The Watertightness of the Anastomosis After Laparoscopic or Robot-Assisted Pyeloplasty: Is a Drainage Necessary?

Abstract

Objective:

To determine whether or not temporary drainage is necessary immediately following laparoscopic (lap) and robot-assisted (rob) pyeloplasty (PP).

Patients and Methods:

Of 99 patients undergoing lap PP (n = 23) or rob PP (n = 76) for treatment of ureteropelvic junction obstruction (UPJO), 52 had no drainage, 47 were given an “easy-flow” drain (EFD). The volume of leaking urine (in mL) was defined as the volume of drainage fluid (in mL) × creatinine concentration in drainage fluid (in μmol/mL)/median urine creatinine concentration (in μmol/mL). An anastomosis was considered to be leaking if the volume of leaking urine exceeded 5 mL/24 hours. During follow-up the PP success rate was evaluated based on clinical symptoms, intravenous urography and diuretic renography for detection of persisting obstruction.

Results:

Median creatinine concentration in drainage fluid was 90 μmol/L (range 44–6270 μmol/L) in a median volume of 84 mL (range 5–1400 mL) drained fluid in 24 hours. The median leaking urine volume was 1.18 mL (range 0.07–291.34 mL), a leaking anastomosis was diagnosed in 5/47 (11%) patients. In patients with EFD and without EFD, complications occurred in 15% and 8% (p = 0.342), respectively, with success rates of 98% and 100% (p = 0.475). Complications (Clavien I-III) occurred in 4/42 (9.5%) patients with watertight and in 3/5 (60%) patients with leaking anastomosis (p = 0.019). No statistically significant differences were noted between lap PP and rob PP patients regarding complication and success rates.

Conclusion:

Lap PP and rob PP were primary watertight in 89% of all patients. A primary leaking anastomosis had no influence on PP outcome, but was associated with a higher risk of complications. However, neither the success rate nor the complication rate differed between drained and undrained patients. We conclude, therefore, that drainage is not necessary.

Introduction

In 1993 Schuessler and colleagues¹ described the first laparoscopic (lap) pyeloplasty (PP). At that time open PP was the gold standard treatment for ureteropelvic junction obstruction (UPJO) with overall success rates ranging from 80% to 100%.² Alternative treatments were antegrade or retrograde endopyelotomy with the advantage of minimal invasiveness but the disadvantage of lower success rates.³ Lap PP combines minimal invasiveness with a high success rate comparable to that of open PP,^4

–11 becoming in the last 10 to 15 years the new standard treatment of patients with UPJO. More recently the robotic approach, if available, has been favored due to its technical simplification of the operation combined with results similar to those of the laparoscopic approach.^{12

–19} One of the unexamined questions regarding both lap PP and rob PP is whether wound drainage is necessary. Some surgeons put a wound drain in place to drain the anastomosis.^20,21 It is the aim of this study to determine whether or not this drainage is necessary for the success of the PP.

Patients and Methods

Between November 2004 and November 2013, a total of 108 consecutive patients with UPJO were treated in the Urology Clinic of the Lucerne Cantonal Hospital by lap PP (n = 25) or rob (n = 83) PP according to Anderson–Hynes.

Indications for UPJO repair were a history of characteristic pain and demonstration of obstruction by intravenous urography (IVU), CT scan or diuretic renography.

IVU or CT scan had to show the typical appearance of a dilated renal pelvis and calices, possibly with deferred excretion of the contrast medium. Some images showed a crossing vessel to the lower pole of the kidney responsible for the obstruction.

The diuretic renography had to show either an obstructive curve (typical ascending curve or curve that remained on maximum level during the examination) or if the washout curve did not show an obstruction (cases of intermittent obstruction) and the patients were asymptomatic we insisted on a split renal function of ≤45% on the affected side.

Preoperative retrograde or antegrade (in cases with a nephrostomy) pyelography was also performed to illustrate classic UPJO findings such as the jet phenomenon and to exclude a second stenosis in the distal ureter. Retrograde pyelography was performed either in advance or during the same anesthesia just before the PP. Usually a Double-J stent was put in place at the same time.

