This protocol provides a standardized method for performing cutaneous vesicostomy and postoperative wound management in rats, enabling continuous low-pressure urinary drainage for preclinical spinal cord injury research.
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Method Article
* These authors contributed equally
This protocol provides a standardized method for performing cutaneous vesicostomy and postoperative wound management in rats, enabling continuous low-pressure urinary drainage for preclinical spinal cord injury research.
The rat is the primary animal model for preclinical research on spinal cord injury (SCI)-induced neurogenic lower urinary tract dysfunction (nLUTD). Owing to its anatomical and functional similarity to humans, rats closely recapitulate key pathological consequences of SCI. However, a crucial translational gap remains: whereas standard bladder management in humans typically relies on continuous or intermittent catheterization, comparable approaches are not feasible in rodents. The common practice of manual bladder expression generates exceptionally high intravesical pressures, which may introduce methodological bias by independently promoting pathological bladder remodeling after SCI. This protocol describes cutaneous vesicostomy in rats, together with postoperative wound management, to establish continuous low-pressure urinary drainage for preclinical SCI research. Cutaneous vesicostomy—the surgical creation of a stoma between the bladder dome and the lower abdominal wall—enables continuous urinary drainage, thereby maintaining a low-resistance drainage route and bypassing the urethra. In this way, excessive urine retention and high intravesical pressures can be avoided, approximating the concept of continuous low-pressure decompression used clinically during the early post-injury phase with suprapubic or transurethral urinary diversion, while recognizing that normal storage and continence mechanisms are abolished. Therapeutic effects that might otherwise be obscured by repetitive overfilling and high-pressure manual bladder expression may thus be more readily detected. Moreover, vesicostomy offers a conceptual strategy to mitigate sex-related constraints in preclinical SCI research. The considerably greater urethral length in male rodents results in higher outflow resistance, making manual bladder expression substantially more difficult and effectively confining most preclinical studies to female animals, despite the predominance of male patients among clinical SCI cases. As an alternative drainage strategy, vesicostomy has the potential to broaden experimental bladder management paradigms and enhance the translational relevance of future studies, while its feasibility and outcomes in male rats will need to be established in dedicated follow-up work.
Healthy bladder function relies on the coordinated function of the bladder muscle and urethral sphincter, achieved through a complex neuronal network involving the brain, central nervous system (CNS), and peripheral nervous system (PNS), which enables conscious control of the lower urinary tract (LUT)1,2. The complexity of these mechanisms and their switch-like circuitry3 renders bladder function susceptible to a wide range of injuries and diseases. Accordingly, following spinal cord injury (SCI), almost all patients experience impaired bladder sensation and control4,5. The term neurogenic bladder encompasses a broad spectrum of dysfunctions affecting urine storage and/or voiding, depending on the characteristics of the injury. In particular, suprasacral injuries lead to detrusor overactivity in combination with sphincter overactivity, often accompanied by loss of coordination between the two—termed detrusor-sphincter dyssynergia (DSD)—resulting in excessive urine retention and high intravesical pressures6,7. This can severely damage the LUT, threaten the integrity of the upper urinary tract (UUT), and, if left untreated, result in life-threatening complications8. Intermittent or continuous urinary drainage via catheterization represents the current standard of bladder management in humans following SCI, preventing bladder overfilling through a safe, pressure-free procedure9,10,11,12.
With no effective treatment currently available for SCI and predominantly symptomatic management of associated neurogenic LUT dysfunction (nLUTD), the development of novel therapeutic strategies remains a major research priority. Animal models enable investigation of disease mechanisms at a level of complexity comparable to that in humans while providing exceptional intragroup homogeneity under standardized experimental conditions13. Among these, the rat is the primary preclinical model, with the majority of SCI studies conducted in this species14,15. This preference reflects its anatomical and functional similarity to humans, reproducible pathological response, and widespread availability. Nevertheless, an important translational gap remains that may limit the interpretation and clinical relevance of bladder-related findings derived from rodent models.
