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Are Modern Imaging Techniques Over Diagnosing Ureteropelvic Junction Obstruction?
~22-5347/95/1542-0659$03.00/0 JOURNAL OF UROLOGY Copyright 0 1995 by AMERICANURUL~CICAL ASSOCLATION, hc.
Vol. 154.659-661. August 1995 Printed in U S A
Hydronephrosis: Antenatal and Postnatal Diagnosis ARE MODERN IMAGING TECHNIQUES OVER DIAGNOSING URETEROPELVIC JUNCTION OBSTRUCTION? JOHN S. WIENER, GREGOR K. EMMERT, HRAIR-GEORGE MESROBIAN,* ARTHUR W. WHITEHURST, L. RICHARD SMITH AND LOWELL R. KING From the Division of Urology, Department of Surgery and Division of Biometry, Department of Community and Family Medicine, Duke University Medical Center and Durham Regional Hospital, Durham and Department of Urology, University of North Carolina a t Chupel Hill, Chapel Hill, North Carolina
ABSTRACT
Since the widespread use of real-time ultrasonography in the early 19808, ureteropelvic junction obstruction has been diagnosed at earlier ages and prenatally on a presumptive basis. However, substantial controversy exists over the diagnosis and treatment of ureteropelvic junction obstruction. We conducted an epidemiological study to determine if modern imaging techniques are leading to the over diagnosis of ureteropelvic junction obstruction. Records were collected retrospectively from 3 hospitals serving 2 adjacent counties to determine the number of pyeloplasties performed in 1970 to 1992.The 2 university hospitals and 1 large private hospital provide a wide variety of services and choice of urologists, and so it was assumed that most patients requiring pyeloplasty in the area would be captured. Of the 555 pyeloplasties 240 (43%) were performed on children 12 years old or younger. Logistic regression analysis revealed an overall increase of pyeloplasties per year of 56.8% in 23 years, which was not markedly dif'ferent from the population growth in the area in the same period (49.3%). A statistically signi6cant increase in the number of pyeloplasties performed in the first year of life was noted. This trend appeared to begin in 1981:8 pyeloplasties were performed in the first year of life between 1970 and 1980 compared to 91 between 1981 and 1992. Pyeloplasties in children 1 to 6 years old increased with time at a much lower rate that was not statistically significant and the number of pyeloplasties decreased in those 7 to 12 years old. Therefore, it appears that modern imaging techniques are not leading to an over diagnosis of ureteropelvic junction obstruction but to detection of the disease at an earlier age. Key
Woms: ureter, kidney, incidence, ultrasonography
Ureteropelvic junction obstruction is the most common teropelvic junction obstruction should be aggressively purcongenital abnormality of the urinary tract.' Since the ad- sued because an inverse relationship exists between age vent of real-time prenatal sonography in the early 1980~1, and the ability of the kidney to recover from the deleterithere has been a dramatic increase in the detection of hydro- ous effects of obstruction.6-7 The degrees of impairment of nephrosis in utero and, thus, the diagnosis of ureteropelvic function below which level pyeloplasty is performed are junction obstruction in newborns. At Boston Children's Hos- often decided arbitrarily.8 Conversely, others have demonpital hydronephrosis has been detected almost 5 times more strated that the function of obstructed kidneys can sponfrequently and the proportion of these cases diagnosed as taneously improve and the surgical relief of obstruction ureteropelvic junction obstruction has nearly doubled since does not always ameliorate function.9.10 The literature is maternal ultrasonography became routine.2 A prospective replete with studies on each side stating their bias. We sought to examine the effects of modern imaging studstudy of prenatal ultrasonography of 6,292 pregnant women in Britain revealed ureteropelvic junction obstruction at a ies on the incidence of pyeloplastiesperformed for the correction of ureteropelvic junction obstruction. A retrospective rate of 1.9 per 1,000live births.3 The diagnosis and subsequent treatment of unilateral review of the pyeloplasty