New treatment for urethral strictures

NEW TREATMENT

MAHMOUD

A. BAZEED,

JOACHIM

W. THUROFF,

RICHARD

A. SCHMIDT,

EMIL

A. TANAGHO,

FOR URETHRAL

STRICTURES*

M.D. M.D. M.D.

M.D.

From the Department of Urology, School of Medicine, San Francisco,

Cniversity California

of California

ABSTRACT - A new operative technique using synthetic, absorbable mesh for grafting a urethral with its defect uxs applied in 7 mongrel male dogs. The ventral half of the urethral circumnference surrounding corpus spongiosum zL’as excised for a length of 3 to 4 cm. A Deson mesh of the same dimensions, woven in our laboratory from polyglycolic acidfEbers, was sutured to the defective area. A perineal urethrotomy was established, and no splints were left behind. Dogs were studied between two and six months. Retrograde urethrography showed that the operative area healed without strictures or irregularities. Intravenous urography showed no back pressure effects, and cultured urine was always sterile. Histologic examination two months after surgery showed that the urothelium was completely healed, without inflammatory changes or disruption. Suburothelial tissues were replaced by dense collagenous connective tissue. The excised corpus spongiosum did not regenerate. After six months, the area of dense collagen described was diminished in size so that tht>operative area could be hardly identi$ed except by the absence of corpus spongiosum.

Satisfactory management of urethral strictures has always been a challenging problem for the urologist. In some cases free patch graft urethroplasty is indicated. Many materials have been investigated for this purpose, including full thickness skin graft,’ tunica vaginalis,’ and lyophilized human dura matter (LHD).3 Devine and associates4 popularized free skin patch graft For grafting the urethra we urethroplasty. thought that a synthetic yet completely absorbable material would be ideal. For this reason we investigated the applicability of a Dexon mesh as patch graft for the urethra. We were encouraged by the good results we had achieved from applying the same mesh to the experimental management of Peyronie disease.’

Material

The Dexon mesh was designed and wo\.en in our laboratory from 308 denier-thick polyglycolic with trans\.erse intersections of acid sutures* polypropylene 4-O as marking fibers (Fig. l).” The mesh was sterilized in eth>-lene oxide for twelve hours, then aired for twenty-four hours before use. Seven male mongrel dogs weighing 18 to 25 Kg were anesthetized by pentobarbital sodium (25 mg/Kg of body weight). An 8-F polyethylene feeding tube was passed into the bladder. An incision 5-cm long was made in the skin co\.ering the penis between the proximal ends of the OS penis and the scrotum. The retractor penile muscle that separates the urethra from the skin was dissected and retracted, exposing the urethra (Fig. 2A). The ventral half of’the urethral

*Supportedt,y Agency for International Dwelopmrnt through thr Egy,3ptian Gwernment and AMIDEAST, Ll’ashington, D.C.. and DFG (Delltschr Forsch~mp Cemeinschaft) TH274/1. Fed& Repuldic of Grrn~nn!

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JANCARY

1983

\‘OI,UIlE

XXI. NUMBER

and Methods

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raphy. The dogs were then sacrificed (1 at two months, 2 at three months, 2 at four months, 1 at five months, and 1 at six months) and the penis was removed and immersed in 10% phosphatebuffered formalin for one week to fix the tissues. The operated area and a control area were studied by light microscopy after being stained with hematoxylin and eosin, Masson trichrome stain, and Van Gieson elastin stain. Sections from both operated and nonoperated areas were examined. This provided an internal control for each dog. Results

FIGURE 1. graft.

Dexon

mesh

used

as a urethral

patch

circumference and its adjacent corpus spongiosum was excised for a length of 3 to 4 cm proximal to the OS penis (Fig. 2B). The resultant defect was repaired with the use of Dexon mesh of the same diameters (Fig. 2C). The repair was done using running 3-O Dexon sutures. An inverted V-shaped perineal incision was done, the urethra exposed, and a perineal urethrotomy established as a means of urinary diversion. The urethral catheter was removed at the end of operation. The dogs were given antibiotics (penicillin and streptomycin) for five days postoperatively. The status of the animals was studied between two to six months by urine culture, excretory and retrograde urethrogurography (IVP),

