Pelvic and Urogenital Reconstruction

Gender-Nonspecific Anatomy

The perineum can be divided into an anterior, urogenital, and a posterior anal triangle by a transverse line connecting the ischial tuberosities ( Fig. 19.1 ). In the urogenital triangle we find the urogenital diaphragm, which spans between both pubic rami and is perforated by the urethra and vagina. It also serves as the insertion point for the musculature of the external genitalia (i.e., ischiocavernal and bulbospongiosal muscles). In the posterior lateral corner of the urogenital triangle, the neurovascular bundle enters the perineal region from the pudendal canal (Alcock canal). It consists of terminal branches of the pudendal nerve, the internal pudendal artery and vein. The pudendal nerve is split into the deep and superficial perineal nerve as well as the dorsal nerve of the penis/clitoris. The artery too splits into three branches: dorsal penile/clitoral artery, deep dorsal penile/clitoral artery, and bulbous artery. The venous drainage happens via the deep dorsal vein, the internal pudendal system, as well as the earlier mentioned superficial dorsal vein. The latter runs in the retropubic space and drains into the vesical plexus. Branches of the internal pudendal, obturator, and external pudendal vessels ensure the blood supply to the vulva and scrotum.

The posterior anal triangle includes the ischioanal fossa, the pudendal canal, and the anal sphincter system.

Pertinent neurovascular structures for the reconstructive surgeon (see Chapter 11 for detailed discussion; also Figs 11.6 and 11.10 ):

• External pudendal artery and vein – superficial and deep branch

• Medial circumflex femoral artery and vein

• Superficial circumflex iliac artery and vein

• Femoral artery and vein

• Saphenous vein

• Obturator artery and vein

• Obturator nerve

• Perineal branch of posterior femoral cutaneous nerve

• Iliohypogastric nerve

• Ilioinguinal nerve

• Genital branch of the genitofemoral nerve

Pertinent Male Anatomy

Skin and fascial layers of the penis ( Fig. 19.2 ):

• Skin

• Dartos fascia (continuation of Scarpa's and Colles' fascia)

• Areolar tissue and superficial dorsal venous system

• Buck's fascia (continuum of suspensory ligament of penis and perineal membrane)

• Unpaired deep dorsal vein, two dorsal arteries, two dorsal penile nerves, spongy urethra

• Tunica albuginea

• Corpora cavernosa including deep penile arteries

Pertinent Female Anatomy

The vagina is an elastic muscular tube that measures 5–10 cm in length and 2 cm in width ( Fig. 19.3 ). It enters the perineum at an angle of inclination of around 30°. It is bordered anteriorly by the bladder and urethra and posteriorly by the rectum and it is attached laterally to the pelvic musculature. An abundance of autonomic innervation is responsible for secretions and involuntary contractions. Pain fibers are derived from the sacral plexus, and the tactile and erogenous sensation is provided via the deep perineal branch of the pudendal nerve. There is a rich vascular supply consisting of multiple arcades that are derived from the vaginal artery via the internal iliac system.

General Principles of Total Phalloplasty

Phallic inadequacy that is not amenable to standard, local penile lengthening procedures (i.e., penile stump ad­vancement, suspensory ligament release, V-Y advancement, penoscrotal web excision) can be treated with reconstructive phalloplasty using local or distant flaps. The goals for penile reconstruction include:

• 1.

  The procedure should be reproducible.

• 2.

  The penile reconstruction should result in a neourethra that is capable of passing urine while standing in those patients who are continent.

• 3.

  The neophallus should have both tactile and erogenous sensation.

• 4.

  The reconstruction should provide enough bulk to accept a prosthetic for erection and sexual penetration.

• 5.

  The neophallus should be aesthetically acceptable to the patient.

Recipient Neurovascular Structures

The options for recipient neurovascular structures ( Fig. 19.4 , see also Fig. 11.3 , 11.6 , and 11.8 ) for microvascular phalloplasty include:

• End-to-side: femoral artery (with or without reversed saphenous interposition graft)

• End-to-end: femoral side branches, inferior epigastric

Recipient vein:

• End-to-end: saphenous vein or inferior epigastric

Recipient nerves:

• Erogenous (S4-Co): dorsal penile nerves (branch of pudendal nerve)

• Dorsal nerve of the clitoris (in Gender affirming surgery)

• Protective sensation: ilioinguinal, iliohypogastric, genito-femoral, (L1–L4) saphenous, femoral nerve

Local Tissue Used for Reconstruction

There is a variable amount of native donor tissue that can be used as part of the reconstruction. This is particularly true for phalloplasty in gender affirming surgery and congenital conditions, where the remnant glans or clitoris can be incorporated into the base of the neophallus. Similarly, preserving the clitoral hood or parts of the labia is useful for scrotal reconstruction. In the case of inadequate phallic length in both congenital and acquired conditions, it is prudent to preserve native corpora cavernosa that can be used to proximally secure the IPP or fibula.

Flap Design

The overall size and design of the phalloplasty is similar, regardless of the flap choice ( Figs 19.5 , 19.6 ). The surgeon may decide to incorporate a urethral section in the flap if immediate urethral reconstruction is desired.

Prelamination Method

( Fig. 19.7 )

A full-thickness skin graft is wrapped around a Foley catheter and placed under the proposed flap 3 months prior to the phalloplasty. This method has been shown to provide a viable continuous urethra of sufficient length, as well as a trend to a lower incidence of urethral fistulas and better-controlled girth.

Immediate Reconstruction with a Tube-in-Tube Design

This is the most commonly described method, where a 1.5 cm wide longitudinal strip is de-epithelialized 3 cm to the lateral border of the flap. The lateral skin bridge is then rolled over a Foley catheter and sutured to itself. The main fasciocutaneous flap is rolled in the counter direction around the neourethra ( Fig. 19.5 ). For a radial forearm free flap phalloplasty, the ulnar side of the flap is generally chosen for the urethra, as it tends to contain less hair.

Immediate Reconstruction with a Vascularized Flap

A thin SCIP flap or a free ulnar forearm flap can be used to create a vascularized neourethra in cases where a tube within a tube is not feasible. Most often this is combined with a pedicled ALT.

Delayed Reconstruction

Implantable Penile Prosthesis

To reduce the risk of implant erosion or extrusion, insertion of the implantable penile prosthesis (IPP) is usually delayed 12 months for the return of sensation. For the same reason, it is prudent to account for sufficient distal soft tissue coverage at the time of phalloplasty. Various techniques are described to reduce the risk of erosion and extrusion, such as reinforcing the most distal area of the IPP prosthesis with fascia latae, acellular dermal matrix, or a polyethylene terephthalate sleeve. In congenital cases, the IPP should only be implanted in the late adolescence to early adulthood, as a high degree of maturity is needed to avoid complications.

The main complications of IPP are:

• Mechanical dysfunction

• Leakage of reservoir

• Erosion and extrusion

• Infection

• Penile fibrosis/disfigurement

Timing of Phalloplasty for Congenital Cases

The normal male genitalia experiences exponential growth during puberty secondary to increased testosterone receptor density. A neophallus lacks these receptors and will only grow longitudinally with the child. Therefore, reconstruction is usually delayed until after puberty to ensure adequate size of the phalloplasty. This, however, has to be balanced against the potential downside of delayed psychosexual development.