Sonographic diagnosis of hydronephrosis in patients with spinal cord injury: influence of bladder fullness

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Sonographic Diagnosis of Hydronephrosis in Patients With Spinal Cord Injury: Influence of Bladder Fullness Liu-Ing

Bih, MD, Su-Ju Tsai, MD, Li-Chen Tung, MD

ABSTRACT. Bih L-I, Tsai S-J, Tung L-C. Sonographic diagnosis of hydronephrosis in patients with spinal cord injury: influence of bladder fullness. Arch Phys Med Rehabil 1998;79: 1.557-9. Objective: To investigate and compare the diagnostic accuracy of prevoid and postvoid renal sonography in detecting hydronephrosis in patients with spinal cord injury. Study Design: A prospective, blind comparison of renal sonography and excretory urography in 67 spinal cord injury patients who underwent periodic urologic examinations. Renal sonography was performed twice, once when the patient’s bladder was physiologically full (prevoid) and again when it was just emptied (postvoid). Results: Of 140 kidneys, 24 from 16 patients were found to have hydronephrosis by excretory urography; 116 kidneys had normal urogram findings. Prevoid sonography missed the diagnosis of hydronephrosis in one kidney and showed hydronephrosis in 18 kidneys that had normal results on excretory urography (sensitivity, 95.8%; specificity, 84.5%; negative predictive value, 99.0%). The postvoid sonograms did not detect hydronephrosis in four kidneys and showed hydronephrosis in six kidneys that had normal results on excretory urography (sensitivity, 83.3%; specificity, 94.8%; negative predictive value, 96.5%). Compared to excretory urography, renal sonography detected eight more upper urinary tract abnormalities, which were confirmed by cystograms or radioisotopic renograms. Conclusion: Performing renal sonography while the bladder is full can increase the sensitivity in detecting hydronephrosis in asymptomatic spinal cord injured patients. 0 1998 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation BELONG, PERIODIC urologic surveillance for patients Ldeclinewith spinal cord injury (SCI) has been responsible for the in urologic morbidity and mortality rates.’ Diagnosis of hydronephrosis is the single most important determination to be made during the periodic urologic evaluation of SC1 patients.2 In 1973, Sanders and Bearman first mentioned that renal sonography was a sensitive screening technique for excluding urinary tract obstruction. Since the early 1980s researchers from many institutions1.2,4-7 have recommended that renal

From the Department of Rehabilitation Medicine, Chung-Shan Medical College (Dr. Bib), and the Department of Rehabilitation Medicine, Taichung Rehabilitation Hosoital iDrs. Tsai. Dow). Taichunz Citv. Taiwan. S;bmi&d for public&n April 2:199k Accepted in revised form July 28, 1998. Presented at the Eighth World Congress of the International Rehabilitation Medicine Association, September 2, 1997, Kyoto, Japan. No commercial patty having a direct or indirect interest in the subject matter of this article has or will offer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to L.I. Bih, MD, T&hung Rehabilitation Hospital, 1142 Section 3, Tay-Yaun Road, Taichung, Taiwan. 0 1998 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003-9993/98/7912-4951$3.00/O

sonography be used on an alternating basis with excretory urography (EXU) for the routine follow-up of SC1patients. Many authors have reported that a nearly full bladder might facilitate visualization of the pelvicaliceal systems and the ureters on excretory urograms * lo because diuresis and bladder filling increase pelvic pressure and ureterovesical outflow resistance, consequently producing pelvic and ureteric dilatation.i1,t2 It is a reasonable assumption that physiologic diuresis and bladder filling can increase the sensitivity of sonography in detecting mild upper urinary tract obstruction. In reviewing the literature, we found that authors rarely mentioned the status of bladder filling in using renal sonography for the diagnosis of hydronephrosis in SC1 patients.2,4-7Therefore, we conducted this prospective study to investigate the influence of physiologic bladder fullness on the sonographic diagnosis of hydronephrosis in SC1patients. METHODS Subjects Sixty-seven patients with SC1 undergoing initial or annual urologic examinations at Taichung Rehabilitation Hospital from January 1993 to June 1996 entered the study. There were 55 men and 12 women (mean age, 32.5yrs; range, 12 to 66yrs) with a mean onset duration of 45.5 months (range, 2mo to 19yrs). Fifty-five patients suffered from upper motor neuron neurogenic bladder dysfunction and 12 suffered from lower motor neuron lesions. Procedures The monitoring programs consisted of a full medical history, physical examinations, laboratory tests, roentgenograms of kidneys, ureters, and bladder, sonograms of kidneys and bladder, radioisotopic renogram (renal scan), EXU, and voiding cystourethrogram (VCUG). Cystometry and cystoscopy were done when some related abnormalities were suspected or detected. The above procedures were usually completed within 2 weeks. The ultrasound equipment used was an Aloka SD-500 portable apparatus with a 3.5MHz transducera Patients were asked to take 300 to 500mL fluid 1 hour before the test. Before renal sonography was performed, bladder volume was evaluated by transabdominal bladder sonography. Renal sonograms were first taken when the bladder was physiologically full. After voiding or catheterization, the second renal sonograms were taken. All sonograms were performed by the same physiatrist, who interpreted the results without knowing the results of other examinations. Hydronephrosis on the sonogram was graded from 0 to IV according to the criteria developed by the Society for Fetal Urology. l3 In grade 0, there is no separation over central echo complex. Grade I hydronephrosis shows dilation of the renal pelvis only. With grade II hydronephrosis, the renal pelvis and a few calices are dilated. A diagnosis of grade III hydronephrosis requires that all calices be dilated. Grade IV hydronephrosis may have a similar appearance to grade III, but the renal cortex over the calices is thinned. The results of EXU were all interpreted by the same Arch

