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Keywords:

  • Penile Prosthesis;
  • Penis;
  • Surgery;
  • Anatomy

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References

Introduction

The primary concern for many prosthetic urologic surgeons in placing the three-piece inflatable penile prosthesis (IPP) is the concept of “blind reservoir placement.” Extensive reports permeate the literature regarding bladder, bowel, vascular, and various hernial complications occurring while attempting to place the reservoir into the retropubic space. However, despite these widely documented complications, there is a paucity of published literature on surgically pertinent anatomical measurements of the retropubic space relating to reservoir placement. The focus of this project was to evaluate the special relationships and anatomical measurements of the retropubic space to better aid the surgeon in the safe placement of the reservoir.

Aim

Analyses of the spatial measurements of reservoir placement into the retropubic space with a focus on utilizing a penoscrotal approach were conducted. In addition, we reviewed and evaluated the published literature for important contributions surrounding the various surgical techniques during placement of a penile prosthesis reservoir.

Methods

Cadaveric pelvic specimens were dissected to determine the distance and angulation (in degrees) from the inguinal ring to several critical anatomic structures in the pelvis. This format was utilized to simulate the basic features of reservoir placement into the classic retropubic space. We also reviewed and evaluated the published literature for important contributions describing the various surgical techniques in the placement of penile prosthesis reservoirs into the retropubic space.

Main Outcome Measures

Anatomic measurements were obtained from the inguinal ring to the bladder, external iliac vein, and superior origin of the dorsal suspensory ligament at the anterior apex of the pendulous penis. The angle was measured from the inguinal ring to these structures and recorded. We also reviewed the published literature for various penoscrotal IPP surgical techniques involving placement of the reservoir into the retropubic space to further supplement the pertinent spatial relationships data acquired in this study.

Results

Of the 28 cadavers, 3 were excluded because of signs of major pelvic surgery, and an additional 6 sides were excluded because of unilateral fibrosis/surgery or difficulty in exposure. Distance to the decompressed bladder was 5–8 cm (average 6.45 cm) at a 15–30 (22.8) degrees medial measurement from the inguinal ring. The filled bladder was 2–4 cm (average 2.61 cm) from the inguinal ring. The external iliac vein distance from the inguinal ring was 2.5–4 cm (average 3.23 cm) at a 20–60 (36.4) degrees lateral measurement from the inguinal ring. Heretofore, the published literature does not appear to have detailed measurements that are provided in this study.

Conclusions

These anatomical measurements of the retropubic space demonstrate the importance of decompressing the bladder and avoiding deep dissection lateral to the inguinal ring, as the external iliac vein is much closer than currently espoused. We feel that these data are significant to the surgeon proceeding with reservoir placement during IPP surgery. Henry G, Hsaio W, Karpman E, Bella AT, Carrion R, Jones L, Christine B, Eisenhart E, Cleves MA, and Kramer A. A guide for inflatable penile prosthesis reservoir placement: Pertinent anatomical measurements of the retropubic space. J Sex Med 2014;11:273–278.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References

Blind reservoir placement is widely considered the bane of the penoscrotal approach to inflatable penile prostheses (IPPs). Extensive reports in the literature abound describing bladder, bowel, vascular, and different types of hernia complications occurring while attempting to place the reservoir into the retropubic space [1–9]. However, despite these widely documented complications, there appears to be no published literature on the important anatomical measurements of the retropubic space relating to reservoir placement. In fact, many urologists compromise the implant models they offer patients because of their inability to perform this step of the procedure. Furthermore, the existing published literature on surgical placement of the reservoir into the retropubic space does not offer a careful, clearly descriptive, step-by-step guide for inexperienced prosthetic urologists [10–12]. Nor does the existing literature provide detailed measurements that may assist the placement of the reservoir into the retropubic space. We evaluated the pertinent anatomical measurements of the retropubic space to better aid in the safe placement of the reservoir.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References

A group of high volume prosthetic surgeons with extensive publication histories on reservoir placement and related complications critically appraised these data. Specifically, this group focused on pertinent anatomical measurements of the retropubic space to assist in placement of the reservoir during implantation of three-piece IPP with special emphasis on surgical safety. A review of the published literature using PubMed line searches was conducted (search terms used “penile prosthesis reservoir complications,” “penile prosthesis reservoir complication,” and “penile prosthesis complication hernia” searched on July 29, 2013) with emphasis on complications involved with placement of the reservoir into the retropubic space.

