- Email: [email protected]
Perineal Urethrostomy
Symposium on Urogenital Surgery
Perineal Urethrostomy Surgical Technique and Management . of Complications
joe Hauptman, D.V.M., M.S.*
Feline urolithiasis syndrome is a common disease in cats characterized by cystitis, urethritis, and urolithiasis. In the male cat, it may progress to urethral obstruction. Urethral obstruction due to the feline urolithiasis syndrome is most commonly seen in the castrated male cat, 1 to 4 years old, who lives indoors and eats dry cat food . 13 Urethral obstruction may result in life-threatening acid-base and electrolyte disturbances, pain, and uremia. If not treated surgically, obstruction will recur in at least 35 per cent of the cats within 6 months. 3 Perineal urethrostomy is highly recommended and frequently performed as a surgical treatment for urethral obstruction due to feline urolithiasis syndrome. While many urethrostomy techniques have been advocated through the years , only a few result in reliable, reproducibly good results. These techniques are outlined in this article and elsewhere. s. 16, 17 Because of the high rate of recurrence, the health danger, and the cost of emergency treatment of urethral obstruction, and the high success rate of perineal urethrostomy, this surgery is indicated in any young cat that obstructs. It is also indicated in any cat who has obstructed three times and/or has not been responsive to medical management. The procedure should be performed on either an elective basis or following treatment and stabilization of urethral obstruction. Renal function, acid-base, fluid and electrolyte balance should be evaluated and treated as necessary. As with any surgical procedure, complications may be encountered related to the performance of feline perineal urethrostomy, The purpose of this article is to detail the technique of perineal urethrostomy and the *Diplomate, American College of Veterinary Surgeons; Assistant Professor of Surgery, Veterinary Clinical Center, Michigan State University College of Veterinary Medicine, East Lansing, Michigan
Veterinary Clinics of North America: Small Animal Practice-Val. 14, No. 1, January 1984
93
94
jOE HAUPTMAN
complications that may occur. The reasons they occur, methods for preventing or managing them, and frequency of occurrence will be discussed.
SURGICAL TECHNIQUE The cat is anesthetized and positioned in ventral or dorsal recumbency according to the preference of the surgeon. I prefer ventral recumbency, and illustrations in this text will be with the cat in that position. The hind limbs are loosely tied down and the tail is retracted cranially over the back and secured. The table is tilted to an angle of approximately 30°. A pursestring suture is placed in the anus. If the urethra is not obstructed, the bladder is emptied of urine by manual expression or catheter. Surgical preparation of the skin is routine. The surgical area is draped in such a manner that the anus is covered. An elliptical incision is made around the scrotum and prepuce. The incision is continued through the subcutaneous tissues to the level of the spermatic cord with its enclosing vaginal tunic, and castration is performed at this time if the cat is intact. If the cat has already been castrated, the incision is continued through the subcutaneous tissues to the level of the body of the penis. Subcutaneous bleeders are ligated, if necessary. Dissection is continued cranially to the level of the ischiocavernosus muscles, which are identified on both sides. They, along with the associated crura of the penis, are isolated and clamped with a hemostat (Fig. lA). These structures are divided lateral to the hemostat and ligated medial to the hemostat, on the penile side. The penis is retracted dorsally (Fig. lB), and the ventral ligament of the penis is palpated. This ligament lies on the midline and firmly fixes the pelvic urethra to the floor of the pelvis. It is cut with fine, angled blade scissors. Care is taken not to inadvertently cut the pelvic urethra. The surgeon's finger is placed between the penis and pubis to the cranial rim of the pubis, to assure complete division of the ventral ligament of the penis. After the ventral ligament, ischiocavernosus muscles, and crura have been cut, the penis can be retracted caudally so that the bulbourethral glands lie caudal to the perineal skin (Fig. lC). Dissection is continued cranially so that the penis is freed for approximately 2 em cranial to the bulbourethral glands. Finger dissection will accomplish this goal ventrally and laterally. Dorsally, there are multiple thin muscular and fascial attachments that are best individually cut with scissors. Dissection should remain close to the penis without lacerating the penis or urethra. The retractor penis muscle is removed from the dorsal aspect of the penis to facilitate identification of the urethra. A tourniquet made from heavy suture material, or lfs-in. umbilical tape, and intravenous tubing (Figure lD) is passed around the penis cranial to the bulbourethral glands 1 to 2 em. It is closed loosely, and held with hemostats, to permit hemostasis. The urethra is then opened with fine scissors from the tip of the penis to the pelvic urethra at the cranial edge of the bulbourethral glands (Fig. IE). The pelvic urethra is differentiated from the penile urethra
95
PERINEAL URETHROSTOMY
B
A
(
c Figure 1. A, The left ischiocavernous muscle crus of the penis has been isolated with a hemostat (a). It should be divided after ligation on the penile side (b). 8, The ventral ligament of the penis has been isolated (a). It should be identified by palpation during surgery and must be cut. This ligament need not be visualized, but it lies dorsal to the ischium (b) and ventral to the penis (c). C, The bulbourethral glands are prominent in this tomcat (arrows). They lie at the junction of the penile-pelvic urethra and should be exteriorized to the level of or caudal to the skin. Illustration continued on following page
by the diameter of its lumen, its relationship cranial to the bulbourethral glands, and color. Sutures are now placed to appose skin and urethral mucosa, allow primary wound healing, and maintain hemostasis. Simple interrupted sutures are placed to include 2 mm of skin, 1 mm of urethral mucosa, and a deep bite of the corpus cavernosum urethrae. The sutures are tied to appose skin to mucosa. The mucosa alone does not hold sutures well, and the tissue of the corpus cavernosum is important as the holding layer and to maintain hemostasis. The initial sutures are placed dorsally, at the apex of the incision, on both sides 1 mm off the midline. The simple interrupted sutures are continued ventrally, spaced 3 mm, for a distance of 2 em. The tourniquet is removed when approximately half the sutures have been placed. The penis is ligated, cut distal to the ligature, and the excess penile and
96
}OE HAUPTMAN
D
Figure 1 (Continued). D, A tourniquet is placed 1 to 2 em cranial to the bulbourethral glands to effect hemostasis from the urethral cavernous tissue. E, The urethra has been incised along its dorsal aspect to the wide pelvic urethra (delineated by arrows), just cranial to the bulbourethral glands. F, Postoperative view of the urethrostomy site of a cat that had been reoperated for stricture after perineal urethrostomy. Closure is identical to that for the original perineal urethrostomy. The strictu red site on the urethra (a) can be identified on the sutured flap of urethra 1 em distal to the new urethrostomy (b).
