- Email: [email protected]
Correlation of Prenatal Renal Pelvic Anteroposterior Diameter with Outcome in Infancy
0022-5347/96!15531050$03.0010 THEJOI.RULO F LTtmi.(X:Y Copyright 0 1996 by A.UEKIV,.W UROUKXAL k s
Val. 155. 1050-1052.March 1996 Printed in 1: S.A.
s o r i ~ ~Isc. i ~ ~ ,
CORRELATION OF PRENATAL RENAL PELVIC ANTEROPOSTERIOR DIAMETER WITH OUTCOME IN INFANCY ALTON S T O C K S , DOUGLAS RICHARDS, BARBARA FRENTZEN
AND
GEORGE RICHARD
Froni the Departments of Pediatrics (Division of Pediatrir Nephrology) and Obstetrics and Gynecology (Dioision of Maternal Fetal Medicine), Uniuersity of Florida College of Medicine. Galnest ille, Florida
ABSTRACT
Purpose: W e attempted to correlate p r e n a t a l renal pelvic anteroposterior d i a m e t e r w i t h o u t come i n infancy. Materials and Methods: B e t w e e n M a y 1992 and March 1994 we identified 27 cases of fetal hydronephrosis in which renal pelvic anteroposterior diameter was 4 mm. or greater before 33 w e e k s of gestation and 7 mm. o r greater at or after 33 w e e k s of gestation. Results: Hydronephrosis w a s bilateral in 18 fetuses and unilateral i n 9. S h o r t l y after birth radiological a s s e s s m e n t revealed vesicoureteral reflw in 6 neonates, ureteropelvic j u n c t i o n obstruction in 6, extrarenal pelves in 3 and persistent nonobstructive hydronephrosis in 4. Radiological e v a l u a t i o n w a s normal in 8 newborns. Conclusions: When these screening criteria for hydronephrosis are met p r e n a t a l l y a complete radiological assessment s h o u l d be d o n e following birth. KEYWORDS:hydronephrosis, kidney, prenatal diagnosis, vesico-ureteral reflux, fetus borns with reflux were placed on prophylactic antibiotics and reflux was graded according to the International Classification of Reflux.13 Neonates in whom postnatal ultrasound showed hydronephrosis but a voiding cystourethrogram was normal after catheterization underwent a 99mtechnetiumpentetic acid (DTPA) scan augmented with 1 mg./kg. furosemide intravenously. Ureteropelvic junction obstruction was diagnosed if the half-time of radiotracer washout was longer than 20 minutes. All postnatal radiographic studies were interpreted by radiologists who were unaware of t h e degree of prenatal hydronephrosis. All cases of persistent radiological renal abnormalities were discussed at t h e combined biweekly pediatric renal, urology and radiology conference. Statistical analysis was performed by sum of least squares analysis of variance with gestational age as a covariate to determine if fetal renal pelvic anteroposterior diameter correlated with postnatal outcome.
Fetal hydronephrosis is the most common fetal anomaly detected on prenatal ultrasound.’ With the growing use of ultrasound in obstetrics the number of otherwise healthy fetuses who are diagnosed with this condition is increasing.’ As a result, more infants with this history are presenting to pediatricians, nephrologists and urologist^.^ The outcome and proper management of fetal hydronephrosis have not been completely defined. Reports describing the postnatal outcome of this finding have several important limitations, including the failure to define hydronephrosis specifically or consistently and inclusion in the outcome review of only surgically related diagnoses, such as ureteropelvic junction obstruction.1.4--” In this prospective study we report the association of postnatal vesicoureteral reflux, ureteropelvic junction obstruction and extrarenal pelves in infants with prenatal hydronephrosis, as defined by specific gestational age related renal pelvic anteroposterior diameters. METHODS
