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A Modification of the Otis Urethrotome as an Aid to Fascial Dilation of Percutaneous Nephrostomy Tracts
0022-534 7/86/1354-0677$02.00/0 Vol. 135, April
THE ,JOURNAL OF UROLOGY
Copyright© 1986 by The Williams & Wilkins Co.
Printed in U.S.A.
Original Articles A MODIFICATION OF THE OTIS URETHROTOME AS AN AID TO FASCIAL DILATION OF PERCUTANEOUS NEPHROSTOMY TRACTS R. C. IRETON,* R. P. GOINEY
AND
J. S. BOWEN
From the Department of Urology, University of Washington School of Medicine and Veterans Administration Medical Center, · Seattle, Washington
ABSTRACT
An Otis urethrotome has been modified by drilling a 3/64-inch hole through the tip to permit passage into the kidney over a 0.038-inch guide wire. This instrument has been used to aid in the performance of 12 nephrostomy tract dilations without significant complications. When compared to 10 Amplatz tract dilations, the modified Otis method required an average of 3.6 minutes versus 8.7 minutes to dilate the nephrostomy tract to 24F. Ease of tract dilation as well as decreased time to dilate make this technique a useful adjunct to standard nephrostomy tract dilation techniques. Removal of upper urinary tract calculi through percutaneous tracts has become a routine urological surgical procedure. The success of this technique depends on the correct selection of entry tracts as well as successful dilation to diameters that will permit effective passage of an operating nephroscope. Common methods of tract dilation include the Amplatz polytetrafluoroethylene (Teflon) sheath system, 1 various balloon dilation systems 2 and telescoping metal 3 dilators. We describe a modification of the Otis urethrotome that permits this instrument to be used as a safe and effective dilator of the perirenal and lumbodorsal fascia during the establishment of nephrostomy tracts for percutaneous operations. MATERIALS AND METHODS
Instrument. An Otis urethrotome with a blunt tip was selected for modification. A %.-inch hole was drilled through the tip at an off-axis angle to permit a 0.038-inch guide wire to exit alongside the tip (fig. 1). Technique of dilation. Percutaneous access was established either acutely in the operating room with C-arm fluoroscopy or 2 days preoperatively in the radiology suite. With general anesthesia, dilation to 14F was performed with Amplatz coaxial dilators. Next, the dilating catheter was removed, leaving the safety wire and dilating guide wire in the renal and down the ureter. The tip of the modified Otis urethrotome then was inserted over the wire into the renal pelvis under fluoroscopic control. The tip of the instrument was positioned to preserve the gentle curve of the guide wire passing through the renal pelvis into the ureter, assuring proper placement (fig. 2). The dial then was set to the desired F diameter and, with the instrument oriented caudad, the blade was pulled back, incising the renal and lumbodorsal fascia (fig. 3). The urethrotome then was removed and the desired size operating sheath or 24F nephroscope was passed into the renal pelvis. Blood loss, ease of dilation, interval required to dilate to 24F and the occurrence of renal pelvic perforation were compared between the 2 types of nephrostomy tract dilation. Accepted for publication November 27, 1985. Read at annual meeting of Western Section, American Urological Association, July 21-25, 1985. *Requests for reprints: Urology, Veterans Administration Medical Center, 1660 S. Columbian Way, Seattle, Washington 98108. 677
RESULTS
There have been 24 tract dilations performed on 18 patients at our hospital since May 1, 1984: 12 were performed with the modified Otis urethrotome in conjunction with initial Amplatz dilation and 12 were accomplished with Amplatz dilators only (see table). Patients were assigned to either the modified Otis technique or Amplatz dilations based on physician preference. Eight patients who had undergone a previous renal operation were assigned to the modified Otis technique of nephrostomy tract dilation. None of the patients undergoing Amplatz dilation only had evidence of a previous renal operation. In the 12 cases of tract dilation with the Otis urethrotome the interval to dilation to 24F was 3.6 ± 0.5 minutes, estimated blood loss was 80 ± 40 cc and 1 minor pelvic perforation occurred but it did not require termination of the procedure. In the 12 cases in which Amplatz dilators were used the interval to dilate to 24F was 8.7 ± 2.4 minutes, estimated blood loss was 90 ± 20 cc and there was 1 renal pelvic perforation that required cessation of surgery and subsequent retrieval of the calculus at a second anesthetic procedure (see table). DISCUSSION
Percutaneous endourological techniques for removal of upper tract calculi are well established. 4 - 6 Tract dilation proceeds without complication using standard techniques in the majority of cases. There are no data relating the degree of
FIG. 1. Otis urethrotome shows details of tip modification (0.038inch guide wire passes easily through %,-inch hole).