Although rats develop nLUTD following SCI that resembles key features observed in humans, bladder management differs substantially between species. Because intermittent catheterization and other permanent urinary drainage approaches are generally not feasible in rats, urine evacuation is routinely achieved by manual bladder expression16. This technique, analogous to the Credé maneuver17, which is generally not recommended in clinical practice, generates markedly elevated intravesical pressures. Consequently, it may introduce methodological bias by independently promoting pathological bladder remodeling after SCI, thereby reducing the translational relevance of experimental findings or obscuring genuine therapeutic effects. An additional limitation arises from sex-related anatomical differences. The considerably greater urethral length in male rodents results in higher outflow resistance, making manual bladder expression substantially more difficult and effectively restricting most preclinical SCI studies to female animals14. Given that the majority of clinical SCI cases occur in males18,19, this discrepancy further emphasizes the need for alternative bladder management strategies in preclinical rat SCI models.
Cutaneous vesicostomy involves the surgical creation of a stoma between the bladder and the lower abdominal wall by advancing the bladder dome to the skin and securing it with sutures. This enables continuous urinary drainage while maintaining a low-pressure drainage route and bypassing the urethra. Primarily used in children with complex medical conditions or when conventional drainage options are unsuitable, cutaneous vesicostomy provides reliable urinary diversion with minimal maintenance requirements and a low complication rate20,21,22. Beyond its clinical application, vesicostomy has also been successfully performed in rodent models23,24,25,26, although not in the context of SCI.
In a recent study16, we addressed the translational limitations associated with manual bladder expression in preclinical SCI models and introduced vesicostomy in rats together with a postoperative wound management regimen that enabled extended follow-up. Direct comparison of the two bladder management approaches demonstrated greater structural bladder alterations following manual bladder expression, whereas vesicostomy animals exhibited values closer to those of healthy controls across several parameters. Most notably, bladder wall thickness increased from a mean of 768.26 µm (SD 28.05) in healthy rats to 1181.94 µm (SD 289.56) two months after SCI with manual bladder expression, with some animals reaching values of up to 1485 µm. In contrast, rats managed by vesicostomy showed a mean bladder wall thickness of 963.08 µm (SD 68.82), and only one animal exceeded 1000 µm.
This study provides a standardized protocol for performing vesicostomy in rats, including perioperative care and postoperative wound management, to enable reproducible continuous low-pressure urinary drainage in preclinical SCI research. The protocol is intended to facilitate reproduction of the technique and assist investigators in determining its suitability for studies in which high-pressure manual bladder expression may introduce methodological bias or in which the inclusion of male animals is desirable. The aim of this project was to establish a standardized vesicostomy protocol for rats with SCI and to evaluate its feasibility and safety over a two-month follow-up period. In addition, a standardized postoperative wound management regimen was applied to minimize skin-related complications and maintain stomal patency through regular calibration.
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Three-month-old female Lewis rats were used for this study. Although this protocol was primarily developed to avoid manual bladder expression following SCI, details of the contusion SCI procedure are not provided here but have been described previously. All procedures were approved by the Austrian Governmental Legal Entity on Animal Research (BMWFW-2022-0.062.928 and BMWFW-2023-0.848.340) and were conducted in accordance with local guidelines for animal use and the ARRIVE guidelines. Overall, the vesicostomy procedure requires approximately 15 min.
1. Preoperative Preparation
2. Animal Preparation
| Body weight (g) | Medetomidine (1 mg/mL), mL | Midazolam (5 mg/mL), mL | Fentanyl (0.05 mg/mL), mL | Total volume (mL) |
| 100 | 0.015 | 0.04 | 0.010 | 0.065 |
| 125 | 0.019 | 0.05 | 0.013 | 0.082 |
| 150 | 0.023 | 0.06 | 0.015 | 0.098 |
| 175 | 0.026 | 0.07 | 0.018 | 0.114 |
| 200 | 0.030 | 0.08 | 0.020 | 0.130 |
| 225 | 0.034 | 0.09 | 0.023 | 0.147 |
| 250 | 0.037 | 0.10 | 0.025 | 0.163 |
| 275 | 0.041 | 0.11 | 0.028 | 0.179 |
| 300 | 0.045 | 0.12 | 0.030 | 0.195 |
| 325 | 0.049 | 0.13 | 0.033 | 0.212 |
| 350 | 0.052 | 0.14 | 0.035 | 0.227 |
| 375 | 0.056 | 0.15 | 0.038 | 0.244 |
| 400 | 0.060 | 0.16 | 0.040 | 0.260 |
| 425 | 0.063 | 0.17 | 0.043 | 0.276 |
| 450 | 0.067 | 0.18 | 0.045 | 0.292 |
| 475 | 0.071 | 0.19 | 0.048 | 0.309 |
| 500 | 0.074 | 0.20 | 0.051 | 0.325 |
| 525 | 0.078 | 0.21 | 0.053 | 0.341 |
| 550 | 0.082 | 0.22 | 0.055 | 0.357 |
| 575 | 0.086 | 0.23 | 0.058 | 0.374 |
| 600 | 0.089 | 0.24 | 0.060 | 0.389 |
Table 1: Intramuscular anesthesia dosing for rats. Volumes of medetomidine (1 mg/mL), midazolam (5 mg/mL), and fentanyl (0.05 mg/mL) required to prepare the intramuscular anesthetic mixture for rats weighing 100–600 g. The total injection volume represents the sum of the individual drug volumes.