incidence at 3 hospitals serving 2 ureteropelvic junction obstruction in newborns are contro- adjacent urban counties in the last 2 decades was conducted versial. There is disagreement even about the definition of to identify any possible new trends in treatment of this the disease. Some diagnose ureteropelvic junction obstruc- disease. By including university medical centers and the sole tion on anatomical grounds while others insist that ob- private hospital serving the area, we attempted to balance struction can only be defined by documenting reduced re- diagnostic and therapeutic biases that may be inherent at nal function.4 The furosemide renogram has become an any 1 institution or with any 1urologist. important tool in determining renal function and diagnosing obstruction but dehydration, poor renal function and MATERIAL AND METHODS variations in methodolob often affect results. In terms of We retrospectively reviewed the recoTd data bases therapy, many believe that early repair of unilateral urefor DveloDlastvmrformed a t Duke Universitv MedicalCenter
in Chapel Hill, North Carolina. These 3 hospitals provide all urological care for Durham and Orange Counties, North Carolina, excluding the Department of Veterans M a i m Hospital in Durham, and include 2 of the 3 urology resident training programs in the state. Records were available fmm 1970 to 1992.No urologist performed surgery at more than 1 hospital. Because surgeons may have defined obstruction slightly differently and changed the threshold for repair during the study, no attempt was made to ascertain indications for surgery. Therefore, in this study significant ureteropelvic junction obstruction was defined by the performance of pyeloplasty. Surgical technique, outcome and complications
TABLE1. Pyeloplasty by hospital and patient
Duke University Medical Center North Carolina Memorial Hospital Durham Regional Hospital Totals
54 44 1 99
0
0
--
0
6
0
g
0 0 0 -
S
L
0
*
0
0
0
R
-
0 0 0
"
0
.
. . .
;
. . .
.
. .
.
.
.
.
.
.
-
.
t
age FIG.
Age at Pyeloplasty Younger Than 1 Yr. '-I2
,=a44
p
2. Analysis of pyeloplasties by agr and t l m c pctforniod
adults 151 pyeloplasties were performed aftcar 1980. tvtiich rep resented a decrease fmm 164 performed fmm 1$17()to IC)80.
Older Yrs. m a n 12yrs.
97 25
213 34
364 103
3
3
-88
141
315
555
l)IS[.l I S S I ( 1 N
TO avoid controversies in the dt.tinition of tlrt~tt~ropelvic junction obstruction we focused our s t u d y o n t l l r . Ilicldrnce of
OVER DIAGNOSING URETEROPELVIC JUNCTION OBSTRUCTION
661
pyeloplasties with time and equated the performance of sur- Seneral Hospital and Watts Hospital, is the only private gery with the diagnosis of obstruction. We included multiple iospital providing urological care in Durham and Orange hospitals with different urologists to minimize the influence 2ounties but it is also a referral center for patients from of individual biases in determining when to proceed with adjacent rural counties. Therefore, neither comparison with surgical repair. The number of pyeloplasties increased in the ;he population of the 2 counties nor the entire state is wholly 23-year study period but this increase was not markedly accurate but the real growth in the population base may lie different from the simultaneous growth in the population 3omewhere between these 2 figures. within the 2-county area. Therefore, we believe that modem Our data suggest that the increase in the incidence of imaging techniques, particularly prenatal sonography, are pyeloplasties was not greater than the growth rate of our not resulting in the over diagnosis of ureteropelvic junction population but that pyeloplasty was being performed in obstruction. younger patients. Thus, it appears that modem imaging A trend for increasing numbers of pyeloplasties in the techniques were not over diagnosing wetempelvic junction first year of life was noted. This trend appeared to begin in obstruction but detecting it before it became symptomatic. 