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© 2021 The Authors. Société Internationale d'Urologie Journal, published by the Société Internationale d'Urologie, Canada.

The Right Instrument for the Right Purpose:  
Spreading the Use of Small Caliber Ureteroscope  
for the Inspection of the Male and Female Urethra
Sanjay B. Kulkarni,1 Marco Bandini,1,2,3 Amey Patil,1 Shreyas Bhadranavar,1 Vipin Sharma,1  
Sandeep Bafna,1 Shreeranga L. Yatam,1 Guido Barbagli,3 Francesco Montorsi,2 Pankaj M. Joshi1

1Kulkarni Reconstructive Urology Center, Pune, India  2Unit of Urology, Urological Research Institute (URI), San Raffaele Hospital, Vita-Salute San Raffaele University,  
Milan, Italy  3Center for Reconstructive Urethral Surgery, Arezzo, Rome, Milan, Italy

Abstract

The inspection of the urethra in patients with documented or suspected urethral stricture should be carried out with 
small caliber ureteroscope of 6/7.5Ch. Different from flexible cystoscope (16Ch) or resectoscope (26Ch), small caliber 
ureteroscope allows a comprehensive evaluation of the stricture, including its length and the status of the mucosa in 
its proximity, without injuring or overstretching the urethra. With a small caliber ureteroscope it is also possible to 
cross the stricture, allowing the evaluation of the proximal urethra, the external urethral sphincter, and the bladder. 
A 6/7.5Ch ureteroscope also allows estimation of the real caliber of the stricture, providing a useful landmark for 
further treatment decisions.

As members of the reconstructive urology community and experts in the field of urethroplasty, it is our duty not only 
to discover new surgical techniques[1] but also to provide advice that can change our daily practice to the advantage 
of our patients. In this regard, we are honored to share our view of the correct management of patients with urethral 
stricture. We believe the assessment of patients with urethral stricture starts with the appropriate and judicious 
evaluation of the urethra. In a patient complaining of poor flow, when the urethrogram shows a narrowing along 
the urethra, the choice of the right endoscopic instrument for inspection is pivotal. Based on our long experience of 
urethroplasty and urethral disease management, we recommend the use of a small caliber ureteroscope to inspect 
the urethra. Specifically, a 6/7.5Ch ureteroscope; the first digit refers to the size of the ureteroscope at the tip and the 
second to the size of the instrument at the base.

The normal caliber of the bulbar urethra is 30Ch[2], which means that the diameter is around 1cm. A resectoscope, 
which is commonly adopted for transurethral resection of the prostate, is 26Ch, and f lexible cystoscopes are 
approximately 16Ch. According to Smith et al.[3], urethral strictures become symptomatic (ie, require dilatation and 
antibiotic treatment) when the urine flow is below 7mL/min, which corresponds approximately to a urethral caliber 
below 16Ch. In other words, when patients come for initial evaluation, the urethral lumen, at the level of the stricture, 
typically does not allow “common” instruments to go across the stricture (Figure 1).

This is an open access article under the terms of a license that permits non-commercial use, provided the original work is properly cited.  
© 2021 The Authors. Société Internationale d'Urologie Journal, published by the Société Internationale d'Urologie, Canada.

Key Words Competing Interests Article Information

Small caliber instrument, education, urethra; 
ureteroscope, reconstructive urology

None declared. Received on April 21, 2021 
Accepted on May 19, 2021 
Soc Int Urol J.2021;2(4):259–263

DOI: 10.48083/NVKO4969

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Kulkarni’s �ow-chart for
bulbar urethral stricture

1) Post-TURP
2) Obese patients

3) Young sexually active male

Redo-case with stricture >7ch

Circumferantial mobilization and
Barbagli dorsal or ventral onlay

In complex
cases

In 
straightforward

cases
Stricture > 3Ch Kulkarni one-side dissection

with dorsal onlay BMG

Asopa

Ventral Onlay

Urethral stricture length <5mm:
• mucosa-to-mucosa anastomosis
 with/without opposite side BMG
 augmentation

Urethral stricture length 5 -15mm:
• double face augmented BMG
 urethroplasty
• augmented non-transecting
 anastomotic urethroplasty

Augmented
anastomotic
urethroplasty

Urethral 
stricture 
length 
>15mm

2-stages

Graft + Flap

If
failure

Non-traumaticObliterated stricture
(<3Ch)

Anastomotic urethroplastyPost-traumatic

Different sizes of bulbar urethra

30Ch 26Ch 16Ch 7Ch 3Ch

Guidewire

Resectoscope

Flexible cystoscope

Small caliber
ureteroscope

(6/7.5Ch)

0Ch

FIGURE 1. 