Between May 1992 and March 1994 we evaluated women at various stages of pregnancy for enrollment in our study who had been referred to our university for prenatal ultrasound due to a range of primary indications. Regardless of the indication for ultrasound the fetal kidneys were visualized in each case. When hydronephrosis was suspected by a certified nurse sonographer, a detailed anatomical evaluation of the fetus was performed by a perinatologist. The diagnosis of hydronephrosis was made when fetal renal pelvic anteroposterior diameter was 4 mm. or greater before 33 weeks of gestation, or 7 mm. or greater at or after 33 weeks of gestation. Possible postnatal outcomes were discussed with the family by a pediatric nephrologist. Further prenatal ultrasound was done at the discretion of the perinatologists. In the absence of other anomalies obstetric management was not altered by the finding of prenatal hydronephrosis. All cases of bladder outlet obstruction were excluded from our study. All neonates with prenatal hydronephrosis were seen by a pediatric nephrologist, and underwent abdominal ultrasound and a voiding cystourethrogram after 48 hours of life. NewAccepted for publication Aukwst 18. 1995
RESULTS
Of the 21 male and 6 female neonates (54 kidneys) prenatal hydronephrosis was bilateral in 18 patients and unilateral in 9. Nine renal units were normal prenatally. We obtained 94 ultrasound measurements of fetal renal pelvic anteroposterior diameters (average 2.3 scans per patient). Mean anteroposterior diameter of the renal pelvis was 4.6 mm. (range 3 to 28) and mean number of weeks of gestation was 29.1 (range 15.9 to 40). Postnatal ultrasound was done a t a mean patient age of 9.3 days (range 1.7 to 41). In all neonates except 1 with a n extrarenal pelvis voiding cystourethrography was done a t a mean age of 15.5days (range 1.7 to 48) and 13 DTPA scans were done at a mean age of 25 days (range 3 to 231, tables 1 and 2). One female and 5 male neonates had vesicoureteral reflux (grade I to V). Only 1patient had bilateral grade 111reflux. One patient with grade V reflux had evidence of hydronephrosis on postnatal ultrasound, and a DTPA scan demonstrated renal accumulation of radiotracer and right megaureter. Obstruction was repaired by pyeloplasty, and ureteral tapering and reimplantation. Five newborns with reflux did not have hydronephrosis on postnatal ultrasound. One female and 5 male neonates had isolated unilateral
1050
PRENATAL RENAL PELVIC DIAMETER AND POSTNATAL OUTCOME TABLE1. Postnatal outcomes No. pts. (INo. )Kidneys (5%)
Diagnosis
Total No. Prenatal hydronephrosis: Bilat. Unilat. Postnatal diagnosis: Vesicoureteral reflux Ureteropelvic junction obstruction Extrarenal pelves Persistent nonobstructive hydronephrosis Normal
27
27 (100) 18 (66.7) 9 (33.3)
54 45 (83.3) 36 (66.7) 9 (33.3)
6 (22.2) 6 (22.2) 3 (11.1) 4 (14.8)
7 (58.3) 6 (50) 5 (83.3) 4 (50)
8 (29.6)
16 (1001
TABLE2 Prenatal Hydronephrosis Unilat. Bilat.
No. Pta.
Postnatal Diagnosis Vesicoureteral reflux Ureteropelvic junction obstruction Extrarenal pelves Persistent nonobstructive hydmnephrosis Normai Totals
Total No' Kidneys
6 6
2
3
4 3
10 9
3 4
0 2
3 2
6 6
8
2
6 -
27
9
18
14 45
ureteropelvic junction obstruction on a DTPA scan. Of these 6 patients the seventy of obstruction required nephrectomy in 1, and resulted in a contralateral multicystic dysplastic kidney with renal insufficiency despite pyeloplasty in 1. The remaining 4 infants have been followed with periodic DTPA renal scans for 12,28,29and 31 months, respectively, and to date none has required surgery. An additional patient with ureteropelvic junction obstruction was included in the vesicoureteral reflux group because grade V reflux with megaureter was more severe than ureteropelvic junction obstruction. Following renal ultrasound and a DTPA renal scan 3 patients were diagnosed with extrarenal pelves (2bilateral and 1 unilateral). The patient with a unilateral extrarend pelvis had had contralateral hydronephrosis prenatally but postnatal ultrasound and a voiding cystourethrogram were normal. Of the remaining 12 patients 8 had normal postnatal ultrasound and voiding cystourethrography, and persistent nonobstructive hydronephrosis was demonstrated on postnatal ultrasound in 4 who had normal voiding cystourethrograms
,.L
!..
.
I
...
.
9
. .
...
I
.