preputial tissue is discarded. The remainder of the closure is routine (Figure lF). A Penrose drain may be placed before closure at the discretion of the surgeon, depending on the amount of dead space, amount of hemorrhage, and viability of tissue. The drain is placed between the urethra and pubis and is exited distal and lateral to the suture line. The pursestring suture in the anus is removed. An Elizabethan collar is placed on the cat to prevent licking of the urethrostomy site. If clotted blood around the urethrostomy site is excessive postoperatively, the area is hot-packed as necessary to loosen the clotted blood. The surgical wound is not otherwise tampered with until removal of sutures 10 days later. If a drain was used, it is removed when drainage ceases, usually 1 to 2 days postoperative. The choice of suture material is, in large part, a matter of surgeon preference. The material should be small gauge (4-0) and have a swagedon needle. Silk, non-absorbable synthetics, and absorbable synthetics have
97
PERINEAL URETHROSTOMY
all been used satisfactorily. If a synthetic suture that possesses "memory" and is relatively stiff is used, care should be taken so that the cut ends of the suture do not irritate the urethrostomy site. Intraoperative prophylactic antibiotics may be used at the discretion of the surgeon. 15 Fluid and electrolyte balance is maintained in the postoperative period as necessary. Kitty litter is replaced by shredded paper in the cat box until suture removal. COMPLICATIONS Stricture Stricture formation is an unfortunate complication of any procedure that attempts to solve feline urethral obstruction by creating a new stoma from the urethra to the outside. If the surgeon chooses the recommended techniques of perineal urethrostomy8 • 16• 17 and uses good surgical technique to anastomose pelvic urethra to skin, postoperative strictures should occur very infrequently. A strictured perineal urethrostomy may be due to factors that the surgeon cannot control, such as self-inflicted trauma to the surgical wound. However, if a strictire is encountered, I recommend a critical analysis of technique and postoperative care to attempt to define the cause of the stricture. Strictures will be commonly encountered in improperly performed urethrostomies. It is reemphasized that the pelvic urethra must be anastomosed to skin and that primary wound healing must occur. Techniques that do not allow this anastomosis or that utilize a prosthetic shunt should not be used as they result in a high rate of strictures, or self-mutilation, or both. If the pelvic urethra is to be anastomosed to the skin, then proper identification and mobilization of the pelvic urethra must be achieved to mobilize the pelvic urethra, it is absolutely necessary that the ventral ligament of the penis, the ischiocavernosus muscles, and the crura of the penis be divided. Division of those structures, along with all other attachments to the penis for 2 em cranial to the bulbourethral glands, will result in adequate caudal retraction of the penis . The pelvic urethra is identified cranial to the bulbourethral gland with a diameter of at least 3 to 6 mm. Direct apposition of skin and urethral mucosa must be achieved to allow primary wound healing. Care must be taken to allow their proper placement. Even with skin-to-mucosa apposition, secondary wound healing with stricture may occur. If sutures engage only urethral mucosa, and not the holding-layer cavernous tissue, then they may tear out and secondary healing will result. Infection of the urethrostomy, irritation due to cut ends of stiff suture, and trauma due to kitty litter, licking, or rubbing all may result in altered wound healing and stricture formation. Stricture formation , regardless of cause, most frequently occurs at the mucocutaneous junction. 9 All postperineal urethrostomy strictures are similarly handled surgically. An elliptical incision of 1 to 2 em is made, with the urethrostomy site at the top of the ellipse. Dissection is performed
98
}OE HAUPTMAN
cranially to free up approximately 2 em of urethra, exactly as in the described original technique. Depending on the manner in which the original urethrostomy was performed, normal structures (ischiocavernosus muscles, crura of penis, ventral ligament of the penis) or only fibrous tissue may be encountered. Frequently, the ischiocavernosus muscles will be found attached to the penis. The interpretation should not necessarily be made that the original surgery did not include division of these muscles, as they may reattach after they have been cut. The surgeon should critically determine the condition of the surrounding tissue and the site of reattachment of these muscles to determine if the structure is due to inadequate cranial dissection or other causes. Once the penis is freed up from within the pelvis (as in the original surgery), it is retracted caudally and cut along its dorsal aspect until the large lumen of the pelvic urethra is adequately opened. The lumen diameter should be at least 3 to 6 mm. The urethral mucosa is anastomosed to the skin by the same technique used in the described original perineal urethrostomy. The tourniquet described may be used in the same manner. It is noted that, regardless of original technique, there is usually sufficient urethra to allow enough caudal retraction to obtain a new urethrostomy. If there is insufficient urethra, an antepubic urethrostomy or cystostomy procedure may be necessary. (Refer to the article on "Traumatic Injuries of the Urogenital Tract" in this symposium for descriptions of these techniques.) Hemorrhage Hemorrhage may occur both during and after surgery and is an annoying complication of any urethrostomy. Intraoperative bleeding, from other than the urethra, should always be controlled by ligation as necessary. There may be subcutaneous bleeders that require ligation. The ischiocavernosus muscles and crura should always be ligated on the penile side. Profuse hemorrhage from the corpus cavernosum urethrae will frequently occur during and after surgery. Intraoperative urethral hemorrhage is very nicely controlled by use of the described tourniquet. 