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Core-Through Urethrotomy

Core-through urethrotomy (CTU) is an endoscopic technique used to re-establish urethral continuity in completely obliterative urethral strictures, typically post-traumatic posterior (bulbomembranous) strictures, where the lumen is entirely occluded and a standard direct vision internal urethrotomy (DVIU) cannot be performed because no lumen exists to incise. First described by Gupta and Gill in 1986, the technique resects or vaporizes the fibrotic tissue between the two blind-ending urethral segments, guided by a metal sound passed through a suprapubic cystostomy tract.[1] In el-Abd’s CTU subset, 46/79 (58.2%) were voiding satisfactorily after 6–55 months; in Dogra and Aron’s selected Nd:YAG CTU series, VCUG showed a stricture-free urethra in 7/8 (87.5%), with last follow-up at 7–14 months.[2][3] Open anastomotic urethroplasty is more successful (95% perineal and 97% transpubic in Koraitim's series), and Koraitim regarded it as the gold standard for posterior urethral distraction defects.[2][3][4][7]

For complete posterior obliteration, EAU 2026 gives a strong recommendation not to perform endoscopic treatment of an obliterative post-traumatic stenosis (§6.3.5.b) or endoluminal treatment of non-traumatic posterior stenosis with complete obliteration (§6.3.5.a). It notes that cut-to-the-light treatment will not be successful and risks a false passage toward the bladder base or rectum; reconstruction is the alternative.[16] The AUA recommends delayed urethroplasty instead of delayed endoscopic procedures after obstruction or obliteration from pelvic fracture urethral injury ; its supporting discussion also advises against blind cut-to-the-light procedures in obliterated PFUI because they are rarely successful.[15]

For the open anastomotic repair, see Pelvic Fracture Urethral Injury (PFUI). For standard endoscopic incision of patent strictures, see DVIU and Urethral Dilation. For paclitaxel-coated balloon adjuncts, see Drug-Coated Balloon Therapy.

Definition and Distinction from Standard DVIU​

Standard DVIU (Sachse urethrotomy) requires a visible, narrowed but patent lumen through which the urethrotome blade can be advanced and the stricture incised under direct vision. In obliterative strictures, there is no residual lumen; the urethral segments end blindly, separated by a plug of dense fibrotic tissue. CTU addresses this by cutting or vaporizing through the fibrotic plug from the distal (retrograde) end toward the proximal end, using a suprapubic sound as a target and guide.[1][3]

The term "core-through" reflects the concept of coring out a channel through solid scar tissue, analogous to coring an apple, which is fundamentally different from incising a narrowed but patent lumen.[1]

Historical Patient Selection​

  • Complete obliterative post-traumatic posterior urethral strictures (bulbomembranous)
  • Stricture length ≤2–2.5 cm on bidirectional uroradiography
  • Good alignment between proximal and distal urethral segments (no significant lateral displacement)
  • No history of rectal injury was a selection criterion in Dogra and Aron’s eight-patient Nd:YAG series.[3]
  • In el-Abd’s historical cohort, 79 patients underwent CTU after initial endoscopic treatment failed because of complete short-segment obliteration.[2]
  • For patients with poor performance status, EAU 2026 weakly recommends considering long-term suprapubic catheterization; it also describes this as an option for patients who decline further surgery and strongly recommends against endoscopic treatment of obliterative post-traumatic stenosis.[16]
  • An existing suprapubic cystostomy is a prerequisite[3][4][5]

Contraindications​

  • Stricture length >2.5 cm (relative; some authors extend to 3 cm)
  • Poor alignment between urethral segments or significant lateral / vesical displacement[1]
  • Complex distraction defects with fistulae, false passages, or associated rectal injury
  • Prior failed CTU with re-obliteration (relative; consider open urethroplasty)
  • Koraitim’s series of 145 operations in 122 patients emphasized that optical urethrotomy was successful only in patients with genuine strictures with a persistent opening between bulbar and prostatic areas, not in true distraction defects with complete loss of continuity, for which he considered anastomotic urethroplasty the gold standard.[7]

Historical Technique Description​

Preoperative requirements​

  • Suprapubic cystostomy in place (typically placed at initial injury or as a staged procedure)
  • Bidirectional urethrography (simultaneous antegrade via SPT and retrograde) to assess length, alignment, and gap[3][4][5]
  • Flexible cystoscopy through the SPT to assess the proximal segment

Step-by-step​

1. Positioning and setup. Dorsal lithotomy under general or spinal anesthesia. C-arm fluoroscopy available in some series for real-time guidance.[6]

2. Suprapubic sound placement. A metal sound (bougie or Van Buren) is passed through the SPT, through the bladder, and into the proximal (prostatic) urethra, advanced until it reaches the proximal end of the obliterative segment, serving as a tactile and visual target for the endoscopic approach from below.[3][4][5]

3. Retrograde endoscopic approach. A resectoscope or urethrotome is introduced per urethra and advanced to the distal end of the obliterative segment, identifying the distal blind-ending lumen.

