What Urologists Need to Know about Female to Male Genital Confirmation Surgery (Phalloplasty and Metoidioplasty): Techniques, Complications, and How to Deal with Them - Beyond the Abstract

Female to male gender affirming surgery (GAS) can be extraordinarily complex and carries with it a breathtaking number and depth of potential complications. Phalloplasty, specifically, is the “Mount Everest” of all flap surgeries.  It requires much larger free and pedicled flaps (21 cm x 16 cm at minimum) than are generally done for other complicated reconstructive surgeries and is usually done together with multiple OTHER significant surgeries.  It is notable that these microvascular techniques were experimental as late as the 1970s, and only widely performed recently i.e. in this century. Much work needs to be done to optimize surgical outcomes.  In all, a one-stage phalloplasty (including vaginoplasty, urethral lengthening and scrotoplasty) represents 200 relative value units (RVU’s) of surgery.  (A craniotomy for removal of a glioblastoma multiforme brain tumor is 85 RVU’s.)   Generally, the surgical team is made up of an experienced “mid-career” team, often with an experienced reconstructive urologist and a plastic surgeon that is especially well-versed in microsurgery.

How many stages?

There is no consensus on how to best design the surgical approach to this complicated surgery.  We generally perform all the stages (except penile prosthesis and testicular prosthesis placement, which is done after 9 months) in one surgical sitting: vaginectomy, urethral lengthening, scrotoplasty, and phalloplasty.  Others stage the operation, sometimes creating the neophallus in one sitting and completing vaginectomy/urethral lengthening/scrotoplasty in a second.  No one yet knows the most advantageous method for completing this massive transformation safely and with the best results.  

The problem of the urethra

The most obvious areas of improvement are improving stricture and fistula rates, which remain the “Achilles heel” of the procedures. It may be that the current techniques (which have been greatly improved in the last years) are nearing their theoretical maximum performance, and entirely new and creative techniques are required for the next big improvements to come along in phalloplasty.

The first urethral improvement step is to take care in the formation of the “pars fixa”, the portion of the urethra that goes from the native urethra to the base of the phallus (where the “pars pendulans” of the phallus itself, usually made of skin, starts).  The flaps to create this urethra must be robust, and flap dissection should not interfere with the blood supply of the neourethra.  This, plus coverage of the urethral suture line with a second coverage of nearby tissue, has significantly decreased complications of this portion of the urethroplasty.  Adding to the proximal portion of the secondary closure layer with a purposeful dissection of the bulbospongiosus muscle (which in the natal female surrounds the upper vagina) and swinging those muscle flaps superomedially to act as a well vascularized second cover has also decreased fistula rates at the proximal neourethra significantly.

The biggest problem is the connection point of the pars fixa to the skin urethra of the phallus. This is a source of a high rate of both fistula and stricture.  We have decreased the stricture rate to an industry-low 20% with multiple small improvements: by creating a urethral extension from the donor flap to improve tensionless closure, protecting the blood supply of this crucial portion of the flap by sparing the nearby dermis, and meticulously dissecting a 2 cm rim of nearby fatty tissue (that might normally be discarded) to further preserve blood supply.    

Further, we have studied tissue engineered technology to potentially improve urethral healing, using a bioactive tissue matrix allograft composed of dehydrated human amnion/chorion membrane (dHACM) (Amniofix™; MiMedx, Marietta, GA).  This allograft material contains hundreds of functioning growth factors and cytokines, in high concentrations and in physiologic ratios, to promote healing and inhibit scarring. This promising technology, however, will surely not solve all the problems of this sensitive, poorly vascularized urethral connection and further work must continue to ultimately solve the problem.

Innovations

We and others endeavor to constantly evaluate and improve the steps of this surgery. We have liberally investigated new concepts and materials in this field in an ongoing effort to further improve results.

Flap monitoring

In general, some technological advancements may also hold keys to current surgical improvement.  We evaluate and use promising new technologies widely and frequently in this surgery.  For example, the health of the flap is constantly monitored with the T-Stat™ VLS Tissue Oximeter (Spectros; Portola Valley, CA). This FDA approved device allows real-time readouts of flap mixed oxygen concentration (correlated with arterial blood flow) and flap hemoglobin levels (rising levels indicate flap venous congestion). The oximeter outputs are easily monitored by bedside caregivers and can be mirrored to the surgeon’s cellphones for real-time monitoring, providing a quantitative, numerical output that clearly shows trends (good and bad) in the flap’s oxygenation. In the unlikely event of a flap emergency, this close monitoring can portent flap problems an hour or more before more subtle clinical signs of flap compromise (like flap paleness, duskiness or impaired capillary refill) become evident. We consider it indispensable in our flap surgeries. 

Nerve regeneration

We painstakingly isolate a donor nerve from the ALT (leg) or RF (arm) flap and microanastomose it to one of the clitoral nerves.  This gives very good sensory results, with about 80% of our patients experiencing sexual sensation in the neophallus, and up to 95% experiencing light touch sensation in the new organ.  We have endeavored to increase the speed and efficiency of nerve regrowth using the Axoguard™ Nerve Protector Wrap (Axogen; Alachua, FL), a sheath made of porcine small intestinal submucosa that is wrapped around and protects the nerve anastomosis. This has been shown to potentially decrease nerve scarring during healing in other surgical indications and is it is currently unknown if it will or will not help the final functional result in our phalloplasty patients.

Artificial dermis

The function and appearance of the forearm donor site can be challenging, as most of the circumference of the forearm is used in the donor flap.  Skin graft coverage of the defect can result in “stepoff” from the normal arm skin, and an unusual appearance where the thin (0.016 inch) split thickness skin graft adheres directly over the nerve, muscle, and tendon.  We place Integra™ Wound Matrix (Thin) (Integra Lifesciences; Plainsboro, NJ) under the skin graft, and then administer negative pressure wound therapy with V.A.C.™ device (KCI; San Antonio, TX) for about 9 days after surgery.  Integra consists of a thin layer of collagen that acts as a dermal regeneration matrix and results in noticeably thicker skin/dermis, less stepoff, and a lower likelihood of tight adhesion of the skin to the deep arm structures. 

All in all, these are modest improvements. But with dedicated effort by many high-volume centers, climbing THIS Mount Everest can and will be improved.

Written by: Min Suk Jun, DO, MS, Reconstructive Urology and Trauma, NYU Langone Health, New York, NY, USA; Curtis N. Crane, MD, Crane Center for Transgender Surgery, Austin, TX, USA; Richard A. Santucci, MD, Department of Urology, Detroit Medical Center, Detroit, MI, USA

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