3. Bladder Preparation
4. Transurethral Catheter Placement
5. Bladder Positioning
6. Bladder Vesicostomy
7. Calibration and Wound Dressing

Figure 1. Representative appearance of the vesicostomy immediately after surgery and following healing. Representative images of the vesicostomy site immediately after surgery and wound dressing at day post-injury (DPI) 0 (left) and after healing at DPI 53, shortly before completion of the 56-day (2-month) follow-up period (right). The inset shows a higher-magnification view of the vesicostomy immediately after surgery. Scale bars = 1 cm (overview images) and 2 mm (inset). Please click here to view a larger version of this figure.
8. Antagonism
| Body weight (g) | Atipamezole (5 mg/mL), mL | Flumazenil (0.1 mg/mL), mL | Total volume (mL) |
| 100 | 0.015 | 0.20 | 0.215 |
| 125 | 0.019 | 0.25 | 0.269 |
| 150 | 0.023 | 0.30 | 0.323 |
| 175 | 0.026 | 0.35 | 0.376 |
| 200 | 0.030 | 0.40 | 0.430 |
| 225 | 0.034 | 0.45 | 0.484 |
| 250 | 0.037 | 0.50 | 0.537 |
| 275 | 0.041 | 0.55 | 0.591 |
| 300 | 0.045 | 0.60 | 0.645 |
| 325 | 0.049 | 0.65 | 0.699 |
| 350 | 0.052 | 0.70 | 0.752 |
| 375 | 0.056 | 0.75 | 0.806 |
| 400 | 0.060 | 0.80 | 0.860 |
| 425 | 0.063 | 0.85 | 0.913 |
| 450 | 0.067 | 0.90 | 0.967 |
| 475 | 0.071 | 0.95 | 1.021 |
| 500 | 0.074 | 1.00 | 1.074 |
| 525 | 0.078 | 1.05 | 1.128 |
| 550 | 0.082 | 1.10 | 1.182 |
| 575 | 0.086 | 1.15 | 1.236 |
| 600 | 0.089 | 1.20 | 1.289 |
Table 2: Subcutaneous anesthetic antagonism dosing for rats. Volumes of atipamezole (5 mg/mL) and flumazenil (0.1 mg/mL) required to prepare the subcutaneous anesthetic antagonist mixture for rats weighing 100–600 g. The total injection volume represents the sum of the individual drug volumes.
9. Waste Disposal
10. Postoperative Management

Figure 2. Postoperative wound healing and vesicostomy calibration during follow-up. (A) Wound score of the vesicostomy site during the 7-week follow-up period. (B) Representative images of wound scores 1–4, illustrating the progression from normal wound appearance to ulcer formation. Animals with open skin lesions were excluded according to the predefined study criteria. Scale bars = 5 mm. (C) Vesicostomy calibration size measured in Charrière during the follow-up period. Data in panels A and C are presented as mean ± standard deviation (SD). Please click here to view a larger version of this figure.
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A total of 18 rats underwent vesicostomy. To establish the technique, the procedure was first performed in six animals without SCI to verify its basic safety and feasibility and to evaluate postoperative management in healthy animals. Subsequently, vesicostomy was performed in combination with a thoracic contusion SCI at the T8/T9 vertebral level in 12 animals. Of these, six animals were used to further refine the postoperative wound management protocol for SCI animals. The resulting regimen was then applied to a second ...
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This protocol provides the first detailed description of vesicostomy in rodents as a method for continuous, low-pressure urinary drainage following SCI. Beyond describing the operative technique, we provide a comprehensive postoperative wound management protocol, which proved critical for achieving prolonged and successful follow-up. Because the rat is a small animal model and the objective is to create a minimal bladder opening to limit confounding influences and promote wound healing, magnifying glasses (2.5–3.5&...
