J. Donald,

Jennifer

Stricture

FRCR

David

#{149}

Disease:

Self-expanding metal stents are emerging as an effective alternative treatment in the management of urethral obstruction. The radiologic studies of 33 men with anterior urethral strictures (subprostatic, n = 11; bulbar, n = 22) that had recurred despite repeated optical urethrotomy and dilation were reported. In all patients, the stricture was successfully treated with stent insertion. Urethrography performed 1 month later in 19 patients showed an irregular intrastent lumen of varying degrees due to a hyperplastic urothelial reaction confirmed at endoscopy the same day. Available follow-up urethrograms in seven patients at 3 months showed that the hyperplasia was settling, and by 6 months, the intrastent lumen was smooth and of good caliber. Urethrography revealed postoperative strictures in 14 patients. Strictures seen at 1 month (n = 6) were due to initial stent misplacement and were treated with the insertion of a second stent. Strictures seen 3 months after insertion (n = 4) occurred within the stent lumen and were considered to be significant at endoscopy in only one patient. Strichires that developed 6-12 months after stent insertion (n = 4) were not within the stent and were considered to represent genuine new strictures. Index

terms:

Genitourmnary

ses, 842.469

dure,

Urethra,

#{149}

842.1299

system,

interventional

Urethra, radiography, #{149} Urethra, stenosis or obstruction, #{149}

prostheproce-

842.123,

843.123 842.29,843.29 Radiology

1

1991;

180:447-450

From the Departments

of Radiology

(J.J.D.,

D.R.) and Urology (E.J.G.M.), Middlesex Hospital, Mortimer St, London WiN 8AA, England. Received January 14, 1991; revision requested February 21; revision received and accepted March 27. Address reprint requests to DR. 0

RSNA,

1991

Rickards,

FFRDSA,

FRCR

Radiology

U

Euan

#{149}

J. C.

strictures are a common problem. Endoscopic and reconstructive urologic procedures are well tried and successful, albeit invasive. Urethral dilation and endoscopic optical urethrotomy are often curative, but recurrent strictures are common. Open surgical urethroplasty is usually successful in the treatment of traumatic strictures but is less successful for strictures that are infective or iatrogenic in origin. Therefore, the requirement for new techniques remains. Balloon dilation performed with radiologic control has been advocated by some workers, but only a few cases, with limited follow-up, have been reported (1,2). In 1985, a new stent (Urolume or Minnetonka,

American

FRCS

ofUrethral

RETHRAL

Wallstent;

Milroy,

Medical

Systems,

Minn) was developed originally for endovascular use. The stent has been shown to be successful in the prevention of restenosis after transiuminal angioplasty in both the peripheral arterial system and coronary arteries (3,4). More recently, use of the stent has been described in the management of biliary obstruction (5), superior vena caval syndrome, and venous stenoses in dialysis shunts (6,7). Since May 1987, the stent has been effectively used in the treatment of urethral obstruction (8-12). The stent is woven in the form of a tubular mesh of fine corrosion-resistant superalloy and is manufactured in various lengths and diameters. For urethral strictures, unconstrained stent lengths of 2 or 3 cm with a diameter of 14 mm were used. The stent is flexible and self-expanding when released from its endoscopic delivery system. The expansile force of the mesh holds it against the wall of the urethra, allowing urothelium to grow over and through the implanted material while holding open the strictured area.

Stents’ MATERIALS

AND

METHODS

The radiologic studies of 33 men aged 30-88 (mean, 62) years who underwent placement of urethral stents were reviewed retrospectively by two radiologists OJ.D.,

D.R.).

All

the

patients

had

recurrent

anterior

urethral strictures treated previously by means of at least two optical arethrotomies and, frequently, many additional urethral dilations. Five patients had strictures that recurred after urethroplasty. Primary causative factors were catheter (n = 11), posttransurethral prostatectomy (n = 7), infection (n = 9), trauma (n = 3), surgery for urethral congenital anomalies (n = 2), and rectal tumor invasion (n = 1). Each patient gave informed consent. Before surgery, all patients underwent uroflowmetry and ascending urethrography from which the appropriate stent diameter and length were selected. In most patients, the stents were inserted by means of endoscopy performed with general anesthesia after dilation of the stricture. Optical urethrotomy was required for impassable strictures (n = 7), and with the associated bleeding of this procedure, subsequent urethral visualization was reduced. The internal diameter of the implanted stent was, in all cases, 14 mm, large enough to permit