678
IRETON, GOINEY AND BOWEN
Muscular Fascia 12th Rib
FIG. 3. Instrument in nephrostomy tract
Comparison of modified Otis urethrotome and Amplatz dilation of percutaneous nephrostomy tracts
FIG. 2. Radiograph of modified Otis urethrotome shows gentle curve of guide wire over which instrument is placed into kidney.
difficulty of tract dilation to pelvic perforation. However, when a scarred kidney is encountered or a tract must be dilated through a scar from a previous open operation, there is an increased risk of renal damage owing to the force with which Amplatz dilators must be applied. 7• 8 This problem has been obviated partly by the introduction of high pressure balloon dilators 2 but even these fail in some severely scarred systems. The use of the modified Otis urethrotome has facilitated greatly nephrostomy tract dilation. To date, there have been no complications and no excessive blood loss with the use of this instrument. The time to dilate to 24F also was reduced significantly from 8.7 ± 2.4 to 3.6 ± 0.5 minutes (p ~0.05). As with any rigid instrument used in nephrostomy tract dilation, the modified Otis urethrotome has the potential to damage the kidney if used improperly. Therefore, several recommendations should be followed. 1) We use only the blunt blade, which will separate scar tissue and leave normal tissue relatively intact. 2) When the tip of the instrument just penetrates the selected calix into the renal pelvis, the position of the blade is at the renal fascia in most kidneys and the incision created by blade withdrawal may open the renal fascia but not a significant portion of renal parenchyma. 3) The instrument should be aligned with the blade in a caudad direction to prevent possible damage to the subcostal neurovascular bundle, which runs inferior to the 12th rib. The Otis urethrotome is modified easily and readily available in most operating rooms. Although it may be used for routine tract dilation, the primary application should be for those patients in whom dilation is difficult by standard methods as a result of a previous operation or scarring. Although our expe-
Modified Otis Urethrotome
Amplatz
No. pts. Interval to dilation to 24F (mins.)*
12 3.8 ± 0.5
12 8.7 ± 2.4
Estimated blood loss (cc)* Pelvic perforation (No. pts.)
80
1
± 40
90 ± 20 1
* Mean ± standard deviation.
rience is small, the ease of Amplatz dilation after Otis urethrotome incision, reduced time of dilation and lack of complications make this technique a useful adjunct to add to the armamentarium of the percutaneous renal surgeon while performing nephrostomy tract dilation. REFERENCES 1. Rusnak, B. W., Castaneda-Zuniga, W., Kotula, F., Herrera, M. and
2.
3. 4. 3. 6.
7. 8.
Amplatz, K.: An improved dilator system for percutaneous nephrostomies. Radiology, 144: 174, 1982. Clayman, R. V., Castaneda-Zuniga, W. R., Hunter, D. W., Miller, R. P., Lange, P.H. and Amplatz, K.: Rapid balloon dilatation of the nephrostomy track for nephrostolithotomy. Radiology, 14 7: 884, 1983. Alken, A.: Percutaneous ultrasonic destruction of renal calculi. Urol. Clin. N. Amer., 9: 145, 1982. Segura, J. W., Patterson, D. E., LeRoy, A. J., May, G. R. and Smith, L. H.: Percutaneous lithotripsy. J. Urol., 130: 1051, 1983. Wickham, J. E. A., Kellett, M. J. and Miller, R. A.: Elective percutaneous nephrolithotomy in 50 patients: an analysis of the technique, results and complications. J. Urol., 129: 904, 1983. Clayman, R. V., Surya, V., Miller, R. P., Castaneda-Zuniga, W. R., Smith, A. D., Hunter, D. H., Amplatz, K. and Lange, P. H.: Percutaneous nephrolithotomy: extraction of renal and ureteral calculi from 100 patients. J. Urol., 131: 868, 1984. Brannen, G. E., Bush, W. H., Correa, R. J., Gibbons, R. P. and Elder, J. S.: Kidney stone removal: percutaneous versus surgical lithotomy. J. Urol., 133: 6, 1985. Clayman, R. V.: Endourology. In: Monographs in Urology. Edited by T. A. Stamey, vol. 6, p. 58, 1985.