8 It is emphasized that excessive tourniquet pressure should be avoided, as only minimal pressure is required to control urethral hemorrhage. Postoperative urethral hemorrhage is best prevented by the precise placement of sutures as described. Postoperative hemorrhage may still occur; if it does, time and patience are effective in controlling it. Laceration and Rupture Lacerations and ruptures of the penis occur infrequently. Lacerations may occur preoperatively at the time of emergency catheterization and treatment or intraoperatively by mistake. The manner in which a laceration is managed is influenced by its extent and position. If the laceration is caudal to the bulbourethral glands, then it is not of consequence and the perineal urethrostomy may proceed routinely. If it is large and accessible, it should be sutured with interrupted sutures of synthetic absorbable suture material, and a Foley catheter (10- to 12-Fr.) placed in the bladder-urethra for 3 to 4 days. If the urethral laceration is small or inaccessible, then the
PERINEAL URETHROSTOMY
99
Foley catheter alone is placed for approximately 4 days. The Foley catheter will divert urine past the lacerated urethra, allowing epithelialization to occur. Ruptures, though rare, occur because of excessive traction on the penis while finger dissection is being performed. If the rupture occurs too far cranial to permit urethrostomy of the perineum, then the urethrostomy must be performed cranial to the pubis. 12• 18 The cat is placed in dorsal recumbency and prepped for a midline skin incision. A midline incision, through the linea alba, is made from the pubis cranially for 5 em. The bladder is identified, and the urethra is followed posteriorly till the ruptured end is found . The ruptured end is cut, so that it is smooth, and is exteriorized through the midline. The linea alba is apposed with a non-absorbable non-reactive suture material, leaving a 1cm opening for the urethra. The subcutaneous tissues are apposed as necessary. The cut edge of the urethra is apposed to the skin by the same method as with perineal urethrostomy. The remainder of the skin closure is routine. Complications of antepubic urethrostomy include cystitis, incontinence, and urine scalding. The cystitis is managed by antibiotic therapy after culture and sensitivity are done. Incontinence will not be a problem if sufficient length of urethra remains. If the rupture is near the neck of the bladder, the cat may be incontinent. Urine scalding may occur in the short-term after surgery. The cat will learn to urinate in a squat, spreadleg position, and this should not be a long-term problem. Cystitis Cystitis is a component of the feline urolithiasis syndrome. It is mentioned because it will occur after perineal urethrostomy, though it is not a true complication. It is emphasized that perineal urethrostomy is a treatment for urethral obstruction, not the feline urolithiasis syndrome, and that cystitis-urethritis-urolithiasis will occur with the same frequency postsurgically as it occurred presurgically. In one study, there was a 39% recurrence of signs of the feline urolithiasis syndrome within 18 months. 1 Cystitis is not serious and may be managed in the same manner as cystitis due to the feline urolithiasis syndrome in the female cat. Treatment for cystitis includes antibiotics, antispasmodics, urinary acidifiers, diet modification, and increased water consumption. Urine from cats with the feline urolithiasis syndrome is usually sterile for bacteria, 2 • 14 and antibiotics are of no benefit. 1 Similarly, parenteral fluids or antispasmodics are of no benefit. 1 It appears as if the clinical signs of uncomplicated cystitis due to the feline urolithiasis syndrome will resolve with or without .the benefit of therapy. Treatment of cystitis is, therefore, best approached from a preventive standpoint. The etiology of the feline urolithiasis syndrome remains obscure, though it is most likely multifactorial. 13 Diet is probably a major factor. Experimentally, cats on diets that are high in magnesium content, with or without elevated phosphate, developed urolithiasis. 11 Commercial cat foods, in general, contain less magnesium than does the experimental calculogenic diet. 5 Therefore, the prophylactic significance of various cat foods remains
100
jOE HAUPTMAN