1051
and DTPA scans. These 4 infants are being followed with renal ultrasound. There was a statistically significant difference at the 95% confidence level for renal pelvic anteroposterior diameter at study entry between patients with a postnatal diagnosis of ureteropelvic junction obstruction (11.19 -C 1.24 mm.) and those with normal kidneys postnatally (7.07 2 0.58 mm.). There was no significant difference for this measurement when normal patients were compared to those with a postnatal diagnosis of vesicoureteral reflux (7.94? 1.21mm.) or extrarenal pelvis (9.19 2 1.35 mm., part A of figure). Although initial anteroposterior diameter tended to be higher with ureteropelvic junction obstruction than vesicoureteral reflux and extrarenal pelvis, the 95% confidence levels overlapped, indicating a lack of statistical significance. Analysis using the largest prenatal pelvic anteroposterior diameter of each kidney also showed a significant difference between the ureteropelvic junction group (15.28-t 1.45 mm.) and the other 3 groups. Many prenatal measurements in patients with postnatal vesicoureteral reflux (9.64 2 1.35 mm.)and extrarenal pelvis (10.332 1.60 mm.) were larger than in those with normal kidneys prenatally (8.45 ? 0.69 mm.) but the ranges significantly overlapped (part B of figure). No correlation was noted between increasing renal anteroposterior diameter (defined as 2 mm. or more) on successive prenatal ultrasound and postnatal outcome. Similarly decreasing prenatal anteroposterior diameter did not predict the absence of hydronephrosis or a normal outcome postnatally. In 5 patients prenatal hydronephrosis was associated with postnatal ureteropelvic obstruction and gastroschisis; ureteropelvic junction obstruction and a multicystic dysplastic kidney; vesicoureteral reflux and hydrocephalus; vesicoureteral reflux and the VACTERL (vertebral, anal, cardiac, trachael, esophageal, renal and limb) association with a single kidney, and vesicoureteral reflux and an arachnoid cyst. DISCUSSION
previous studies correlated prenatal hydronephrosis with ureteropelvic junction obstruction and/or vesicoureteral reflux but few compared specific measurements of prenatal hydronephrosis with postnatal outcome.1.3.4.6-10.12 When these studies used fetal renal pelvic dilatation of 9,lO or 12 mm. as the lower limit definition of hydronephrosis, ureteropelvic junction obstruction was the most common diagnosis in infancy.s.9,14 Blachar et al used a ratio of fetal pelvic-torenal anteroposterior diameter of greater than 0.35 mm. as a definition of hydronephrosis and ureteropelvic junction obstruction was the most common postnatal outcome as well.16
.. h
E
" I 4-
t
U
n
a
st
t
-I
UPJ
B
NL
ERP
VUR
Infant Outcome
A, transverse antemposterior (Ap) diameter of fetal renal pelvis at study entry (mean and 95% confidence intervals of mean) acco postnatal o u t e o m e w - u y 1-r antempsterior diameter correlates w i t h uretempelvic junction ohtruetion. m,n o m d i extrarend pelvis veimmteral reflux. B , largest transverse anteroposterior diameter of fetal renal pe1vis.r fetus (mean and 95% confidence lnte&& &mean) according to postnatal outcome. Largest antemposterior diameter correlates ~1 ureteropelvic junction obstruction.
1052
PRENATAL RENAL PELVIC DIAMETER AND POSTNATAL OUTCOME
Corteville e t a1 found that a fetal renal pelvic anteroposterior diameter of 4 mm. or greater before 33 weeks of gestation, or 7 mm. or greater after 33 weeks of gestation was more sensitive than anteroposterior diameter of the renal pelvis-to-kidney ratio or the transverse diameter of the renal pelvis-to-kidney ratio when correlating these measures with postnatal outcome.’” They also noted t h a t a 10 mm. anteroposterior diameter threshold would not have detected all cases of postnatal hydronephrosis, and suggested that lower cutoffs, as described, should be used to ensure detection. The most common diagnosis in infancy in their series was ureteropelvic junction obstruction. I t is not evident that all infants were evaluated for vesicoureteral reflux.16 In other prenatal hydronephrosis studies voiding cystourethrography was done only when hydronephrosis persisted on postnatal ultrasound.3.4 Zerin e t al observed that 32% of infants with prenatal hydronephrosis and other renal abnormalities had vesicoureteral reflux despite the absence of hydronephrosis on postnatal ultrasound.17 Our results revealed an equal number of cases of ureteropelvic junction obstruction and vesicoureteral reflux. Using the lower threshold measurements of anteroposterior diameter may have enabled detection of more cases of vesicoureteral reflux than in previous studies, which used larger anteroposten o r diameters or pelvic-to-renal anteroposterior diameter ratios. If we had used a 10 mm. anteroposterior diameter as a definition of fetal hydronephrosis, only 1 of 6 cases of vesicoureteral reflux in our study would have been detected. Of interest is that 5 of 6 infants in our study with vesicoureteral reflux had normal postnatal ultrasound. The correlations of initial fetal anteroposterior diameter a t study entry and largest fetal anteroposterior diameter with ureteropelvic junction obstruction were statistically significant. Although not statistically significant, initial and largest fetal anteroposterior diameters in infants with vesicoureteral reflux were greater than those in normal infants. I t is possible that a greater difference would have been noted if ultrasound in fetuses with vesicoureteral reflux had been performed during or immediately after voiding. The use of prophylactic antibiotics to prevent urinary tract infection in cases of vesicoureteral reflux is standard. When reflux is present, it is most oRen detected during evaluation of a child with a history of urinary tract infection.” Detection of reflux in the neonatal period may enable antibiotics to be administered before the development of a urinary tract infection and possibly improve outcome in these cases. High grade neonatal reflux has been associated with decreased renal function even in the absence of clinically detected urinary tract infection.18-20 Early identification of these patients is important to ensure adequate followup care. CONCLUSIONS
Detection of vesicoureteral reflux in the neonatal period enables early intervention and management. Given that reflux can exist despite normal postnatal renal ultrasound, we recommend that all infants who fulfill the screening criteria for prenatal hydronephrosis, as used in our study, should be evaluated with voiding cystourethrography. REFERENCES
1. Helin, I. and Persson, P. H.: Prenatal diagnosis of urinary tract abnormalities by ultrasound. Pediatrics, 78:879,1986.
