Suture versus staple ligation of the dorsal venous complex during robot-assisted laparoscopic radical prostatectomy

Authors


Robert B. Nadler, Department of Urology, Northwestern University Feinberg School of Medicine, 675 North St. Clair Street, Galter 20–150, Chicago, IL 60611, USA.
e-mail: r-nadler@northwestern.edu

Abstract

Study Type – Therapy (case series)
Level of Evidence 4

OBJECTIVES

To present our operative and postoperative functional outcomes of sutured compared with endovascular staple ligation of the dorsal venous complex (DVC) during robot-assisted laparoscopic radical prostatectomy (RALP). Ligation of the DVC during RALP with an endovascular stapler has purported advantages of decreased apical positive surgical margin (PSM) rate, blood loss, and operative time when compared with suture ligation.

PATIENTS AND METHODS

In all, 162 patients who underwent RALP between October 2005 and April 2008 by one surgeon (R.B.N.) were assessed. We retrospectively analysed two different treatment groups: group 1 underwent DVC ligation with a single suture, while group 2 underwent endovascular staple ligation.

RESULTS

Of the 162 patients evaluated, 67 had suture ligation (group 1) and 95 had staple ligation (group 2) of the DVC. Baseline patient characteristics (age, body mass index, biopsy Gleason score, clinical stage) and tumour characteristics (specimen weight, tumour volume, pathological Gleason score and stage) did not differ between the groups. Estimated blood loss (494 mL vs 288 mL), time to dissect out, ligate and transect the DVC (30 min vs 24 min), apical PSM rate (13.4% vs 2.1%) differed significantly between groups 1 and 2 respectively, favouring staple ligation of the DVC. At 6 months follow-up, there was no difference between the groups for PSA recurrence (3.7% vs 0%), complete continence (63.4% vs 55.7%) and Sexual Health Inventory for Men score (8.4 vs 8.6).

CONCLUSIONS

In the present study, staple ligation of the DVC during RALP resulted in improved apical PSM rates, faster operative times and less blood loss.

Abbreviations
DVC

dorsal venous complex

RALP

robot-assisted laparoscopic radical prostatectomy

PSM

positive surgical margin

(R)RP

(retropubic) radical prostatectomy

SHIM

Sexual Health Inventory for Men

EBL

estimated blood loss

BMI

body mass index.

INTRODUCTION

Robot-assisted laparoscopic radical prostatectomy (RALP) has become a widely used technique in the primary treatment of prostate cancer in the USA. Since first described in 2000 [1], RALP has progressively gained in popularity. It is estimated that ≈50 000 radical prostatectomies (RPs) were performed in the USA using the da Vinci robot system (Intuitive Surgical, Sunnyvale, CA, USA); this is ≈60% of all RPs performed [2]. For the handling of the dorsal venous complex (DVC), both suture and stapled ligation have been described [3–6]. Potential advantages of staple ligation of the DVC include decreased apical positive surgical margin (PSM) rate as reported by Ahlering et al. in 2004 [5]. Other potential benefits of stapling the DVC are decreased blood loss, damage to external urinary sphincter, and operative time. We present our operative and postoperative outcomes in comparing suture vs endovascular staple ligation of the DVC in our RALP patients.

PATIENTS AND METHODS

Between October 2005 and April 2008, 162 consecutive patients underwent RALP by a single surgeon (R.B.N.) at Northwestern Memorial Hospital (Chicago, IL, USA). In all, 67 consecutive patients’ DVCs were secured with suture (group 1) followed by 95 consecutive patients who had staple ligation with an endovascular stapler (group 2). No patients received neoadjuvant therapy. Patient data was collected prospectively and stored in a central data base with Institutional Review Board approval. Baseline patient characteristics analysed obtained through history and physical examination included age, body mass index (BMI), preoperative PSA level, biopsy Gleason score, clinical stage, complete continence and Sexual Health Inventory for Men (SHIM) score. Operative outcomes analysed included estimated blood loss (EBL), operative duration for ligating the DVC, apical PSMs and overall PSMs on pathological evaluation. Tumour characteristics analysed included prostate specimen weight, tumour volume expressed as a percentage of tissue histologically examined containing tumour, pathological Gleason score, and pathological stage. Early functional outcomes at 6 months evaluated were continence (i.e. 0 vs ≥1 pad/day), PSA recurrence (defined as a PSA level of ≥0.2 ng/mL) and SHIM score.

