Suture-Induced Urolithiasis: A Preventable Cause of Stone Recurrence

Suture nidus is often overlooked as a differential diagnosis for recurrent urolithiasis but should be considered whenever stones recur after surgical removal. In a retrospective case-control study, suture-associated uroliths accounted for 9.4% of recurrent canine stones and 4% of recurrent feline stones.¹ 

Recurrent stones that form around suture material may have a linear shape that resembles the underlying suture.² More commonly, however, a suture nidus is identified only after the stone has been fractured or sectioned. The stone may contain residual suture material or a suture cast (a hollow cylindrical channel) left behind after the suture has dissolved.

In 2025, 1.0% of 68,652 canine stones and 0.5% of 28,714 feline stones submitted to the Minnesota Urolith Center contained a suture or suture-cast nidus. Calcium oxalate was the most common mineral associated with these stones. To reduce the risk of suture-induced urolith recurrence, utilize bladder closure techniques that do not expose suture to the lumen of the bladder.  To eliminate the risk of suture-induced urolith recurrence, consider minimally-invasive removal techniques, such as medical dissolution, voiding urohydropropulsion, basket retrieval, and lithotripsy. 

1. Appel SL, et al. Evaluation of risk factors associated with suture-nidus cystoliths in dogs and cats: 176 cases (1999–2006). Am Vet Med Assoc 2008;233:1889–1895.

2. Hickey JM. et al. Radiographic features of suspected suture-associated cystic calculi in dogs. Vet Radiol Ultrasound. 2020;61:394–398