2. Steele, B. T., Robitaille, P.. DeMaria. J . and Grignon, A,: Follow-up evaluation of prenatally recognized vesicoureteric reflw. J. Ped., 1: 95,1989. 3. Johnson, C.E., Elder, J . S., Judge, N. E., Adeeb. F. N.. Grisoni, E. R. and Fattlar, D. C.: The accuracy of antenatal ultrasonography in identifying renal abnormalities. h e r . J. Dis. Child., 146: 1181. 1992. 4. Dejter. S.W. and Gibbons, M. D.: The fate of infant kidneys with fetal hydronephrosis but initially normal postnatal sonography. J. Urol., part 2, 142 661,1989. 5. Gordon, I., Dhillon. H. K., Gatanash, H. and Peters, A. M.: Antenatal diagnosis of pelvic hydronephrosis: assessment of renal function and drainage a s a guide to management. J. Nucl. Med., 32: 1649,1991. 6. Grignon, A,, Filion, R., Filiatrault, D.. Robitaille, P.. Homsy. Y., Boutin, H. and Leblond, R.: Urinary tract dilatation in utero: classification and clinical applications. Radiology. 160 645, 1986. 7. Grignon, A., Filiatrault. D., Homsy, Y.. Robitaille. P., Filion. R., Boutin, H. and Leblond, R.: Ureteropelvic junction stenosis: antenatal ultrasonographic diagnosis, postnatal investigation, and follow-up. Radiology, 160: 649,1986. 8. Homsy, Y. L.,Saad, F., Laberge, I., Williot. P. and Pison, C.: Transitional hydronephrosis of the newborn and infant, J. Urol., part 2, 144: 579, 1990. 9. Livera, L.N.,Brookfield, D. S. K., Egginton, J . A. and Hawnaur, J. M.: Antenatal ultrasonography to detect fetal renal abnormalities: a prospective screening programme. Brit. Med. J., 298 1421,1989. 10. Najmaldin, A,, Burge, D. M. and Atwell, J. D.: Fetal vesicoureteric reflux. Brit. J. Urol.. 65:403, 1990. 11. Paltiel, H. J . and Lebowitz, R.: Neonatal hydronephrosis due to primary vesicoureteral reflw: trends in diagnosis and treatment. Radiology, 170 787, 1989. 12. Steele, B. T., DeMaria, J., Toi. A., Stafford, A., Hunter, D. and Caco, C.: Neonatal outcome of fetuses with urinary tract abnormalities diagnosed by prenatal ultrasonography. Canad. Med. Ass. J., 131: 117, 1987. 13. Lebowitz, R. L., Olbing, H.. Parkkulainen, K. V.. Smellie. J. M. and Tamminen-Mobius, T. E.: International system of radiographic grading of vesicoureteral reflux. International Reflux Study in Children. Ped. Rad., 15: 105,1985. 14. Arger, P. H., Coleman, B. G., Mintz, M. C., Snyder, H. P., Camardese, T.. Arenson, R. L., Gabbe, S. G. and Aquino, L.: Routine fetal genitourinary tract screening. Radiology, 156 485, 1985. 15. Blachar, A., Blachar, Y., Livne, P. M., Zurkowski, L., Pelet. D. and Mogilner, B.: Clinical outcome and follow-up of prenatal hydronephrosis. Ped. Nephrol., 8:30, 1994. 16. Corteville, J. E.. Gray, D. L. and Crane, .J. P.: Congenital hydronephrosis: correlation of fetal ultrasonographic findings with infant outcome. Amer. J . Obst. Gynec., 165: 384. 1991. 17. Zerin, J. M., Ritchey, M. L. and Chang, A. C.: Incidental vesicoureteral reflw in neonates with antenatally detected hydronephrosis and other renal abnormalities. Radiology. 187: 157, 1993. 18. Anderson, P. A. M. and Rickwood. A. M. K.: Features of primary vesicoureteric reflux detected by prenatal sonography: Brit. J. Urol., 67: 267, 1991. 19. Marra, G., Barbieri, G., Dell’Agnola. C. A.. Caccamo. M. L., Castellani, M. R. and Assael, B. M.: Congenital renal damage associated with primary vesicoureteral reflux detected prenatally in male infants. J. Ped., 124: 726, 1994. 20. Najmaldin, B., Burge, D. M. and Atwell, J. D.: Reflux nephropathy secondary to intrauterine vesicoureteric reflux. J. Ped. Surg., 2 5 387,1990.