1981,which coincided with the widespread use of real-time Some investigators would conclude that many pyeloplasties prenatal sonography. The technical advances in the early were performed unnecessarilyB.10 but there are no data to 1980s allowed for routine screening of a large proportion of support the hypothesis that the nonoperative management of pregnant women and the accurate diagnosis of fetal hydro- ureteropelvic junction obstruction results in equivalent longnephrosis. In our study population 23 pyeloplasties were term maintenance of renal function, perfusion and reserve, in performed in 1970 to 1980 on children born during that comparison to kidneys that undergo repair. However, previperiod (1.9per year) but in comparison 132 children born ous studies document long-term improvement in renal funcduring 1981 to 1992 underwent pyeloplasty (11.0per year). tion after the successful correction of a variety of causes of This nearly 6-fold increase in children undergoing pyelo- obstruction when relieved in the first year of life.14.16 Definplasty primarily reflects the impact of diagnosing hydro- itive resolution of this dilemma of early repair versus obsernephrosis prenatally. I n a review published as recently as vation of ureteropelvic junction obstruction will require a 1982 all neonates and infants with ureteropelvic junction prospective randomized trial. Until such a study proves othobstruction still presented symptomatically with abdomi- erwise we w i l l continue to recommend the repair of signifinal mass, urinary tract infection or anuria (in a solitary cant ureteropelvic junction obstruction in the first year of life kidney).'Z In contrast, only 6 years later a similar study rather than risk potential long-term renal deterioration. reported that 83% of patients with ureteropelvic junction obstruction were asymptomatic and the condition was diREFERENCES agnosed by prenatal sonography.6 Conversely, a declining trend in the number of pyeloplas1. Witten, D. M., Myers, G. H., Jr. and Utz, D. C.: Emmett's Clinical ties was noted in patients 7 to 12 years old and those older Urography: An Atlas and Textbook of RoentgenologicBagnothan 12 years. This decline occurred concomitantly with the ais, 4th ed. Philadelphia, W. B. Saunders Co., vol. 1, chapt. 11, pp. 986-999,1977. increase in pyeloplasties in neonates and infants. The overall 2. Brown,T., Mandell, J. and Lebowitz, R. L.: Neonatal hydrone effect was an increase in the incidence of pyeloplasties in all phrosia in the sonographic era. AJFt, 148: 959,1987. age groups that was roughly equivalent to population 3. Livera, L. N., Brookfield, D.S., Egginton, J. A. and Hawnaur, growth. This increase is presumably a result of diagnosing J. M.: Antenatal ultrasonography to detect fetal renal abnorand treating ureteropelvic junction obstruction earlier, bemalities: a prospective screening programme. Brit. Med. J., fore symptomatic presentation. The decline in pyeloplasties 298: 1421,1989. after 1980 in patients older than 12 years is an interesting 4. Koff, S. A: Problematic ureteropelvic junction obstruction. J. observation and cannot be explained by the effecta of new Urol., 138: 390,1987. imaging techniques since these patients were born before 5. Dowling, K J., Harmon, E. P., Ortenberg, J., Polanco, E. and Evans, B. B.: Ureteropelvic junction obstruction: the effect of routine prenatal sonography. Regardless, future urologists pyeloplasty on r e d function.J. Urol., part 2,laO: 1227,1988. will likely see fewer older children and adults presenting 6. Bematein, G. T., Mandell, J., Lebowitz, R L., Bauer, S. B., with primary ureteropelvic junction obstruction because this Colodny. A. H. and Retik, A. B.: Ureteropelvic junction obcongenital disease is b e i i detected at earlier ages and in struction in the neonate. J. Urol., part 2,140: 1216,1988. many cases before birth. 7. Perez, L. M.,F'riedman, R.M.and King,L. R.: The case for relief Although it is impossible to measure, other confounding of ureteropelvic junction obstruction in neonates and young factors may have also contributed to this trend toward children at time of diagnosis. Urology, 38:195,1991. earlier pyeloplasty. The presence of full-time pediatric 8. Duckett, J. W.,Jr.: When to operate on neonatal hydronephrosis. urologists at the academic hospitals and improved training Urology, 42:617,1993. 