obscure. Regardless of cat food and mineral content, I recommend increasing water consumption by feeding a canned cat food and/or salting the food . Wound Dehiscence and Infection Minor wound dehiscence that results in scar formation may occur as discussed in the section on stricture formation. Major wound dehiscence is most frequently associated with urethral laceration, which leads to leakage of urine, devitalization of tissues, and infection. The dehisced wound is managed as an open wound. It is debrided if necessary, flushed with isotonic fluids, and allowed to heal by second intention. A Foley catheter is placed to prevent further urine contamination of the wound. If a stricture occurs, it is managed as previously discussed. If subcutaneous urine is present before surgery, due to urethral laceration at the time of unblocking, then the tissues may not be sufficiently healthy to allow healing and wound dehiscence may be expected. Surgical judgment of tissue viability will dictate if surgery should be immediately performed or delayed. If delayed, a cystostomy (with placement of a Foley catheter) may be performed to allow bypass of the urethra and catheter drainage of urine anterior to the pubis. When perineal tissues become more healthy, perineal urethrostomy and routine closure of the midline abdomen and bladder can be performed. Infection unassociated with leakage of urine is most likely associated with fecal contamination or faulty technique. Contamination should be minimized by placement of a pursestring suture, proper prepping and draping, and good surgical technique. Unless gross contamination is present, antibiotics should be used prophylactically only during surgery at the discretion of the surgeon. 15 Mortality Mortality may be due to anesthesia or to metabolic derangements secondary to urethral obstruction. Anesthesia for urethral obstruction is discussed elsewhere in this symposium. Metabolic derangements include altered fluid , electrolyte, and acid-base balance, and uremia due to kidney failure . Renal function should always be assessed by BUN and/or creatinine, as well as urinalysis. Postrenal uremia will frequently be present in urethral obstruction. The BUN should return to a normal range after appropriate fluid therapy. If it does not and if urine specific gravity is isosthenuric (1.008 to 1.012), then primary renal disease may be present. This should be taken into account in the overall prognosis. Fluid, electrolyte, and acid-base balance should be restored prior to surgery. In most cases, this is accomplished by urethral catheterization and intravenous lactated Ringer's solution. In the more severe case, intravenous 5 per cent dextrose should be given to combat hyperkalemia, followed by lactated Ringer's solution. Fluid therapy should be more intense, serum electrolytes and urine output should be monitored, and electrolytes supplemented as necessary. In a small percentage of cases, a urethral catheter cannot be passed. Surgery can then be performed on an emergency basis. If the cat' s condition precludes against emergency surgery, then cystocentesis with a 23-gauge
101
PERINEAL URETHROSTOMY
needle may be performed followed by an attempt to recatheterization. Alternately, a cystostomy, with catheter drainage cranial to the pubis, may be performed. Complications Due to Excessive Dissection Dissection in perineal urethrostomy should remain reasonably close to the penis and these complications should rarely occur. If dissection is continued cranially to the neck and lateral ligaments of the bladder, nerve damage may occur and urinary incontinence may result. Urinary continence may return within several weeks. If dissection is excessive dorsally and laterally, damage to external anal sphincter nerve supply (caudal rectal nerve, internal pudendal nerve) and/ or perineal musculature may occur. Fecal incontinence and/or perineal hernia may result. Fecal incontinence can be treated only by providing a fascial sling, but results are inconsistent. 10 The management of perineal hernia would be similar to that of perineal hernia in old, intact male dogs.4· 6, 7 Rotation of the Penis Care should be taken when dissecting and freeing up the penis so that rotation on its long axis does not occur. Proper orientation of the bulbourethral glands, ischiocavernosus muscles, and retractor penis muscle should be maintained. If a twist occurs prior to suturing and is corrected, it is of no consequence. If the twist is sutured into place, dysuria will likely be seen. Surgery should be performed again, the rotation corrected, and the urethrostomy resutured. REFERENCES 1. Barsanti, J. A., et al.: Feline urologic syndrome: Further investigations into therapy. J. Am . Anim. Hosp. Assoc., 18:387, 1982. 2. Barsanti, J. A., et al.: Feline urologic syndrome: Further investigations into etiology. J. Am . Anim. Hosp. Assoc., 18:391, 1982. 3. Bovee, K. C., et al.: Recurrence offeline urethral obstruction. J. Am. Vet. Med. Assoc., 174:93, 1979. 4. Burrows, C. F. , and Harvey, C. E. : Perineal hernia in the dog. J. Small. Anim. Pract., 14:315, 1973. 5. Chow, F. C., et al.: Feline urolithiasis/cat foods: Concentration of calcium, magnesium, phosphate and chloride in various cat foods and their relationship to feline urolithiasis. Feline Pract., 5:15, 1975. 6. Dieterich, H. F.: Perineal hernia repair in the canine. VET. CLIN. NORTH AM., 5:383, 1975. 7. Harvey, C. E. : Treatment of perineal hernia in the dog-A reassessment. J. Small Anim. Pract., 18:505, 1977. 8. Johnston, D. E. : Feline urethrostomy-A critique and new method. J. Small Anim. Pract., 15:421, 1974. 9. Kusba, J. K., and Lipowitz, A. J. : Repair of strictures following perineal urethrostomy in the cat. J. Am. Anim. Hosp. Assoc., 18:308, 1982. 10. Leeds, E . B., and Reneger, W. R.: A modified fascial sling for the treatment of fecal incontinence: Surgical technique. J. Am. Anim. Hosp. Assoc., 17:663, 1981. 11. Lewis, L. D., et al.: Effect of various dietary mineral concentrations on the occurrence offeline urolithiasis. J. Am. Vet. Med. Assoc., 172:559, 1978.