Val. 155. 1050-1052.March 1996 Printed in 1: S.A.
s o r i ~ ~Isc. i ~ ~ ,
CORRELATION OF PRENATAL RENAL PELVIC ANTEROPOSTERIOR DIAMETER WITH OUTCOME IN INFANCY ALTON S T O C K S , DOUGLAS RICHARDS, BARBARA FRENTZEN
AND
GEORGE RICHARD
Froni the Departments of Pediatrics (Division of Pediatrir Nephrology) and Obstetrics and Gynecology (Dioision of Maternal Fetal Medicine), Uniuersity of Florida College of Medicine. Galnest ille, Florida
ABSTRACT
Purpose: W e attempted to correlate p r e n a t a l renal pelvic anteroposterior d i a m e t e r w i t h o u t come i n infancy. Materials and Methods: B e t w e e n M a y 1992 and March 1994 we identified 27 cases of fetal hydronephrosis in which renal pelvic anteroposterior diameter was 4 mm. or greater before 33 w e e k s of gestation and 7 mm. o r greater at or after 33 w e e k s of gestation. Results: Hydronephrosis w a s bilateral in 18 fetuses and unilateral i n 9. S h o r t l y after birth radiological a s s e s s m e n t revealed vesicoureteral reflw in 6 neonates, ureteropelvic j u n c t i o n obstruction in 6, extrarenal pelves in 3 and persistent nonobstructive hydronephrosis in 4. Radiological e v a l u a t i o n w a s normal in 8 newborns. Conclusions: When these screening criteria for hydronephrosis are met p r e n a t a l l y a complete radiological assessment s h o u l d be d o n e following birth. KEYWORDS:hydronephrosis, kidney, prenatal diagnosis, vesico-ureteral reflux, fetus borns with reflux were placed on prophylactic antibiotics and reflux was graded according to the International Classification of Reflux.13 Neonates in whom postnatal ultrasound showed hydronephrosis but a voiding cystourethrogram was normal after catheterization underwent a 99mtechnetiumpentetic acid (DTPA) scan augmented with 1 mg./kg. furosemide intravenously. Ureteropelvic junction obstruction was diagnosed if the half-time of radiotracer washout was longer than 20 minutes. All postnatal radiographic studies were interpreted by radiologists who were unaware of t h e degree of prenatal hydronephrosis. All cases of persistent radiological renal abnormalities were discussed at t h e combined biweekly pediatric renal, urology and radiology conference. Statistical analysis was performed by sum of least squares analysis of variance with gestational age as a covariate to determine if fetal renal pelvic anteroposterior diameter correlated with postnatal outcome.
Fetal hydronephrosis is the most common fetal anomaly detected on prenatal ultrasound.’ With the growing use of ultrasound in obstetrics the number of otherwise healthy fetuses who are diagnosed with this condition is increasing.’ As a result, more infants with this history are presenting to pediatricians, nephrologists and urologist^.^ The outcome and proper management of fetal hydronephrosis have not been completely defined. Reports describing the postnatal outcome of this finding have several important limitations, including the failure to define hydronephrosis specifically or consistently and inclusion in the outcome review of only surgically related diagnoses, such as ureteropelvic junction obstruction.1.4--” In this prospective study we report the association of postnatal vesicoureteral reflux, ureteropelvic junction obstruction and extrarenal pelves in infants with prenatal hydronephrosis, as defined by specific gestational age related renal pelvic anteroposterior diameters. METHODS