9. Gordon, I., Dhillon, H. K, Gatanaeh, H. and Peters, A. M.: in pediatric urology of those finishing residencies in the Antenatal diagnosis of pelvic hydronephis: assessment of last decade may have led to more conscious efforts to renal function and drainage as a guide to management. J. diagnose and treat ureteropelvic junction obstruction earNucl. Med., 92: 1649,1991. lier. Advances in surgical technique and pediatric anestheS. A. and Campbell, K D.: The nonoperative management sia have made pyeloplasty a n extremely safe procedure 10. Koff, of unilateral neonatal hydronephmsis: natural history of even in neonates and have eliminated any contraindicapoorly functioning kidneys. J. Urol., part 2 , 1 5 2 593,1994. tions to early repair.13 11. North C a r o h State Government Statistical Abstract, State Data The rate of increase in pyeloplasties was compared to the Center, Management & Information SeMces, Of6ce of State Bud& Management, Raleigh, North Carolina, 1984 and 1991. population growth for the 2 counties in which the 3 hospitals are located and for North Carolina. There is no ideal popu- 12. Bejjani, B. and Belman,A. B.: Ureteropelvicjunction obstruction in newborns and infanta. J. Urol.. 128.770,1982. lation with which to gauge this increase because each hospital has a unique referral pattern. Duke University Medical 13. Shaul, D. B.. Cunningham, J. A, Lowe, P., Skaist, L. B. and Hardy, B. E.: Infant pyeloplaety is a low-risk procedure. J. Center is a regional tertiary referral center and draws paPed. Surg., 29: 343,1994. tients from North Carolina and the surrounding states, in- 14. Mayor, G., Genton, N., Torrado, A. and Guignard, J.-P.: R e d cluding South Carolina, Tennessee, Virginia and West Virfunction in obstructive nephropathy: long-term effect of reconginia. North Carolina Memorial Hospital, also a tertiary structive surgery. Pediatrics, 6& 740,1975. center, is a governmental institution of the state of North 16. McCrory, W. W., Shibuya, M.,Leumann, E.and Karp, R:StudCarolina that treab patients from the entire state. Durham ies of renal function in children with chronic hydmnephmib. Ped. Clin. N. h e r . . 18: 445.1971. Regional Hospital, previously known ae Durham ComQr
Vol. 154.659-661. August 1995 Printed in U S A
Hydronephrosis: Antenatal and Postnatal Diagnosis ARE MODERN IMAGING TECHNIQUES OVER DIAGNOSING URETEROPELVIC JUNCTION OBSTRUCTION? JOHN S. WIENER, GREGOR K. EMMERT, HRAIR-GEORGE MESROBIAN,* ARTHUR W. WHITEHURST, L. RICHARD SMITH AND LOWELL R. KING From the Division of Urology, Department of Surgery and Division of Biometry, Department of Community and Family Medicine, Duke University Medical Center and Durham Regional Hospital, Durham and Department of Urology, University of North Carolina a t Chupel Hill, Chapel Hill, North Carolina
ABSTRACT
Since the widespread use of real-time ultrasonography in the early 19808, ureteropelvic junction obstruction has been diagnosed at earlier ages and prenatally on a presumptive basis. However, substantial controversy exists over the diagnosis and treatment of ureteropelvic junction obstruction. We conducted an epidemiological study to determine if modern imaging techniques are leading to the over diagnosis of ureteropelvic junction obstruction. Records were collected retrospectively from 3 hospitals serving 2 adjacent counties to determine the number of pyeloplasties performed in 1970 to 1992.The 2 university hospitals and 1 large private hospital provide a wide variety of services and choice of urologists, and so it was assumed that most patients requiring pyeloplasty in the area would be captured. Of the 555 pyeloplasties 240 (43%) were performed on children 12 years old or younger. Logistic regression analysis revealed an overall increase of pyeloplasties per year of 56.8% in 23 years, which was not markedly dif'ferent from the population growth in the area in the same period (49.3%). A statistically signi6cant increase in the number of pyeloplasties performed in the first year of life was noted. This trend appeared to begin in 1981:8 pyeloplasties were performed in the first year of life between 1970 and 1980 compared to 91 between 1981 and 1992. Pyeloplasties in children 1 to 6 years old increased with time at a much lower rate that was not statistically significant and the number of pyeloplasties decreased in those 7 to 12 years old. Therefore, it appears that modern imaging techniques are not leading to an over diagnosis of ureteropelvic junction obstruction but to detection of the disease at an earlier age. Key