102
JOE HAUPTMAN
12. Mendham, J. H . : A description and evaluation of antepubic urethrostomy in the male cat. J. Small Anim. Pract., 11 :709, 1970. 13. Reif, J. S., et al.: Feline urethral obstruction: A case-control study. J. Am. Vet. Med. Assoc., 170:1320, 1977. 14. Schechter, R. D. : The significance of bacteria in feline cystitis and urolithiasis. J. Am. Vet. Med. Assoc., 156:1561, 1970. 15. Van Scoy, R. E.: Prophylactic use of antimicrobial agents. Mayo Clin. Proc., 52:701, 1977. 16. Wilson, G. P., and Harrison, J. W. Perineal urethrostomy in cats. J. Am . Vet. Med. Assoc., 159:1789, 1971. 17. Wilson, G. P.: Perineal urethrostomy in the cat. In Bojrab, M. J. (ed.): Current Techniques in Small Animal Surgery. Philadelphia, Lea & Febiger, 1975. 18. Yoshioka, M. M., and Carb, A. : Antepubic urethrostomy in the dog. J. Am. Anim. Hosp. Assoc., 18:290, 1982. Veterinary Clinical Center College of Veterinary Medicine Michigan State University East Lansing, Michigan 48824
Perineal Urethrostomy Surgical Technique and Management . of Complications
joe Hauptman, D.V.M., M.S.*
Feline urolithiasis syndrome is a common disease in cats characterized by cystitis, urethritis, and urolithiasis. In the male cat, it may progress to urethral obstruction. Urethral obstruction due to the feline urolithiasis syndrome is most commonly seen in the castrated male cat, 1 to 4 years old, who lives indoors and eats dry cat food . 13 Urethral obstruction may result in life-threatening acid-base and electrolyte disturbances, pain, and uremia. If not treated surgically, obstruction will recur in at least 35 per cent of the cats within 6 months. 3 Perineal urethrostomy is highly recommended and frequently performed as a surgical treatment for urethral obstruction due to feline urolithiasis syndrome. While many urethrostomy techniques have been advocated through the years , only a few result in reliable, reproducibly good results. These techniques are outlined in this article and elsewhere. s. 16, 17 Because of the high rate of recurrence, the health danger, and the cost of emergency treatment of urethral obstruction, and the high success rate of perineal urethrostomy, this surgery is indicated in any young cat that obstructs. It is also indicated in any cat who has obstructed three times and/or has not been responsive to medical management. The procedure should be performed on either an elective basis or following treatment and stabilization of urethral obstruction. Renal function, acid-base, fluid and electrolyte balance should be evaluated and treated as necessary. As with any surgical procedure, complications may be encountered related to the performance of feline perineal urethrostomy, The purpose of this article is to detail the technique of perineal urethrostomy and the *Diplomate, American College of Veterinary Surgeons; Assistant Professor of Surgery, Veterinary Clinical Center, Michigan State University College of Veterinary Medicine, East Lansing, Michigan
Veterinary Clinics of North America: Small Animal Practice-Val. 14, No. 1, January 1984
93
94
jOE HAUPTMAN
complications that may occur. The reasons they occur, methods for preventing or managing them, and frequency of occurrence will be discussed.
SURGICAL TECHNIQUE The cat is anesthetized and positioned in ventral or dorsal recumbency according to the preference of the surgeon. I prefer ventral recumbency, and illustrations in this text will be with the cat in that position. The hind limbs are loosely tied down and the tail is retracted cranially over the back and secured. The table is tilted to an angle of approximately 30°. A pursestring suture is placed in the anus. If the urethra is not obstructed, the bladder is emptied of urine by manual expression or catheter. Surgical preparation of the skin is routine. The surgical area is draped in such a manner that the anus is covered. An elliptical incision is made around the scrotum and prepuce. The incision is continued through the subcutaneous tissues to the level of the spermatic cord with its enclosing vaginal tunic, and castration is performed at this time if the cat is intact. If the cat has already been castrated, the incision is continued through the subcutaneous tissues to the level of the body of the penis. Subcutaneous bleeders are ligated, if necessary. Dissection is continued cranially to the level of the ischiocavernosus muscles, which are identified on both sides. They, along with the associated crura of the penis, are isolated and clamped with a hemostat (Fig. lA). These structures are divided lateral to the hemostat and ligated medial to the hemostat, on the penile side. The penis is retracted dorsally (Fig. lB), and the ventral ligament of the penis is palpated. This ligament lies on the midline and firmly fixes the pelvic urethra to the floor of the pelvis. It is cut with fine, angled blade scissors. Care is taken not to inadvertently cut the pelvic urethra. The surgeon's finger is placed between the penis and pubis to the cranial rim of the pubis, to assure complete division of the ventral ligament of the penis. After the ventral ligament, ischiocavernosus muscles, and crura have been cut, the penis can be retracted caudally so that the bulbourethral glands lie caudal to the perineal skin (Fig. lC). Dissection is continued cranially so that the penis is freed for approximately 2 em cranial to the bulbourethral glands. Finger dissection will accomplish this goal ventrally and laterally. Dorsally, there are multiple thin muscular and fascial attachments that are best individually cut with scissors. Dissection should remain close to the penis without lacerating the penis or urethra. The retractor penis muscle is removed from the dorsal aspect of the penis to facilitate identification of the urethra. A tourniquet made from heavy suture material, or lfs-in. umbilical tape, and intravenous tubing (Figure lD) is passed around the penis cranial to the bulbourethral glands 1 to 2 em. It is closed loosely, and held with hemostats, to permit hemostasis. The urethra is then opened with fine scissors from the tip of the penis to the pelvic urethra at the cranial edge of the bulbourethral glands (Fig. IE). The pelvic urethra is differentiated from the penile urethra
95
PERINEAL URETHROSTOMY
B
A
(
c Figure 1. A, The left ischiocavernous muscle crus of the penis has been isolated with a hemostat (a). It should be divided after ligation on the penile side (b). 8, The ventral ligament of the penis has been isolated (a). It should be identified by palpation during surgery and must be cut. This ligament need not be visualized, but it lies dorsal to the ischium (b) and ventral to the penis (c). C, The bulbourethral glands are prominent in this tomcat (arrows). They lie at the junction of the penile-pelvic urethra and should be exteriorized to the level of or caudal to the skin. Illustration continued on following page
by the diameter of its lumen, its relationship cranial to the bulbourethral glands, and color. Sutures are now placed to appose skin and urethral mucosa, allow primary wound healing, and maintain hemostasis. Simple interrupted sutures are placed to include 2 mm of skin, 1 mm of urethral mucosa, and a deep bite of the corpus cavernosum urethrae. The sutures are tied to appose skin to mucosa. The mucosa alone does not hold sutures well, and the tissue of the corpus cavernosum is important as the holding layer and to maintain hemostasis. The initial sutures are placed dorsally, at the apex of the incision, on both sides 1 mm off the midline. The simple interrupted sutures are continued ventrally, spaced 3 mm, for a distance of 2 em. The tourniquet is removed when approximately half the sutures have been placed. The penis is ligated, cut distal to the ligature, and the excess penile and
96
}OE HAUPTMAN
D
Figure 1 (Continued). D, A tourniquet is placed 1 to 2 em cranial to the bulbourethral glands to effect hemostasis from the urethral cavernous tissue. E, The urethra has been incised along its dorsal aspect to the wide pelvic urethra (delineated by arrows), just cranial to the bulbourethral glands. F, Postoperative view of the urethrostomy site of a cat that had been reoperated for stricture after perineal urethrostomy. Closure is identical to that for the original perineal urethrostomy. The strictu red site on the urethra (a) can be identified on the sutured flap of urethra 1 em distal to the new urethrostomy (b).