Between May 1992 and March 1994 we evaluated women at various stages of pregnancy for enrollment in our study who had been referred to our university for prenatal ultrasound due to a range of primary indications. Regardless of the indication for ultrasound the fetal kidneys were visualized in each case. When hydronephrosis was suspected by a certified nurse sonographer, a detailed anatomical evaluation of the fetus was performed by a perinatologist. The diagnosis of hydronephrosis was made when fetal renal pelvic anteroposterior diameter was 4 mm. or greater before 33 weeks of gestation, or 7 mm. or greater at or after 33 weeks of gestation. Possible postnatal outcomes were discussed with the family by a pediatric nephrologist. Further prenatal ultrasound was done at the discretion of the perinatologists. In the absence of other anomalies obstetric management was not altered by the finding of prenatal hydronephrosis. All cases of bladder outlet obstruction were excluded from our study. All neonates with prenatal hydronephrosis were seen by a pediatric nephrologist, and underwent abdominal ultrasound and a voiding cystourethrogram after 48 hours of life. NewAccepted for publication Aukwst 18. 1995
RESULTS
Of the 21 male and 6 female neonates (54 kidneys) prenatal hydronephrosis was bilateral in 18 patients and unilateral in 9. Nine renal units were normal prenatally. We obtained 94 ultrasound measurements of fetal renal pelvic anteroposterior diameters (average 2.3 scans per patient). Mean anteroposterior diameter of the renal pelvis was 4.6 mm. (range 3 to 28) and mean number of weeks of gestation was 29.1 (range 15.9 to 40). Postnatal ultrasound was done a t a mean patient age of 9.3 days (range 1.7 to 41). In all neonates except 1 with a n extrarenal pelvis voiding cystourethrography was done a t a mean age of 15.5days (range 1.7 to 48) and 13 DTPA scans were done at a mean age of 25 days (range 3 to 231, tables 1 and 2). One female and 5 male neonates had vesicoureteral reflux (grade I to V). Only 1patient had bilateral grade 111reflux. One patient with grade V reflux had evidence of hydronephrosis on postnatal ultrasound, and a DTPA scan demonstrated renal accumulation of radiotracer and right megaureter. Obstruction was repaired by pyeloplasty, and ureteral tapering and reimplantation. Five newborns with reflux did not have hydronephrosis on postnatal ultrasound. One female and 5 male neonates had isolated unilateral
1050
PRENATAL RENAL PELVIC DIAMETER AND POSTNATAL OUTCOME TABLE1. Postnatal outcomes No. pts. (INo. )Kidneys (5%)
Diagnosis
Total No. Prenatal hydronephrosis: Bilat. Unilat. Postnatal diagnosis: Vesicoureteral reflux Ureteropelvic junction obstruction Extrarenal pelves Persistent nonobstructive hydronephrosis Normal
27
27 (100) 18 (66.7) 9 (33.3)
54 45 (83.3) 36 (66.7) 9 (33.3)
6 (22.2) 6 (22.2) 3 (11.1) 4 (14.8)
7 (58.3) 6 (50) 5 (83.3) 4 (50)
8 (29.6)
16 (1001
TABLE2 Prenatal Hydronephrosis Unilat. Bilat.
No. Pta.
Postnatal Diagnosis Vesicoureteral reflux Ureteropelvic junction obstruction Extrarenal pelves Persistent nonobstructive hydmnephrosis Normai Totals
Total No' Kidneys
6 6
2
3
4 3
10 9
3 4
0 2
3 2
6 6
8
2
6 -
27
9
18
14 45
ureteropelvic junction obstruction on a DTPA scan. Of these 6 patients the seventy of obstruction required nephrectomy in 1, and resulted in a contralateral multicystic dysplastic kidney with renal insufficiency despite pyeloplasty in 1. The remaining 4 infants have been followed with periodic DTPA renal scans for 12,28,29and 31 months, respectively, and to date none has required surgery. An additional patient with ureteropelvic junction obstruction was included in the vesicoureteral reflux group because grade V reflux with megaureter was more severe than ureteropelvic junction obstruction. Following renal ultrasound and a DTPA renal scan 3 patients were diagnosed with extrarenal pelves (2bilateral and 1 unilateral). The patient with a unilateral extrarend pelvis had had contralateral hydronephrosis prenatally but postnatal ultrasound and a voiding cystourethrogram were normal. Of the remaining 12 patients 8 had normal postnatal ultrasound and voiding cystourethrography, and persistent nonobstructive hydronephrosis was demonstrated on postnatal ultrasound in 4 who had normal voiding cystourethrograms
,.L
!..
.
I
...
.
9
. .
...
I
.