required. performed

future

endoscopic

The procedure with

examination

as

was routinely

use of prophylactic

antibi-

otics for 48 hours. Repeated uroflowmetry, urethrography, and endoscopy were used to follow up all patients at 1 month and the majority at 3, 6, and 12 months after stent insertion. From the preoperative studies, the following details were recorded: the site, length, and position relative to the external sphincter of the urethral stricture and appearance of the remainder of the anterior urethra. The postoperative urethrographic studies were examined to assess the site and caliber of the stent and, if multiple, the relationship between stents; the appearance and diameter (calculated as a percentage of the stent diameter) of the intrastent urethra; any evidence of recurrence of stricture in the intrastent urethra and the relationship of the stricture, if present, to the original stricture; and the appearance of the extrastent urethra, any evidence of recurrence of stricture there,

447

and the relationship present,

to the

of the stricture,

original

if

stricture.

RESULTS All of the anterior urethral stnictunes have been successfully treated with stents irrespective of their lengths on degree of obstruction. In seven lapping cover

patients, more than one stent has been required the strictured areas.

overto

On the preoperative urethrogram, all patients had proximal anterior urethral (subprostatic, 11; bulbar, 22) strictures

of varying

lengths. There entire anterior tients,

severity

and

was irregularity urethra in seven

indicating

extensive

of the pa-

a. Figure

b. 1.

(a) Preoperative

larity of the remainder poststncture fusiform obtained after stent

covered

urethrogram

of the dilatation insertion

shows

anterior urethra is the result shows marked

a long

indicates of repeated hyperplasia.

bulbar

stricture

(arrow).

Slight

irregu-

more extensive disease. The slight urethral dilations. (b) Urethrogram The entire length of the stricture

is

by the stent.

disease

with a stricture as the focal presenting problem (Fig 1). Maximal flow rates ranged from 1 to 17 mL/sec (mean, 8 mL/sec).

In 19 patients, the postprocedural urethrogram obtained at 1 month showed irregular narrowing of the intrastent tween

16%

lumen, and

with 100%

a diameter beof the stent diat the time that

ameter. It was noted even in the cases of marked apparent narrowing, the contrast agent flowed with unexpected ease through the stent

into

rate

the

bladder.

The

mean

peak

of flow

measured with uroflowmetry was 8-30 mlJsec (mean, 22 mIJ sec). In these cases, endoscopy performed the same day revealed a hyperplastic urothelial reaction, through which the cystoscope easily pass. Further follow-up

would ure-

thrograms were available in seven of these patients, and the intrastent lumen became smooth at 6 months (Fig 2) and remained so at 1 year. Peak flow rates were unchanged.

In 14 cases, the was smooth from mained

so, with

intrastent the outset no

evidence

“hyperplasia” either phy or at endoscopy 3). Flow rates improved erative maximal flow mean postoperative rate at 1 month, 14.5 pearances unchanged

Postoperative

and

remained in eight

were

pa-

seen

1 month in six patients, was due to initial of the stent, which did original stricture. No preoperative and post-

448

Radiology

#{149}

patients

shows mild intrastent hyperplasia, (b) and remained unchanged at 1

at 12

operative flow rates was seen. These strictures were subsequently successfully treated with additional stents

(Fig 4). Four

2. (a) Follow-up urethrogram obtained at 1 month became smooth at 6-month follow-up urethrography

of

in five

strictures

in 14 cases. At this stricturization misplacement not cover the change in the

Figure which year.

at urethrograat 1 month (Fig (mean preoprate, 6.5 mL/sec; maximal flow mljsec). The ap-

and flow rates at follow-up

tients at 6 months months.

lumen and re-

a.

developed

in-

.;.

a.

Figure infection. smooth

b.

3.

(a) Preoperative

(b) Urethrogram with no hyperplasia.

urethrogram obtained The

shows

1 month appearance

a long after was

bulbar

surgery identical

urethral shows the at 1 year.

stricture intrastent

secondary urethra

August

to is

1991

a. Figure stricture months

b. 4.

(a) Preoperative urethrogram shows persists (solid arrow) because of stent after insertion of a second, overlapping

C.

a short bulbar stricture (arrow). (b) In a postoperative urethrogram obtained at 1 month, the misplacement, and intrastent hyperplasia is seen (open arrow). (c) In a urethrogram obtained stent that now covers the initial stricture, there is a smooth intrastent lumen with no hyper-

6

plasia.

