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Comparing suture materials for perineal urethrostomy

  • February 8, 2019 12:35 PM EST

    Perineal urethrostomy (PU) is a useful and frequently successful salvage surgery for male cats that have experienced repeat distal urethral obstruction secondary to lower urinary tract disease, urolithiasis, or following trauma. Crucial to the success of this procedure is meticulous, accurate apposition of the skin to the urethral mucosa, and this has been traditionally accomplished employing simple interrupted sutures of nonabsorbable suture material such as nylon or polypropylene, both of which have low tissue reactivity. However, removal of sutures in this anatomic area after healing has taken place, usually about 2 weeks postoperatively, is uncomfortable for the patient, and often requires heavy sedation or general anesthesia. Use of absorbable suture material, as long as it maintains sufficient tensile strength for the time required to heal the skin-mucosal closure, would obviate the need to remove sutures at the surgical site.

    Poliglecaprone 25 is a synthetic monofilament absorbable suture impregnated with a broad spectrum antimicrobial (not antibiotic) substance. It is considered rapidly absorbable, being degraded by hydrolysis, in that it loses 2/3 of its tensile strength in vitro within 14 days, and is completely absorbed within 4 months. In this retrospective case series, the medical records of 61 cats who underwent PU surgery at a specialty practice between 2007 and 2012  in which poliglecaprone 25 was utilized to appose skin to the urethral mucosa, were reviewed. The authors hypothesized that short- and long-term complication rates following PU closure with poliglecaprone 25 would be comparable to those in which PU closure was performed using nonabsorbable or slowly absorbable (e.g., polydioxanone) suture. Short-term complications were defined as those occurring within the first two months following surgery, while long-term complications were those occurring > 2 months postoperatively.

    Board-certified surgeons performed all of the procedures. All of the 61 study cats had at least one follow-up evaluation a minimum of 10 days after surgery. The 61 patients represented a variety of breeds; most were domestic shorthairs (45/61). Median age was 5.4 years, and median body weight was 5.6 kg. All study cats had undergone PU due to urethral obstruction, secondary to idiopathic lower urinary tract disease in the majority of cases (34/61; 56%).  Urethral calculi (21/61; 34%) and urinary tract infection based on bacterial culture (10/61; 16%) were other presenting problems; four of the cats had both urethral calculi and bacterial urinary tract infection.  

    All patients had an Elizabethan collar in place during recovery. Three-quarters of the patients (46/61) had an indwelling urinary catheter placed after surgery, which remained in place for 0-4 days postoperatively. The range of hospitalization time for the patients following surgery was 1-6 days (mean, 2.6 days). Although the use of an indwelling urethral catheter following PU is controversial and considered in some studies to be conducive to formation of urethral stricture and promotion of ascending bacterial infection, in this study use of an indwelling urinary catheter after surgery was not significantly associated with development of postoperative complications.

    Minor short-term complications, considered minor because they resolved with medical management only, developed in 11/61 (18%) of the patients, including incisional dehiscence due to self-trauma in two of the cats. Both cats experiencing incisional dehiscence had owner-reported self-trauma after removal of the Elizabethan collar. In both of these cases, rapid degradation of the suture material could not be ruled out, even though self-trauma involves significant mechanical stress and tissue irritation. The only major (requiring surgical revision) short-term complication developed in one cat who had a stricture at the PU site resulting in reobstruction, and this cat was noted to have a large (1 cm diameter) mucosal defect at the time of surgery. Thirty-eight of the cats had long-term follow-up information available. Of these, 16 (42%) developed minor complications requiring medical management; in 15/16 cases the complications involved recurrent signs of lower urinary tract disease. 

    Overall, the short- and long-term postoperative complication rates in the study cats whose skin and urethral mucosa were apposed with poliglecaprone 25 were comparable to those in which nonabsorbable or slowly absorbable monofilament sutures were used. A prospective study in which several types of suture materials (poliglecaprone 25, polydioxanone, and nylon) and patterns (continuous versus interrupted) could be compared with respect to surgical outcomes for PU patients is recommended by the authors.