Placement of the Penile Pump Cylinders
For the penile incision, we use a high longitudinal scrotal approach, on the median raphe about 1 inch inferior to the junction with the penis, rather than a classic penoscrotal incision. We favor the scrotal incision, rather than a transverse scrotal or an infra-pubic approach, for several reasons: it only needs to be 1 inch in length, it provides easy access to the penis in both obese and thin patients, thus allowing excellent placement of penile cylinders as well as pump and reservoir; and it closes and heals without scarring, thus giving a better cosmetic result than a transverse scrotal or infra-pubic incision, as the scar will be concealed by the scrotal raphe. We find with an infra-pubic approach that accurate penile pump placement and concealment of tubing are more difficult and unpredictable. With that approach, the penile pump has a tendency of migrating to a high scrotal position next to the base of the shaft of the penis, leaving the tubing readily palpable at the base of the penile shaft and the pump more visible in an antero-lateral position in the scrotum. In this situation, the penile pump could be felt by the partner during sexual activity and penetration.
Using the Foley catheter and urethra for traction, dissection is minimized, by pushing surrounding tissues laterally prior to making an incision. An incision is made on to the peno-scrotal raphe and the dissection is carried down through the subcutaneous tissues to the level of Bucks fascia. Five yellow hooks are then utilized to secure the edges of the incision to the Scott retractor in order to obtain and maintain exposure.
Making the penile incision straight down onto the urethra reduces postoperative swelling and edema and also fashions a thick layer of subcutaneous tissue. This will provide for deeper placement of penile pump tubing in the scrotum, better closure of the penile incision and complete separation and concealment of tubing from the skin suture line.
At this point, the “No-Touch” principles are employed. The procedure is halted and all of the surgical instruments used thus far, including the Bovie, are discarded and considered contaminated. All surgical gloves that touched the patient's skin are changed. A 3M #1012 drape is used to loosely drape the operative field. A small fenestration is made in the drape and 4 blunt yellow hooks are used to secure and retract the cut edges of the drape to the edges of the skin incision.
Implantation of the penile device proceeds with the usual steps associated with a multi-component prosthesis, including the penile incision and dilation of the corpora; sizing and placement of the penile cylinders; and placement of the penile pump in the scrotum and the reservoir in the retropubic space, all through the small fenestration in the #1012 drape. All are placed without direct contact with the skin.
With the scrotal skin completely covered and proceeding within the small fenestration of the drape, we follow a downward course directly on the urethra to the level of Buck’s fascia. At that point the urethra is mobilized to the left, Buck's fascia is incised and the tunica albuginea of the right proximal cyrus exposed. Downward traction applied with a short right-angle retractor (small Rich) exposes the proximal cyrus and at the same time retracts the urethra towards the left. Utilizing a marking pen, a 2-cm mark is made on the tunica of the cyrus parallel to and 1 cm lateral from the junction of the tunica albuginea and the urethra. Two 3-0 PDS suture with RB-1 needle (Ethicon) tags are placed deep and wide on either side of this mark and tagged with straight mosquito clamps. (Curved mosquito clamps may be used for the left side for identification purposes). Making the corporotomy close to the urethra allows direct downward orientation of cylinder input tubing to the penile pump and makes it less likely that the tubing will be palpable by the patient at the base of the penis.
After the right cyrus is tagged, instead of making another incision in Buck’s fascia on the left, the urethra is mobilized to the right, and exposure of the tunica albuginea of the left cyrus is obtained by reflecting the edges of Buck's fascia towards the left and securing it with the yellow hooks on the left. This effectively preserves Buck's fascia and enables the use of the second layer of tissue that will further conceal input tubing to the penile cylinders when closing. The cyrus on the patient’s left side is similarly marked and tagged with two 3 O PDS sutures and curved mosquito clamps. A #15 blade is used to make a small 1.5-cm corporotomy between the traction sutures. The penile incision is limited to the tunica albuginea, thus avoiding cutting of cavernosal muscle tissue. Keeping the corporotomy small is advantageous as it enables us to close it quickly and with less postoperative bleeding, swelling and pain. This also reduces infection risk.
Dilation of the corpora
It is during this process that a perforation can occur. To prevent perforation of the tunica albuginea, the operator must avoid the use of force during dilation. The length of the corporotomy should be just large enough to accommodate a #14 French Hegar dilator. Dilating at the level of the venous plexus at the periphery of cavernosal muscle tissue right underneath the tunica albuginea is preferable and easier than centrally through cavernosal muscle tissue. This also will preserve cavernosal smooth muscle and partial erectile function much is described by patients even after penile implantation.
Proximal dilation of the corpus cavernosum, using the blunt tip of a large Yankauer suction catheter, is performed first. The blunt tips of a long curved Mayo scissors are then positioned at the junction of the tunica albuginea and the cavernosal muscle tissue, and the distal portion of the corpus is dilated to the mid glans penis in the following fashion:
Dilation is done slowly and gradually, advancing until resistance is met, spreading the scissors, and then pulling back with the scissors open, closing the scissors, advancing further, then spreading the scissors again and pulling back. There is no need to use force. Crossover into the contralateral corpus during distal dilation is avoided by applying constant traction on the glans penis as well as by maintaining the curvature of the Mayo scissors away from the midline of the penis, with the tips next to the tunica albuginea.