Woms: ureter, kidney, incidence, ultrasonography
Ureteropelvic junction obstruction is the most common teropelvic junction obstruction should be aggressively purcongenital abnormality of the urinary tract.' Since the ad- sued because an inverse relationship exists between age vent of real-time prenatal sonography in the early 1980~1, and the ability of the kidney to recover from the deleterithere has been a dramatic increase in the detection of hydro- ous effects of obstruction.6-7 The degrees of impairment of nephrosis in utero and, thus, the diagnosis of ureteropelvic function below which level pyeloplasty is performed are junction obstruction in newborns. At Boston Children's Hos- often decided arbitrarily.8 Conversely, others have demonpital hydronephrosis has been detected almost 5 times more strated that the function of obstructed kidneys can sponfrequently and the proportion of these cases diagnosed as taneously improve and the surgical relief of obstruction ureteropelvic junction obstruction has nearly doubled since does not always ameliorate function.9.10 The literature is maternal ultrasonography became routine.2 A prospective replete with studies on each side stating their bias. We sought to examine the effects of modern imaging studstudy of prenatal ultrasonography of 6,292 pregnant women in Britain revealed ureteropelvic junction obstruction at a ies on the incidence of pyeloplastiesperformed for the correction of ureteropelvic junction obstruction. A retrospective rate of 1.9 per 1,000live births.3 The diagnosis and subsequent treatment of unilateral review of the pyeloplasty incidence at 3 hospitals serving 2 ureteropelvic junction obstruction in newborns are contro- adjacent urban counties in the last 2 decades was conducted versial. There is disagreement even about the definition of to identify any possible new trends in treatment of this the disease. Some diagnose ureteropelvic junction obstruc- disease. By including university medical centers and the sole tion on anatomical grounds while others insist that ob- private hospital serving the area, we attempted to balance struction can only be defined by documenting reduced re- diagnostic and therapeutic biases that may be inherent at nal function.4 The furosemide renogram has become an any 1 institution or with any 1urologist. important tool in determining renal function and diagnosing obstruction but dehydration, poor renal function and MATERIAL AND METHODS variations in methodolob often affect results. In terms of We retrospectively reviewed the recoTd data bases therapy, many believe that early repair of unilateral urefor DveloDlastvmrformed a t Duke Universitv MedicalCenter
in Chapel Hill, North Carolina. These 3 hospitals provide all urological care for Durham and Orange Counties, North Carolina, excluding the Department of Veterans M a i m Hospital in Durham, and include 2 of the 3 urology resident training programs in the state. Records were available fmm 1970 to 1992.No urologist performed surgery at more than 1 hospital. Because surgeons may have defined obstruction slightly differently and changed the threshold for repair during the study, no attempt was made to ascertain indications for surgery. Therefore, in this study significant ureteropelvic junction obstruction was defined by the performance of pyeloplasty. Surgical technique, outcome and complications
TABLE1. Pyeloplasty by hospital and patient
Duke University Medical Center North Carolina Memorial Hospital Durham Regional Hospital Totals
54 44 1 99
0
0
--
0
6
0
g
0 0 0 -
S
L
0
*
0
0
0
R
-
0 0 0
"
0
.
. . .
;
. . .
.
. .
.
.
.
.
.
.
-
.
t
age FIG.
Age at Pyeloplasty Younger Than 1 Yr. '-I2
,=a44
p
2. Analysis of pyeloplasties by agr and t l m c pctforniod
adults 151 pyeloplasties were performed aftcar 1980. tvtiich rep resented a decrease fmm 164 performed fmm 1$17()to IC)80.
