Materials and Methods

Medical records of all client-owned cats and dogs undergoing cystotomy at the University of Florida Veterinary Medical Center from 1993 to 2010 were reviewed to determine short-term complication rates. Study inclusion criteria required that the animal have a complete medical record that included signalment; medical history; physical examination findings; daily medical documentations that followed the subjective, objective, assessment, and plan (ie, SOAP) format; clinical laboratory analyses; surgical report; and hospital discharge summary. Of the 437 medical records reviewed for inclusion in this study, 144 met these inclusion criteria. During this period, the hospital changed from paper medical records to computerized medical records. Three different computerized medical record systems were used sequentially, which resulted in many incomplete medical records. Data retrieved from the medical records included signalment, reason for cystotomy, method of cystotomy closure, complications that developed during hospitalization, and length of hospitalization.

Surgical technique—All cystotomies were performed by faculty surgeons who acted as a primary surgeon or in supervision of a small animal surgical resident or a rotating intern. Animals were assigned to 1 of 2 groups on the basis of cystotomy closure technique: appositional single-layer closure technique (group A) or inverting double-layer closure technique (group I).

Complications—Complications that developed during hospitalization were categorized as major and minor. Minor complications included abnormalities that were managed nonsurgically, such as hematuria, dysuria, and seroma formation. Major complications were considered to be complications necessitating a second surgery, such as dehiscence of the bladder wall and uroabdomen.

Statistical analysis—Complication rates and postoperative duration of hospitalization were analyzed and compared between groups with a Fisher exact test. Duration of hospitalization was categorized as short (1 to 3 days) or long (> 3 days) for comparison. Values of P < 0.05 were considered significant.

Results

Of the 144 animals included in the study, 120 were dogs and 24 were cats. There were 44 spayed females, 68 castrated males, 20 sexually intact males, and 12 sexually intact females. The mean age of the animals was 5.3 years, and the median age was 7.5 years (range, 4 months to 16 years). Several cat breeds were represented including domestic shorthair (n = 11), domestic medium hair to longhair (4), Persian (2), Ragdoll (2), and Russian Blue, Siamese, Bengal, Bombay, and Somali (1 each). Many dog breeds were represented, with the most common being mixed breed (n = 12), Dalmatian (10), and Bischon Frise (10).

The most common indication for cystotomy was urolith removal (116/144 [81%]). Other reasons included surgery to correct ectopic ureter (n = 10), bladder mass removal or biopsy (13), bladder rupture (2), urinary bladder diverticulum (2), and ureterolith (1).

An appositional single-layer pattern was used for cystotomy closure in 79 of 144 (55%; group A) animals. A simple continuous suture pattern was used for cystotomy closure in 65 of 79 (82%) animals (25 with polydioxanone,^a 39 with poliglecaprone 25,^b and 1 with polyglyconate^c). A simple interrupted pattern was used for cystotomy closure in 13 of 79 (16%) animals (3 with poliglecaprone 25 and 10 with polydioxanone).

A double-layer suture pattern with at least one of the layers being an inverting pattern was used for cystotomy closure in 65 of 144 (45%; group I) animals. In this group, the bladder mucosa and submucosa were closed with 1 suture line and the seromuscular layer was closed with a second suture line. Suture patterns for the mucosa and submucosa included simple continuous (n = 49), Lembert (1), Cushing (12), and simple interrupted (3). The mucosa and submucosa were closed with the following: polydioxanone (n = 58),^a poliglecaprone 25 (5),^b polyglactin 910^d (1), and polyglyconate^c (1). Suture patterns for the seromuscular layer included Cushing (n = 32), Lembert (21), simple continuous (8), and simple interrupted (4). The seromuscular layer and the mucosal layer were closed with the same type and size of suture material in all animals except one. In the 1 exception, the seromuscular layer was closed with 3-0 polydioxanone, whereas the mucosa was closed with 3-0 poliglecaprone 25.^b

Sixty-six of 144 (45.8%) animals had complications during hospitalization: 64 of 66 (97%) complications were minor, and 2 of 66 (3%) complications were major. Affected animals had the following minor complications: hematuria (n = 39), urinary incontinence (9), stranguria (8), and incisional complications (3; bruising, swelling, or seroma). One animal required a reoperation unrelated to cystotomy closure. In this animal, uroliths were detected on postoperative radiographic images and the cystotomy site was reopened for urolith removal.

Two animals had a major complication that necessitated reoperation. One animal in each group (group A, 1/79 [1.3%]; group I, 1/66 [1.5%]) had urine leakage, resulting in an overall incidence of uroabdomen of 1.4% (2/144).

Leakage of urine following cystotomy occurred in a group A male cat following incomplete removal of cystic struvite uroliths and resultant penile obstruction. Leakage of urine that occurred following cystotomy in a group I male dog was secondary to bladder wall necrosis following substantial urethral obstruction. In both of these animals with major complications, the patients recovered uneventfully following revision surgery addressing obstruction and cystotomy closure. Group A and group I animals did not differ significantly (P = 0.99) with regard to major complications.