When the tip of the scissors reach the glans, the meatus is squeezed between the thumb and index finger and the glans penis tilted away from the dissecting instrument. This maneuver prevents perforation of the tunica of the distal tip of the corpus cavernosum into the meatus. The scissor tip is rotated medially, the blades gently spread to complete the dilation and ensure that the distal tip of the cylinder is positioned under the glans penis. That care must be taken not to apply force or unnecessary pressure during this maneuver cannot be overemphasized. Next, using a blunt-tip Dilamezinsert (blue disposable insert), the distal portion of the penile corpus is dilated to number #12 French diameter. The instrument is flipped into the cyrus and the cyrus similarly dilated before the instrument is returned to the scrub nurse. A #13/14 Hegar is used to complete the dilation, first for the proximal aspect of the penis to #14 French diameter, and subsequently to #13 French diameter distally.
Sizing of the corpora
There is a tendency for inexperienced implanters to oversize the length of the penis. To properly size it, a blunt instrument such as the Dilamezinsert is preferable to a narrower one. It is important when measuring to have a fixed point of reference (we use the distal apex of the corporotomy) and to measure distally and proximally without repositioning this point of reference. The penis must not be overstretched over the measuring instrument, especially during measurement of the distal portion of the corpus cavernosum.
It is at this point that the choice of cylinders is made. The best method for determining the correct size, we find, is to create an artificial erection by irrigating the corpora with saline irrigation (another good reason for keeping the corporotomy small facilitates this maneuver). This erection helps determine if the penis is straight or curved. Hydraulic expansion of the penis is also useful for detecting or ruling out urethral injury by documenting the presence or absence of irrigant leakage from the meatus around the foley catheter.
Several points need to be considered when selecting a device. Always pick a cylinder size that will permit length adjustment. If possible, a smaller cylinder is preferable to a longer one as it will provide for better axial rigidity (ratio of girth to length is larger) and will require fewer pumps to reach maximal inflation. This enables the patient to achieve an erection faster and also possibly extends the life expectancy of the penile pump. However using rear tip extenders will negatively impact the quality of the erection as the non-inflatable portion of the cylinders will dilate the pseudo-capsule over time and the base of the penile cylinders will not be held firmly to the patients' body. The erection will wobble and we recommend judicious use of rear tip extenders.
If dilation to #13 French distally and #14 French proximally has not been possible, we use a narrow device such as the Coloplast Alpha Narrow or AMS-CXR cylinders. For a large and capacious penis, a Coloplast Titan will give a better fit, provided the glans penis is also large. With a narrow glans penis, the tip of this cylinder can migrate laterally as it is fully inflated to 21-mm diameter and can become palpable at the lateral aspect of the penile shaft. We avoid using the 21-cm AMS 700 LGX or CX cylinders for these large penises, especially if rear tip extenders are needed. These cylinders do not provide adequate rigidity when inflated especially in patients with long and wide penises.
The reason for this is that in general long penises tend to also have larger diameters that are not filled by the 21cm LGX cylinders (girth expansion limited to 18 mm). This may cause the penile cylinders to curve inside the corpora as they lengthen with inflation. For penises longer than 18cm, as previously mentioned, a Coloplast Titan 20 or 22cm cylinder, will provide the patient with a better erection.
Finally, when using pre-connected cylinders it is also important to determine the distance from the rear of the cylinder to the point where the input tubing will exit the corpora. If the patient has a small tight scrotum, we would use a larger cylinder in order to bury input tubing in the corpora and reduce the length of tubing in the scrotum. In a larger, longer scrotum adding rear tip extenders to a shorter cylinder will advance the connection of the input tubing to the cylinder forward in the shaft of the penis, providing longer tubing length and lower scrotal placement of the penile pump.
Only after the choice of penile device is made and it is ready to be implanted, the device is opened on the surgical field. Air must be purged prior to cylinder insertion and the penile device is primed with injectable saline. With the Furlow introducer and Keith needle, the cylinder traction suture is passed through the glans penis, through the "No-Touch" drape and we secure the traction suture with clamps. Prior to the passing of the traction suture, the right and left cylinders are oriented so that input tubing from the two cylinders do not cross over each other.
After both traction sutures have been passed through the glans penis, the proximal portion of each cylinder is inserted first, then the distal tip placed in the corporal orifice and the traction suture pulled to insert the distal portion of the cylinder. The cylinder must lay flat in the corpora when traction is applied with the cylinder traction suture. Any folds noted in the cylinder indicate that it may be oversized or that the rear tip is not in its proper position. After both penile cylinders have been inserted, a surrogate test with saline is performed, using a filled 60-cc syringe. If an adjustment in cylinder length needs to be performed, saline is completely removed from the cylinders prior to adding or removing rear tip extenders and repositioning of the penile cylinders. This facilitates the maneuver and prevents injury to the cylinder.
Closure of the corporotomy
The corporotomy is closed with a running 3-0 PDS suture, using a hemostatic stitch. While this takes more time than approximating the previously placed tagging 3-0 PDS sutures and has the potential of causing needle injury to the prosthesis, it provides for a watertight closure. Prior to ligation of the suture, 3cc of Surgiflo hemostatic Matrix (Ethicon) is injected in each corpora. If hemostasis cannot be accomplished, drains should be used to prevent the formation of a scrotal hematoma. Any bleeding could result in a large scrotal hematoma, which if not evacuated with drains, will liquefy and possibly provide a wonderful milieu for bacterial growth, and subsequently, infect the penile implant. After completion of corporotomy closure, the penile pump is activated and deactivated several times. Each time, the penis is examined, cylinder size and erection assessed and the integrity of the cylinders confirmed.