THE ,JOURNAL OF UROLOGY
Copyright© 1986 by The Williams & Wilkins Co.
Printed in U.S.A.
Original Articles A MODIFICATION OF THE OTIS URETHROTOME AS AN AID TO FASCIAL DILATION OF PERCUTANEOUS NEPHROSTOMY TRACTS R. C. IRETON,* R. P. GOINEY
AND
J. S. BOWEN
From the Department of Urology, University of Washington School of Medicine and Veterans Administration Medical Center, · Seattle, Washington
ABSTRACT
An Otis urethrotome has been modified by drilling a 3/64-inch hole through the tip to permit passage into the kidney over a 0.038-inch guide wire. This instrument has been used to aid in the performance of 12 nephrostomy tract dilations without significant complications. When compared to 10 Amplatz tract dilations, the modified Otis method required an average of 3.6 minutes versus 8.7 minutes to dilate the nephrostomy tract to 24F. Ease of tract dilation as well as decreased time to dilate make this technique a useful adjunct to standard nephrostomy tract dilation techniques. Removal of upper urinary tract calculi through percutaneous tracts has become a routine urological surgical procedure. The success of this technique depends on the correct selection of entry tracts as well as successful dilation to diameters that will permit effective passage of an operating nephroscope. Common methods of tract dilation include the Amplatz polytetrafluoroethylene (Teflon) sheath system, 1 various balloon dilation systems 2 and telescoping metal 3 dilators. We describe a modification of the Otis urethrotome that permits this instrument to be used as a safe and effective dilator of the perirenal and lumbodorsal fascia during the establishment of nephrostomy tracts for percutaneous operations. MATERIALS AND METHODS
Instrument. An Otis urethrotome with a blunt tip was selected for modification. A %.-inch hole was drilled through the tip at an off-axis angle to permit a 0.038-inch guide wire to exit alongside the tip (fig. 1). Technique of dilation. Percutaneous access was established either acutely in the operating room with C-arm fluoroscopy or 2 days preoperatively in the radiology suite. With general anesthesia, dilation to 14F was performed with Amplatz coaxial dilators. Next, the dilating catheter was removed, leaving the safety wire and dilating guide wire in the renal and down the ureter. The tip of the modified Otis urethrotome then was inserted over the wire into the renal pelvis under fluoroscopic control. The tip of the instrument was positioned to preserve the gentle curve of the guide wire passing through the renal pelvis into the ureter, assuring proper placement (fig. 2). The dial then was set to the desired F diameter and, with the instrument oriented caudad, the blade was pulled back, incising the renal and lumbodorsal fascia (fig. 3). The urethrotome then was removed and the desired size operating sheath or 24F nephroscope was passed into the renal pelvis. Blood loss, ease of dilation, interval required to dilate to 24F and the occurrence of renal pelvic perforation were compared between the 2 types of nephrostomy tract dilation. Accepted for publication November 27, 1985. Read at annual meeting of Western Section, American Urological Association, July 21-25, 1985. *Requests for reprints: Urology, Veterans Administration Medical Center, 1660 S. Columbian Way, Seattle, Washington 98108. 677
RESULTS
There have been 24 tract dilations performed on 18 patients at our hospital since May 1, 1984: 12 were performed with the modified Otis urethrotome in conjunction with initial Amplatz dilation and 12 were accomplished with Amplatz dilators only (see table). Patients were assigned to either the modified Otis technique or Amplatz dilations based on physician preference. Eight patients who had undergone a previous renal operation were assigned to the modified Otis technique of nephrostomy tract dilation. None of the patients undergoing Amplatz dilation only had evidence of a previous renal operation. In the 12 cases of tract dilation with the Otis urethrotome the interval to dilation to 24F was 3.6 ± 0.5 minutes, estimated blood loss was 80 ± 40 cc and 1 minor pelvic perforation occurred but it did not require termination of the procedure. In the 12 cases in which Amplatz dilators were used the interval to dilate to 24F was 8.7 ± 2.4 minutes, estimated blood loss was 90 ± 20 cc and there was 1 renal pelvic perforation that required cessation of surgery and subsequent retrieval of the calculus at a second anesthetic procedure (see table). DISCUSSION
Percutaneous endourological techniques for removal of upper tract calculi are well established. 4 - 6 Tract dilation proceeds without complication using standard techniques in the majority of cases. There are no data relating the degree of
FIG. 1. Otis urethrotome shows details of tip modification (0.038inch guide wire passes easily through %,-inch hole).