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DIAGNOSIS

radiologist according to the criteria described by Lloyd.14 The EXU results were used as the standard in the detection of hydronephrosis, and were compared with the prevoid and postvoid renal sonograms. The sensitivity, specificity, and negative predictive value were calculated. The VCUG and renal scan findings were applied to complete the clinical diagnosis. The classification of vesicoureteric reflux (VUR) was made according to the criteria of the International Reflux Study Committee. I5 The results of the renal scans were classified using the criteria described by Bih.16 RESULTS Three of the 67 patients received urologic survey twice in two consecutive years, so there were study results of 140 kidneys. Of 140 kidneys, 24 showed hydronephrosis by EXU and 116 had normal urograms. Prevoid renal sonography showed one false-negative result and 18 false-positive results (sensitivity, 95.8%; specificity, 84.5%; negative predictive value, 99.0%). Four false-negative results and six false-positive results occurred in the postvoid sonograms (sensitivity, 83.3%; specificity, 94.8%; negative predictive value, 96.5%). The discrepancy between the sonographic and urographic diagnoses occurred most often in cases of mild hydronephrosis. All moderate or severe cases of hydronephrosis on EXU were detected by both prevoid and postvoid renal sonography. The study results of four patients with false-negative postvoid renal sonograms (table 1) revealed grade I pyelocaliectasis. For the first patient, who had false-negative results in both prevoid and postvoid studies, all other tests including roentgenograms of kidneys, ureters, and bladder, renal scan, and VCUG, were normal; therefore, no clinical management was indicated. The remaining three patients with false-negative postvoid studies showed VUR in VCUG or excretion delay (with peak time longer than 10 minutes) in renal scan. Their prevoid sonograms revealed grade I to II hydronephrosis. The results of IO patients who had 12 false-positive sonograms in prevoid status but not in postvoid status are summarized in table 2. In four patients, all other diagnostic tests were negative. Bladder overdistention occurred in one patient. The leakage pressure of the bladder was abnormally high in two patients, and excretion delay (with peak time longer than 10 minutes) in the renal scan was noted in three patients. The results of five patients who had six false-positive sonograms in both prevoid and postvoid status are summarized in table 3. These patients all had significant clinical problems, including contralateral severe hydronephrosis resulting in ipsilateral renal compensatory hypertrophy, excretion delay (one with half clearance time greater than 30 minutes and two with peak time longer than 10 minutes) in renal scan, and a grade III VUR. Causes to induce false-positive renal sonograms included bladder overdistention in two, high intravesical pressure in Table 1: Summary With False-Negative

of Studies in 4 Patients Sonograms: 4 Postvoid Renal Sonography Prevoid

1 2 3

Grl Gr I Grl

GrO Gr I Gr II

GrO GrO GrO

All negative Gr I VUR Gr Ill VUR

4

Gr I

Gr I

GrO

Excretion

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Postvoid

urogram;VCUG, Gr, grade; VUR,

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Units)

Renal Sonography Postvoid

4 1, bilat

GrO Gr 0

Gr I Gr I

GrO GrO

All negative Bladder volume

1, bilat I*

Gr 0 GrO

Gr I Gr II

GrO GrO

Leakage Leakage

pressure pressure

3

GrO

Gr I

GrO

Excretion

delay

Abbreviations: gram; CMG, bilateral: VUR, * This patient’s gram and Gr I

EXU, excretory cystometrogram; vesicoureteric contralateral hydronephrosis

Renal Scan, VCUG, CMG

800mL 1 lScmHzO 123cmH20 in RS

urogram;VCUG, voiding cystourethroGr, grade; RS, renal scan; bilat, reflux. renal unit revealed Gr I VUR on cystoon EXU and sonogram.