The choice of the correct instrument according to the different sizes of urethra. Kulkarni’s flow chart  
for urethroplasty techniques according to stricture characteristics 

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The 6/7.5Ch ureteroscope was introduced into 
urological practice more than 10 years ago. Since then, 
it has been employed mainly for stone management[4] 
and/or pediatric urolog y[5], and its use has not 
been popularized among reconstructive urologists. 
Nonetheless, we believe that small caliber ureteroscope 
should become the gold standard for the inspection of the 
urethra in patients referred for stricture management. 
First and foremost, it decreases the risk of injuring the 
urethra. Indeed, the 6/7.5Ch ureteroscope allows the 
surgeon to navigate the urethra away from the urethral 
walls, preventing accidental injury of the mucosa. It 
also avoids trauma to the surrounding spongy tissue, 
preventing over-distension and stretching. Second, 
a sma ll ca liber ureteroscope may a llow close-up 
visualization of the stricture and may enable visualization 
across the length of the stricture. This second aspect is 
very important, especially for planning the subsequent 
t reat ment. Indeed, ret rog rade a nd a nterog rade 
urethrograms may underestimate the real complexity 
of the stricture (Video 1). In particular, retrograde and 
anterograde urethrograms may not always give a realistic 
representation of either the extension or the severity of 
the urethral stricture. Moreover, urethrograms do not 
provide information on the status of the mucosa across 
and in proximity to the stricture (Figure 2). Assessing 
the real length of the stricture and the status of the 

surrounding mucosa is pivotal in patients with lichen 
sclerosus or any non-traumatic etiologies, which may 
involve longer segments of the urethra. Surgical decision-
making may change considerably depending on the 
length of the stricture or the aspect of the forthcoming 
urethral mucosa. For instance, the choice of end-to-end 
anastomosis, augmented urethroplasty, or stricturoplasty 
can be made only with knowledge of the extension of the 
stricture and the status of the urethra before and after the 
stricture. This vital information can be acquired only with 
a full inspection of the urethral lumen. In our experience, 
the estimation of stricture length is more accurate when 
it is carried out with the endoscopic view rather than 
urethrograms. Indeed, the endoscopic findings more 
frequently match with the surgical view. Only with the 
use of these small caliber instruments does the surgeon 
have the advantage of a comprehensive evaluation of the 
urethra for planning the correct treatment. Third, only 
small ureteroscope may give access to false passage or 
fistulae encountered during the inspection of the urethra 
with minimal risk of extravasation or perforation. The 
latter is extremely important in patients referred for 
redo surgery, pelvic fracture urethral injury, or stricture 
related to infection with concomitant abscess. Fourth, 
with a small caliber ureteroscope it is possible to cross the 
stricture reaching the proximal urethra and the bladder. 
This opportunity is of paramount importance, especially 

VIDEO 1. 
Patient with distal anastomotic stenosis after dorsal onlay BMG urethroplasty. The 6/7.5Ch ureteroscope  
was able to cross the stricture and to allow the inspection of the proximal urethra

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to rule out the presence of stones or neoplasms, which 
can radically change the management of the patient. 
The use of small caliber ureteroscope is particularly 
advantageous in female patients. To rule out the presence 
of stricture in women, the inspection of the urethra must 
be carried out with great care and attention because the 
female urethra is short, poorly distensible, and has great 
mobility. Larger caliber instruments are inappropriate 
for this task because they do not allow a comprehensive 
evaluation of the length and severity of the stricture. 
Indeed, larger caliber instrument may be unable to enter 
the meatus when fibrotic or, when the stricture is more 
proximal, they may overstretch the urethra, hiding 
the presence of the stenosis and its extension. Last but 
not least, small caliber instruments provide a useful 
calibration of the urethral lumen to determine the most 
appropriate urethroplasty technique. According to our 
personal flow chart (Figure. 1), a stricture which allows 
only a 6/7.5Ch ureteroscope can be approached with 
augmented urethroplasty following the Barbagli[6] 
or Kulkarni[7] principles. Conversely, an obliterated 

or semi-obliterated stricture (<3 Ch) can be repaired 
with anastomotic urethroplasty when secondary to 
trauma, or with non-transecting approaches (including 
double face[8], mucosa-to-mucosa[9], augmented non-
transecting anastomotic urethroplasty[10]), graft plus 
flap or two-stage urethroplasty when secondary to non-
traumatic etiologies. Finally, we acknowledge that the 
use of small caliber ureteroscope can be challenging at 
the beginning because of the difficulties of handling and 
maneuvering this long and thin instrument, as well as 
the suboptimal view. However, we believe that the great 
benefit derived from its use justifies the effort needed for 
the learning curve.

In summary, we suggest that all reconstructive urologists 
dealing with urethroplasty consider discontinuing the 
use of flexible or rigid cystoscopes with caliber above 
16Ch. Instead, we recommend they embrace a small 
caliber ureteroscope (6/7.5Ch) for the evaluation of the 
urethra in patients, male or female, with a confirmed or 
suspected diagnosis of urethral stricture, before surgery.

FIGURE 2. 
Examples of retrograde urethrograms where length and characteristics of the strictures cannot  
be assessed without endoscopic inspection

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References
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5SIUJ.ORG SIUJ  •  Volume 2, Number 4  •  July 2021

The Right Instrument for the Right Purpose: Spreading the Use of Small Caliber Ureteroscope

https://link.springer.com/book/10.1007%2F978-1-4614-7708-2
https://link.springer.com/book/10.1007%2F978-1-4614-7708-2
https://link.springer.com/book/10.1007%2F978-1-4614-7708-2
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https://doi.org/10.1111/j.1464-410x.1966.tb09783.
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https://doi.org/10.1159/000475032
https://doi.org/10.4103/0970-1591.74454
https://doi.org/10.4103/0970-1591.74454
https://doi.org/10.1016/j.eururo.2013.05.046
https://doi.org/10.1111/j.1464-410X.2009.08590.x
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https://doi.org/10.1016/j.urology.2011.12.008
http://www.siuj.org