Data of the two groups were compared using Student’s t-test for continuous variables and chi-squared test for categorical variables. All tests were two-tailed, of unequal variance, with P < 0.05 considered to indicate statistical significance. Multivariate analysis using regression models were used to compare EBL, operative duration in ligating the DVC, apical PSM and overall PSM rates, and functional outcomes (PSA recurrence, SHIM score, and continence at 6 months). Univariate analysis was performed with Microsoft Excel 2007 (Redmond, WA, USA) and multivariate analysis using SAS 9.2 (SAS Institute, Cary NC, USA).

We perform a transperitoneal RALP with the four-arm da Vinci robot system (Intuitive Surgical). We used all three robotic arms in addition to the camera arm of the robot. A brief description of our technique entails beginning the dissection by freeing the bladder from its peritoneal attachments allowing it to drop posteriorly, thus allowing access to the retropubic space. The endopelvic fascia is then incised and the muscle fibres of the levator ani muscles are laterally swept off the prostate. The dissection is continued distally towards the urethra and DVC where the muscle fibres and overlying fat are swept off the DVC. Furthermore, the puboprostatic ligaments are divided sharply which provides excellent exposure of the DVC.

At this point, the DVC is ligated. For suture ligation, we pass a zero polyglactin suture on a ½ circle 37 mm taperpoint needle in the groove visualized between the DVC anteriorly and the urethra posteriorly. The suture is tied down and a second ‘back-bleeding’ suture is placed more proximally on the dorsal aspect of the prostate. The DVC is then divided between the sutures. For staple ligation, 3.5 mm Multifire Endo GIA 30 stapler (Tyco Health Care, Norwalk, CT, USA) is placed through a 12-mm assistant laparoscopic port that is positioned 2–3 cm cephalad to the patient’s right anterior superior iliac spine. The stapler is clamped down on the DVC, but before the stapler is fired, the Foley catheter is checked to ensure that it is freely mobile within the urethra and not caught in the stapler. Once this is confirmed, the stapler is fired to ligate and transect the DVC.

The remainder of the operation entails transection of the anterior and posterior bladder neck to uncover and allow the seminal vesicles and ampullae of the vas deferens to be dissected free. A plane between the rectum and prostate is developed after incision of Denonvilliers’ fascia. Antegrade nerve sparing is then performed, with the urethra transected and prostate freed just before making the vesicourethral anastomosis.

RESULTS

Of the 162 patients evaluated, 67 had suture ligation of the DVC (group 1) during surgery, and 95 had staple ligation of the DVC (group 2; Table 1).

Table 1.  Comparison between suture (group 1) vs staple (group 2) ligation of the DVC during RALP
VariableGroup 1Group 2P
UnivariateMultivariate
Baseline
No. patients6795  
Mean (sd):    
 Age, years60.8 (8.0)60.4 (8.0)0.78 
 BMI, kg/m228.7 (4.3)28.0 (4.3)0.33 
 PSA level, ng/mL6.7 (3.8)7.1 (10.4)0.76 
 SHIM score20.6 (6.3)17.6 (8.2)0.005 
N (%):    
 Gleason score:    
  ≤650 (74.6)55 (57.9)0.028 
  713 (19.4)33 (34.7)0.033 
  ≥84 (6.0)7 (7.4)0.73 
 Full continence63 (94.0)95 (98.9)0.075 
 Clincial stage:    
  cT1c54 (80.6)79 (83.2)0.68 
  cT213 (19.4)16 (16.8)0.68 
Operative outcomes
Mean (sd):    
 EBL, mL494.5 (265.4)288.0 (192.3)<0.001<0.001
 Time to ligate DVC, min30.0 (12.0)24 (11.1)0.0060.002
N (%):    
 Apical PSM9 (13.4)2 (2.1)0.0050.010
 Overall PSM12 (17.9)6 (6.3)0.0210.056
Tumour characteristics
Mean (sd):    
 Specimen weight, g52.5 (19.0)54.2 (17.4)0.56 
N (%):    
 Tumour volume    
  Extensive >50%1 (1.5)4 (4.3)0.32 
  Moderate >10 and <50%26 (38.8)28 (29.4)0.21 
  Low ≤10%40 (59.7)63 (66.3)0.39 
 Post-op Gleason score    
  ≤639 (58.2)48 (50.5)0.33 
  723 (34.3)36 (38)0.64 
  ≥85 (7.5) 11 (11.6)0.39 
 Pathological stage    
  pT255 (82.1)81 (85.3)0.59 
  pT3 11 (16.4)14 (14.7)0.77 
  pT41 (1.5)00.23 
6 month PSA and functional outcomes:
N (%):    
 PSA recurrence2 (3.7)00.110.068
 Continence status, no. of pads    
  039 (63.4)49 (55.7)0.310.075
Mean (sd) SHIM score8.4 (6.9)8.6 (7.6)0.990.47

