Minimally invasive bladder urolith removal

Minimally invasive options for removal of uroliths are now the standard of care in human medicine, and similar methods are finding increasing application in veterinary medicine, as Marilyn Dunn describes.
 

Marilyn Dunn
DMV, MVSc, Dipl. ACVIM
 

Introduction

Lower urinary tract stones, not amenable to medical dissolution, can be removed through various minimally invasive methods. Stone removal is generally recommended as their continued presence can induce inflammation, obstruction or recurrent infection. Surgical removal of uroliths by cystotomy or urethrotomy has been the traditional method of choice, but both techniques have been associated with various complications – including urine leakage, wound dehiscence, bleeding, stricture formation and incomplete stone removal – reported in 20% of canine patients ( 1 ). Additionally, suture material within the urethra or bladder wall may serve as a nidus for future urolith formation in stone-forming patients; analysis of recurrent lower urinary tract stones in patients that had undergone surgical cystotomy determined that 9.4% were suture-induced ( 2 ). Recently, complications associated with traditional surgical cystotomy, regardless of closure method, were reported in 37-50% of cases, with a mean duration of hospitalization of 4 days ( 3 ).

In humans, minimally invasive treatment options have mostly replaced traditional surgical stone removal, as this is associated with a high recurrence rate of calculi, the need for serial surgeries that can lead to suture-induced stones, strictures, adhesions, bleeding, uroabdomen, pain and other life-threatening complications ( 4 ) ( 5 ). The current standard of care for human urinary tract stones that cannot be passed or medically dissolved typically involves the use of minimally invasive methods.

Such approaches have a multitude of advantages over standard surgery, including shorter hospitalization times, little to no recovery time and less discomfort. In small animals, minimally invasive treatment options for lower urinary tract stones consist of voiding urohydropropulsion (VUH), cystoscopic stone basket retrieval, intracorporeal lithotripsy and percutaneous cystolithotomy (PCCL) (Figure 1).
 

Minimally invasive removal options should be considered, discussed and offered to owners of pets suffering from uroliths ( 6 ). While at times appearing technically simple, these procedures have been associated with serious complications when performed by inadequately trained personnel, and referral to a formally trained and experienced specialist is indicated.

This article will review the current minimally invasive treatment options for bladder and urethral urolith removal. All the procedures described below should be performed in a sterile manner, with patients clipped and aseptically prepared, and all instruments which will enter the urinary tract must be sterile.

Bladder and urethral urolithiasis

Various interventional approaches may be considered for removal of lower urinary tract uroliths, depending on the species, sex, type of stone present and stone burden, and consideration of a minimally invasive approach to stone removal in lieu of surgical cystotomy is to be recommended in most cases. Correct assessment of stone size is critical in selecting the most appropriate intervention. Uroliths should be measured by standard radiography (or contrast radiography for radiolucent stones) using a radiopaque marker, rather than by ultrasound, which tends to overestimate urolith size and underestimate the number of uroliths ( 6 ). [...]