Lap PP (n = 25) and rob PP (n = 83) were performed according to the Anderson–Hynes technique. The three operating surgeons were well experienced in laparoscopic surgery. We started data collection just after we switched from endoscopic/open to laparoscopic PP and continued later by robot-assisted PP.

Patients were bedded in flank position. All patients received perioperative antibiotic prophylaxis by a single shot of cefazolin 2 g. After mobilization of the colon, stenotic area was resected, the ureter spatulated, and the ureteropelvic anastomosis achieved end to side with a 4–0 Vicryl running suture. In cases with a crossing vessel, the ureteropelvic junction was transferred from the posterior to an anterior position.

The anastomosis was stented by a 6F Double-J catheter. Removal of the ureteral stent was performed cystoscopically in our outpatient clinic under local anesthesia 1 or 4 weeks postoperatively according to a randomization protocol, which investigated 1 vs 4 weeks stenting after lap or rob PP and did not show any difference in outcome and complications.¹⁸ Patients having a nephrostomy tube preoperatively were stented the same way, but the nephrostomy tube was left open for 48 hours, then closed and removed after another 24 hours if no signs of obstruction occurred (which did not occur in any patient).

All patients had a bladder catheter for at least 2 days to assure low pressure in the urinary tract.

In 57 patients, a 12 mm silicon easy-flow drain (EFD) (by Ulrich Swiss) was placed next to the anastomosis at the end of the operation. The EFD was usually removed after 24 or 48 hours, depending on when the volume of drained fluid reached ≤100 mL/24 hours.

The drained fluid volume consists of urine and lymph fluid. Differentiation of urine from lymph fluid is difficult; therefore a simplification was necessary. The creatinine concentration in the lymph fluid is the same as in the blood serum and is approximately a 100-fold lower than in urine. Therefore we neglected the amount of creatinine in the lymph fluid and calculated the volume of urine extravasation from the drainage fluid volume, its creatinine concentration, and a gender-specific median urine creatinine concentration, the latter taken from the literature.²²

The serum creatinine concentrations were measured pre- and postoperatively, the volume of drained fluid and its creatinine concentration at 24 and 48 hours postoperatively.

The median urine creatinine concentration—6362 μmol/L (range 2464–19,096 μmol/L) for females, 8580 μmol/L (range 3432–22,792 μmol/L) for males—was taken from the literature²² since we did not measure this parameter in our own patients. Our calculations focused on the first 24 hours since the majority of drains were dry after 24 hours.

Then the volume of urine in the drainage fluid was calculated according to the following formula: leaking urine (in mL) = volume of drainage fluid (in mL) × creatinine concentration in drainage fluid (in μmol/mL)/median urine creatinine concentration (in μmol/mL).

A leaking anastomosis was defined as a leakage of ≥5 mL urine in 24 hours, assuming that this volume could be a residual leftover after perioperative opening of the pyelon.

Peri- and postoperative complications were classified using the modified Clavien–Dindo classification.

For follow-up, patients had an IVU 3 months postoperatively, an ultrasound, as well as a diuretic renography, 6 months postoperatively. Patients with no residual symptoms were evaluated 1 year postoperatively by an ultrasound and every second year thereafter. In patients with residual symptoms, a diuretic renography was performed to objectify a possible obstruction. If a new or remaining obstruction was found, surgical therapy was recommended.

When evaluating the 3-month IVU, an obstruction was ruled out if contrast agent appeared in the 5-minute image and diminished from the renal pelvis and if the calices were less dilated compared to the preoperative finding.

The washout curve of the postoperative diuretic renography was evaluated only if the split renal function was ≥20%. We rated an efflux as proper if the washout curve decreased during examination. In case the decrease of the washout curve was deferred compared to the healthy side, we compared the pre- and postoperative washout curves of the affected side to decide if the operation would be counted as effective or not. We assumed that a residual dilatation of the pelvis would cause a pooling effect and, therefore, defer the decrease of the washout curve. Therefore, if the decrease of the washout curve showed an amelioration after the operation, we assumed no residual obstruction but a residual dilatation to be responsible for the deferred decrease of the washout curve.

