Reflux and
Pediatric Radiology
Trapping 1
Robert M. Weiss, M.D., Martin Schiff, Jr., M.D., and Bernard Lytton, M.B., FRCS Although functional ureteral obstruction results in a decrease in the rate of antegrade urine flow, urine may still traverse the obstructed segment in a retrograde direction. Decreased musculature is found in the obstructing area. The combination of these processes results in reflux with trapping. This process has been demonstrated radiographically at both the ureterovesical and the ureteropelvic junctions. INDEX TERMS:
Ureters, obstruction. Ureters, reflux
Radiology 118:129-131, January 1976
ESICOURETERA L REFLUX
is sometimes associated with
V a functional obstruction (1). Allen, in a study of func-
tional ureteral obstruction, noted a reduction in the muscular bulk of the involved segments and a narrowing of the ureteral lumen, which indicates a local developmental arrest resulting in a congenital stricture (2). A decrease in musculature has also been reported when the functional obstruction has occurred at either the ureteropelvic (3) or ureterovesical junction (1, 2). Functional obstructions at different levels of the ureter have thus been shown to be associated with similar histological findings.
Although functional obstruction impedes the rate of antegrade urine flow, retrograde flow may still traverse the obstructed segment. The combination of these processes results in reflux with trapping; the following cases demonstrate this process of functional obstruction. CASE REPORTS CASE I. Routine urinalysis disclosed a klebsiella urinary infection in M. T:,a two-year-old Puerto Rican girl. Blood urea nitrogen was 17 mg per 100 ml, and serum creatinine was 0.8 mg per 100 ml. Excretory urography showed bilateral hydroureteronephrosis (Fig. 1). A
Fig. 1. CASE I. Excretory urography shows bilateral hydroureteronephrosis. Fig. 2. CASE I. A: Voiding cystourethrogram shows left vesicoureteral reflux with bladder filling. B. Film taken after voiding shows complete bladder emptying and retention of contrast material in the dilated left upper collecting system, indicative of an associated obstructive factor at the ureterovesical junction.
1 From the Department of Surgery, Section of Urology, Yale University School of Medicine, New Haven, Conn. Accepted for publication in 55 June 1975.
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creatinine was 0.7 mg per 100 ml, and urinalysis was normal. Excretory urography showed mild right hydronephrosis due to a ureteropelvic junction obstruction with a narrowed proximal ureteral segment 1.5 cm long (Fig. 4). A dilated left pelvicalyceal system was only minimally visualized. A voiding cystourethrogram showed no evidence of bladder outlet obstruction and no vesicoureteral reflux Oil the filling or post-voiding films (Fig. 5, A and B). The patient did not empty his bladder completely during the study, probably due to nervousness, as no residual urine was found by subsequent evaluation. On the day following the cystogram, contrast material was seen to be trapped in a massively hydronephrotic left pelvicalyceal system; there was evidence of functional ureteropelvic junction obstruction (Fig. 6). A left nephrectomy was performed, and the right hydronephrosis has remained unchanged during the past four years.
DISCUSSION Fig. 3. voiding cystourethrogram after the urinary infection was cleared revealed a prompt vesicoureteral reflux into a dilated left upper collecting system (Fig. 2, A); there was no reflux on the right. Radiographs after voiding showed retention of contrast material in the dilated system (Fig. 2, B). Both ureteral orifices appeared normal at cystoscopic examination, but distension of the bladder caused the left ureteral orifice to retract laterally and become patulous. Bilateral ureteroneocystotomies were performed with excision of a 1.2 cm segment of narrowed terminal ureter (Fig. 3). CASE II. S. H.; a four-year-old white boy, was admitted with a four-month history of intermittent gross hematuria and lower abdominal discomfort. Blood urea nitrogen was 12 mg per 100 ml, serum
CASE 1 is an example of vesicoureteral reflux and distal ureteral obstruction. Left vesicoureteral reflux was present with filling of the bladder, and delayed films demonstrated a retention of contrast material in the left collecting system, indicating the associated obstructive factor. The radiographic appearance of reflux and trapping is characterized by delayed ureteral drainage and a rounded appearance of the distal ureter, which appears separated from the bladder by an apparent space caused by the narrowing of the distal ureteral segment. Reflux is occasionally intermittent, and this may explain the absence of right vesicoureteral reflux in this case.
Fig. 4. CASE II. Excretory urography shows mild right hydroureteronephrosis due to a ureteropelvic junction obstruction. There is only minimal visualization of the dilated left pelvicalyceal system. Fig. 5. CASE II. A. Filling phase of voiding cystourethrogram shows no veslcoureteral reflux. B. Post-voiding film shows no vesicoureteral reflux and residual contrast material in the bladder. Fig. 6. CASE II. Plain film of the abdomen obtained 16 hours after the voiding cystourethrogram shows contrast material in a diiated left pelvicalyceal system. Contrast material had refluxed from the bladder and through the marked functional obstruction at the ureteropelvic junction. Antegrade trapping of contrast material in the pelvis had occurred.