The baseline patient characteristics (age, BMI, PSA level, clinical stage) and tumour characteristics (specimen weight, tumour volume, pathological Gleason score and stage) were similar between the groups, except that a greater proportion of patients in group 2 had Gleason 7 cancer on biopsy (Table 1). However, the mean (sd) preoperative SHIM score was higher in group 1 than group 2, at 20.6 (6.3) vs 17.6 (8.2) (P= 0.005), but there was no difference in preoperative continence between the groups with 94.0% of men in group 1 reporting complete continence compared with 98.9% of men in group 2 (P= 0.075).

In group 1, nine patients (13.4%) had apical PSMs compared with two (2.1%) patients from group 2 (univariate P= 0.005, multivariate P < 0.001). Overall, PSMs occurred in 12 patients (17.9%) in group 1 and six patients (6.3%) in the group 2 (univariate P= 0.021, multivariate P= 0.056). The overall PSM rate for patients with pT2 disease who underwent staple ligation (group 2) was 2.5% (2/81) and 9.1% (5/55) for patients in the suture group (group 1) compared with four of 14 and seven of 12 for patients with pT3 disease (Table 2). Additionally, the mean (sd) time to open the endopelvic fascia, dissect out and ligate the DVC was 30 (12.0) min for group 1 vs 24 (11.1) min for group 2 (univariate P < 0.006, multivariate P= 0.002). The mean (sd) EBL was 484 (265) mL for group 1 and 288 (192) mL for group 2 (univariate P < 0.001, multivariate P < 0.001; Table 1). The location and rates of PSMs are shown in Table 2. No intraoperative complications occurred during stapling of the DVC. In using the stapler, we did not encounter any urethral injuries (i.e. inadvertent stapling of the urethra) or migration of staples into the urethra. We also found that the stapled ends of the DVC typically retracted away from the vesicourethral junction and did not interfere with performing the vesicourethral anastomosis.

Table 2. 
PSMs in patients undergoing RALP with either suture (group 1) or staple (group 2) ligation of the DVC
VariableGroup 1Group 2
Location of PSM, n  
 Apex only61
 Non-apex margin only34
 Positive apex and non-apex margin31
 Total126
Apical PSM rate, n/N (%)  
 pT25/55 (9.1)1/81 (1.2)
 pT34/121/14
Overall PSM rate, n/N (%)  
 pT25/55 (9.1)2/81 (2.5)
 pT37/124/14

Two patients (3.7%) developed PSA recurrences in group 1 at 6 months compared with none of the patients in group 2, which was not statistically different. Of the two patients that had PSA recurrence, one had a non-apical PSM for a pT2c Gleason 7 tumour and a 53-g prostate (25% tumour volume). The other patient had negative margins and a pT3a Gleason 7 tumour and a 43-g prostate (10% tumour volume). At 6 months after RALP, 63.4% of men in group 1 were not using any pads for incontinence compared with 55.7% men in group 2, which did not differ with univariate analysis (P= 0.27) or with multivariate analysis (P= 0.57); 11.8% vs 24.7% of men were using 1 pad/day, respectively (P= 0.056); and 21.6% and 17.2% of men were using >1 pad/day (P= 0.55). The mean (sd) SHIM scores were equivalent at 6 months, at 8.4 (6.9) in group 1 vs 8.6 (7.6) in group 2 (Table 1).

