Complex urethral strictures in men are one of the most difficult problems in urology because of the complexity of the local lesions and the specificity of the urethral anatomy, the difficulty of repair or reconstruction surgery, and the imbalance in the mastery of repair and reconstruction treatment techniques among medical units, the high failure rate of surgery and the many postoperative complications. With the progress of medical science and technology and the continuous development of medical devices, great progress has been made in its treatment, and the current treatment research is reviewed.
1.Definition
There is no definite definition of complex urethral stricture, but it is generally considered to be a complex urethral stricture if the following conditions are present.
(i) the length of the stricture exceeds 2 cm in the posterior urethra and 3 cm in the anterior urethra, which is often surrounded by scarring due to the mechanization of the pelvic floor hematoma;
(ii) complications such as stones, inflammatory polyps, diverticula, urethrorectal fistula, urethral skin fistula or periurethritis;
(iii) Dysfunction of the urethral sphincter;
④The presence of pseudo-ducts;
(⑤) severe pelvic deformity;
(6) Complicated osteomyelitis of the pubic bone;
(vii) High strictures close to the bladder neck;
(viii) More than two strictures.
2.Etiology
The etiology of urethral stricture includes trauma, inflammation, medical injury, congenital malformation, etc. Trauma is the main etiology of urethral stricture. In recent years, with the widespread development of transurethral surgery, the number of urethral strictures due to various medical operations such as transurethral electrodesis of the prostate, including indwelling catheters, has increased significantly and has become the second major cause of urethral strictures. Due to the early standardized application of effective antibiotics, urethral strictures due to gonorrhea are less common than before, while anterior urethral strictures due to sclerosing tinea (LS), also known as occlusive dry priapism (BXO), are on the rise.
3. Preoperative imaging
Perioperative estimation of the length of the stricture and the extent of the surrounding scar is an important basis for developing a treatment plan and assessing the healing process. A thorough preoperative examination should be performed for complex urethral strictures. Currently, urethrocystography is the most commonly used clinical diagnostic method for complex urethral strictures, but it can only reflect the situation in the urethral lumen and cannot show the urethral wall and its surroundings, and cannot measure the depth and extent of the urethral scar. Since the X-ray contrast does not adequately fill the entire urethra, the measured value is often smaller than the actual length of the stricture. If only X-ray contrast is performed before surgery, surgical exploration is usually required to decide which surgical procedure to choose.
Transrectal urethral ultrasound is also more commonly used for the diagnosis of urethral strictures. This test not only indicates the location and length of the stricture, but also provides a clearer understanding of the scarring around the stricture than urethral cystography, and has a higher diagnostic value for the display of the pseudo-tract. The ultrasound image shows an abnormal duct-like liquid dark area in the periurethral tissue communicating with the urethra. For urethra with multiple atresia, urethral ultrasound can be used to detect the urethra within the atretic segment.
Surgical treatment There are many surgical treatments for complex urethral strictures, including open surgical treatment as well as endoscopic treatment, to correctly estimate the length and extent of multiple strictures in the urethra, which can guide the use of normal urethra during surgery. Ultrasound of the urethra can also indicate fistulas, inflammatory masses, and urinary extravasation. Urethral ultrasonography is clearly superior to conventional X-ray urography in many ways, and because it is intuitive, inexpensive, painless, radiation-free, and reproducible, it should be included as a routine test for urethral strictures. Since X-ray urography still has greater value in the visualization of posterior urethral fistulae and pelvic deformities, combining urethral ultrasound imaging with X-ray urography can provide more comprehensive information about urethral stricture lesions.