three kidneys (table 2), and compensatory hypertrophy in one kidney (table 3). DISCUSSION The effect of bladder filling on urine transport is well known. As early as 1903, Sampson (as quoted by Pajewski and Manor9) advanced the idea that the ureterovesical junction is passively occluded with increased vesical pressure, due to the oblique passage of the ureter through the bladder wall. Previous studies have shown that full bladder urography can be used to improve the visualization of the pelvicalyceal systems and the ureters.8-10Thus, it is no longer considered necessary that patients be dehydrated in preparation for EXU.17 JonesI conducted a study measuring the pelvic and bladder pressure simultaneously during different stages of bladder filling. The results showed that pelvic pressure increased gradually as urine flowed into the bladder in patients with high bladder pressure. As observed in our study, for the patients who had different grades of hydronephrosis, the diameter of the pelvicaliceal system was prominently wider on prevoid sonograms than on postvoid. To increase the sensitivity of detecting hydronephrosis on sonography, our study protocol required sonograms to be taken after patients drank 300 to 500mL of fluid to induce a physiologically full bladder. Overhydration or overdistention of the bladder were avoided because that might induce false-positive results, as demonstrated by Morin, l* whose subjects drank 1,600mL of fluid prior to sonography, with a false-positive rate of 73.7%. In our study, there were four false-positive results, which were probably caused by overhydration and overdistention of bladder (table 2). The prevoid sonograms showed one false-negative study compared to EXU. All the other urologic tests in that case were negative, except for mild pyelocaliectasis on EXU. This might be considered a false-positive result of EXU due to contrast induced diuresis. From our experience in this study, full bladder sonography is excellent in identifying hydronephrosis. The postvoid sonograms revealed three more false-negative

Cases (4

in RS

in 10 Patients (12 Renal Prevoid Sonograms

Prevoid

Table 3: Summary With False-Positive

voiding cystourethrovesicoureteric reflux;

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2: Summary of Studies With False-Positive

EXU

1 1, bilat 2 delay

Bih

Cases (n)

Renal Scan, VCUG, CMG

EXU

Arch

Table

(4 Renal Units) and 1 Prevoid

Patients

Abbreviations: EXU, excretory gram; CMG, cystometrogram; RS, renal scan.

OF HYDRONEPHROSIS,

1

of Studies Prevoid

in 5 Patients and Postvoid

(6 Renal Units) Sonograms

Renal Sonography EXU

Prevoid

Postvoid

GrO Gr 0

Gr I Grl

Grl Gr I

Compensatory Excretion delay

Renal Scan, VCUG, CMG

GrO GrO

Gr I Grl

Gr I Grl

Excretion delay Gr Ill VUR

Abbreviations: EXU, excretory urogram;VCUG, gram; CMG, cystometrogram; bilat, bilateral; scan; VUR, vesicoureteric reflex.

hypertrophy in RS in RS

voiding cystourethroGr, grade; RS, renal

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DIAGNOSIS

results when compared to the prevoid studies. These three patients suffered from early upper urinary tract abnormalities; early intervention preserved the renal function. From these results, performing sonography with a full bladder increased the sensitivity of detection of hydronephrosis from 83.3% to 95.8%. Of the 10 patients with exclusively false-positive prevoid sonograms, three revealed excretion delay by renal scan. Among the five patients who had six false-positive prevoid and postvoid sonograms, five upper urinary tract abnormalities were detected by VCUG or renal scan. We found that renal sonograms, especially prevoid ones, can identify the upper urinary tract in early compromised stage. For these cases, close follow-up of urinary tract function is indicated. Sonography is now widely available and has been shown to be effective in the evaluation of urinary calculi, renal and bladder masses, bladder volume, and bladder wall changes, as well as hydronephrosis.7 Furthermore, advantages such as its simplicity, noninvasiveness, lack of radiation, lack of side effects, and ease of reproducibility, make sonography a popular and efficient screening instrument for urologic follow-up of SC1 patients. In contrast, EXU carries a certain degree of inconvenience and risk to patients, many of whom refuse to undergo the unpleasant test repetitively. 2,6Sonography represents an alternative method of imaging the kidneys. The desired information about renal size and contour, the state of the renal pelvis and calices (obstructed or not), and the presence or absence of calculi or parenchymal disease can be more easily and rapidly obtained with sonography than with EXU.i9 We suggest that renal sonography be performed with a full bladder and be repeated after the patient voids, if hydronephrosis is noticed. Other invasive urologic examinations such as EXU, VCUG, cystometry, or cystoscopy are indicated when new abnormalities are demonstrated. The above regimen is effective for the early detection of urinary complications and increases the willingness of SC1patients to comply with regular urologic follow-up. CONCLUSIONS Noninvasive and easily reproducible renal sonography is a sensitive test to detect hydronephrosis in asymptomatic SC1 patients. Performing renal sonography while the bladder is physiologically full increases the test’s sensitivity for detecting hydronephrosis. Renal sonography is more sensitive than EXU in early detection of upper urinary tract dysfunction. Renal sonography can replace EXU or may be used alternatively with EXU in routine periodic follow-up for asymptomatic SC1 patients. References 1. Lloyd LK. Long-term follow up of neurogenic bladder. Phys Med Rehabil North Am 1993;4:391-409.