DISCUSSION

Ahlering et al.[5] supported the use of an endovascular stapler in ligating the DVC as a way to decreased apical PSM rates. However, the benefit associated with stapling might have been attributable to clearing off all the fat overlying the DVC before stapling (this was not done in patients with suture ligation), thus providing better visualization before ligation. Nguyen et al.[7] published a direct comparison evaluating suture vs staple ligation of the DVC and reported no difference in EBL, operative time, or PSM rate. In an analysis of risk factors for PSMs after RALP, Liss et al.[8] also reported no difference between stapling and suturing the DVC. On the contrary, the present study shows a significant advantage with regard to EBL; operative time required from incising the endopelvic fascia to dissecting free, ligating and transecting the DVC, and apical PSM rates that favours the use of an endovascular stapler. This was confirmed on both univariate and multivariate analysis. The lower overall PSM rate in the stapled group (group 2) approached but did not achieve statistical significance. The present PSM rate compares favourably to rates reported in both open [9–12] and RALP series [4,5,7,13,14]. Furthermore, in both the suture and staple groups, we consistently removed all overlying fat from the DVC and divided the puboprostatic ligaments before ligating and transecting the DVC, thus visualization was not a problem. The present patient groups were comparable in baseline and tumour characteristics, except that a greater proportion of the staple group patients had Gleason 7 cancer on biopsy.

At 6 months after RALP, the PSA and functional outcomes were equivalent as well. RALP is becoming a widely accepted technique in the surgical treatment of prostate cancer. Open retropubic RP (RRP) has been the standard of care; based on data from open RRP series, PSMs have been associated with PSA and local disease recurrence [15–19], increased likelihood to undergo adjuvant treatment [18], and potential anxiety and stress for the patient when it occurs. Randomized, prospective trials have documented improved biochemical progression-free survival, local control [20,21] and potentially even metastasis-free and overall survival (with longer follow-up) [22] with adjuvant radiotherapy after RP in patients with locally advanced prostate cancer (including PSMs). However, this finding is not universal [10,23] and no universal guidelines exist for adjuvant radiation. Furthermore, patients treated for PSMs with adjuvant radiotherapy face increased morbidity [20,21] and in many cases may be unnecessary [10,24,25]. Obviously, the impact of a PSM during RP can be enormous.

The present series represents our first 162 consecutive patients who underwent RALP. The non-randomized nature of the present study is certainly a weakness, although no patients were omitted from analysis and the groups were comparable for baseline patient and tumour characteristics. Improvement in the apical PSM rate with stapled ligation of the DVC may be attributable to improved technique with experience, although we did not change our technique aside from suturing to stapling the DVC. Missing follow-up data was due in part to patients not engaging in sexual intercourse, incompletely answering validated questionnaires, or seeking follow-up with a primary urologist not at Northwestern University. Finally, although there was no difference in continence rates, longer follow-up is needed as continence continues to change for the patients.

In our experience, the use of an endovascular stapler to ligate and transect the DVC during RALP leads to decreased blood loss, operative time and rate of apical PSMs. This has significant implications for potential disease-free survival. A longer follow-up will be necessary to assess the impact on functional outcomes after surgery (i.e. continence, erectile function). We show that surgical technique can significantly influence PSM rates with RALP and therefore avoid potential attendant morbidities and decreased quality of life associated with disease recurrence and adjuvant therapies.

ACKNOWLEDGEMENTS

Joshua J. Meeks is an AUA Research Scholar with a grant from the AUA Foundation with contributions from Sanofi-Aventis.

CONFLICT OF INTEREST

Robert B. Nadler is a Speaker for Intuitive Surgical and Angio Dynamics.