Older Yrs. m a n 12yrs.
97 25
213 34
364 103
3
3
-88
141
315
555
l)IS[.l I S S I ( 1 N
TO avoid controversies in the dt.tinition of tlrt~tt~ropelvic junction obstruction we focused our s t u d y o n t l l r . Ilicldrnce of
OVER DIAGNOSING URETEROPELVIC JUNCTION OBSTRUCTION
661
pyeloplasties with time and equated the performance of sur- Seneral Hospital and Watts Hospital, is the only private gery with the diagnosis of obstruction. We included multiple iospital providing urological care in Durham and Orange hospitals with different urologists to minimize the influence 2ounties but it is also a referral center for patients from of individual biases in determining when to proceed with adjacent rural counties. Therefore, neither comparison with surgical repair. The number of pyeloplasties increased in the ;he population of the 2 counties nor the entire state is wholly 23-year study period but this increase was not markedly accurate but the real growth in the population base may lie different from the simultaneous growth in the population 3omewhere between these 2 figures. within the 2-county area. Therefore, we believe that modem Our data suggest that the increase in the incidence of imaging techniques, particularly prenatal sonography, are pyeloplasties was not greater than the growth rate of our not resulting in the over diagnosis of ureteropelvic junction population but that pyeloplasty was being performed in obstruction. younger patients. Thus, it appears that modem imaging A trend for increasing numbers of pyeloplasties in the techniques were not over diagnosing wetempelvic junction first year of life was noted. This trend appeared to begin in obstruction but detecting it before it became symptomatic. 1981,which coincided with the widespread use of real-time Some investigators would conclude that many pyeloplasties prenatal sonography. The technical advances in the early were performed unnecessarilyB.10 but there are no data to 1980s allowed for routine screening of a large proportion of support the hypothesis that the nonoperative management of pregnant women and the accurate diagnosis of fetal hydro- ureteropelvic junction obstruction results in equivalent longnephrosis. In our study population 23 pyeloplasties were term maintenance of renal function, perfusion and reserve, in performed in 1970 to 1980 on children born during that comparison to kidneys that undergo repair. However, previperiod (1.9per year) but in comparison 132 children born ous studies document long-term improvement in renal funcduring 1981 to 1992 underwent pyeloplasty (11.0per year). tion after the successful correction of a variety of causes of This nearly 6-fold increase in children undergoing pyelo- obstruction when relieved in the first year of life.14.16 Definplasty primarily reflects the impact of diagnosing hydro- itive resolution of this dilemma of early repair versus obsernephrosis prenatally. I n a review published as recently as vation of ureteropelvic junction obstruction will require a 1982 all neonates and infants with ureteropelvic junction prospective randomized trial. Until such a study proves othobstruction still presented symptomatically with abdomi- erwise we w i l l continue to recommend the repair of signifinal mass, urinary tract infection or anuria (in a solitary cant ureteropelvic junction obstruction in the first year of life kidney).'Z In contrast, only 6 years later a similar study rather than risk potential long-term renal deterioration. reported that 83% of patients with ureteropelvic junction obstruction were asymptomatic and the condition was diREFERENCES agnosed by prenatal sonography.6 Conversely, a declining trend in the number of pyeloplas1. Witten, D. M., Myers, G. H., Jr. and Utz, D. C.: Emmett's Clinical ties was noted in patients 7 to 12 years old and those older Urography: An Atlas and Textbook of RoentgenologicBagnothan 12 years. This decline occurred concomitantly with the ais, 4th ed. Philadelphia, W. B. Saunders Co., vol. 1, chapt. 