(14,15),

and

stricture

disease.

Balloon

dilation of urethral strictures has been successful, and only limited

not suc-

cess

of

has

been

claimed

for

the

use

balloons in prostate outflow obstruclion (16). The success of the metal stent for stricture disease is dependent on milial accurate placement of the stent across the stricture. During our early experience, the stent was occasionally misplaced, requiring an additional overlapping stent to successfully complete the treatment. Now, with the introduction of a new delivery system, it has been possible to reposition

the

stent

With

a. Figure urethral the site

scope namic

b. 5.

(a) Preoperative

urethrogram

shows

a short

bulbar

dilations. (b) At 3 months, there is considerable of the original stricture. The patient’s flow rate

easily passed or cystoscopic

through this area, grounds. Biopsy

the narrowing of the narrowed

stricture

narrowing was much

resistant

of the improved,

been found misplaced,

to repeated

intrastent and,

lumen at as the cysto-

was not considered significant area revealed hyperplasia.

before

and

trastent narrowing at the site of their original strictures at 3 months, the appearances of which were different from the hyperplastic urothelial reaclion. These intrastent narrowings were considered unimportant (n = 3) (Fig 5) or important (n = 1) (Fig 6) on the basis of findings at uroflowmetry and cystoscopy. Genuine “new” strictures

were

observed

in four

Volume

resolved

180

within

Number

#{149}

6 months.

2

incontinence

due

to a small

urine remaining within the the stent (Fig 7), and urinary tions.

In no

patient

ten function

was

volume

lumen infec-

distal

of

of

sphinc-

compromised.

patients:

proximal to the stent in three patients and distal to it in one. Postprocedural complications have all been minor and, in most, completely

They included transient discomfort at the site of the stent, intermittent hematuria, postmictunlion dribbling

DISCUSSION Expanding in use

for

obstruction (13),

detrusor

metallic the

treatment

due

stents

are now

of outflow

to prostatomegaly

sphincter

dyssynergia

it has

that if the stent it can be removed

was

months after urothelial

frequently

observed

the lumen of the of both radiology

copy.

This

is initially easily

correctly.

the first few a hyperplaslic

response

within means

deployment.

experience,

replaced

During placement,

on urody-

its final

increasing

response

stent and

was

by endos-

initially

a

cause for concern, as the appearances were suggestive of recurrent obstruction. It then became apparent that the response

is a common

which

completely

variable

period

phenomenon,

resolves

after

(usually

the

within

months),

once

has been urothelium.

completely covered It is interesting

intrastent

a 4-6

urethra with that de-

spite the apparent narrowing at urethrography, contrast material flowed freely proximally into the bladder and results

tory.

of uroflowmetry

The

degree

were

satisfac-

of hyperplastic

re-

Radiology

449

#{149}

7

SS_

5%

4 a.

b.

Figure 6. (a) Urethrogram a urethroplasty. (b) A stent ated because of recurrence

sponse most

was marked

had

variable but in patients

a number

appears to be who have

of previous

procedures

who

shows a tight bulbar stricture (arrow) that developed was placed in the stricture, but the intrastent lumen of stricture.

and,

urethral

in particular,

underwent

those

urethroplasty

(Ta-

ble).

Four patients have had recurrent intrastent narrowing at the site of their original strictures, but in only one of these patients has this been considered

to be significant

ative flow 19 mljsec;

rate, 5 mljsec; at 3 months,

Cystoscopy

was

used

In those

sertion

of an

knowledge sponse and

(preoper-

clinical reserve

an

intrastent narrowing due to fibrous tissue, which was excised. In the other three, the findings at endoscopy and

aminations

uroflowmetry remained (mean preoperative peak

References

mI.Jsec; 17.5

postoperative There

mlisec).

between

the cause

satisfactory flow rate,

7

no

of the

correlation

stricture

its previous treatment and lence of intrastent narrowing.

the

developed

or

four

patients

who

new stent,

strictures disease

near the ends of the was evident throughout

that

“new”

strictures

are

riod

was

Use

new

and

too

short

of urethral

development

of recurrent

urethral

our experience has We do not propose stent thral

the

follow-up is an

in the

in the

preoperative

6.

7.

and

for uneis essential

assessment

of pa-

Radiology

#{149}

of the variable in association

for

Causes of Appearances

Hyperplasia Catheter

can with

Infection Posttransurethral

resection Trauma Congenital Tumor invasion

patient. We now radiologic ex-

patients

with

failures.