MRI has the advantages of cross-sectional, coronal, and sagittal imaging in three dimensions, good tissue contrast, and no radiation, and can clearly show the layers of the urethral cavity and its surrounding structures, which is superior in locating the urethral stricture site, measuring the stricture length, and estimating the extent of scarring around the urethral stricture break, etc. MRI can show not only the scarring pattern but also the amount of scarring. With the continuous improvement of scanning technology, MRI has an irreplaceable role in showing the scar around the urethra and urethra that cannot be replaced by other diagnostic methods. [5]
The choice of procedure should be determined by the location and length of the stricture and the severity of the scar around the stricture, the number of previous urethral surgeries, and the presence of comorbidities. The surgical approach to urethral strictures has changed significantly over the past 50 years, mainly in the treatment of anterior urethral and extra-long segment urethral strictures, while the surgical treatment of posterior urethral strictures has changed little, but the difficulty of the surgical operation cannot be ignored, and complete excision of the urethra and its surrounding scar as well as achieving a tension-free anastomosis between the prostatic urethra and the bulbous urethra are the keys to successful surgery.
4.1 Anterior urethral autologous tissue replacement urethroplasty
4.1.1 Reconstruction of the urethra with a tipped penile or scrotal flap This procedure was first used in clinical practice and has the advantage of being easy to obtain and simple to perform. It is the first choice for stenosis of the penile segment or in cases where the blood supply to the urethral bed is poor, scarring is severe or local radiotherapy is performed, and free grafts are difficult to survive. However, the tissue contraction is large, the recurrence rate of stenosis is related to the length of time after surgery, and the long-term outcome is not satisfactory.
A common complication is urethral restenosis, the incidence of which is related to the length of time postoperatively. barbagli et al. reported immediate (21 months), intermediate (71 months), and long-term (111 months) success rates of 90%, 73%, and 66%, respectively, for penile skin flap bulb urethral replacement, with surgical efficacy decreasing with longer follow-up. The occurrence of this stenosis may be related to insufficient flap width, postoperative contracture, high tension during anastomotic suturing and inadequate drainage of exudate around the anastomosis, with fluid accumulation around the anastomosis causing local infection. The scrotal skin is wet skin, followed by sebaceous glands and hair, and the forming segment of the urethra is prone to hair growth, diverticulum formation and stones causing infection.
4.1.2 Free mucosal replacement urethroplasty
In 1998, Barbagli et al. established dorsal urethral substitution, which is a popular technique that allows reliable mechanical support of the graft from the penile corpus cavernosum, exact suture fixation, easy formation of new vessels, and no damage to the ventral urethral corpus cavernosum. 2001, Asopa et al [9] proposed a mosaic dorsal urethroplasty, in which the urethral cavity is dissected from the ventral side and the longitudinal median is fully dissected. The dorsal side of the urethra (urethral plate) of the stenotic segment is incised deep to the penile leukoplast, and the graft is sutured in the split urethral plate with a flat inlay.
The advantage of this procedure is that it is simple and does not require excessive freeing of the dorsal urethra, and is suitable for patients with severe adhesions between the dorsal urethra and the penile corpus cavernosum due to multiple direct visualization endourethrotomies (DVIU). There was no difference in terms of stricture recurrence, painful erection, but the incidence of urethral fistula formation, post-void drip, diverticulum formation and ejaculatory disorders was lower with dorsal implantation than with ventral implantation.
Urethral substitution options.
(1) bladder mucosa: bladder mucosa has the advantages of easy retrieval, adequate material, regenerative power and resistance to infection, and its main complications are the tendency to cause stricture of the reconstructed urethral orifice, mucosal prolapse and granulomatous reaction. kinkead et al [11] reported long-term follow-up after 95 cases of complex urethral reconstructive surgery using bladder mucosa, resulting in 63 cases (66%) with complications and 21 cases requiring reoperation. Secondly, the bladder mucosa cannot be utilized for those who have a history of bladder surgery, inflammation and edema of the mucosa, especially in those with long-term cystostomy.