The mesh was easy to manipulate intraoperatively. In the postoperative period, the dogs did well; no complications occurred. The perineal urethrotomies were partially healed in two weeks, so that most of the urine came through the penile urethra and dribbling from the perineal stoma was minimal. Intravenous urography showed no back pressure on the bladder or the upper urinary tract. Retrograde urethrography showed no stricture or extravasation in the operative area (Fig. 3). In some animals minimal leak occurred in the

2. Operative technique. (A) Penile urethra exposed. (B) Anterior one half of urethral circumference and its corpus spongiosum are excised for length of 3 to 4 cm. (C) Urethral defect is repaired via Deron mesh of same dimensions. FIGURE

x

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FIGURE 3. Retrograde urethrography. c-4 and B,) Anteroposterior and lateral expoSur-es six weeks after surgery. (C and D) Anteropo.sterior and lateral ~.-tpos~~rcs after six months (it appeur,\ that this mongwl dog ca.v prwiously shot; bullets appcrlr on all f;lmi.

On histologic euunination healing of the follobing components of the penile urethra was subnrothelial connective j~ldged: klrothelillm. The corpus tissues, and corpus spongiosum. spongioxum directly contiguous to the operative side ~‘;a al,sent hut intact along the nonoperated of’ the urethra (Fig. 4A-D). The region llrothelium \vas completely intact (Fig. 3E, F). A ~11x111~OCII~ of dense collagen \vithout elastic

fibers could be identified contigrlolls to the operative site where the corpus spongiosunl was Asent (Fig. 4.2). Otherwise the collagen and elustin of the suburothelial connecti\~e tissue were intact. These histologic findings were essentially the same in the dogs sacrificed after t\vo, three, four, five, or six months. li noticeable difference was that the Deson mesh 1%as incompletel!, alxorl)ed after t\vo months but completely alxorbed after three months. :Ilso, after six months, the area of dense collagen described

FIGURE 4. Hematoxylin and eosin-stained cross-section of operated site. Two months after surgery, operated site (A) and control area (B) (original magnzjkation x 40); arrow indicates intact corpus spongiosum in {B) and its absence in (A). (C and D) Higher magnification ( x 100); arrow indicates intact corpus spongiosum in (0) and absence in (C). [E and F) Magnification to x 400 show complete regeneration of urothelium in (A).

was diminished in size so that the operative side could hardly be identified except by the absence of corpus spongiosum (Fig. 5). Comment The lumen of the penile urethra is lined with a thin layer of transitional epithelium supported by

,556

a rather dense matrix of connective tissue which, on histologic staining, shows abundant collagen and elastic fibers. Prominent interlacing vascular channels are lined by a single endothelial cell layer forming a circumferential coat around the urethra (corpus spongiosum). Different methods have been used for repair of urethral strictures

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along

the

of fi-ee grafting \vith endogmaterials, or according to the principle of illtuluted urethrotom~~.” The tlisatl\.alltajit,s of the procedure of free grafting \vith ei~dogenous patches. especially fi-oin the surger\. and time to ol)tain akin , WC xlditional tlrc grat‘t. The principle oi‘ regeneration on ai iiid~~~clling stent requires long stenting time.” m.ith incwased risk of infection. In OII~ c~speriments the Dexon mesh completcl!. disqqwured and was replaced ly collagcworls fihro~~s tissue having the same orientation as that of thr, normal urethra. This healing process was complete 1)~ two months. CTrethrog~xph\- did not show signs of obstruction, and IF’P tlisc*loscd ;L iiornial ririnary tract without an!. signs of hack pressure. \\7e ~isecl s\-nthetic ahsorbable material foi \ve;i\ ing 011r patch paf‘t (Dexon sutures). This Illuterial has all the acl\mtages of synthetics (inant 1 cl\;pcansi\ (‘ and easy to obtain, store. stcbrilizcsi. aid it also dissolves completely after implantation. Pol!.glycolic acid suture (Deson) is ;L synthetic polylner of hydroxyacetic acid. It C’;IIIS(~ miniinal tissue reaction.i It shows minini;il al~sorption at ten to fifteen days, almost complete al~sorption at thirty days, and total all wrption at sixty to ninetv days.’ Our rationale foi losing Deson mesh is that it provides a matrix fbl tile collagen fillers and epithelium to f:,wilitate liealilig. In dogs studied after three, four, and six nlonths the Deson mesh had disappeared and \V;IS replacetl 1)~ ;l collagenous network providing I~ormal rlrc~tliral srlpport. ~'11011s'~2

principle

or

e\;0,q?11011s”