11, pp. 986-999,1977. increase in pyeloplasties in neonates and infants. The overall 2. Brown,T., Mandell, J. and Lebowitz, R. L.: Neonatal hydrone effect was an increase in the incidence of pyeloplasties in all phrosia in the sonographic era. AJFt, 148: 959,1987. age groups that was roughly equivalent to population 3. Livera, L. N., Brookfield, D.S., Egginton, J. A. and Hawnaur, growth. This increase is presumably a result of diagnosing J. M.: Antenatal ultrasonography to detect fetal renal abnorand treating ureteropelvic junction obstruction earlier, bemalities: a prospective screening programme. Brit. Med. J., fore symptomatic presentation. The decline in pyeloplasties 298: 1421,1989. after 1980 in patients older than 12 years is an interesting 4. Koff, S. A: Problematic ureteropelvic junction obstruction. J. observation and cannot be explained by the effecta of new Urol., 138: 390,1987. imaging techniques since these patients were born before 5. Dowling, K J., Harmon, E. P., Ortenberg, J., Polanco, E. and Evans, B. B.: Ureteropelvic junction obstruction: the effect of routine prenatal sonography. Regardless, future urologists pyeloplasty on r e d function.J. Urol., part 2,laO: 1227,1988. will likely see fewer older children and adults presenting 6. Bematein, G. T., Mandell, J., Lebowitz, R L., Bauer, S. B., with primary ureteropelvic junction obstruction because this Colodny. A. H. and Retik, A. B.: Ureteropelvic junction obcongenital disease is b e i i detected at earlier ages and in struction in the neonate. J. Urol., part 2,140: 1216,1988. many cases before birth. 7. Perez, L. M.,F'riedman, R.M.and King,L. R.: The case for relief Although it is impossible to measure, other confounding of ureteropelvic junction obstruction in neonates and young factors may have also contributed to this trend toward children at time of diagnosis. Urology, 38:195,1991. earlier pyeloplasty. The presence of full-time pediatric 8. Duckett, J. W.,Jr.: When to operate on neonatal hydronephrosis. urologists at the academic hospitals and improved training Urology, 42:617,1993. 9. Gordon, I., Dhillon, H. K, Gatanaeh, H. and Peters, A. M.: in pediatric urology of those finishing residencies in the Antenatal diagnosis of pelvic hydronephis: assessment of last decade may have led to more conscious efforts to renal function and drainage as a guide to management. J. diagnose and treat ureteropelvic junction obstruction earNucl. Med., 92: 1649,1991. lier. Advances in surgical technique and pediatric anestheS. A. and Campbell, K D.: The nonoperative management sia have made pyeloplasty a n extremely safe procedure 10. Koff, of unilateral neonatal hydronephmsis: natural history of even in neonates and have eliminated any contraindicapoorly functioning kidneys. J. Urol., part 2 , 1 5 2 593,1994. tions to early repair.13 11. North C a r o h State Government Statistical Abstract, State Data The rate of increase in pyeloplasties was compared to the Center, Management & Information SeMces, Of6ce of State Bud& Management, Raleigh, North Carolina, 1984 and 1991. population growth for the 2 counties in which the 3 hospitals are located and for North Carolina. There is no ideal popu- 12. Bejjani, B. and Belman,A. B.: Ureteropelvicjunction obstruction in newborns and infanta. J. Urol.. 128.770,1982. lation with which to gauge this increase because each hospital has a unique referral pattern. Duke University Medical 13. Shaul, D. B.. Cunningham, J. A, Lowe, P., Skaist, L. B. and Hardy, B. E.: Infant pyeloplaety is a low-risk procedure. J. Center is a regional tertiary referral center and draws paPed. Surg., 29: 343,1994. tients from North Carolina and the surrounding states, in- 14. Mayor, G., Genton, N., Torrado, A. and Guignard, J.-P.: R e d cluding South Carolina, Tennessee, Virginia and West Virfunction in obstructive nephropathy: long-term effect of reconginia. North Carolina Memorial Hospital, also a tertiary structive surgery. Pediatrics, 6& 740,1975. center, is a governmental institution of the state of North 16. McCrory, W. W., Shibuya, M.,Leumann, E.and Karp, R:StudCarolina that treab patients from the entire state. Durham ies of renal function in children with chronic hydmnephmib. Ped. Clin. N. h e r . . 18: 445.1971. Regional Hospital, previously known ae Durham ComQr