Vol. 118
131
REFLUX AND TRAPPING
The excretory urogram suggests the presence of a similar process bilaterally. These patients should be treated by surgical revision of the ureterovesical junction; they should not be managed conservatively because of the obstructive element. It is important, therefore, to identify this entity in patients with vesicoureteral reflux. In CASE II; the child did not completely empty his bladder after the voiding cystourethrogram, and veslcouretera' reflux must have occurred during the ensuing sixteen hours (Fig. 6). The contrast material refluxed through the marked functional obstruction, and antegrade trapping occurred. Contrast material was retained in the pelvis for 48 hrs and represents an example of reflux and trapping at the ureteropelvic junction. Tanaqho et al. (4) related the functional obstruction at the ureterovesical junction to an abnormal abundance of circularly-oriented fibers at the proximal end of the non-dilated segment. Murnaghan, on the other hand, showed that there was frequently an unusual predominance of longitudinal muscle in place of the normal arrangement of mixed oblique fibers, and also noted that there may be a reduction in total muscle mass when he examined histologically the pelvi-ureteric junction in congenital hydronephrosis (5, 6). In both of our cases a decrease in musculature was noted on histological ex-
Pediatric Radiology
aminatioh of the specimen resected from the site of the functional ureteral obstruction; this is consistent with previous reports (1-3). The cases of reflux with trapping which have been reported demonstrate the importance of delayed exposures when performing a voiding cystourethrogram.
REFERENCES 1. Weiss RM, Lytton B: Vesicoureteral reflux and distal ureteral obstruction. J UroI111:245-249, Feb 1974 2 Allen TO: Congenital ureteral strictures. J Urol 104:196-204, Jul 1970 3 Foote JW, Blennerhassett JB, Wiglesworth FW, et al.: Observations on the ureteropelvic junction. J UroI104:252-257, Aug 1970 4. Tanagho EA, Smith DR, Guthrie TH:. Pathophysiology of functional ureteral obstruction. J UroI104:73-88, Jul 1970 5. Murnaghan GF: The mechanism of congenital hydronephrosis with reference to the factors influencing surgical treatment. Ann Roy Coli Surg 23:25-46, Jul 1958 6. Murnaghan GF: Experimental aspects of hydronephrosis. Brit J UroI31:370-376, Dec 1959
Yale-New Haven Hospital 789 Howard Avenue New Haven, Conn. 06504
Pediatric Radiology
Trapping 1
Robert M. Weiss, M.D., Martin Schiff, Jr., M.D., and Bernard Lytton, M.B., FRCS Although functional ureteral obstruction results in a decrease in the rate of antegrade urine flow, urine may still traverse the obstructed segment in a retrograde direction. Decreased musculature is found in the obstructing area. The combination of these processes results in reflux with trapping. This process has been demonstrated radiographically at both the ureterovesical and the ureteropelvic junctions. INDEX TERMS:
Ureters, obstruction. Ureters, reflux
Radiology 118:129-131, January 1976
ESICOURETERA L REFLUX
is sometimes associated with
V a functional obstruction (1). Allen, in a study of func-
tional ureteral obstruction, noted a reduction in the muscular bulk of the involved segments and a narrowing of the ureteral lumen, which indicates a local developmental arrest resulting in a congenital stricture (2). A decrease in musculature has also been reported when the functional obstruction has occurred at either the ureteropelvic (3) or ureterovesical junction (1, 2). Functional obstructions at different levels of the ureter have thus been shown to be associated with similar histological findings.
Although functional obstruction impedes the rate of antegrade urine flow, retrograde flow may still traverse the obstructed segment. The combination of these processes results in reflux with trapping; the following cases demonstrate this process of functional obstruction. CASE REPORTS CASE I. Routine urinalysis disclosed a klebsiella urinary infection in M. T:,a two-year-old Puerto Rican girl. Blood urea nitrogen was 17 mg per 100 ml, and serum creatinine was 0.8 mg per 100 ml. Excretory urography showed bilateral hydroureteronephrosis (Fig. 1). A
Fig. 1. CASE I. Excretory urography shows bilateral hydroureteronephrosis. Fig. 2. CASE I. A: Voiding cystourethrogram shows left vesicoureteral reflux with bladder filling. B. Film taken after voiding shows complete bladder emptying and retention of contrast material in the dilated left upper collecting system, indicative of an associated obstructive factor at the ureterovesical junction.
1 From the Department of Surgery, Section of Urology, Yale University School of Medicine, New Haven, Conn. Accepted for publication in 55 June 1975.