1051
and DTPA scans. These 4 infants are being followed with renal ultrasound. There was a statistically significant difference at the 95% confidence level for renal pelvic anteroposterior diameter at study entry between patients with a postnatal diagnosis of ureteropelvic junction obstruction (11.19 -C 1.24 mm.) and those with normal kidneys postnatally (7.07 2 0.58 mm.). There was no significant difference for this measurement when normal patients were compared to those with a postnatal diagnosis of vesicoureteral reflux (7.94? 1.21mm.) or extrarenal pelvis (9.19 2 1.35 mm., part A of figure). Although initial anteroposterior diameter tended to be higher with ureteropelvic junction obstruction than vesicoureteral reflux and extrarenal pelvis, the 95% confidence levels overlapped, indicating a lack of statistical significance. Analysis using the largest prenatal pelvic anteroposterior diameter of each kidney also showed a significant difference between the ureteropelvic junction group (15.28-t 1.45 mm.) and the other 3 groups. Many prenatal measurements in patients with postnatal vesicoureteral reflux (9.64 2 1.35 mm.)and extrarenal pelvis (10.332 1.60 mm.) were larger than in those with normal kidneys prenatally (8.45 ? 0.69 mm.) but the ranges significantly overlapped (part B of figure). No correlation was noted between increasing renal anteroposterior diameter (defined as 2 mm. or more) on successive prenatal ultrasound and postnatal outcome. Similarly decreasing prenatal anteroposterior diameter did not predict the absence of hydronephrosis or a normal outcome postnatally. In 5 patients prenatal hydronephrosis was associated with postnatal ureteropelvic obstruction and gastroschisis; ureteropelvic junction obstruction and a multicystic dysplastic kidney; vesicoureteral reflux and hydrocephalus; vesicoureteral reflux and the VACTERL (vertebral, anal, cardiac, trachael, esophageal, renal and limb) association with a single kidney, and vesicoureteral reflux and an arachnoid cyst. DISCUSSION
previous studies correlated prenatal hydronephrosis with ureteropelvic junction obstruction and/or vesicoureteral reflux but few compared specific measurements of prenatal hydronephrosis with postnatal outcome.1.3.4.6-10.12 When these studies used fetal renal pelvic dilatation of 9,lO or 12 mm. as the lower limit definition of hydronephrosis, ureteropelvic junction obstruction was the most common diagnosis in infancy.s.9,14 Blachar et al used a ratio of fetal pelvic-torenal anteroposterior diameter of greater than 0.35 mm. as a definition of hydronephrosis and ureteropelvic junction obstruction was the most common postnatal outcome as well.16
.. h
E
" I 4-
t
U
n
a
st
t
-I
UPJ
B
NL
ERP
VUR
Infant Outcome
A, transverse antemposterior (Ap) diameter of fetal renal pelvis at study entry (mean and 95% confidence intervals of mean) acco postnatal o u t e o m e w - u y 1-r antempsterior diameter correlates w i t h uretempelvic junction ohtruetion. m,n o m d i extrarend pelvis veimmteral reflux. B , largest transverse anteroposterior diameter of fetal renal pe1vis.r fetus (mean and 95% confidence lnte&& &mean) according to postnatal outcome. Largest antemposterior diameter correlates ~1 ureteropelvic junction obstruction.
1052
PRENATAL RENAL PELVIC DIAMETER AND POSTNATAL OUTCOME
Corteville e t a1 found that a fetal renal pelvic anteroposterior diameter of 4 mm. or greater before 33 weeks of gestation, or 7 mm. or greater after 33 weeks of gestation was more sensitive than anteroposterior diameter of the renal pelvis-to-kidney ratio or the transverse diameter of the renal pelvis-to-kidney ratio when correlating these measures with postnatal outcome.’” They also noted t h a t a 10 mm. anteroposterior diameter threshold would not have detected all cases of postnatal hydronephrosis, and suggested that lower cutoffs, as described, should be used to ensure detection. The most common diagnosis in infancy in their series was ureteropelvic junction obstruction. I t is not evident that all infants were evaluated for vesicoureteral reflux.16 In other prenatal hydronephrosis studies voiding cystourethrography was done only when hydronephrosis persisted on postnatal ultrasound.3.4 Zerin e t al observed that 32% of infants with prenatal hydronephrosis and other renal abnormalities had vesicoureteral reflux despite the absence of hydronephrosis on postnatal ultrasound.17 Our results revealed an equal number of cases of ureteropelvic junction obstruction and vesicoureteral reflux. Using the lower threshold measurements of anteroposterior diameter may have enabled detection of more cases of vesicoureteral reflux than in previous studies, which used larger anteroposten o r diameters or pelvic-to-renal anteroposterior diameter ratios. If we had used a 10 mm. anteroposterior diameter as a definition of fetal hydronephrosis, only 1 of 6 cases of vesicoureteral reflux in our study would have been detected. Of interest is that 5 of 6 infants in our study with vesicoureteral reflux had normal postnatal ultrasound. The correlations of initial fetal anteroposterior diameter a t study entry and largest fetal anteroposterior diameter with ureteropelvic junction obstruction were statistically significant. Although not statistically significant, initial and largest fetal anteroposterior diameters in infants with vesicoureteral reflux were greater than those in normal infants. I t is possible that a greater difference would have been noted if ultrasound in fetuses with vesicoureteral reflux had been performed during or immediately after voiding. The use of prophylactic antibiotics to prevent urinary tract infection in cases of vesicoureteral reflux is standard. When reflux is present, it is most oRen detected during evaluation of a child with a history of urinary tract infection.” Detection of reflux in the neonatal period may enable antibiotics to be administered before the development of a urinary tract infection and possibly improve outcome in these cases. High grade neonatal reflux has been associated with decreased renal function even in the absence of clinically detected urinary tract infection.18-20 Early identification of these patients is important to ensure adequate followup care. CONCLUSIONS
Detection of vesicoureteral reflux in the neonatal period enables early intervention and management. Given that reflux can exist despite normal postnatal renal ultrasound, we recommend that all infants who fulfill the screening criteria for prenatal hydronephrosis, as used in our study, should be evaluated with voiding cystourethrography. REFERENCES
1. Helin, I. and Persson, P. H.: Prenatal diagnosis of urinary tract abnormalities by ultrasound. Pediatrics, 78:879,1986.