4. Core-through incision / vaporization. Depending on energy source:

  • Cold knife (Sachse): the blade incises the fibrotic tissue at the 12 o'clock position (toward the symphysis pubis), cutting down toward the metal sound. The incision is deepened progressively until the sound is encountered.[1][6]
  • Nd:YAG laser: a 600 μm contact bare fiber at 15–25 W vaporizes the fibrotic tissue toward the metal sound. Hemostasis is good, with a clinically effective ablation depth of 3–4 mm at these CTU-series settings; the 1064 nm wavelength's general optical penetration in tissue is deeper (reported up to 5–10 mm, the deepest of the clinical lasers), which is why deeper unintended thermal injury is the main safety concern with this platform.[3][4]
  • Holmium:YAG laser: approximately 0.4 mm penetration depth; more precise tissue ablation with less collateral thermal damage than Nd:YAG.[5]
  • Thulium laser: A 2-μm continuous-wave laser used for hemostatic incision and tissue vaporization in short, passable strictures.[9][10]

5. Establishing continuity. Incision or vaporization continues until the metal sound is visualized endoscopically, confirming the obliterative segment has been traversed. The channel is widened by further incision or resection. A guidewire may be passed through the new channel into the bladder.

6. Catheterization. Goel left an 18 Fr Foley for 4 weeks, then repeated urethrotomy and advised all 13 patients to perform clean intermittent self-catheterization; the Dogra/Nabi and Dogra/Ansari laser series removed the catheter at 6 weeks.[4][5][6] These CTU-series durations are longer than after standard DVIU.[3][4][5][6]

7. Postoperative assessment. VCUG at catheter removal (6 weeks); urethroscopy at 1–3 months; uroflowmetry at 3 months and periodically thereafter. Many patients require repeat DVIU or dilation 1–2 times before the stricture stabilizes.[3][4][6]

Energy Sources — Comparison​

Energy SourcePenetration DepthAdvantagesDisadvantagesReferences
Cold knife (Sachse)N/A (mechanical)Widely available, no special equipmentBleeding, poor visualization in dense scar, less precise[1]
Nd:YAG laser3–4 mmHemostasis, good vaporization, outpatientDeeper thermal injury, risk of collateral damage[3][4]
Holmium:YAG laser~0.4 mmPrecise ablation, minimal thermal damage, outpatientLess hemostatic than Nd:YAG[5]
Thulium laser~0.25 mmHemostasis, continuous-wave incision, precise tissue vaporization in passable stricturesThe cited studies do not evaluate CTU for complete post-traumatic obliteration[9][10]

A meta-analysis of 9 comparative studies (659 patients) of laser versus cold-knife urethrotomy for strictures shorter than 2 cm (not CTU-specific) found a higher 12-month Qmax with laser (MD 2.13 mL/s, 95% CI 1.02–3.25), less postoperative bleeding (RR 0.28) and a lower 1-year recurrence rate (RR 0.67, 95% CI 0.46–0.98).[11]

Key Outcomes by Series​

StudyYearnTechniqueStricture LengthSuccessFollow-upFindings
Gupta / Gill[1]198610Cold-knife CTUshort obliterative80% (8/10)6–24 moFirst description
el-Abd[2]199579 (CTU subset)Cold-knife CTUshort obliterative58.2% (46/79)mean 2 yrLargest cold-knife series; 41.8% required open urethroplasty
Goel / Kumar[6]199713Cold-knife CTU + fluoroscopy≤2 cm61% (8/13) did well with repeat urethrotomy/self-catheterization protocolmean 17.7 moNot primary stricture-free success; 5/13 classed as failures, including 2 lost to follow-up; 69% recurrence at 3 mo
Dogra / Aron[3]19998Nd:YAG laser CTU≤2 cm87.5% (7/8) stricture-free on VCUGmean 10.25 moFirst laser CTU; mean Qmax 18.6 mL/s in the 7 stricture-free patients
Dogra / Nabi[4]200265Nd:YAG laser CTUmean 2.2 cm~94% technically successful9–44 moLargest laser CTU series; 4 technical failures, 2 re-obliterations
Dogra / Ansari[5]200429Holmium laser CTU≤2.5 cm19/29 excellent; 9/29 acceptable after 1–2 repeat endoscopic proceduresmean 15 moOne further patient required urethroplasty.
Koraitim (urethrotomy subset)[7]199512Optical urethrotomygenuine stricture only58% (7/12)not reported (17-year series)Successful only in genuine strictures, not distraction defects