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January 1976
creatinine was 0.7 mg per 100 ml, and urinalysis was normal. Excretory urography showed mild right hydronephrosis due to a ureteropelvic junction obstruction with a narrowed proximal ureteral segment 1.5 cm long (Fig. 4). A dilated left pelvicalyceal system was only minimally visualized. A voiding cystourethrogram showed no evidence of bladder outlet obstruction and no vesicoureteral reflux Oil the filling or post-voiding films (Fig. 5, A and B). The patient did not empty his bladder completely during the study, probably due to nervousness, as no residual urine was found by subsequent evaluation. On the day following the cystogram, contrast material was seen to be trapped in a massively hydronephrotic left pelvicalyceal system; there was evidence of functional ureteropelvic junction obstruction (Fig. 6). A left nephrectomy was performed, and the right hydronephrosis has remained unchanged during the past four years.
DISCUSSION Fig. 3. voiding cystourethrogram after the urinary infection was cleared revealed a prompt vesicoureteral reflux into a dilated left upper collecting system (Fig. 2, A); there was no reflux on the right. Radiographs after voiding showed retention of contrast material in the dilated system (Fig. 2, B). Both ureteral orifices appeared normal at cystoscopic examination, but distension of the bladder caused the left ureteral orifice to retract laterally and become patulous. Bilateral ureteroneocystotomies were performed with excision of a 1.2 cm segment of narrowed terminal ureter (Fig. 3). CASE II. S. H.; a four-year-old white boy, was admitted with a four-month history of intermittent gross hematuria and lower abdominal discomfort. Blood urea nitrogen was 12 mg per 100 ml, serum
CASE 1 is an example of vesicoureteral reflux and distal ureteral obstruction. Left vesicoureteral reflux was present with filling of the bladder, and delayed films demonstrated a retention of contrast material in the left collecting system, indicating the associated obstructive factor. The radiographic appearance of reflux and trapping is characterized by delayed ureteral drainage and a rounded appearance of the distal ureter, which appears separated from the bladder by an apparent space caused by the narrowing of the distal ureteral segment. Reflux is occasionally intermittent, and this may explain the absence of right vesicoureteral reflux in this case.
Fig. 4. CASE II. Excretory urography shows mild right hydroureteronephrosis due to a ureteropelvic junction obstruction. There is only minimal visualization of the dilated left pelvicalyceal system. Fig. 5. CASE II. A. Filling phase of voiding cystourethrogram shows no veslcoureteral reflux. B. Post-voiding film shows no vesicoureteral reflux and residual contrast material in the bladder. Fig. 6. CASE II. Plain film of the abdomen obtained 16 hours after the voiding cystourethrogram shows contrast material in a diiated left pelvicalyceal system. Contrast material had refluxed from the bladder and through the marked functional obstruction at the ureteropelvic junction. Antegrade trapping of contrast material in the pelvis had occurred.
Vol. 118
131
REFLUX AND TRAPPING
The excretory urogram suggests the presence of a similar process bilaterally. These patients should be treated by surgical revision of the ureterovesical junction; they should not be managed conservatively because of the obstructive element. It is important, therefore, to identify this entity in patients with vesicoureteral reflux. In CASE II; the child did not completely empty his bladder after the voiding cystourethrogram, and veslcouretera' reflux must have occurred during the ensuing sixteen hours (Fig. 6). The contrast material refluxed through the marked functional obstruction, and antegrade trapping occurred. Contrast material was retained in the pelvis for 48 hrs and represents an example of reflux and trapping at the ureteropelvic junction. Tanaqho et al. (4) related the functional obstruction at the ureterovesical junction to an abnormal abundance of circularly-oriented fibers at the proximal end of the non-dilated segment. Murnaghan, on the other hand, showed that there was frequently an unusual predominance of longitudinal muscle in place of the normal arrangement of mixed oblique fibers, and also noted that there may be a reduction in total muscle mass when he examined histologically the pelvi-ureteric junction in congenital hydronephrosis (5, 6). In both of our cases a decrease in musculature was noted on histological ex-
Pediatric Radiology
aminatioh of the specimen resected from the site of the functional ureteral obstruction; this is consistent with previous reports (1-3). The cases of reflux with trapping which have been reported demonstrate the importance of delayed exposures when performing a voiding cystourethrogram.
REFERENCES 1. Weiss RM, Lytton B: Vesicoureteral reflux and distal ureteral obstruction. J UroI111:245-249, Feb 1974 2 Allen TO: Congenital ureteral strictures. J Urol 104:196-204, Jul 1970 3 Foote JW, Blennerhassett JB, Wiglesworth FW, et al.: Observations on the ureteropelvic junction. J UroI104:252-257, Aug 1970 4. Tanagho EA, Smith DR, Guthrie TH:. Pathophysiology of functional ureteral obstruction. J UroI104:73-88, Jul 1970 5. Murnaghan GF: The mechanism of congenital hydronephrosis with reference to the factors influencing surgical treatment. Ann Roy Coli Surg 23:25-46, Jul 1958 6. Murnaghan GF: Experimental aspects of hydronephrosis. Brit J UroI31:370-376, Dec 1959
Yale-New Haven Hospital 789 Howard Avenue New Haven, Conn. 06504