(2) Oral mucosa (including buccal mucosa and lingual mucosa): for bulbous urethral stricture, with well-developed urethral spongiosa and rich blood supply, it is generally advisable to choose intra-oral mucosal urethroplasty, which has the advantages of simple operation and does not affect the appearance of the penis. Also in the case of urethral strictures after failed surgery for sclerosing tinea (LS) or hypospadias, where no penile flap is available, intraoral mucosal urethroplasty can be considered. The greatest advantage is the thick epithelial cell layer, strong tissue toughness, good abrasion resistance, strong resistance to infection, and less trauma to the patient. However, oral mucosa is difficult to use as a graft for complex or long urethral strictures or atresia urethral reconstruction because of the limited source of material.
(3) Colonic mucosa: For extra-long segment urethral strictures or atresia ≥12 cm, one-stage colonic mucosal urethroplasty or other graft combination graft urethroplasty can be considered if the scar is completely excised and the urethral bed is in good condition [12]. This method provides a new route for the treatment of long segment urethral strictures, but this surgical approach requires open resection of the sigmoid segment, which is surgically invasive and increases the possibility of intestinal complications. Therefore, this method should not be the preferred method and the indications should be strictly controlled.
4.1.3 Intestinal reconstruction of the urethra In recent years, the use of intestinal tubes for the repair of complex urethral strictures has been reported in the literature, and Bales et al. used a section of free jejunum with a vascular tip, which was cut and grafted to the vulva to reconstruct the urethra by microsurgical techniques.
However, this method is time-consuming and difficult to perform, and requires the operator to have experience in microvascular anastomosis, which will lead to necrosis of the transplanted intestinal segment if the anastomosed vessel becomes diseased. Secondly, the morphology of the lumen of the urethra reconstructed with the intestinal segment as shown in the voiding radiograph still shows a circular folding of the intestine, which may become a factor of urinary obstruction in the future.Lee et al. treated a case of complicated posterior urethral stricture by transferring a segment of sigmoid colon with a vascular tip to the vulva and replacing the urethra after narrowing the lumen. However, the morphology of the lumen of the urethra reconstructed with the intestinal segment as shown in the voiding phase film still showed a circular fold of the intestine. In practice, it is difficult to transfer the sigmoid colon with a vascular tip to the vulva to replace the urethra, so this method is difficult to implement in most patients.
4.1.4 Extended urethral anastomosis (AAU) The recently developed extended urethral anastomosis is a surgical approach between end-to-end urethral anastomosis and urethral replacement. It emphasizes the dorsal or ventral urethral anastomosis after resection of the stenotic segment of the urethra and the urethral substitution on the contralateral side of the anastomosis. This procedure allows for the removal of longer stenotic segments of urethra (up to 3 cm), and the size of the oral mucosal graft can be reduced by dilation.
El-Kassaby, A.W. et al [16] reported 234 cases of longer bulbar urethral strictures (mean 4.2 cm) treated with urethral expansion anastomosis with a mean follow-up of 36 months and a cure rate of 93.7%, suggesting that urethral expansion anastomosis is suitable for longer bulbar urethral strictures. It is believed that urethral extension anastomosis is suitable for longer segmental bulbar urethral strictures.
4.2 Treatment of complex posterior urethra
4.2.1 Transepithelial route The ideal treatment for posterior urethral strictures is a complete resection of the stricture followed by a tension-free anastomosis of the two dissected ends. Most patients with posterior urethral strictures can be repaired transconjunctivally. However, it is limited by the length of the stenosis or atresia and is indicated for stenosis segments up to 2 cm in length.
4.2.2 Transperineal joint pubic route In recent years, the transperineal joint infrapubic resection route has been widely used for the treatment of various complex posterior urethral strictures (atresia). This approach significantly enlarges the posterior urethral surgical field and makes the excision of the posterior periurethral scar and end-to-end urethral anastomosis easier to perform [17]. In addition, this surgical pathway is particularly suitable for pediatric patients, as resection of the inferior pubic rim does not affect the development of the pelvic ring in children and avoids the occurrence of chronic low back pain and gait instability after partial resection of the pubic bone.