CTU vs. Open Urethroplasty​

The Cochrane review identified one randomized trial comparing urethrotomy with primary urethroplasty, in 50 men with traumatic posterior urethral stricture after pelvic fracture. The review did not give the trial's stricture-length criteria or its technique for the endoscopic arm; the results describe urethrotomy in general and not only core-through technique:[12]

  • In the first 6 months, further intervention for recurrence was reported in 13/16 (81%) men after urethrotomy, with nine men whose initial procedure was unsuccessful outside that denominator, versus 6/25 (24%) after primary urethroplasty (RR 3.39, 95% CI 1.62–7.07).[12]
  • At 2 years, 16/25 (64%) of men treated by urethrotomy required continued self-dilation or further surgery for recurrence versus 6/25 (24%) of men treated by primary urethroplasty.[12]
  • The review found insufficient data to perform meta-analysis or to determine effect size reliably.

Koraitim's 17-year experience with 145 posterior urethral strictures showed the same pattern in a retrospective series:[7]

ApproachSuccess
Perineal anastomotic urethroplasty95%
Transpubic urethroplasty97%
Optical urethrotomy58% (genuine strictures only)
Urethroscrotal inlay43%

Koraitim specifically cautioned that "repeated urethrotomy of a long fibrous segment between a widely distracted prostatic and bulbar urethra would not only have a poor result but, by jeopardizing the elasticity of the anterior urethra, it also may undermine the chance for subsequent anastomotic urethroplasty."[7]

Complications​

  • Stricture recurrence. This is the most common complication. Goel reported recurrence in 69% at 3 months and 25% at 12 months after the initial procedure; many strictures stabilize after one or two repeat dilations or urethrotomies.[6]
  • Urinary incontinence. Stress incontinence occurred in 2/10 (transient) in Gupta and Gill and in 4 of the 46 men voiding satisfactorily in el-Abd.[1][2] It was not reported in the Nd:YAG, holmium or Goel series.[1][2][3][5][6]
  • Erectile dysfunction. The small laser series reported preserved potency among selected men; the eight-patient Nd:YAG series excluded men with preexisting ED.[3][4][5]
  • Bleeding and hematuria. Dogra and Aron's eight-patient Nd:YAG CTU series reported negligible blood loss, and Dogra and Nabi's 65-patient Nd:YAG CTU series reported no need for transfusion.[3][4] A meta-analysis of urethrotomy for strictures <2 cm found less postoperative bleeding with laser than cold knife (RR 0.28, 95% CI 0.08–0.98).[11]
  • False passage is a risk when cutting through dense scar without adequate guidance.
  • Rectal injury is rare but serious; the 12 o'clock incision direction (toward the symphysis) is chosen specifically to avoid the rectum posteriorly.[3]
  • Extravasation occurred in 1/29 in the Dogra Ho:YAG series and resolved conservatively.[5]
  • Re-obliteration occurred in 2/65 in the largest Nd:YAG series.[4]

The "Cut to the Light" Variant​

A related technique uses a combined antegrade-retrograde approach. A cystoscope is passed through the SPT into the proximal urethra, and its light is the target for the retrograde endoscopic incision instead of a metal sound. In a complete obliteration, an illuminated proximal target does not remove the risk of a false passage toward the bladder base or rectum.[16] The AUA advises avoiding blind cut-to-the-light procedures because they are rarely successful.[15]

Role in Contemporary Practice​

The AUA Urotrauma Guideline (2020) states that clinicians should perform percutaneous or open suprapubic tube placement as the preferred initial management for most pelvic fracture urethral injuries (Recommendation; Grade C).[14] In hemodynamically stable patients with pelvic fracture-associated urethral injury, primary realignment is an option (Grade C).[17] Primary endoscopic realignment has been associated with a longer course and multiple procedures for recurrent obstruction.[14] In the Italian arm (n=138) of a retrospective PFUI cohort, 68.1% of strictures were classified as simple and laser urethrotomy accounted for 21.1% of repairs.[13]

In its discussion of recurrent anterior urethral strictures after failed dilation or DVIU, the AUA Urethral Stricture Disease Guideline (2023) reports failure rates >80% with another endoscopic procedure.[15]

Patients unsuitable for reconstruction require individualized drainage and specialist review.[14][15][16]

Critical Distinction — Genuine Stricture vs. Distraction Defect​

Koraitim's preoperative decision-making framework is used for patient selection:[8]

