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Collins Knife

Hook-shaped or right-angled monopolar / bipolar electrosurgical electrode that mounts on a standard resectoscope working element — designed to make precise, controlled, single-plane linear incisions under direct endoscopic vision rather than the scoop-and-shave resection of a wire loop. Also commonly spelled "Collings knife." The reconstructive surgeon's instrument for TUIP, transurethral incision of bladder-neck contracture (BNC) and vesicourethral anastomotic stenosis (VUAS), external sphincterotomy, and transurethral bladder-cuff excision at nephroureterectomy.[1][2]

Design​

  • Thin hook-shaped wire protruding from the resectoscope sheath in place of the standard loop.
  • Powered by the standard ESU; typical setting 20 W cut / 20 W coag (mono- or bipolar).[3]
  • Single-plane scalpel-like cut — the operative distinction from a loop, which removes tissue in chips rather than incising in a controlled line.

Reconstructive-Urology and Functional-Urology Uses​

TUIP — transurethral incision of the prostate​

  • Indication: bladder-outlet obstruction from BPH with prostate ≤ 30 g.
  • Technique: deep incisions at 5 and 7 o'clock (or single 6 o'clock) from the interureteric ridge through the bladder neck and prostatic urethra to the verumontanum, cutting down to the prostatic capsule.[4][5]
  • Outcome vs TURP — Yang 2001 meta of 9 RCTs found equivalent symptom improvement at 12 mo with significantly lower complications: retrograde ejaculation 15% vs 66%, transfusion 1% vs 6%, incontinence 1% vs 6%.[6]

See the TUIP procedure page for full technique and outcomes.

TUIBNC and TUIVUAS — bladder-neck contracture / VUAS incision​

  • Standard endoscopic treatment for post-prostatectomy / post-radiation / post-TURP BNC and VUAS.
  • Incisions at 3 and 9 o'clock (lateral) typical, sparing the rectum at 6 o'clock.[2][3]
  • Nealon 2022 (n = 123, 12 years) — Collins-knife TUIBNC after balloon dilation to 24 Fr → 82.1% single-session patency, 94.3% after two procedures.[2]
  • AUA 2023 urethral-stricture guideline — bladder-neck incision and resection have comparable outcomes; repeat endoscopic treatment is sometimes necessary.[7]

See Transurethral Incision of BNC for the full procedure page.

External sphincterotomy for detrusor-sphincter dyssynergia (DSD)​

  • Performed in spinal-cord-injury and selected neurogenic-bladder patients to reduce urethral resistance.
  • Linker / Tanagho cadaveric standard: 2 cm incision from the verumontanum × 6 mm depth is needed to completely divide external-sphincter fibers.[1]

Bladder-cuff excision at radical nephroureterectomy​

  • The Collins knife is used to circumscribe the ureteric orifice with a bladder cuff, detaching the intramural ureter from the bladder wall, as the transurethral step of laparoscopic / robotic nephroureterectomy for UTUC.[8][9][10]
  • Allard 2013 (n = 110) — transurethral Collins-knife technique produced equivalent recurrence and metastasis rates compared with open extravesical and open intravesical bladder-cuff excision.[11]

Endoscopic transvesical ureterotomy​

  • For distal ureteral strictures, the Collins knife can make a full-thickness incision at 12 o'clock through the strictured segment over a previously placed ureteral catheter.[12]

En-bloc resection of small bladder tumors​

  • Saito 2001 described circumferential Collins-knife incision ~ 10 mm from the tumor edge to the superficial muscle followed by a level subjacent incision, retrieving the lesion as a single specimen — n = 35 patients / 50 lesions with accurate pathologic staging and no serious complications.[13]

Percutaneous nephrostomy tract creation — niche use​

  • In difficult percutaneous access (scarification, failed wire passage), the Collins knife can create a nephrostomy tract from within the collecting system — Davis 1991 reported success in all 19 cases at an average of 12 min.[14]

Advantages​

  • Precision — single-plane incision in a defined direction and depth that a loop cannot replicate.
  • Versatility — same electrode mounts on any standard resectoscope working element.
  • Low cost — disposable or autoclavable; no dedicated platform required.