2. Steele, B. T., Robitaille, P.. DeMaria. J . and Grignon, A,: Follow-up evaluation of prenatally recognized vesicoureteric reflw. J. Ped., 1: 95,1989. 3. Johnson, C.E., Elder, J . S., Judge, N. E., Adeeb. F. N.. Grisoni, E. R. and Fattlar, D. C.: The accuracy of antenatal ultrasonography in identifying renal abnormalities. h e r . J. Dis. Child., 146: 1181. 1992. 4. Dejter. S.W. and Gibbons, M. D.: The fate of infant kidneys with fetal hydronephrosis but initially normal postnatal sonography. J. Urol., part 2, 142 661,1989. 5. Gordon, I., Dhillon. H. K., Gatanash, H. and Peters, A. M.: Antenatal diagnosis of pelvic hydronephrosis: assessment of renal function and drainage a s a guide to management. J. Nucl. Med., 32: 1649,1991. 6. Grignon, A,, Filion, R., Filiatrault, D.. Robitaille, P.. Homsy. Y., Boutin, H. and Leblond, R.: Urinary tract dilatation in utero: classification and clinical applications. Radiology. 160 645, 1986. 7. Grignon, A., Filiatrault. D., Homsy, Y.. Robitaille. P., Filion. R., Boutin, H. and Leblond, R.: Ureteropelvic junction stenosis: antenatal ultrasonographic diagnosis, postnatal investigation, and follow-up. Radiology, 160: 649,1986. 8. Homsy, Y. L.,Saad, F., Laberge, I., Williot. P. and Pison, C.: Transitional hydronephrosis of the newborn and infant, J. Urol., part 2, 144: 579, 1990. 9. Livera, L.N.,Brookfield, D. S. K., Egginton, J . A. and Hawnaur, J. M.: Antenatal ultrasonography to detect fetal renal abnormalities: a prospective screening programme. Brit. Med. J., 298 1421,1989. 10. Najmaldin, A,, Burge, D. M. and Atwell, J. D.: Fetal vesicoureteric reflux. Brit. J. Urol.. 65:403, 1990. 11. Paltiel, H. J . and Lebowitz, R.: Neonatal hydronephrosis due to primary vesicoureteral reflw: trends in diagnosis and treatment. Radiology, 170 787, 1989. 12. Steele, B. T., DeMaria, J., Toi. A., Stafford, A., Hunter, D. and Caco, C.: Neonatal outcome of fetuses with urinary tract abnormalities diagnosed by prenatal ultrasonography. Canad. Med. Ass. J., 131: 117, 1987. 13. Lebowitz, R. L., Olbing, H.. Parkkulainen, K. V.. Smellie. J. M. and Tamminen-Mobius, T. E.: International system of radiographic grading of vesicoureteral reflux. International Reflux Study in Children. Ped. Rad., 15: 105,1985. 14. Arger, P. H., Coleman, B. G., Mintz, M. C., Snyder, H. P., Camardese, T.. Arenson, R. L., Gabbe, S. G. and Aquino, L.: Routine fetal genitourinary tract screening. Radiology, 156 485, 1985. 15. Blachar, A., Blachar, Y., Livne, P. M., Zurkowski, L., Pelet. D. and Mogilner, B.: Clinical outcome and follow-up of prenatal hydronephrosis. Ped. Nephrol., 8:30, 1994. 16. Corteville, J. E.. Gray, D. L. and Crane, .J. P.: Congenital hydronephrosis: correlation of fetal ultrasonographic findings with infant outcome. Amer. J . Obst. Gynec., 165: 384. 1991. 17. Zerin, J. M., Ritchey, M. L. and Chang, A. C.: Incidental vesicoureteral reflw in neonates with antenatally detected hydronephrosis and other renal abnormalities. Radiology. 187: 157, 1993. 18. Anderson, P. A. M. and Rickwood. A. M. K.: Features of primary vesicoureteric reflux detected by prenatal sonography: Brit. J. Urol., 67: 267, 1991. 19. Marra, G., Barbieri, G., Dell’Agnola. C. A.. Caccamo. M. L., Castellani, M. R. and Assael, B. M.: Congenital renal damage associated with primary vesicoureteral reflux detected prenatally in male infants. J. Ped., 124: 726, 1994. 20. Najmaldin, B., Burge, D. M. and Atwell, J. D.: Reflux nephropathy secondary to intrauterine vesicoureteric reflux. J. Ped. Surg., 2 5 387,1990.