mortality during excretory urography: Mayo clinic experience. AJR 1982: 139; 919-922. 6 Hill MC, Rich JI, Mardiat JG, Finder CA. Sonography vs. excretory urography in acute flank pain. AJR 1985: 144; 1235-1238. 7 Jut11N, Holm-Bentzen M, Rygaard H, Holm HH. Ultrasonographic diagnosis of renal stones. Stand J Urol Nephrol 1987: 21; 135-137. 8 Kamholtz RG, Cronan JJ, Dorfman GS. Obstruction and the minimally dilated renal collecting system: US evaluation. Radiology 1989; 170: 51-53. 9 Kuuliala IK, Niemi LK, Ala-Opas MY. Ultrasonography for diagnosis of obstructing ureteral calculus. Stand J Urol Nephrol 1988: 22; 275-277. 10 Laing FC, Jeffrey RB, Wing WW. Ultrasound versus excretory urography in evaluating acute flank pain. Radiology 1985: 154; 613-616. 11 Lyons K, Matthews P, Evans C. Obstructive uropathy without dilatation, a potential diagnostic pitfall. Br Med J 1988: 296; 1517-1518. CG, Scholl AJ, Rowntree LG. 12 Osborne ED, Sutherland Roentgenography of urinary tract during excretion of sodium iodid JAMA 1923: 80; 368-373. 13 Peake SL, Roxburgh HB, Langlois SLP. Ultrasonic assessment of hydronephrosis of pregnancy. Radiology 1983: 146; 167-170. 14 Shehadi WH. Adverse reactions to intravascularly administered contrast media: a comprehensive study based on a prospective survey. AJR 1975: 124; 145-152. 15 Weil FS, Bihr E, Rohmer P, Zeltner F. 2. Examination techniques in Weill, Bihr, Rohmer, Zeltner: Renal sonography. 2nd edn pp. 27-38, Berlin: Springer-Verlag, 1987.