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2. Rao KG, Hackler RH, Woodlief RM, Ozer MN, Fields WR. Real-time renal sonography in spinal cord injury patients: prospective comparison with excretory urography. J Urol 1986;135:72-7. 3. Sanders RC, Bearman S. B-scan ultrasound in the diagnosis of hydronephrosis. Ultrasound 1973;105:375-82. 4. Brandt TD, Neiman HL, Calenoff L, Greenberg M, Kaplan PE, Nanninga JB. Ultrasound evaluation of the urinary systemin spinal cord iniurv natients. Ultrasound 1981:141:473-7. 5. Calendff L:Neiman HL, Kaplan Pe, Nanninga JB, Brandt TD, Hamilton BB. Urosonography in spinal cord injury patients. J Urol 1982;128:1234-7. 6. Morcos SK, Thomas DG. A comparison of real-time ultrasonography with intravenous urography in the follow-up of patients with spinal cord injury. Clin Radio1 1988;39:49-50. I. Bodner DR, Witcher M, Resnick MI. Application of office ultrasound in the management of the spinal cord injury patient. J Urol 1990;143:969-72. 8. Nogrady MB, Dunbar JS, MacEwan DW. The effect of bladder distention on the intravenous pyelogram. Am J Roentgen01 1963; 90:37-54. 9. Pajewski M, Manor A. Enhanced intravenous urography in infants and children produced by distention of the urinary bladder. Clin Radio1 1973;24:376-80. 10. Gill WB, Curtis GA. The influence of bladder fullness on upper urinary tract dimensions and renal excretory function, J Urol 1977;117:573-6. 11. Coolsaet BO. Upper urinary tract function. In: Yalla SV, Mcguire EJ, Elbadawi A, Blaivas JG, editors. Neurourology and urodynamits: principles and practice. New York: Macmillan; 1988. p. 41-4. 12. Jones DA, Holden D, George NJR. Mechanism of upper tract dilatation in patients with thick walled bladders, chronic retention of urine and associated hydroureteronephrosis. J Urol 1988;140: 326-9. 13. Fernbach SK, Maizels M, Conway JJ. Ultrasound grading of hydronephrosis: introduction to the system used by the Society for Fetal Urology. Pediatr Radio1 1993;23:478-80. 14. Llovd LK. Dubovskv EV. Bueschen AJ. Witten DM. Scott JW. Kuhlemeier K, et al. Comprehensive renal scintillation’procedures in spinal cord injury: comparison with excretory urography. J Urol 1981;126:10-3. 15. International Reflux Study Committee. Medical versus surgical treatment of primary vesicoureteral reflux: a prospective intemational reflux study in children. J Urol 1981;125:277-83. 16. Bih LI, Changlai SP, Ho CC, Lee SP. Application of radioisotope renography with technetium-99m mercaptoacetyltriglycine on patients with spinal cord injury. Arch Phys Med Rehabil 1994;75: 982-6. 17. Hricak H, Tangho EA. Radiology of the urinary tract. In: Tanagho EA, McAninch, editors. Smith’s general urology. London: Appleton &Lange; 1992. p. 61-114. 18. Morin ME, Baker DA. The influence of hydration and bladder distention on the sonographic diagnosis of hydronepbrosis. J Clin Ultrasound 1979;7:192-4. 19. Arafa NM, Fathi MM, Safwat M, Moro H, Torkey H, Kenawi M, et al. Accuracy of ultrasound in the diagnosis of nonfunctioning kidneys. J Urol 1982;128:1165-9. Supplier a. Aloka Co., Ltd., 6-22-l Mure, Mitaka-shi, Tokyo, 181 Japan.

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