Cystotomy is one of the most common procedures in veterinary surgery.1,2 Because of the role of the urinary bladder as a urine reservoir, cystotomy closure must ensure a hydrostatic seal that prevents leakage and exceeds physiologic forces.3,4 The ultimate goals are realignment of tissue planes and maintenance of lumen diameter while avoiding mucosal penetration and resultant functional impairment.1,3,5 Failure of cystotomy closure results in uroperitoneum and peritonitis with resultant adhesions, fibrosis, discomfort, prolonged hospitalization, and, potentially, death.4
Healing of the bladder is similar to that of other viscera, with initial strength attributed to suture. Because all layers contribute to the initial gain in wound strength and healing, proper realignment of tissue planes would be ideal.3,6,7 Compared with healing of the intestines, the bladder has a more rapid healing rate and tensile strength gain with a similar rate of collagen synthesis and no increase in synthesis of noncollagenous protein or smooth muscle regeneration.1,3,6 Postoperative wound strength approximates preoperative values at the end of the fibroblastic stage (14 days).1,3,6 Healthy epithelium rapidly bridges the wound, forming the initial water-tight seal; providing early, rapid strength gain; and quickly embedding suture with minimal reaction.3,7
Suture material used in cystotomy closure should provide adequate strength during the lag phase of wound healing, followed by rapid absorption to avoid lithogenesis in the event of mucosal penetration. Although any suture may be lithogenic, multiple-filament braided or rough-surfaced nonabsorbable sutures are associated with a greater degree of inflammation and complications.4,6,8 With nonabsorbable suture, lumen exposure is acceptable when epithelialization precedes lithogenesis.7 Monofilament absorbable suture appears to be ideal because it induces minimal inflammation and is associated with reduced lithogenesis; however, not all are absorbed rapidly.2,6 The monofilament absorbable, poliglecaprone 25, is acceptable for closure of laparotomy, hysterotomy, gastrotomy, enterotomy, and capsulotomy incisions.9 Poliglecaprone 25 possesses excellent early tensile strength with complete early absorption and minimal reaction, which make it a logical choice for cystotomy closure.2,9 Although it has been used experimentally for cystotomy closure, scant information is available regarding its clinical use.2,9
Inverting patterns are believed to offer leak-proof serosal seals, adequate strength gain, and superior healing, compared with other methods, with these properties further enhanced by the placement of a second inverting layer.2,3 Consequently, textbooks routinely recommend single- or double-layer Cushing patterns for cystotomy closure. However, inverting patterns are technically challenging in thickened bladders and contradict basic goals of realignment of tissue planes and maintenance of lumen diameter for optimal healing of visceral wounds. Appositional patterns are technically simpler in thickened bladders and, in theory, preserve lumen diameter. Studies3,4 on intestinal anastomosis and cystotomy closure in dogs reveal that bursting pressures for appositional methods equal or exceed bursting pressures for inverting techniques early in wound healing.
Studies3,5 on cystotomy closure have used naïve bladders, which do not mimic the in vivo clinical situation with cystitis or cystolithiasis because of the lack of inflammation and secondary bladder thickening. Rats are acceptable for use in evaluating experimentally induced cystitis because of their alkaline urine and propensity for lithogenesis when there is a foreign body.5 Various methods have been described, with reduction of vesicular volume by as much as one fifth.10 In rats, the aromatic hydrocarbon, xylene, induces a reproducible complex inflammatory response through stimulation of sensory nerves and direct damage to tissues.11,12
The purpose of the study reported here was to biomechanically and histologically compare single-layer continuous Cushing (inverting) and simple continuous appositional (appositional) cystotomy closure in rats with xylene-induced cystitis. We hypothesized that the appositional method would be more rapid, cause a lower magnitude of overall inflammation, have similar leakage and failure pressures, and result in greater vesicular volumes, compared with results for the inverting method. Furthermore, we hypothesized that poliglecaprone 25 would prove acceptable for cystotomy closure in rats with experimentally induced inflammation of the urinary bladder.
Monocryl, Ethicon Inc, Somerville, NJ.
IsoFlo, Abbott Laboratories, North Chicago, Ill.
Angiocath, Becton Dickinson Infusion Therapy Systems Inc, Sandy, Utah.
Monoject, Sherwood Medical Co, St Louis, Mo.
Histologic grade xylene, Fisher Scientific International Inc, Hampton, NH.
Fisherbrand 25-mm nylon, 0.2-μm sterile syringe filter, Fisher Scientific International Inc, Hampton, NH.
0.9% Sodium Chloride Irrigation, USP, Baxter Healthcare Corp, Deerfield, Ill.
Jeweller's forceps, ASSI Corp, Westbury, NY.
Bard-Parker Rib-Back carbon steel No. 11 surgical blade, Becton, Dickinson & Co, Franklin Lakes, NJ.
PDS II, Ethicon Inc, Somerville, NJ.
46-mm, 20-gauge, 0.7-mm side-port McIntyre Straight Lacrimal Cannula, Bausch & Lomb Inc, Rochester, NY.
Hemoclip, Weck Closure Systems, Research Triangle Park, NC.
Triadine, Triad Disposables Inc, Brookfield, Wis.
Model PX603, Omega Engineering Inc, Stamford, Conn.
IOX V8.0, EMKA Technologies, Falls Church, Va.
Euthasol, Delmarva Laboratories Inc, Midlothian, Va.
Formalin, neutral buffered, 10% (phosphate buffer/certified), Fisher Scientific International Inc, Hampton, NH.
Elastin stain kit, Richard-Allan Scientific, Kalamazoo, Mich.
SigmaStat, version 3.0, Systat Software Inc, Richmond, Calif.
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