Wire-Calibrated Induction of Segmental Ureteral Strictures in Rats via Midline Laparotomy

Summary

This protocol describes a reproducible rat model for inducing graded segmental ureteral strictures using wire‑calibrated partial ligation via midline laparotomy. A 6‑0 ligature around the ureter and a metal calibration wire generate a defined residual lumen, enabling immediate functional confirmation of obstruction severity.

Abstract

Ureteral strictures remain a major challenge in reconstructive urology and can arise from iatrogenic injury, chronic inflammation, trauma, congenital anomalies, or radiation.​ These lesions frequently lead to progressive obstructive uropathy and loss of renal function. Despite advances in endoscopic and surgical techniques, ureteral strictures remain challenging to address, and their remodeling effects on the renal parenchyma remain the subject of ongoing research, underscoring the need for robust preclinical models. This study establishes a reproducible rat model for controlled induction of various degrees of segmental ureteral strictures using wire‑calibrated partial ligation via midline laparotomy. The protocol enables segmental, non‑transecting constriction of the ureter, intended to approximate fibrotic narrowing at a functional and anatomical level while minimizing evident ischemic damage and maintaining macroscopic tissue viability with ureteral continuity. By providing a reliable experimental platform with low inter‑animal and inter-surgeon variability, this approach supports translational research on biomolecular mechanisms, biomaterials, imaging modalities, and reconstructive techniques for ureteral stricture disease.

Introduction

Ureteral strictures are relatively common and pose a significant challenge in urology. They are reported in up to 4.9% of patients following endoscopic procedures for stone disease^1,2,3, with even higher incidences among high-risk populations, such as kidney transplant recipients, where up to 7% may be affected⁴. Although many strictures are caused by surgical injury or medical interventions, non-iatrogenic causes also comprise an important proportion. These include chronic inflammation, urinary tract infections, physical trauma, congenital abnormaliti....

Protocol

All animal activities described here were conducted in accredited facilities and approved by the institutional animal care and use committee (IACUC) of the Baden-Württemberg Regional Council in Karlsruhe, Germany. Experimental animals were handled in accordance with institutional protocols and in compliance with German legislation governing animal welfare, as well as the guidelines set forth by the European Community Council (2010/63/EU) and the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines. Male Sprague Dawley rats (average weight: 400 g) were used following a 7-day acclimatization period in the animal facility under standardized conditions. T....

Results

The calibrated ligation technique produced a diameter‑dependent reduction in urine flow across all experimental groups. Urine flow was assessed in a total of 14 rats using both kidneys, resulting in measurements from 5 organs per partial obstruction level (0.65, 0.55, 0.30, and 0.20 mm diameter). Additionally, 4 animals were included that received Sham treatment on one side (the ureter was mobilized, and a loose, non-constricting air-knot ligature was tied without wire) and complete occlusion on the other (a ligatu.......

Discussion

This study establishes a reproducible surgical method for inducing unilateral ureteral strictures in rats through midline laparotomy and calibrated partial ligation, resulting in segmental ureteral narrowing with preserved macroscopic tissue viability that functionally and anatomically resembles benign human ureteral strictures.

Clinically, ureteral stricture disease remains a major contributor to upper tract obstruction and renal morbidity with long-term functional loss, frequently arising af.......

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	BD (Beckton, Dickinson)	301300	BD Microlance 3 cannula 20 G
capillary tubes	Sigma Aldrich	P1174	Microcapillary tube, calibrated 100 µL
carprofen	cp pharma	115	carprofen 0,5% (5% with 50 mg/mL diluted 1:10) (Carprosol®)
cotton whool swaps	Amazon	ASIN: B0FPDB8ZGS	non-sterile cotton whool swaps (autoclave for survival experiments)
fixation rods	legefirm	‎500343896	tuning forks used as y-shaped metal fixation rods
gauze swaps	Medrull	ASIN: B09164D1JG	sterile gauze swaps
heating pad	Royal Gardineer	IP67	Royal Gardineer Heating Pad Size S, 20 Watt
isoflurane	Piramal Critical Care	PZN / EAN 09714675 / 4150097146757	100% isoflurane 250 mL
isoflurane vaporizer	UNO ROESTVASTSTAAL BV	180000002	isoflurane vaporizer
isotonic sodiumchloride solution	B. Braun	ASIN: B007PZJOQ4	0,9% sodiumchloride solution
ketamine	cp pharma	1202	ketamine 10% (100 mg/mL)
metal calibration wire (0.20 mm diameter)	QUARKZMAN	ASIN: B0DCZBT4LW	Cr20Ni80-Nichrom metal wire (0.20 mm diameter)
metal calibration wire (0.30 mm diameter)	Rayher	4006166052859	Cr20Ni80-Nichrom metal wire (0.30 mm diameter)
metal calibration wire (0.55 mm diameter)	SKYPRO	UPC: 792138793816	Cr20Ni80-Nichrom metal wire (0.55 mm diameter)
metal calibration wire (0.65 mm diameter)	twipp	ASIN: B07WFWNNRM	Cr20Ni80-Nichrom metal wire (0.65 mm diameter)
methylene blue 0,5%	Provepharm	PZN / EAN 10179678 / 4150101796787	METHYLTHIONINIUMCHLORID Proveblue 5 mg/mL in 10 ml vials
non-resorbable monofilament 6-0 ligatures	COVIDIEN	VP-889-X	monofilament surgical suture from non-resorbable poly-propylene; needle can be removed
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")
steel plate	Maschinenbau Feld GmbH	C010206	Galvanized sheet plate, 40 x 50 cm, thickness 4.0 mm
syringe with integrated needle	BLPRKOT	BL2509L3yici08	1 ml syringe with integrated 30 G needle
xylazine	cp pharma	1206	xylazine 0,2% (2% with 20 mg/mL diluted 1:10) (Xylavet)