678
IRETON, GOINEY AND BOWEN
Muscular Fascia 12th Rib
FIG. 3. Instrument in nephrostomy tract
Comparison of modified Otis urethrotome and Amplatz dilation of percutaneous nephrostomy tracts
FIG. 2. Radiograph of modified Otis urethrotome shows gentle curve of guide wire over which instrument is placed into kidney.
difficulty of tract dilation to pelvic perforation. However, when a scarred kidney is encountered or a tract must be dilated through a scar from a previous open operation, there is an increased risk of renal damage owing to the force with which Amplatz dilators must be applied. 7• 8 This problem has been obviated partly by the introduction of high pressure balloon dilators 2 but even these fail in some severely scarred systems. The use of the modified Otis urethrotome has facilitated greatly nephrostomy tract dilation. To date, there have been no complications and no excessive blood loss with the use of this instrument. The time to dilate to 24F also was reduced significantly from 8.7 ± 2.4 to 3.6 ± 0.5 minutes (p ~0.05). As with any rigid instrument used in nephrostomy tract dilation, the modified Otis urethrotome has the potential to damage the kidney if used improperly. Therefore, several recommendations should be followed. 1) We use only the blunt blade, which will separate scar tissue and leave normal tissue relatively intact. 2) When the tip of the instrument just penetrates the selected calix into the renal pelvis, the position of the blade is at the renal fascia in most kidneys and the incision created by blade withdrawal may open the renal fascia but not a significant portion of renal parenchyma. 3) The instrument should be aligned with the blade in a caudad direction to prevent possible damage to the subcostal neurovascular bundle, which runs inferior to the 12th rib. The Otis urethrotome is modified easily and readily available in most operating rooms. Although it may be used for routine tract dilation, the primary application should be for those patients in whom dilation is difficult by standard methods as a result of a previous operation or scarring. Although our expe-
Modified Otis Urethrotome
Amplatz
No. pts. Interval to dilation to 24F (mins.)*
12 3.8 ± 0.5
12 8.7 ± 2.4
Estimated blood loss (cc)* Pelvic perforation (No. pts.)
80
1
± 40
90 ± 20 1
* Mean ± standard deviation.
rience is small, the ease of Amplatz dilation after Otis urethrotome incision, reduced time of dilation and lack of complications make this technique a useful adjunct to add to the armamentarium of the percutaneous renal surgeon while performing nephrostomy tract dilation. REFERENCES 1. Rusnak, B. W., Castaneda-Zuniga, W., Kotula, F., Herrera, M. and
2.
3. 4. 3. 6.
7. 8.
Amplatz, K.: An improved dilator system for percutaneous nephrostomies. Radiology, 144: 174, 1982. Clayman, R. V., Castaneda-Zuniga, W. R., Hunter, D. W., Miller, R. P., Lange, P.H. and Amplatz, K.: Rapid balloon dilatation of the nephrostomy track for nephrostolithotomy. Radiology, 14 7: 884, 1983. Alken, A.: Percutaneous ultrasonic destruction of renal calculi. Urol. Clin. N. Amer., 9: 145, 1982. Segura, J. W., Patterson, D. E., LeRoy, A. J., May, G. R. and Smith, L. H.: Percutaneous lithotripsy. J. Urol., 130: 1051, 1983. Wickham, J. E. A., Kellett, M. J. and Miller, R. A.: Elective percutaneous nephrolithotomy in 50 patients: an analysis of the technique, results and complications. J. Urol., 129: 904, 1983. Clayman, R. V., Surya, V., Miller, R. P., Castaneda-Zuniga, W. R., Smith, A. D., Hunter, D. H., Amplatz, K. and Lange, P. H.: Percutaneous nephrolithotomy: extraction of renal and ureteral calculi from 100 patients. J. Urol., 131: 868, 1984. Brannen, G. E., Bush, W. H., Correa, R. J., Gibbons, R. P. and Elder, J. S.: Kidney stone removal: percutaneous versus surgical lithotomy. J. Urol., 133: 6, 1985. Clayman, R. V.: Endourology. In: Monographs in Urology. Edited by T. A. Stamey, vol. 6, p. 58, 1985.