Limitations​

  • Thermal injury to adjacent structures — particularly the rectum at 6 o'clock during bladder-neck or prostatic incision; lateral cuts (3 / 9 or 5 / 7) are preferred.
  • Fluid management with monopolar setups — same TUR-syndrome considerations as any monopolar resectoscope work; bipolar setups eliminate this risk.
  • Not for bulk resection — for tissue removal use the resectoscope loop; for stone fragmentation use a laser fiber or pneumatic lithotripsy.

See also: Resectoscope, Sachse Urethrotome (DVIU), Otis Urethrotome, Balloon Dilator, Electrosurgical Pencil, TUIP, Transurethral Incision of BNC.

References​

1. Linker DG, Tanagho EA. "Complete external sphincterotomy: correlation between endoscopic observation and the anatomic sphincter." J Urol. 1975;113(3):348–52. doi:10.1016/s0022-5347(17)59478-1

2. Nealon SW, Bhanvadia RR, Badkhshan S, et al. "Transurethral incisions for bladder neck contracture: comparable results without intralesional injections." J Clin Med. 2022;11(15):4355. doi:10.3390/jcm11154355

3. Quarta L, Bandini M, Corsini C, et al. "Assessing predictors of failure after bladder neck incision in patients who developed bladder neck stenosis following transurethral surgery for benign prostatic enlargement." Prostate. 2025;85(15):1424–31. doi:10.1002/pros.70027

4. Tkocz M, Prajsner A. "Comparison of long-term results of transurethral incision of the prostate with transurethral resection of the prostate, in patients with benign prostatic hypertrophy." Neurourol Urodyn. 2002;21(2):112–6. doi:10.1002/nau.10013

5. Oesterling JE. "Benign prostatic hyperplasia — medical and minimally invasive treatment options." N Engl J Med. 1995;332(2):99–109. doi:10.1056/NEJM199501123320207

6. Yang Q, Peters TJ, Donovan JL, Wilt TJ, Abrams P. "Transurethral incision compared with transurethral resection of the prostate for bladder outlet obstruction: a systematic review and meta-analysis of randomized controlled trials." J Urol. 2001;165(5):1526–32.

7. Wessells H, Morey A, Souter L, Rahimi L, Vanni A. "Urethral stricture disease guideline amendment (2023)." J Urol. 2023;210(1):64–71. doi:10.1097/JU.0000000000003482

8. Agarwal DK, Khaira HS, Clarke D, Tong R. "Modified transurethral technique for the management of distal ureter during laparoscopic-assisted nephroureterectomy." Urology. 2008;71(4):740–3. doi:10.1016/j.urology.2007.11.048

9. Gill IS, Soble JJ, Miller SD, Sung GT. "A novel technique for management of the en bloc bladder cuff and distal ureter during laparoscopic nephroureterectomy." J Urol. 1999;161(2):430–4.

10. Wong C, Leveillee RJ. "Hand-assisted laparoscopic nephroureterectomy with cystoscopic en bloc excision of the distal ureter and bladder cuff." J Endourol. 2002;16(6):329–32. doi:10.1089/089277902760261329

11. Allard CB, Alamri A, Dason S, et al. "The method of bladder cuff excision during laparoscopic radical nephroureterectomy does not affect oncologic outcomes in upper tract urothelial carcinoma." World J Urol. 2013;31(1):175–81. doi:10.1007/s00345-012-0915-0

12. Gardiner RA. "Endoscopic transvesical ureterotomy." J Urol. 1985;134(4):729–32. doi:10.1016/s0022-5347(17)47411-8

13. Saito S. "Transurethral en bloc resection of bladder tumors." J Urol. 2001;166(6):2148–50.

14. Davis BE, Noble MJ, Mebust WK. "Use of the Collings knife electrode for percutaneous access in difficult endourology cases." J Urol. 1991;145(2):257–61. doi:10.1016/s0022-5347(17)38308-8