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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] Success rates range from 58–87% depending on patient selection, technique, and definition of success, but the procedure carries a significantly higher failure rate than open anastomotic urethroplasty (95–97% success), which remains the gold standard for posterior urethral distraction defects.[2][3][4][7]

For the open gold-standard 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 (antegrade) 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 — fundamentally different from incising a narrowed but patent lumen.[1]

Indications​

  • 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 (relative contraindication — risk of rectourethral fistula)
  • Patients who have failed initial optical urethrotomy for a passable stricture that subsequently obliterated[1]
  • Patients who are poor candidates for open urethroplasty (comorbidities, patient preference, resource-limited settings)
  • 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 landmark 145-patient series 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 anastomotic urethroplasty is the gold standard.[7]

Surgical Technique​

Preoperative requirements​

  • Suprapubic cystostomy in place (typically placed at initial injury or as a staged procedure)
  • Bidirectional urethrography (simultaneous antegrade via SPT + 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. Excellent hemostasis with a penetration depth of 3–4 mm.[3][4]
  • Holmium:YAG laser: ~0.4 mm penetration depth; more precise tissue ablation with less collateral thermal damage than Nd:YAG.[5]
  • Thulium laser: 2-μm continuous-wave laser with excellent hemostasis and tissue vaporization.[9][10]

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

6. Catheterization. 18 Fr Foley placed across the reconstructed segment and left for 4–6 weeks (significantly 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 mmExcellent hemostasis, 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 mmExcellent hemostasis, continuous wave, preciseLimited data for CTU specifically[9][10]

A meta-analysis of 9 studies (659 patients) comparing laser vs cold-knife urethrotomy (not CTU-specific) found that laser approaches had significantly better 12-month Qmax (MD 2.13, p < 0.05) and lower recurrence.[11]

Key Outcomes by Series​

StudyYearnTechniqueStricture LengthSuccessFollow-upKey Findings
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)mean 17.7 mo39% failure; 69% recurrence at 3 mo
Dogra / Aron[3]19998Nd:YAG laser CTU≤2 cm87.5% (7/8)mean 10.25 moFirst laser CTU; Qmax 18.6 mL/s
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 cm65.5% excellent + 31% acceptable (96.5%)mean 15 moFirst Ho:YAG series; 1 failure (3.4%) requiring urethroplasty
Koraitim (urethrotomy subset)[7]199512Optical urethrotomygenuine stricture only58% (7/12)17 yr experienceSuccessful only in genuine strictures, not distraction defects

CTU vs. Open Urethroplasty​

The only randomized trial comparing CTU to urethroplasty for posterior urethral distraction defects (Ravichandran 2003, summarized in the Cochrane review) randomized 50 men with traumatic posterior urethral strictures ≤2 cm:[12]

  • At 6 months, CTU patients were significantly more likely to require further surgery (RR 3.39, 95% CI 1.62–7.07).
  • At 2 years, 64% (16/25) of CTU patients required continued self-dilation or further surgery vs 24% (6/25) of urethroplasty patients.
  • Technical failure was significantly more common with CTU.

Koraitim's 17-year experience with 145 posterior urethral strictures further reinforced the superiority of open repair:[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 — most common; 39–69% at 3 months in some series, though many stabilize after 1–2 repeat dilations / urethrotomies.[6]
  • Urinary incontinence — 0–15%; typically stress, often transient.[1][3][6]
  • Erectile dysfunction — generally not caused by the procedure itself, though pre-existing ED from the original pelvic fracture is common.[3][4][5]
  • Bleeding / hematuria — minimal with laser; more common with cold knife.[3][4][11]
  • False passage creation — risk when cutting through dense scar without adequate guidance.
  • Rectal injury — rare but devastating; the 12 o'clock incision direction (toward the symphysis) is chosen specifically to avoid the rectum posteriorly.[3]
  • Extravasation — 1/29 in the Dogra Ho:YAG series, resolved conservatively.[5]
  • Re-obliteration — 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 becomes the target for the retrograde endoscopic incision. The surgeon cuts toward the transilluminated light from the suprapubic cystoscope rather than toward a metal sound, providing better directional guidance when alignment between segments is suboptimal.[13]

Role in Contemporary Practice​

The AUA Urotrauma Guideline (2020) recommends suprapubic tube placement as preferred initial management for most pelvic fracture urethral injuries, noting that most patients will develop obliterative strictures amenable to open posterior urethroplasty, which has a high probability of success at referral centers. Primary endoscopic realignment has been associated with a longer clinical course due to multiple procedures required for recurrent obstruction.[14]

The AUA Urethral Stricture Disease Guideline (2023) states that strictures previously treated with dilation or DVIU are unlikely to be successfully treated with another endoscopic procedure, with failure rates >80%.[15]

In contemporary practice, CTU occupies a niche role for:[3][4][7][8][16]

  1. Resource-limited settings where open urethroplasty expertise or infrastructure is unavailable
  2. Patients unfit for open surgery due to comorbidities
  3. Patient preference for a minimally invasive approach after informed consent regarding the lower success rate
  4. Salvage attempt before committing to open urethroplasty, with the understanding that a failed CTU does not appear to compromise subsequent urethroplasty outcomes[16]
  5. Genuine short strictures (not true distraction defects) with a persistent opening between bulbar and prostatic urethra — the best candidates[7][8]

Critical Distinction — Genuine Stricture vs. Distraction Defect​

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

  • Genuine stricture (narrowing with some residual continuity) — may be amenable to optical urethrotomy or CTU.
  • 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​

CTU is a minimally invasive endoscopic technique for obliterative posterior urethral strictures that re-establishes continuity by cutting or vaporizing through the fibrotic plug separating the blind-ending urethral segments. While technically feasible with success rates of 58–96% depending on patient selection and energy source, it is significantly inferior to open anastomotic urethroplasty (95–97% success) and carries a high recurrence rate requiring repeat interventions. Laser-based CTU (Nd:YAG or Ho:YAG) appears superior to cold knife CTU in hemostasis and precision. The procedure is best reserved for short obliterative segments (≤2 cm) with good alignment in patients who are poor candidates for or decline open surgery, and careful distinction between genuine strictures and true distraction defects is critical for appropriate patient selection.[1][3][4][7][8]

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.
  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 <3 cm). 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. Moudouni SM, Patard JJ, Manunta A, et al. Early endoscopic realignment of post-traumatic posterior urethral disruption. Urology. 2001;57(4):628-32. doi:10.1016/s0090-4295(00)01068-2.