Standardized Ileal Bladder Augmentation For Enterocystoplasty In Rats via Midline Laparotomy

Summary

This protocol describes a standardized rat enterocystoplasty model using a pedicled, vascularized, and detubularized ileal patch with temporarily externalized urinary diversion via a cannula tube to achieve reproducible bladder augmentation.

Abstract

Bladder augmentation using intestinal segments remains a cornerstone reconstructive procedure for patients with low-capacity or poorly compliant bladders when conservative therapies fail. Despite its clinical relevance, experimental progress and in-depth study are limited by the lack of standardized, reproducible protocols that reliably model surgical principles in a controlled preclinical setting. Here, we present a step-by-step rat enterocystoplasty protocol that uses a vascularized, detubularized ileal patch as a pedicled flap to augment the native bladder. The procedure includes midline laparotomy, controlled exposure, and stabilization of the bladder with holding sutures, urinary diversion via an exteriorized cannula tube Foley, isolation of a short ileal segment with an intact mesenteric pedicle, detubularization, and tension-free anastomosis with the bladder wall. Emphasis is placed on maintaining mesenteric perfusion, preventing pedicle torsion, ensuring watertight suturing, and securing catheter patency, which are critical for procedural success and reproducibility. Representative intraoperative validation using hyperspectral imaging (HSI) in eight non-survival rats demonstrated preserved tissue oxygenation and perfusion of the bowel segment after key operative steps, supporting tissue viability at the end of this procedure. Thus, this protocol provides a standardized experimental approach for reproducible surgical implementation of rat enterocystoplasty. Potential downstream applications of the model include the investigation of metabolic and electrolyte alterations, infection susceptibility, mucus production, and induction of dysplasia or malignancy, and remain to be addressed in future survival investigations.

Introduction

A physiological urinary bladder function is fundamental to maintaining a high quality of life, as effective urine storage and voiding are critical for continence, social well-being, and overall health. Disorders affecting bladder function can result in substantial morbidity, including urinary incontinence, recurrent infections, renal impairment, and a profound negative impact on daily life.

Both congenital and acquired bladder pathologies can cause significant functional impairment, often necessitating surgical intervention when conservative and pharmacological treatments prove insufficient. Congenital anomalies such as posterior urethral v....

Protocol

All animal procedures outlined in this document were carried out within accredited facilities and have been granted approval by the institutional animal care and use committee (IACUC) of the Baden-Württemberg Regional Council in Karlsruhe, Germany (35-9185.81/G-62/23). Experimental animals were handled in accordance with institutional protocols and in compliance with German legislation governing animal welfare, as well as adhering to the guidelines set forth by the European Community Council (2010/63/EU) and the ARRIVE guidelines. Male Sprague-Dawley rats (n = 8), aged 8–12 weeks and weighing 400 g, obtained from Janvier Labs, were used following a one-week acclimatiz....

Results

To confirm tissue viability after this protocol, tissue oxygenation and perfusion were assessed during the procedure in eight rats (Table 1). Before enterocystoplasty, hyperspectral imaging (HSI) of the small bowel was performed to visualize tissue oxygen saturation (StO₂) and perfusion (NIR) (Figure 5A.1). As a negative control, maximal hypoperfusion was induced by clamping of the aorta (Figure 5A.2). HSI of re.......

Discussion

This work provides a reproducible surgical protocol for enterocystoplasty in rats using a midline laparotomy, extracorporeal cannulation, and incorporation of a detubularized ileal segment. The technique follows the principles described by Tizzoni and Foggi for bladder augmentation and adapts them to a rodent model by combining precise anesthesia, aseptic preparation, exteriorized cannulation for urine diversion, and the harvesting of a vascularized small‑bowel patch.

This protocol was c.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Atraumatic preparation forceps	Aesculap	FB395R	DE BAKEY ATRAUMATA atraumatic forceps, straight
Blunt overholt clamps	Aesculap	BJ012R	BABY-MIXTER preparation and ligature clamp, bent, 180 mm
Cannula tube foley for flusing and diversion	Mdk Mart	23-CA-CD-UL-CD	Cannula G18 (only the tube is used to flush the diversion cannula)
Carprofen	cp pharma	115	Carprofen 0,5% (5% with 50 mg/mL diluted 1:10) (Carprosol)
Cotton whool swabs	Amazon	ASIN: B0FPDB8ZGS	Non-sterile cotton whool swabs (autoclave for survival experiments)
Fast resorbable polyfilament 4-0 sutures	COVIDIEN	SV-494	Single-armed polyfilament surgical suture from resorbable polyglactin with one P-13 needle
Fixation rods	legefirm	‎500343896	Tuning forks used as y-shaped metal fixation rods
Foley catheter	B. Braun	4242010-02	20 Gauge 50 mm Introcan Safety 2 Catheter as diversion cannula
Gauze swabs	Medrull	ASIN: B09164D1JG	Sterile gauze swabs
Heating pad	Royal Gardineer	IP67	Royal Gardineer Heating Pad Size S, 20 Watt
Hyperspectral imaging camera system	Diaspective Vision	TIVITA Tissue Halogen	HSI system for validation
Isoflurane	Piramal Critical Care	PZN / EAN 09714675 / 4150097146757	100% isoflurane 250 mL
Isoflurane vaporizer	UNO ROESTVASTSTAAL BV	180000002	Isoflurane vaporizer
Isotonic sodium chloride solution	B. Braun	ASIN: B007PZJOQ4	0,9% sodium chloride solution
Ketamine	cp pharma	1202	Ketamine 10% (100 mg/mL)
Metal cannula	BD (Beckton, Dickinson)	301300	BD Microlance 3 cannula 20 Gauge as preparation hooks
Neontal face mask	asia connection	ME03016-0	Neontal face mask size #0 for neonate
Non-resorbable monofilament 4-0 sutures	COVIDIEN	SP-670	Single-armed monofilament surgical suture from non-resorbable poly-propylene with one C-16 needle
Non-resorbable monofilament 6-0 sutures	COVIDIEN	VP-733-X	Double-armed monofilament surgical suture from non-resorbable poly-propylene with two CV-22 needles
Ophthalmic ointment	Bayer Vital GmbH	1578681	5% dexpanthenol
Plastic perfusor tube	M. Schilling GmbH	S702NC150	Connecting tube COEX 150 cm
Preparation scissors	Aesculap	BC177R	JAMESON preparation scissors, bent, fine model, blunt/blunt, 150 mm (6")
Rat induction chamber	wpiinc	EZ-1785	Induction chamber for narcosis
Steel plate	Maschinenbau Feld GmbH	C010206	Galvanized sheet plate, 40 x 50 cm, thickness 4.0 mm
Xylazine	cp pharma	1206	Xylazine 0,2% (2% with 20 mg/mL diluted 1:10) (Xylavet)