An operation was considered effective if patients had no pain due to obstruction and no signs of obstruction in the postoperative IVU or diuretic renography. The operation was also counted as effective if patients had residual symptoms not requiring pain medication and no signs of obstruction in the IVU or diuretic renography.

In 7/115 patients an EFD was placed, but the necessary parameters (volume and creatinine concentration) were not obtained and they were excluded from the study. In another nine patients the follow-up was less than 3 months and they were also excluded from the study. This left a total of 99 patients (23 lap PP, 76 rob PP; 47 with EFD, 52 without EFD) who were analyzed for this study (Table 1).

Table 1.

Preoperative Characteristics of Patients Undergoing PP With and Without an EFD

	Overall (n = 99)	EFD (n = 47)	No EFD (n = 52)	p
Age in years, median (range)	42 (15–82)	47 (15–82)	35 (15–79)	0.402
Gender [F : M], %	46: 54	55: 45	37: 63	0.061
Side [left: right], %	49: 51	47: 53	56: 44	0.373
Split renal function, affected side in%, median (range)	42 (5–62)	42 (5–61)	44 (13–62)	0.749
Serum creatinine in μmol/L, median (range)	77 (32–265)	78 (41–215)	76 (32–265)	0.960

EFD = easy-flow drain.

All data were collected prospectively. Primary end points were the watertightness of the anastomosis, the complication rates, and the effectiveness of the operation in both drained and undrained patients.

For statistical analysis IBM SPSS Statistics software was used. Basic descriptive data (e.g., average, standard deviation, median and range) were calculated. Mann–Whitney U-test was used to compare scaled, not normally distributed data, t-test for scaled normally distributed data, and chi-square test or Fisher's exact test for nonscaled data. Significance level was defined as p < 0.05.

Informed written consent was obtained from all patients. The study was performed according to the Declaration of Helsinki and was approved by the local ethics committee (Submission File 12050).

Results

Patients with an EFD had a median creatinine concentration of 90 μmol/L (range 44–6270 μmol/L) in a median volume of 84 mL (range 5–1400 mL) of drained fluid 24 hours postoperatively. The median volume of leaking urine after 24 hours was 1.18 mL (range 0.07–291.34 mL). In 5/47 (11%) patients the volume of leaking urine exceeded 5 mL, meeting our definition of a leaking anastomosis.

Clavien ≤III complications occurred in 9.5% (4/42) of patients with a watertight anastomosis vs 60% (3/5) of patients with a leaking anastomosis (p = 0.019). Complications in the watertight group were Double-J stent dislocation or Double-J stent obstruction in three patients and paralytic ileus in another patient. Complications in the leaking group were paralytic ileus in one patient, Double-J stent dislocation and paralytic ileus in another patient, and systemic inflammation signs in a third patient. In two patients the EFD and the bladder catheter were removed later than 24 hours postoperatively due to ongoing secretion.

Preoperative data on patients with and without EFD (age, gender, affected side, split renal function, serum creatinine, etc.) were comparable (Table 1).

Perioperative Clavien ≤III complications were comparable in patients with and without EFD (15% vs 8%; p = 0.342). Of 47 patients with EFD, 7 had a total of 8 complications (4 × Double-J stent dislocation or obstruction, 3 × paralytic ileus, and 1 × systemic inflammation signs); of 52 patients without EFD, 4 had 5 complications (3 × systemic inflammation signs, 1 × paralytic ileus, and 1 × herniation).

Median follow-up times, median postoperative serum-creatinine concentrations, residual symptoms and signs of obstruction in follow-up examinations, and split renal function after 6 months were comparable in patients with and without EFD (shown in Table 2).

Table 2.