Minor complications were reported for 30 of 79 (38%) group A animals and 34 of 65 (52%) group I animals. Hematuria was the most common complication in both groups: 16 of 30 (53%) group A animals and 23 of 34 (68%) group I animals. Group A and group I animals did not differ significantly (P = 0.09) with regard to minor complications.

The mean length of hospitalization was 4.1 days and ranged from 1 to 19 days. The length of hospitalization was 1 to 3 days in 100 animals, 4 to 5 days in 26 animals, and 6 or more days in 18 animals. Of group A animals, 76% (60/79) were hospitalized for 1 to 3 days and 24% (19/79) were hospitalized > 3 days. Of group I animals, 62% (40/65) were hospitalized for 1 to 3 days and 38% (25/65) were hospitalized > 3 days. Group A and group I animals did not differ significantly (P = 0.06) with regard to short (1 to 3 days) or long (> 3 days) duration of hospitalization.

Discussion

Findings of the present study suggest that an appositional single-layer suture technique for cystotomy closure is appropriate for clinical use in dogs and cats. Animals in group A did not have a significantly different short-term complication rate or duration of hospitalization, compared with that of animals in group I. Given this, loss of luminal diameter of the bladder or malalignment of tissue planes following an inverting double-layer closure technique may not play a substantial role in the development of short-term cystotomy complications. Alternatively, the present study lacked the number of cases needed to demonstrate a significant difference between groups. Duration of hospitalization may be a reflection of complication rate, which was not different between the 2 groups. Because the complications reported in group A and group I were not significantly different between groups and serious complications were rare, we suggest that a single-layer approximating pattern is a safe alternative to traditional inverting double-layer closure.

An appositional single-layer suture pattern may have some benefits over an inverting double-layer suture pattern. The double-layer inverting pattern requires 2 suture layers and presumably prolongs surgery time. Although the time to complete the cystotomy closure was not available for inclusion in the present study, a single-layer pattern should take less time to perform than a double-layer pattern. Many of the group I animals underwent a simple continuous closure of the mucosa and submucosa. The major difference between these animals and the group A animals was a second inverting layer in the seromuscular layer. Presumably, the second inverting layer adds time to the procedure but does not decrease the complication rate. Another potential advantage of a single-layer closure is that less suture material will be used in the single-layer versus a double-layer closure, resulting in a diminished foreign body reaction. This might be of importance in animals with bacterial cystitis. Furthermore, penetration of the lumen and suture placement within the lumen during cystotomy closure are concerns.¹⁴ The risk of luminal penetration might be reduced with a single-layer closure, thereby lowering the incidence of postoperative calculus formation. However, these animals were not followed up for subsequent urolith formation to determine whether the 2 suture patterns differ in the rate of recurrent cystolithiasis. Future studies will need to address long-term complications such as the recurrence of bacterial cystitis or cystic calculi between appositional single-layer and inverting double-layer techniques for cystotomy closure.

The use of an appositional single-layer technique for cystotomy closure is supported experimentally in in vivo studies in dogs⁷ and rats.⁸ Initially, all tissue layers, especially the submucosa, contribute to a gain in wound strength and healing.^7,9,15 Appropriate tissue realignment of the serosa, muscularis, submucosa, and mucosa may be provided with an appositional pattern, whereas an inverting pattern will not anatomically realign those tissue planes. A previous study⁸ involving cystitis in rats revealed that both appositional and inverting suture techniques for cystotomy closure exceeded in vivo physiologic forces.

In 2 animals of the present study (1 from group A and 1 from group I), major complications were reported. The conditions under which both of the animals developed uroabdomen indicate that failure of the original surgery may play a more important role in the development of uroabdomen after surgery than bladder closure technique. Both of the animals developed uroabdomen following an episode of increased urinary bladder pressure. The group A animal leaked urine through the cystotomy site, and the group I animal had necrosis of the bladder wall. It is possible that the inverting suture pattern for cystotomy closure reduced the bladder lumen, leading to increased pressure and bladder wall necrosis.

This retrospective study had inherent limitations. Recognition of complications that developed during hospitalization such as hematuria and stranguria was dependent on the recording of these complications in the medical record. Another limitation is the variability of length in postoperative hospitalization. The duration of hospitalization is largely dependent on clinician preference. Additionally, this study did not take into account whether faculty, residents, or interns performed the procedure.

To our knowledge, the present study is the first to compare the results of appositional single-layer closure with inverting double-layer closure for cystotomy in dogs and cats. There was no significant difference between closure types in regard to short-term complication rate and length of hospitalization following cystotomy. On the basis of these results, a single-layer appositional pattern is considered a safe and effective alternative to an inverting double-layer pattern for cystotomy closure.