preputial tissue is discarded. The remainder of the closure is routine (Figure lF). A Penrose drain may be placed before closure at the discretion of the surgeon, depending on the amount of dead space, amount of hemorrhage, and viability of tissue. The drain is placed between the urethra and pubis and is exited distal and lateral to the suture line. The pursestring suture in the anus is removed. An Elizabethan collar is placed on the cat to prevent licking of the urethrostomy site. If clotted blood around the urethrostomy site is excessive postoperatively, the area is hot-packed as necessary to loosen the clotted blood. The surgical wound is not otherwise tampered with until removal of sutures 10 days later. If a drain was used, it is removed when drainage ceases, usually 1 to 2 days postoperative. The choice of suture material is, in large part, a matter of surgeon preference. The material should be small gauge (4-0) and have a swagedon needle. Silk, non-absorbable synthetics, and absorbable synthetics have
97
PERINEAL URETHROSTOMY
all been used satisfactorily. If a synthetic suture that possesses "memory" and is relatively stiff is used, care should be taken so that the cut ends of the suture do not irritate the urethrostomy site. Intraoperative prophylactic antibiotics may be used at the discretion of the surgeon. 15 Fluid and electrolyte balance is maintained in the postoperative period as necessary. Kitty litter is replaced by shredded paper in the cat box until suture removal. COMPLICATIONS Stricture Stricture formation is an unfortunate complication of any procedure that attempts to solve feline urethral obstruction by creating a new stoma from the urethra to the outside. If the surgeon chooses the recommended techniques of perineal urethrostomy8 • 16• 17 and uses good surgical technique to anastomose pelvic urethra to skin, postoperative strictures should occur very infrequently. A strictured perineal urethrostomy may be due to factors that the surgeon cannot control, such as self-inflicted trauma to the surgical wound. However, if a strictire is encountered, I recommend a critical analysis of technique and postoperative care to attempt to define the cause of the stricture. Strictures will be commonly encountered in improperly performed urethrostomies. It is reemphasized that the pelvic urethra must be anastomosed to skin and that primary wound healing must occur. Techniques that do not allow this anastomosis or that utilize a prosthetic shunt should not be used as they result in a high rate of strictures, or self-mutilation, or both. If the pelvic urethra is to be anastomosed to the skin, then proper identification and mobilization of the pelvic urethra must be achieved to mobilize the pelvic urethra, it is absolutely necessary that the ventral ligament of the penis, the ischiocavernosus muscles, and the crura of the penis be divided. Division of those structures, along with all other attachments to the penis for 2 em cranial to the bulbourethral glands, will result in adequate caudal retraction of the penis . The pelvic urethra is identified cranial to the bulbourethral gland with a diameter of at least 3 to 6 mm. Direct apposition of skin and urethral mucosa must be achieved to allow primary wound healing. Care must be taken to allow their proper placement. Even with skin-to-mucosa apposition, secondary wound healing with stricture may occur. If sutures engage only urethral mucosa, and not the holding-layer cavernous tissue, then they may tear out and secondary healing will result. Infection of the urethrostomy, irritation due to cut ends of stiff suture, and trauma due to kitty litter, licking, or rubbing all may result in altered wound healing and stricture formation. Stricture formation , regardless of cause, most frequently occurs at the mucocutaneous junction. 9 All postperineal urethrostomy strictures are similarly handled surgically. An elliptical incision of 1 to 2 em is made, with the urethrostomy site at the top of the ellipse. Dissection is performed
98
}OE HAUPTMAN
cranially to free up approximately 2 em of urethra, exactly as in the described original technique. Depending on the manner in which the original urethrostomy was performed, normal structures (ischiocavernosus muscles, crura of penis, ventral ligament of the penis) or only fibrous tissue may be encountered. Frequently, the ischiocavernosus muscles will be found attached to the penis. The interpretation should not necessarily be made that the original surgery did not include division of these muscles, as they may reattach after they have been cut. The surgeon should critically determine the condition of the surrounding tissue and the site of reattachment of these muscles to determine if the structure is due to inadequate cranial dissection or other causes. Once the penis is freed up from within the pelvis (as in the original surgery), it is retracted caudally and cut along its dorsal aspect until the large lumen of the pelvic urethra is adequately opened. The lumen diameter should be at least 3 to 6 mm. The urethral mucosa is anastomosed to the skin by the same technique used in the described original perineal urethrostomy. The tourniquet described may be used in the same manner. It is noted that, regardless of original technique, there is usually sufficient urethra to allow enough caudal retraction to obtain a new urethrostomy. If there is insufficient urethra, an antepubic urethrostomy or cystostomy procedure may be necessary. (Refer to the article on "Traumatic Injuries of the Urogenital Tract" in this symposium for descriptions of these techniques.) Hemorrhage Hemorrhage may occur both during and after surgery and is an annoying complication of any urethrostomy. Intraoperative bleeding, from other than the urethra, should always be controlled by ligation as necessary. There may be subcutaneous bleeders that require ligation. The ischiocavernosus muscles and crura should always be ligated on the penile side. Profuse hemorrhage from the corpus cavernosum urethrae will frequently occur during and after surgery. Intraoperative urethral hemorrhage is very nicely controlled by use of the described tourniquet. 