Triangular Ligament In Urethroplasty

Flap Design and Elevation

The perineal artery medial thigh flap is a vertically oriented composite of skin, subcutaneous tissue, deep fascia, and adductor epimysium that measures 15x6 cm, with its proximal base in the male located at the level of the mid perineum 3 cm distal to the anal margin (O Fig. 19.1). The medial border is the crease of the groin lateral to the edge of the scrotum. Wee and Joseph [6] described the maximal safe dimensions of the flap as less than 6 cm in width from the base and 15 cm in length reaching the femoral triangle, including some random circulation at the distal point. The vascular basis of this flap is the superficial perineal artery, which is centered just medial to the groin crease with branches going to the scrotum and skin of the thigh. These vessels interconnect with branches of the deep external pudendal artery and the medial circumflex femoral artery, which arises directly from the profunda femoralis. A connection to the anterior branch of the obdurator artery exists near the proximal region of the adductor muscle (O Fig. 19.2).

The innervation of the proximal flap is supplied by branches of the pudendal nerve and perineal rami of the posterior cutaneous nerve of the thigh, which create a partially sensate structure.

This flap is elevated with the patient in the exaggerated lithotomy position and the thigh abducted using well-padded Direct OR stirrups. The lower abdomen, genitalia, perineum, and both thighs are prepared and exposed. The proximal and distal limits of the urethral stricture are marked on the skin surface, and the margins of the flap are outlined carefully with an indelible skin scribe. The initial incisions are made in parallel vertical lines and deepened down to the fascia on both sides, raising the epimysium with the fascia and suturing them to the dermis to prevent shearing injury to the segmental vessels. The flap is lifted until the proximal transverse margin is reached. The vas-cularity of the distal edge is confirmed by de-epithelializing a 1-cm area of the distal margin to identify a bleeding dermis. This step is followed by intravenous injection of two ampoules of fluorescein dye and examined with a Wood's light. The tissue bridge between the base of the flap and the urethral exposure is divided rather than attempt tunneling during transfer of the flap. This will prevent a compression effect and potential compromise of flap circulation. This technique provides ease of transfer of the somewhat tenuous distal island to the deep proximal urethra and release of tension on the closure of the donor wound site.

Urethral Flap

O Fig. 19.2. Vascular basis of the medial thigh perineal artery fasciocu-taneous flap centers around perineal artery (4), which arises proximally from an internal pudendal artery. This courses lateral to the scrotum and arborizes with branches from the deep external pudendal (2), medial circumflex (3), femoral (i),and obturator (5), which arises from common and profunda femoralis

O Fig. 19.2. Vascular basis of the medial thigh perineal artery fasciocu-taneous flap centers around perineal artery (4), which arises proximally from an internal pudendal artery. This courses lateral to the scrotum and arborizes with branches from the deep external pudendal (2), medial circumflex (3), femoral (i),and obturator (5), which arises from common and profunda femoralis

Pudendal Fasciocutaneous Flaps
O Fig. 19.1. Medial thigh flap measurements are consistently 15x6 cm, with the proximal base located at the level of the mid-perineum. The medial border is the crease lateral to the edge of the scrotum. The distal border is the mid-femoral triangle

Urethral Reconstruction

Four different variations of the Singapore fasciocutaneous flap transfer have been used in the management of a group of high-risk, complex proximal strictures. The selection of application has been based on length and proximal extent of the stricture, the pressure of an intact urethral roof, the absence of a segment of bulbomembranous urethra or co-morbid features of radiation, prior perineal and genital surgery or decubiti.

Most patients managed by this flap require an onlay patch designed in a traverse direction and rotated with a slight twist to a caudal position. This island onlay augment is performed in a ventral position and optimally combined with partial excision of the narrowest point followed by a »roof strip« anastomosis (O Fig. 19.3).

Technique of Onlay Patch Urethroplasty

The urethra is exposed with the patient in the dorsolitho-tomy position and both thighs draped into the operative field. A retrograde bougienage will readily define the distal limits of the stricture, while a #5 Fogarty balloon distended with 1 ml of saline will identify the proximal limit. An inverted Y-incision that extends to the midscrotal raphe permits access to the relevant portion of the urethra and will allow a proper entry site for the flap (□ Fig. 19.1). The bulbocavernosus muscle is divided in the midline and separated from the corpus spongiosum. The spongiosum is mobilized if partial excision is contemplated from the suspensory to the triangular ligament, avoiding the neu-rovascular pedicle to the muscle and the bulbar arteries.

A urethrotomy (stricturotomy) is started distally on the ventral surface of the bulbar urethra and extended proximally to the palpable intraurethral balloon across the apex of the prostatic urethra if necessary (□ Fig. 19.3).

A running locked hemostatic suture of 5-0 chromic catgut is used to approximate the adventitia to the ure-thral edge, thus controlling the bleeding spongiosa edge while permitting more precise fixation of the flap onlay.

When segments of the urethra are too narrow and fibrotic for a uniform onlay, partial resection with a roof strip anastomosis is performed utilizing interrupted 4-0 Monocryl sutures and fixing the mobilized spongiosa to the ventral side of the corpora cavernosa. The urethroto-my must extend to 2-3 cm of normal, healthy, uninvolved urethra at the proximal and distal limits of the disease. Reluctance to perform an aggressive urethrotomy accounts for most recurrent strictures since nonobstructive cryptic spongiofibrosis can be difficult to define without incising the spongiosa. The length and width of the prepared ure-throtomy are measured with an indwelling 24-F catheter as a sizing template for the proximal urethral lumen. If the stricture extends across the sphincter, a series of 4-0 Monocryl sutures are placed in the proximal apex of the urethrotomy in preparation for the onlay or tube island flap. A suprapubic cystotomy is established at this point.

Attention is then directed to the perineal artery flap retrieval, which then needs to be elevated with a secure circulation and a well-perfused distal margin. A 6- to 8-cm by 2-cm transverse island is outlined around the edge of the flap (□ Fig. 3). A 3-cm-wide strip of skin just proximal to the island is de-epithelialized, leaving a thin layer of dermis to prevent ischemic injury to the transverse island. The flap is rotated medially and inferiorly and the island patch is sutured over the urethrotomy defect by inserting the previously placed apical sutures into the proximal edge of the skin island (□ Fig. 19.4). Two running sutures of 4-0 Monocryl are used to complete the onlay repair. These are reinforced with widely spaced, interrupted sutures of 5-0 Vicryl and a #16 silastic catheter is inserted.

The donor site and perineal incision are closed by advancing the lateral thigh wound edge toward the

□ Fig. 19.3. A bulbomembranous urethrotomy is performed and then managed by a horizontal or transverse onlay patch

Penis Ligaments

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Responses

  • jean
    Is urethra conected tp perineum?
    3 years ago

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