REFERENCES

EDITORIAL COMMENT

Positive surgical margins (PSMs) after radical prostatectomy are an undesirable outcome that predispose to earlier biochemical recurrence, occurring most frequently at the prostatic apex [1–3]. The challenges in ensuring complete cancer extirpation at the apex are many: the narrow tapering apical beak transitions imperceptibly into the adjoining membranous urethra, often without a clearly defined capsule; the anterior apex is obscured by large veins intermingled with fibromuscular stroma, hindering clear identification of the apical urethral junction; bleeding from poor vascular control of the dorsal venous complex (DVC) can obscure vision of the operative field, impairing precise apical dissection; and considerable surgeon experience in appreciating the myriad configurations of the prostatic apex (beaks and protrusions) is required to identify the correct plane of dissection [4,5]. Furthermore, balancing cancer clearance with good functional outcomes is akin to walking a tightrope during apical dissection with little room to fall either way. The prostatic apex comprises the final common pathway for exit of the erectogenic nerves to the penile tissue. Optimizing membranous urethral length has been shown to correlate with early continence return [6]. As such, there is little room for wide excision at the apical urethral junction without ultimate compromise of sexual and urinary function.

In this paper, the authors are to be congratulated on their almost six-fold reduction of the apical PSM rate in transitioning from suture to endovascular staple ligation of the DVC, alongside lessened intraoperative blood loss and operative time with the latter approach. The authors’ results differ from previously published series showing no benefit in the apical PSM rate with endovascular staple DVC ligation [7,8]. However, the authors fail to give any meaningful explanation of how the endovascular stapler improved their surgical dissection, and downplay the effect of ‘learning curve’ in their pilot cohort of 67 patients receiving suture ligation, before they eventually transitioned to staple ligation in their robotic programme.

In our own series, we have avoided early staple ligation of the DVC, as we feel that firing of the bulky stapler device here does not afford adequate visualization of the apical-urethral junction before DVC transection, and may predispose to inadvertent anterior or apical prostatic caspulotomy, with resultant PSMs. Instead, we have recently adopted an alternative approach of synchronous apical dissection commenced via a retro-apical approach in 209 patients. This technical modification uses a 30 ° upward lens to facilitate retro-apical and lateral dissection of the apex and membranous urethra. Urethral transection is performed from a posterior approach with full appreciation of the prostatic apex anatomy, after which we tackle the adhering fibro-fatty tissue and DVC keeping the prostate suspended to the pubis. In most cases, we divide the DVC without suture ligation using sharp scissors only under a transiently raised pneumoperitoneum, keeping a clear distance of the visible apical capsule. Caudal traction of the inflated Foley balloon is then applied once the prostate is free, and the DVC then controlled using a CT-1 needle and a zero polyglactin suture. Comparing the apical PSM rates of these patients with those of our previous cohort of 1 665 patients receiving conventional early DVC suture ligation and anterior urethral transection, we noted significantly lower apical PSM rates in the group that underwent the new technique (1.4% vs 4.4%, P= 0.04). This marked improvement in the retro-apical cohort occurred despite a significantly higher incidence of aggressive cancer (≥pT3a) documented on final specimen pathology (16% vs 10%, P= 0.027).

We feel that leaving DVC ligation and apical transection until after the membranous urethra and prostatic apex have been precisely dissected out and the prostate circumferentially mobilized, allows the surgeon to: (i) laterally release the nerves converging at the apex, optimizing nerve-sparing outcomes; (ii) gently push the posterior apical beak away from the sphincter, thus gaining a few extra millimetres of length; (iii) preserve maximum urethral length, puboprostatic ligaments and the arcus tendineus, all of which play critical roles in preservation of continence. Controlling the DVC with a staple device at this juncture should not compromise apical margin positivity if it may be fired safely clear of the apical capsule.

Ultimately, surgical technique with good handling of varying tissue anatomy, surgeon caseload and experience, remain the most significant tenets for delivering complete extirpation of cancer alongside good continence and potency outcomes for radical prostatectomy in what remains a technically challenging urological procedure.

Ashutosh K. Tewari and Gerald Y. Tan,
LeFrak Center of Robotic Surgery & Prostate Cancer Institute, James Buchanan Brady Foundation Department of Urology, Weill Medical College of Cornell University, New York, NY, USA

REFERENCES

Ancillary