8 It is emphasized that excessive tourniquet pressure should be avoided, as only minimal pressure is required to control urethral hemorrhage. Postoperative urethral hemorrhage is best prevented by the precise placement of sutures as described. Postoperative hemorrhage may still occur; if it does, time and patience are effective in controlling it. Laceration and Rupture Lacerations and ruptures of the penis occur infrequently. Lacerations may occur preoperatively at the time of emergency catheterization and treatment or intraoperatively by mistake. The manner in which a laceration is managed is influenced by its extent and position. If the laceration is caudal to the bulbourethral glands, then it is not of consequence and the perineal urethrostomy may proceed routinely. If it is large and accessible, it should be sutured with interrupted sutures of synthetic absorbable suture material, and a Foley catheter (10- to 12-Fr.) placed in the bladder-urethra for 3 to 4 days. If the urethral laceration is small or inaccessible, then the
PERINEAL URETHROSTOMY
99
Foley catheter alone is placed for approximately 4 days. The Foley catheter will divert urine past the lacerated urethra, allowing epithelialization to occur. Ruptures, though rare, occur because of excessive traction on the penis while finger dissection is being performed. If the rupture occurs too far cranial to permit urethrostomy of the perineum, then the urethrostomy must be performed cranial to the pubis. 12• 18 The cat is placed in dorsal recumbency and prepped for a midline skin incision. A midline incision, through the linea alba, is made from the pubis cranially for 5 em. The bladder is identified, and the urethra is followed posteriorly till the ruptured end is found . The ruptured end is cut, so that it is smooth, and is exteriorized through the midline. The linea alba is apposed with a non-absorbable non-reactive suture material, leaving a 1cm opening for the urethra. The subcutaneous tissues are apposed as necessary. The cut edge of the urethra is apposed to the skin by the same method as with perineal urethrostomy. The remainder of the skin closure is routine. Complications of antepubic urethrostomy include cystitis, incontinence, and urine scalding. The cystitis is managed by antibiotic therapy after culture and sensitivity are done. Incontinence will not be a problem if sufficient length of urethra remains. If the rupture is near the neck of the bladder, the cat may be incontinent. Urine scalding may occur in the short-term after surgery. The cat will learn to urinate in a squat, spreadleg position, and this should not be a long-term problem. Cystitis Cystitis is a component of the feline urolithiasis syndrome. It is mentioned because it will occur after perineal urethrostomy, though it is not a true complication. It is emphasized that perineal urethrostomy is a treatment for urethral obstruction, not the feline urolithiasis syndrome, and that cystitis-urethritis-urolithiasis will occur with the same frequency postsurgically as it occurred presurgically. In one study, there was a 39% recurrence of signs of the feline urolithiasis syndrome within 18 months. 1 Cystitis is not serious and may be managed in the same manner as cystitis due to the feline urolithiasis syndrome in the female cat. Treatment for cystitis includes antibiotics, antispasmodics, urinary acidifiers, diet modification, and increased water consumption. Urine from cats with the feline urolithiasis syndrome is usually sterile for bacteria, 2 • 14 and antibiotics are of no benefit. 1 Similarly, parenteral fluids or antispasmodics are of no benefit. 1 It appears as if the clinical signs of uncomplicated cystitis due to the feline urolithiasis syndrome will resolve with or without .the benefit of therapy. Treatment of cystitis is, therefore, best approached from a preventive standpoint. The etiology of the feline urolithiasis syndrome remains obscure, though it is most likely multifactorial. 13 Diet is probably a major factor. Experimentally, cats on diets that are high in magnesium content, with or without elevated phosphate, developed urolithiasis. 11 Commercial cat foods, in general, contain less magnesium than does the experimental calculogenic diet. 5 Therefore, the prophylactic significance of various cat foods remains
100
jOE HAUPTMAN
obscure. Regardless of cat food and mineral content, I recommend increasing water consumption by feeding a canned cat food and/or salting the food . Wound Dehiscence and Infection Minor wound dehiscence that results in scar formation may occur as discussed in the section on stricture formation. Major wound dehiscence is most frequently associated with urethral laceration, which leads to leakage of urine, devitalization of tissues, and infection. The dehisced wound is managed as an open wound. It is debrided if necessary, flushed with isotonic fluids, and allowed to heal by second intention. A Foley catheter is placed to prevent further urine contamination of the wound. If a stricture occurs, it is managed as previously discussed. If subcutaneous urine is present before surgery, due to urethral laceration at the time of unblocking, then the tissues may not be sufficiently healthy to allow healing and wound dehiscence may be expected. Surgical judgment of tissue viability will dictate if surgery should be immediately performed or delayed. If delayed, a cystostomy (with placement of a Foley catheter) may be performed to allow bypass of the urethra and catheter drainage of urine anterior to the pubis. When perineal tissues become more healthy, perineal urethrostomy and routine closure of the midline abdomen and bladder can be performed. Infection unassociated with leakage of urine is most likely associated with fecal contamination or faulty technique. Contamination should be minimized by placement of a pursestring suture, proper prepping and draping, and good surgical technique. Unless gross contamination is present, antibiotics should be used prophylactically only during surgery at the discretion of the surgeon. 