A total of 22 cadaver bodies in 5 different surgical training courses and at 2 locations were used for a total of 44 possible sides. Cadaveric dissection was performed, and measurements were done by a group of six experienced prosthetic urologists. In addition, an independent, seventh prosthetic urologist at a large university anatomy lab evaluated 6 bodies for possible 12 sides. A total of 56 sides were evaluated. Exclusion criteria included any signs of surgery/fibrosis in the pertinent anatomic areas or difficulty in exposure.

All measurements were taken from the ipsilateral inguinal ring at the point nearest to the pubic bone and to the nearest point of the decompressed bladder, with the bladder filled to 200 mL. In addition, measurements to the nearest point of the external iliac vein and to the superior anterior insertion point of the apex of the penile dorsal suspensory ligament were performed (Figure 1). The angulation medially (for the bladder) and laterally (for the vein) was determined using the ipsilateral inguinal ring. The pubic tubercle was the baseline for this measurement, and the superior ridge of the pubic bone for the zero degree axis tilt was taken using a handheld protractor. If unable to catheterize the cadaver, intra-pelvic measurements were not taken. In addition, the pelvis was tilted in a Trendelenburg position for the measurements (the authors advise positioning the patient in Trendelenburg position for placement of the reservoir in the retropubic space). The insertion point of the superior anterior insertion point of the penile dorsal suspensory ligament at the point of the ring nearest to the pubic bone (using both inguinal rings) was then determined, both in terms of measurement and angulation.

figure

Figure 1. Cadaver photo showing the ruler with the decompressed bladder, external iliac vein, and the ipsilateral inguinal ring.

Download figure to PowerPoint

Statistical Analysis

Distance measurements were summarized by their means, standard deviations, medians, and ranges. The intra-class correlation coefficient and corresponding asymptotic 95% confidence interval were used to evaluate intrarater reliability [13]. The nonparametric two-sample Wilcoxon rank-sum (Mann–Whitney U) test was used to compare distances measured on cadavers from two different sources [14].

Main Outcome Measures

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References

Anatomical measurements from the inguinal ring to the bladder, external iliac vein, and superior origin of the dorsal suspensory ligament at the anterior apex of the pendulous penis were analyzed. This study specifically reviews and evaluates the penoscrotal IPP surgical techniques for placement of the reservoir into the retropubic space in the published literature.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References

Of the 28 cadavers, 3 were excluded because of signs of major pelvic surgery, and an additional 6 sides were excluded because of unilateral fibrosis/surgery or difficulty in exposure. Distance measurements are summarized on Table 1. Distance to the decompressed bladder was 5–8 cm (average 6.4 cm) at a 15–35 (average 23) degrees medial measurement from the inguinal ring (Figure 1). Meanwhile, the measurement to the bladder filled with 200 mL of fluid was 1.5–4 cm (average 2.4 cm) from the inguinal ring. The distance from the external iliac vein to the inguinal ring was 2.5–4.5 cm (average 3.4 cm) at a lateral measurement 20–57.5 (average 35.3) degrees from the inguinal ring. The distance from the anterior apex of the penile dorsal suspensory ligament to the inguinal ring was 6–7 cm (average 6.6 cm) and 25–55 (average 38.6) degrees superior to the inguinal ring.

Table 1. Summary of anatomical measurements from the inguinal ring to various locations
 Number of cadaversMean (SD)MedianRange
  1. SD = standard deviation

Both sides (combined)    
Distance to bladder (degree)2023.0 (5.2)22(15.0–35.0)
Distance to bladder (cm)206.4 (0.8)6.2(5.0–8.0)
Distance to vein (degree)2035.3 (10.2)32(20.0–57.5)
Distance to vein (cm)203.4 (0.6)3.4(2.5–4.5)
Distance to full bladder (cm)202.4 (0.7)2.2(1.5–4.0)
Distance to dorsal susp. ligament (cm)66.6 (0.4)6.5(6.0–7.0)
Distance to dorsal susp. ligament (degree)638.6 (9.2)40(25.0–55.0)
Right    
Distance to bladder (degree)1724.2 (5.7)25(15.0–35.0)
Distance to bladder (cm)176.5 (0.8)6.35 (5.4–8.0)
Distance to vein (degree)1735.3 (10.5)30(20.0–57.5)
Distance to vein (cm)173.4 (0.6)3.4(2.5–4.5)
Distance to full bladder (cm)172.3 (0.7)2.2(1.5–4.0)
Distance to dorsal susp. ligament (cm)56.7 (0.4)7(6.0–7.0)
Distance to dorsal susp. ligament (degree)542.0 (9.7)45(30.0–55.0)
Left    
Distance to bladder (degree)1821.8 (4.5)20.5(15.0–30.0)
Distance to bladder (cm)186.3 (0.7)6.13(5.0–7.9)
Distance to vein (degree)1835.3 (10.2)33.75(20.0–57.5)
Distance to vein (cm)183.4 (0.6)3.35(2.5–4.1)
Distance to full bladder (cm)182.5 (0.7)2.2(1.8–4.0)
Distance to dorsal susp. ligament (cm)66.4 (0.4)6.35(6.0–7.0)
Distance to dorsal susp. ligament (degree)635.8 (8.6)35(25.0–45.0)

