FOR DOCTORS – PART V
Tubularized Incised Plate Urethroplasty (TIP)
The Tubularized Incised Plate repair (Snodgrass 1994) is based on the assumption that midline incision into the urethral plate may widen it sufficiently for urethroplasty without stricture. Many centres report excellent results with this technique. There are two important criteria to achieve good results: the urethral plate should not be less than 1 cm wide and there should be no distal deep chordee. The technique has gained popularity because it is easily performed, with few complications and results in a slit like meatus. The importance of regular dilatation is still controversial.
- A traction suture is placed in the glans just beyond the anticipated dorsal lip of the neomeatus. A circumscribing skin incision is made 1 to 2 mm proximal to the meatus and the shaft skin is degloved to the penoscrotal junction. If a portion of the native urethra is excessively thin, however, a “U” shaped incision is made extending to more healthy tissues.
- The urethral plate is separated from the glans wings by parallel incisions along their junction. A tourniquet placed at the base of the penis provides better visualization of the operative field. The glans wings are mobilized avoiding damage to the margins of the urethral plate.
- A relaxing incision is made using scissors in the midline from within the meatus to the end of the plate. The incision should not reach the tip of glans. The depth of the relaxing incision depends on the plate width and depth. A 6 Fr stent is secured into the bladder. A 7-0 polyglactin is preferred to tubularize the urethra, with the first stitch placed at approximately the midglans. Tubularization is completed with a 2 layer running subepithelial closure.
- Any adjacent dartos tissues are used to cover the neourethra and then a dartos pedicle is developed from the dorsal shaft skin, button-holed, and transposed to the ventrum to additionally cover the repair.
- The coronal margins of the glans are approximated with subepithelial 6 – 0 polyglactin. The skin edges of the glans are sutured, and the meatus with 7 – 0 ophthalmic chromic catgut.
- Byars’ flaps are created from the preputial skin to mimic the median raphe. Subepithelial stitches are used throughout to avoid suture tracks. A tegaderm dressing is applied. The stent is removed approximately 1 week later.
Complications: Complications occurs in 5-35 % in distal hypospadias and upto 65 % in proximal hypospadias. Complications include meatal stenosis, persistent fistula, functional urethral obstruction and persistent chordee (vental curvature of the penis).
Transverse Preputial Island Flap
- A deep Y-shaped incision is made on the glans as in the Lateral based (LB) flap technique. Meticulous excision of any chordee or fibrous bands is carried out. This fibrous tissue is particularly heavy in the midline but may extend well laterally. The meatus is assessed and a cut back is made to widen the meatus. A sub coronal incision is made around the glans. The incision continues laterally until it reaches the gap where the fibrous chordee was excised.
- The penile and preputial skin is dissected free off the shaft from distal to proximal close to the Buck’s fascia preserving the arteries that constitute the pedicle to the preputial flap.
- A 1.5 cm wide rectangular flap is prepared. The length must suffice the gap between the meatus and the tip of the glans. Extra length can be obtained by going down into the penile skin in a horseshoe fashion on either side. The flap is tubularised around a 10 Fr catheter and sutured into the meatus beginning with the suture line underneath the pedicle utilizing interrupted 7-0 polyglactin suture.
- Then, the pedicle is separated from the outer preputial skin in a plane just below the intrinsic blood supply of the outer prepuce down to the root of the penis.
- The upper small median flap resulting from the Y incision is sutured to the upper dorsal end of the tube. A V is excised from the tip to obtain a slit like meatus. The mobilized glans wings are rotated medially around the neo-urethra. Three transverse mattress sutures maintain firm approximation of the glanular wings in the midline. The mobilized glans wings are rotated medially and three transverse mattress sutures maintain firm approximation of the glanular wings in the midline. De-epithelialisation of skin to protect the neourethra.
Complications: Fistula, wound disruption, diverticulum and rotation occur in 10 – 30 % of patients.
MAGPI (Meatal Advancement and Glanuloplasty Incorporated)
This technique may be used in glanular hypospadias with mobile urethral meatus that can be pushed to the tip of the glans. If the meatus is not mobile enough, the results are less satisfactory.
Meatal advancement: The dorsal lip distal to the meatus is cut longitudinally to avoid urine deflecting downwards. In the classic MAGPI, the incision is closed transversely (Heineke Mickulicz technique). Thus the dorsal meatal edge is advanced distally. Recently, some surgeons leave it without closure as a modification from Snodgrass technique.
The glanuloplasty is accomplished by elevating the ventral edge of the meatus forwards and rotating the flattened glanular wings upwards and ventrally in a conical manner. It is important to reapproximate glans tissue in a two layers fashion with a deep closure of glans mesenchyme and a superficial layer of glans epithelium.
There have been several modifications of this technique (Duckett and Baskin, 1996).
Complications: Meatal regression may occur if the technique is used in patients with immobile urethral meatus. Precision is required to achieve a conical glans.
Onlay Island Flap
The Onlay Island Flap is ideal for patients with proximal hypospadias without deep Chordee. According to the author experience, most patients with proximal hypospadias have deep chordee that necessitates excision. However, recently, many surgeons prefer to perform dorsal placation if the chordee is less than 30o after skin degloving and preserve the urethral plate.
- The tip of the neo-meatus is identified. This point is where the flat ventral surface of the glans begins to curve around the meatus. A midline vertical incision is made in the glans until the width of the glanular groove is adequate for the meatus. The vertical incision is left open without closure for secondary epithelialisation.
- A subcoronal incision is made around the glans. The incision continues on either side of the urethral plate at the junction with the normal ventral skin, then up on either side of the glanular groove to the apex of the glansplasty.
- The skin is degloved from distal to proximal close to the Buck’s fascia preserving the arteries that constitute the pedicle to the preputial flap. The pedicle is then separated from the outer preputial skin in a plane just below the intrinsic blood supply of the outer prepuce. The elevation of the glans wings will permit them to be rotated around the urethroplasty.
- A 1-cm wide onlay flap is prepared from the inner prepuce. The onlay flap is sutured into place beginning with the suture line underneath the pedicle utilizing running 7-0 polyglactin suture. The glans should be drawn together setting up the first stitch of the glansplasty ventrally at its apex.
- The mobilized glans wings are rotated medially around the neo-urethra. Three transverse mattress sutures maintain firm approximation of the glanular wings in the midline.