15 Mortality Mortality may be due to anesthesia or to metabolic derangements secondary to urethral obstruction. Anesthesia for urethral obstruction is discussed elsewhere in this symposium. Metabolic derangements include altered fluid , electrolyte, and acid-base balance, and uremia due to kidney failure . Renal function should always be assessed by BUN and/or creatinine, as well as urinalysis. Postrenal uremia will frequently be present in urethral obstruction. The BUN should return to a normal range after appropriate fluid therapy. If it does not and if urine specific gravity is isosthenuric (1.008 to 1.012), then primary renal disease may be present. This should be taken into account in the overall prognosis. Fluid, electrolyte, and acid-base balance should be restored prior to surgery. In most cases, this is accomplished by urethral catheterization and intravenous lactated Ringer's solution. In the more severe case, intravenous 5 per cent dextrose should be given to combat hyperkalemia, followed by lactated Ringer's solution. Fluid therapy should be more intense, serum electrolytes and urine output should be monitored, and electrolytes supplemented as necessary. In a small percentage of cases, a urethral catheter cannot be passed. Surgery can then be performed on an emergency basis. If the cat' s condition precludes against emergency surgery, then cystocentesis with a 23-gauge
101
PERINEAL URETHROSTOMY
needle may be performed followed by an attempt to recatheterization. Alternately, a cystostomy, with catheter drainage cranial to the pubis, may be performed. Complications Due to Excessive Dissection Dissection in perineal urethrostomy should remain reasonably close to the penis and these complications should rarely occur. If dissection is continued cranially to the neck and lateral ligaments of the bladder, nerve damage may occur and urinary incontinence may result. Urinary continence may return within several weeks. If dissection is excessive dorsally and laterally, damage to external anal sphincter nerve supply (caudal rectal nerve, internal pudendal nerve) and/ or perineal musculature may occur. Fecal incontinence and/or perineal hernia may result. Fecal incontinence can be treated only by providing a fascial sling, but results are inconsistent. 10 The management of perineal hernia would be similar to that of perineal hernia in old, intact male dogs.4· 6, 7 Rotation of the Penis Care should be taken when dissecting and freeing up the penis so that rotation on its long axis does not occur. Proper orientation of the bulbourethral glands, ischiocavernosus muscles, and retractor penis muscle should be maintained. If a twist occurs prior to suturing and is corrected, it is of no consequence. If the twist is sutured into place, dysuria will likely be seen. Surgery should be performed again, the rotation corrected, and the urethrostomy resutured. REFERENCES 1. Barsanti, J. A., et al.: Feline urologic syndrome: Further investigations into therapy. J. Am . Anim. Hosp. Assoc., 18:387, 1982. 2. Barsanti, J. A., et al.: Feline urologic syndrome: Further investigations into etiology. J. Am . Anim. Hosp. Assoc., 18:391, 1982. 3. Bovee, K. C., et al.: Recurrence offeline urethral obstruction. J. Am. Vet. Med. Assoc., 174:93, 1979. 4. Burrows, C. F. , and Harvey, C. E. : Perineal hernia in the dog. J. Small. Anim. Pract., 14:315, 1973. 5. Chow, F. C., et al.: Feline urolithiasis/cat foods: Concentration of calcium, magnesium, phosphate and chloride in various cat foods and their relationship to feline urolithiasis. Feline Pract., 5:15, 1975. 6. Dieterich, H. F.: Perineal hernia repair in the canine. VET. CLIN. NORTH AM., 5:383, 1975. 7. Harvey, C. E. : Treatment of perineal hernia in the dog-A reassessment. J. Small Anim. Pract., 18:505, 1977. 8. Johnston, D. E. : Feline urethrostomy-A critique and new method. J. Small Anim. Pract., 15:421, 1974. 9. Kusba, J. K., and Lipowitz, A. J. : Repair of strictures following perineal urethrostomy in the cat. J. Am. Anim. Hosp. Assoc., 18:308, 1982. 10. Leeds, E . B., and Reneger, W. R.: A modified fascial sling for the treatment of fecal incontinence: Surgical technique. J. Am. Anim. Hosp. Assoc., 17:663, 1981. 11. Lewis, L. D., et al.: Effect of various dietary mineral concentrations on the occurrence offeline urolithiasis. J. Am. Vet. Med. Assoc., 172:559, 1978.
102
JOE HAUPTMAN
12. Mendham, J. H . : A description and evaluation of antepubic urethrostomy in the male cat. J. Small Anim. Pract., 11 :709, 1970. 13. Reif, J. S., et al.: Feline urethral obstruction: A case-control study. J. Am. Vet. Med. Assoc., 170:1320, 1977. 14. Schechter, R. D. : The significance of bacteria in feline cystitis and urolithiasis. J. Am. Vet. Med. Assoc., 156:1561, 1970. 15. Van Scoy, R. E.: Prophylactic use of antimicrobial agents. Mayo Clin. Proc., 52:701, 1977. 16. Wilson, G. P., and Harrison, J. W. Perineal urethrostomy in cats. J. Am . Vet. Med. Assoc., 159:1789, 1971. 17. Wilson, G. P.: Perineal urethrostomy in the cat. In Bojrab, M. J. (ed.): Current Techniques in Small Animal Surgery. Philadelphia, Lea & Febiger, 1975. 18. Yoshioka, M. M., and Carb, A. : Antepubic urethrostomy in the dog. J. Am. Anim. Hosp. Assoc., 18:290, 1982. Veterinary Clinical Center College of Veterinary Medicine Michigan State University East Lansing, Michigan 48824