  • Genuine stricture (narrowing with some residual continuity): may be considered for standard endoscopic treatment in selected short lesions.
  • Distraction defect (complete loss of urethral continuity with a gap filled by fibrosis): requires anastomotic urethroplasty; CTU has poor results in this setting.
  • Defects with significant lateral or cephalad bladder displacement, or gaps that cannot be bridged tension-free, should bypass CTU and proceed directly to perineal or transpubic anastomotic urethroplasty.[7][8]

Key Takeaways​

Core-through urethrotomy documents an earlier attempt to manage obliterated posterior strictures endoscopically. The current distinction is between a selected nonobliterative stenosis that may permit endoscopic treatment and complete loss of continuity requiring reconstructive assessment. Historical CTU success ranges describe selected treated cohorts.[16]

References​

  1. Gupta NP, Gill IS. Core-through optical internal urethrotomy in management of impassable traumatic posterior urethral strictures. J Urol. 1986;136(5):1018-21. doi:10.1016/s0022-5347(17)45193-7.

  2. el-Abd SA. Endoscopic treatment of posttraumatic urethral obliteration: experience in 396 patients. J Urol. 1995;153(1):67-71. doi:10.1097/00005392-199501000-00025.

  3. Dogra PN, Aron M, Rajeev TP. Core through urethrotomy with the neodymium:YAG laser for posttraumatic obliterative strictures of the bulbomembranous urethra. J Urol. 1999;161(1):81-4. doi:10.1016/s0022-5347(01)62071-8.

  4. Dogra PN, Nabi G. Core-through urethrotomy using the neodymium:YAG laser for obliterative urethral strictures after traumatic urethral disruption and/or distraction defects: long-term outcome. J Urol. 2002;167(2 Pt 1):543-6. doi:10.1016/S0022-5347(01)69082-7.

  5. Dogra PN, Ansari MS, Gupta NP, Tandon S. Holmium laser core-through urethrotomy for traumatic obliterative strictures of urethra: initial experience. Urology. 2004;64(2):232-5; discussion 235-6. doi:10.1016/j.urology.2004.03.050.

  6. Goel MC, Kumar M, Kapoor R. Endoscopic management of traumatic posterior urethral stricture: early results and followup. J Urol. 1997;157(1):95-7. doi:10.1016/s0022-5347(01)65295-9

  7. Koraitim MM. The lessons of 145 posttraumatic posterior urethral strictures treated in 17 years. J Urol. 1995;153(1):63-6. doi:10.1097/00005392-199501000-00024.

  8. Koraitim MM. Post-traumatic posterior urethral strictures: preoperative decision making. Urology. 2004;64(2):228-31. doi:10.1016/j.urology.2004.03.019.

  9. Rehan M, Elnady EA, Khater S, et al. Comparative study between thulium laser and cold knife visual urethrotomy for treatment of short bulbomembranous urethral stricture. Medicine. 2022;101(35):e30235. doi:10.1097/MD.0000000000030235.

  10. Wang L, Wang Z, Yang B, Yang Q, Sun Y. Thulium laser urethrotomy for urethral stricture: a preliminary report. Lasers Surg Med. 2010;42(7):620-3. doi:10.1002/lsm.20934.

  11. Chen C, Qin J, Wang C, et al. Comparison of laser versus cold knife visual internal urethrotomy in the treatment of urethral stricture (stricture length <2 cm): a systematic review and meta-analysis. Medicine. 2024;103(18):e37524. doi:10.1097/MD.0000000000037524.

  12. Wong SS, Aboumarzouk OM, Narahari R, O'Riordan A, Pickard R. Simple urethral dilatation, endoscopic urethrotomy, and urethroplasty for urethral stricture disease in adult men. Cochrane Database Syst Rev. 2012;12:CD006934. doi:10.1002/14651858.CD006934.pub3.

  13. Kulkarni SB, Barbagli G, Kulkarni JS, Romano G, Lazzeri M. Posterior urethral stricture after pelvic fracture urethral distraction defects in developing and developed countries, and choice of surgical technique. J Urol. 2010;183(3):1049-54. doi:10.1016/j.juro.2009.11.045.

  14. Morey AF, Broghammer JA, Hollowell CMP, McKibben MJ, Souter L. Urotrauma guideline 2020: AUA guideline. J Urol. 2021;205(1):30-35. doi:10.1097/JU.0000000000001408.

  15. 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.

  16. European Association of Urology. Urethral Strictures: Disease Management in Males, sections 6.3.5.a–b. 2026. Official guideline.

  17. Morey AF, Brandes S, Dugi DD III, et al. "Urotrauma: AUA Guideline." J Urol. 2014;192(2):327-335. doi:10.1016/j.juro.2014.05.004