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The authors declare no conflicts of interest.
The authors thank wound care specialist Gerlinde Wiesinger for her invaluable contribution to the optimization of the wound management protocol.
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| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| 0.9% sodium chloride | Fresenius Kabi, Graz, Austria | — | Sterile saline |
| 20G hypodermic needle | Servoprax, Wesel, Germany | REF L1 0201 | Used for stainless-steel wire placement |
| 24G peripheral venous catheter | B. Braun, Sempach, Switzerland | REF 4254074B | Used as a transurethral catheter (without stylet) |
| 27G hypodermic needle | B. Braun, Melsungen, Germany | REF 4657705 | Used for injections |
| 6-0 coated Vicryl suture | Ethicon, Puerto Rico, USA | REF V134H | Used for bladder fixation |
| Actimaris Wound Irrigation Solution forte | ActiMaris, Appenzell, Switzerland | REF 30350 | 0.2% sodium hypochlorite solution |
| Actimaris Wound Irrigation Solution sensitive | ActiMaris, Appenzell, Switzerland | REF 30300 | 0.04% sodium hypochlorite solution |
| Atipamezole (Antisedan 5 mg/mL) | Orion Pharma, Espoo, Finland | No catalog number available | Anesthetic antagonist |
| Bladder calibration sticks (6–11 Charrière) | No manufacturer available | No catalog number available | Used for vesicostomy calibration |
| Carbon steel scalpel blade No. 11 | Aesculap, Tuttlingen, Germany | REF BB511 | Scalpel blade |
| Dexpanthenol ophthalmic ointment (2%) | Fresenius Kabi, Graz, Austria | REF RA4302436 | Eye ointment |
| Enrofloxacin (Baytril 25 mg/mL) | Elanco, Monheim, Germany | No catalog number available | Antibiotic |
| Female Lewis rats (12 weeks old) | Charles River Laboratories, Sulzfeld, Germany | — | Experimental animals |
| Fentanyl (50 µg/mL) | hameln pharma, Hameln, Germany | No catalog number available | Anesthetic |
| Flumazenil (0.1 mg/mL) | Fresenius Kabi, Graz, Austria | No catalog number available | Anesthetic antagonist |
| Heating pad | Lenric, Littlehampton, UK | No catalog number available | Used to maintain body temperature |
| Hooked (Adson) forceps | Fine Science Tools, Heidelberg, Germany | 11019-12 | Tissue handling |
| Hooked micro forceps | Medicon, Tuttlingen, Germany | 13.71.62 | Microsurgical forceps |
| Long-acting meloxicam (Metacam 5 mg/mL) | Boehringer Ingelheim, Ingelheim am Rhein, Germany | No catalog number available | Analgesic |
| Lubricating gel (Cathejell C) | Montavit, Absam, Austria | No catalog number available | Used for transurethral catheterization and vesicostomy calibration |
| Medetomidine (Sedator 1 mg/mL) | Dechra, Aulendorf, Germany | No catalog number available | Anesthetic |
| Microscope or surgical magnification glasses (2.5–3.5×) | Evident Europe GmbH, Vienna, Austria | Olympus SZ61 | Used during microsurgery |
| Micro scissors (Bonn scissors) | Fine Science Tools, Heidelberg, Germany | 14084-08 | Microsurgical scissors |
| Mosquito hemostat | Fine Science Tools, Heidelberg, Germany | 13009-12 | Used to secure stay sutures |
| Oil-based moisturizing protective film | Panin, Rovigo, Italy | No catalog number available | Postoperative skin protection |
| Povidone-iodine solution (7.5%) | B. Braun, Melsungen, Germany | No catalog number available | Skin antiseptic |
| Scalpel handle No. 3 | Fine Science Tools, Heidelberg, Germany | 10003-12 | Compatible with No. 11 scalpel blade |
| Small serrated forceps | Fine Science Tools, Heidelberg, Germany | 11050-10 | Used for periurethral skin manipulation |
| Stainless-steel wire | Vömel, Kronberg, Germany | No catalog number available | Used for protective wire sutures |
| Syringe, 1 mL | Becton Dickinson, Vienna, Austria | REF 303172 | Used for anesthetic and antagonist administration |
| Topical skin adhesive | Ethicon, Puerto Rico, USA | REF AHVM12 | Skin adhesive |
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