Intrarater reliability was performed using nine cadavers (Table 2). The intra-class correlation was high for all measurements (P < 0.001), indicating high consistency in the measurement across surgeons. A comparison of measurements between the two study sites are summarized in Table 3. Only distance to vein in centimeters and distance to the full bladder in centimeters were significantly different between the two sites, which suggest either variability in the way these were measured or true differences between the cadavers examined [15].

Table 2. Summary of intrarater reliability
 Number of cadaversIntra-class correlation coefficient (95% CI)
  1. CI = confidence interval

Both sides  
Distance to bladder (degree)90.74 (0.51–0.97)
Distance to bladder (cm)90.93 (0.87–1.00)
Distance to vein (degree)90.90 (0.81–1.00)
Distance to vein (cm)90.92 (0.85–1.00)
Distance to full bladder (cm)90.94 (0.88–1.00)
Right  
Distance to bladder (degree)60.71 (0.30–1.13)
Distance to bladder (cm)60.91 (0.78–1.05)
Distance to vein (degree)60.92 (0.80–1.05)
Distance to vein (cm)60.94 (0.83–1.04)
Distance to full bladder (cm)60.98 (0.94–1.02)
Left  
Distance to bladder (degree)90.80 (0.57–1.04)
Distance to bladder (cm)90.96 (0.90–1.01)
Distance to vein (degree)90.90 (0.76–1.03)
Distance to vein (cm)90.92 (0.82–1.02)
Distance to full bladder (cm)90.92 (0.82–1.02)
Table 3. Comparison of measurements between the two study sites
 Primary siteSecondary siteP value*
Number of cadaversMean (SD)Number of cadaversMean (SD)
  1. *Wilcoxon rank-sum (Mann–Whitney U) test

  2. SD = standard deviation

Both sides     
Distance to bladder (degree)1423.2 (5.4)622.5 (5.0)0.8472
Distance to bladder (cm)146.5 (0.8)66.1 (0.7)0.1980
Distance to vein (degree)1434.8 (11.2)636.3 (8.3)0.4386
Distance to vein (cm)143.2 (0.5)63.7 (0.4)0.0068
Distance to full bladder (cm)142.6 (0.7)62.0 (0.3)0.0023
Right     
Distance to bladder (degree)1124.8 (6.2)623.2 (5.1)0.5771
Distance to bladder (cm)116.6 (0.9)66.2 (0.6)0.4504
Distance to vein (degree)1134.3 (11.5)637.2 (9.2)0.6026
Distance to vein (cm)113.2 (0.5)63.7 (0.5)0.1302
Distance to full bladder (cm)112.6 (0.7)61.9 (0.3)0.0171
Left     
Distance to bladder (degree)1221.8 (4.3)621.8 (5.3)0.9622
Distance to bladder (cm)126.4 (0.7)66.0 (0.8)0.4530
Distance to vein (degree)1235.3 (11.4)635.3 (8.2)0.8140
Distance to vein (cm)123.2 (0.6)63.8 (0.4)0.0208
Distance to full bladder (cm)122.7 (0.8)62.0 (0.3)0.0561

A PubMed review revealed multiple publications discussing complications of surgical placement of the reservoir. However, none of these articles report on the pertinent anatomical measurements, and these articles lack careful, step-by-step description of placement into the retropublic space.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References

The most significant concern that prosthetic implanters have with three-piece IPP is blind placement of the reservoir in the space of Retzius (SOR)/retropubic space. Reservoir placement in the SOR has been associated with the most devastating complications with this procedure including bladder, bowel, and vascular injuries [16]. The increasing popularity of robotic-assisted laparoscopic prostatectomy (RALP) has added additional challenges to placing a reservoir in the SOR because the space becomes obliterated with this technique [17]. A recent study has shown that 82% of experienced implant surgeons feel that placing a reservoir in the SOR in RALP patients is more difficult [18]. These recent concerns of reservoir placement in the SOR, particularly in RALP patients, have fueled the recent interest in alternative reservoir placement sites.