*patieflts

clinical

H, PuelJ, Joffre F, et al. Selfendovascular prosthesis: an exstudy. AJR 1987; 164:709-714.

Sigwart U, PuelJ, Mirovitch V. Joifre F, Kappenberger L. Intravascular stents to prevent occlusion and restenosis after transluminal angioplasty. N EnglJ Med Dick R, Gillams

A, Dooley

JS, Hobbs

hires: stent.

11.

12.

8.

EJG,

Chapple

A new treatment

13.

9.

Lancet Milroy

H. 10.

CR,

1989;

JE, et al.

strictures. A, Wallsten

for the treatment

thral strictures. BrJ Milroy EJG, Chapple

A new treatment

5(1*) 5

4(1*)

4 2 (2*)

3 1

2 1

0 0

undergone

a permanently

6(1*)

urethroplasty.

15.

16.

implanted

urethral

P, Rous-

seau H, Eldin A, Wallsten H. Proth#{232}se endo-ur#{233}thrale “wallstent” dans les st#{233}nosesr#{233}cidivantes de l’ur#{232}thre. Ann Urol (Paris) 1989; 23:383-387. Sarramon JP, Joifre F, Rischmann P. Rousseau H, Eldin A. Use of the Wallstent en-

prosthesis

in the treatment

of

recurrent urethral strictures. Eur Urol 1990; 18:281-285. Chapple CR, Milroy EJG, Rickards D. Permanently implanted urethral stent for prostatic obstruction in the unfit patient: preliminary report. BrJ Urol 1990; 66:5865. Shaw PJR, Milroy EJG, Timoney AG, Eldin A, Mitchell N. Permanent external sin-

ated sphincter

167:727-

Cooper

1988; 1:1424-1427. EJG, Chapple CR, Eldin

A new stent

14.

with expand-

for urethral

had

(n=14)

J Urol 1989; 141:1120-1122. Sarramon JP, Joffre F, Rischmann

dourethral

EF.

Stainless steel mesh stents for biliary strictures. J Intervent Radiol 1989; 4:95-98. Gunther RW, Vorwerk D, Bohndorf K, et al. Venous stenosis in dialysis shunts: treatment with self-expanding metallic stents. Radiology 1989; 170:401-405. Putnam JS, Uchida BT, Antonovic R, Rosch

728. Milroy

who

Smooth

(n=19)

#{149}

1988; 31:231-233.

Rousseau expanding perimental

Postoperative

e and

Cause

normal rewith the

or late

Strictur

Postoperative Appearance

The

Mohammed SH, Wirima J. Balloon catheter dilatation of urethral strictures. AJR 1988; 150:327-330. Daughtry JD, Rodan BA, Bean WJ. Balloon dilatation of urethral strictures. Urol

H.

450

irregu-

stent.

J. SVC syndrome treated able wire stents. Radiology

management

strictures,

as a primary treatment strictures. Radiology

5.

exciting

been encouraging. the use of the

attenu-

Figure 7. Cystogram shows that a small amount of contrast material remains within the stent lumen at interruption of micturition. This pooling can result in postmicturition dribbling.

1987; 316:701-706.

pe-

for assessment. stents

4.

likely

to develop as part of the natural history of extensive urethral disease. These strictures were treated with urethrotomy,

overlapping

state of the postoperative

Radiol 3.

genuine

the length of the anterior urethra on the preoperative unethrogram. We believe that it is in this group of patients

1.

2.

prevaIn the

with

after stent placement if not interpreted

complications

at 3 months, was

patients

is very

after

larity of the entire anterior urethral urothelium, new strictures are likely to appear as a natural expression of the disease process. It is interesting that they seem to do so near the stent and can thus be treated with the inappearances be misleading

at 1 month, 8 mljsec). to confirm

tients.

5 years

nal injuries. Mclnerney Stephenson stents for BrJ Urol McLoughin Machann prostatic Urol 1991;

stents

in patients

with spi-

BrJ Urol 1990; 66:297-302. PD, Vanner TF, Harris SAB, TP. Permanent urethral detrusor sphincter dyssynergia. 1991; 67:291-294.

J, Keane

PF, Jager R, Gill KP,

L, Williams G. Dilatation urethra with 35 mm balloon. 67:177-181.

of the Br

August

1991

of ure-

Urol 1989; 63:392-396. CR, Eldin A, Wallsten

for urethral

stric-