Postoperative Characteristics of Patients Undergoing PP With and Without an EFD

	Overall (n = 99)	EFD (n = 47)	No EFD (n = 52)	p
Follow-up in months, median (range)	26 (3–105)	20 (3–105)	33 (4–69)	0.336
Complications in %	11	15	8	0.342
Residual symptoms in %	2	4	0	0.223
Split renal function, operated side in %, median (range)	46 (5–70)	46 (5–57)	45 (17–70)	0.228
Obstruction in diuretic renography and intravenous urography in %	1	2	0	0.290
Improvement in renal function, operated side in %, median (range)	0 (−18 to 28)	0 (−8 to 13)	1 (−18 to 28)	0.270
Serum creatinine in μmol/L, median (range)	73 (31–388)	73 (31–224)	74 (34–388)	1.000
Success rate in %	99	98	100	0.475

The success rates in patients with and without EFD were 98% and 100% (p = 0.475), respectively. The only patient whose treatment failed underwent rob PP, had an EFD, and a leaking anastomosis. This is not surprising since the inflamed tissue of the renal pelvis was difficult to suture in this patient even though we had waited 3 months after an extracorporeal shock wave therapy to perform the operation. The patient was effectively treated by a secondary retrograde endopyelotomy.

Patients treated by lap PP and rob PP had comparable creatinine concentrations in the drainage fluid (83 μmol/L [range 59–6270 μmol/L] vs 99 μmol/L [range 44–1326 μmol/L]; p = 0.298), drainage volume (142 mL [range 22–830 mL] vs 62.5 mL [range 5–1400 mL]; p = 0.65), and leaking urine volume (1.63 mL [range 0.28–193.65 mL] vs 0.91 mL [range 0.07–291.34 mL]; p = 0.099). A leaking anastomosis was noted in 2/19 lap PP vs 3/28 rob PP patients (p = 1), with a primary watertight anastomosis in 89% of both groups. Complications rates of lap PP and rob PP were also comparable (17% vs 9%; p = 0.275).

Discussion

Lap PP and rob PP are established techniques for correction of UPJO.^{4

–19} For both procedures some surgeons report draining the stented anastomosis.^20,21 To date, however, nobody has investigated whether or not this drainage is necessary.

Our patients undergoing lap PP and rob PP had a low anastomosis leakage rate of 11%. Patients with and without EFD had comparably low complication rates of 15% and 8% and high success rates of 98% and 100%, respectively. Drainage of the anastomosis, therefore, does not appear to provide significant benefits, but might bear a certain morbidity.

Among patients with an EFD, those with a temporarily leaking anastomosis had a significantly higher complication rate than those with a watertight anastomosis (60% vs 9.5%, p = 0.019). This is not surprising since some of the complications, for example, a paralytic ileus or systemic inflammation, are more likely with an extravasation of urine in the retroperitoneal space. Moreover, the EFDs in our patients clearly did not prevent complications due to leakage because the rates of complication and success were comparable with or without EFD. The most that can be done to prevent complications is to sew the ureteropelvic anastomosis as carefully as possible to achieve optimum watertightness. In this context, neutralization of upper urinary tract pressure by a transurethral catheter for 2 days, although unproven, might be helpful because the majority of patients had a watertight anastomosis no later than 48 hours after surgery.

In addition to our findings on watertightness and anastomosis leakage, our overall success rate was 98% and our complication rate was 11%, findings that are in line with the meta-analysis of Autorino.¹³ Our lap PP and rob PP patients had comparable complication rates of 17% and 9% (p = 0.28), respectively, with success rates of 98% and 100%, results which are in line with the literature.^{4

–19}

Our study has the limitations that the patients were not randomized and that calculation of the leaking volume was based on a median urine creatinine concentration for men and women taken from the literature.²² If this parameter had been measured in every patient, calculation of the leaking volume for each patient would have been more precise. In addition, our method for calculating the leaking urine volume was not absolutely precise because lymph fluid and irrigation fluid could have influenced the drainage volume. However, because the creatinine concentration in urine is high compared to that of lymph and irrigation fluid, we think these factors can be ignored.

To confirm and prove our finding a prospective randomized trial, drainage vs no drainage after PP, with additional measurement of the mentioned parameters in the drained group would be necessary.

Conclusions

Urine leakage after lap PP and rob PP is rare, with a minimal volume of leaking urine in most patients. Although such a rare extravasation appears to have some impact on complication rates, the present findings show that temporary drainage of this extravasation does not influence overall complication and success rates. We conclude, therefore, that temporary drainage of the stented anastomosis after lap PP or rob PP might not be necessary.

Footnotes

Acknowledgment

Source of work: clinical trial.

Author Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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