Despite the significant consequences of reservoir placement, there have not been any studies to date specifically addressing the relationship of the reservoir with important adjacent anatomic landmarks. The published literature on surgical placement of the reservoir into the retropubic space does not appear to have a careful, clearly descriptive, step-by-step guide for inexperienced prosthetic urologists [10–12,19–22]. In fact, with a PubMed search using the terms “penile prosthesis reservoir placement,” only 36 entries appear (accessed July 29, 2013). Of these, only one publication provides an illustration of the surgical techniques of reservoir placement [23]. Additionally, a number of publications have focused on techniques of “ectopic” reservoir placement, but do not provide a step-by-step guide to the “traditional” SOR reservoir placement [24,25].

Most physicians complete their anatomic training in medical school and receive minimal additional anatomic training afterward. Some physicians interested in urologic prosthetics can receive additional cadaver training in the form of industry-sponsored labs; however, this does not include careful dissection of the pelvis and evaluation of these important landmarks and their relative distances. The present study is the first study (to the authors' knowledge) to carefully evaluate these important anatomic landmarks of surgical placement of the reservoir into the SOR. Additionally, this study emphasizes the relatively short distance of the IPP reservoir in the SOR to the filled bladder and the external iliac vein. Importantly, the second site did not place the cadaver in the Trendelenburg position, which resulted in even closer measurements than the primary study site. These findings reveal that placing the patient in the Trendelenburg position should help achieve greater distance of both the bladder and the external iliac vein from the inguinal ring for reservoir placement in the SOR.

The previously mentioned concerns are not moot and should not be underestimated. The development and current use of two-piece prostheses emphasize these points. Despite the less favorable flaccidity and rigidity profiles and lower patient satisfaction rates compared with the three-piece IPP, some surgeons still prefer to use the two-piece IPP because of these very concerns [26]. Are surgeon practice patterns changing to place two-piece IPP in patients because of these concerns over reservoir placement? Are surgeons using more two-piece IPPs because of a paucity of published literature addressing guiding placement?

Multiple experienced and published prosthetic surgeons performed this study at various locations to eliminate observer bias and to test the reproducibility of these results. Consideration was given to using magnetic resonance imaging (MRI) images of the SOR to evaluate the relationships of the SOR. MRI imaging is costly and would be cost prohibitive in a prospective study that is adequately powered. Moreover, retrospective evaluations of MRI images are flawed because of inconsistent bladder volumes among subjects. Using a cadaver model, we were able to evaluate the distance to the bladder precisely with a completely decompressed bladder using a standardized volume of 200 mL. Additionally, the cadaver model allowed for evaluation of relative distances from the external inguinal ring from a real-life surgical perspective than a radiographic perspective.

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References

A study of the anatomical measurements of the retropubic space reveals the importance of bladder decompression and avoiding placement too lateral to the inguinal ring, as the external iliac vein is closer than anticipated by many surgeons. Trendelenburg is critical in reducing the risk of bladder injury, and likely vascular injury as well. In Table 3, the Trendelenburg and non-Trendelenburg sites are compared, with the angle of Trendelenburg being approximated at 20 degrees. The critical comparison is distance to full bladder of 2.6 cm for the Trendelenburg site vs. 2.0 cm for the non-Trendelenburg site. This is statistically significant. Trendelenburg increases the distance of reservoir to full bladder. In theory, Trendelenburg should decompress the external iliac vein, thus making reservoir placement safer from a vascular standpoint as well. But likely, this anatomy was distorted in the cadaver and could not be definitively demonstrated.

A surgeon should have an arsenal of tools and options when considering reservoir placement, so even difficult situations can be navigated. While a “perseverance at all costs” approach seems a bit extreme, there should be an option for even the most challenging anatomy. Options available to the surgeon include the ectopic vs. retropubic space, assessing both the left and the right sides, slight underfilling of the reservoir if possible, use of additional tools such as a nasal speculum, and even making a counter-incision. In extreme cases such as patients with transplanted organs in the pelvis or those who have had cystectomies, preemptively choosing semirigid devices or an Ambicor or self-contained inflatable device could be considered, although the above troubleshooting options can still be employed successfully.

Placing a reservoir through the inguinal canal can always be done or at least attempted, although an understanding of options to circumvent this approach should be known, and methods of mitigating danger such as Trendelenburg and proper technique should be practiced.

Conflict of Interest: The authors report no conflicts of interest.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Main Outcome Measures
  6. Results
  7. Discussion
  8. Conclusions
  9. References