Posterior urethral stricture combined with urethrorectal fistula makes the condition more complicated and the clinical management is extremely difficult. For low-grade urethrorectal fistula, the trans-perineal inferior pubic rim resection approach should be used as far as possible. This approach not only fully exposes the posterior pubic space, but also does not destroy the stability of the pubic ring, with little surgical trauma and few postoperative complications, and should be the preferred surgical approach for posterior urethral stricture combined with urethrorectal fistula.
However, this procedure is more complicated and has the possibility of complications such as osteomyelitis of the pubic bone, postpubic infection and sexual dysfunction. Therefore, this procedure is only indicated for the treatment of refractory complex posterior urethral strictures or atresia. In individual cases such as long-segment complex posterior urethral atresia combined with high and large urethrorectal impotence, a trans-perineal combined trans-pubic route can be chosen to obtain good exposure. If the urethral length is insufficient after scar resection, in addition to applying the transcubital for urethral anastomosis method, a scrotal flap with O is advisable for one-stage urethroplasty with two broken ends joined by anastomosis. The skin incision should be designed and the flap site should be predetermined before surgery. For extensive urethral defects, a posterior urethrostomy and staged urethroplasty are appropriate.
4.2.3 Urethrorectal fistula repair via the rectal sphincter (York Mason procedure) This procedure is more commonly used in clinical practice. In the past, transverse colostomy was performed first, and the fistula hole was repaired in the second stage. In recent years, it is believed that the York Mason procedure can be performed in patients with urorectal fistula in the following cases.
(i) medically induced injuries, especially in small fistulae due to prostatectomy;
Renschler et al. reported a group of 24 cases, 22 of which were repaired successfully, with colostomy in the early cases and without colostomy in the later 11 cases, and the surgery was completed in one stage. There was one postoperative failure in both groups. This procedure was considered to be the ideal route for the treatment of urethrorectal fistula, with the advantages of high success rate, adequate exposure, rapid recovery, and few complications.
4.2.4 Urethral drag-in This method was first used by Solovov in 1932 to treat traumatic posterior urethral strictures. Yu Gang et al. concluded that the indications for urethral drag-in surgery are.
(i) posterior urethral stricture or atresia of 3 to 5 cm in length;
(ii) posterior urethral stricture of 2 cm or more, combined with perineal or scrotal urethral fistula, which can be treated simultaneously with this procedure;
(③Severe pelvic fracture and pelvic deformation, although the stenosis segment is short, but the endoscopic treatment is ineffective for 2 times. In 32 cases of traumatic posterior urethral stricture or atresia treated with this method, with follow-up from 1 to 9 years, 28 cases had urination, 3 cases were treated with recent urethral dilation, and 1 case failed. It is believed that urethral tow-in surgery is a more ideal method for the treatment of complex posterior urethral stricture because of its simple operation, small damage, precise efficacy, and no effect on sexual function.
4.3 Intracavitary surgery treatment Because of the large damage, high difficulty and poor efficacy of open surgery, various invasive treatments will also form new scars, which will affect the treatment effect. Therefore, intracavitary treatment with less trauma, fewer complications and repeatable operations is currently attracting attention. The indications for direct visualization endourethrotomy (DVIU) have been expanding in recent years. It is now believed that, except for urethral tumors and extensive urethral strictures, this method can be used in all cases where the ureteral catheter can be passed through the strictured segment into the bladder, even in complex cases such as long segments of urethral strictures or atresia and combined pseudo-ducts. For severe urethral strictures, endourethrotomy can also be used for those who can be guided by indigo carmine or melphalan, trans-pubic metal urethral probes, and suprapubic cystoscopy. However, with the expansion of indications, the overall efficacy of endoluminal treatment has decreased.
4.3.1 Simple endourethrotomy Since 1972, when saches first applied cold knife endourethrotomy under direct vision, most scholars now believe that it is safe and reliable, and can be repeatedly performed. Greenwell TJ et al. concluded that initial endourethrotomy or urethral dilatation with recurrence of stricture treated with urethroplasty is the most economical and clinically optimal treatment strategy.
4.3.2 Cold knife endourethrotomy combined with urethral electrodesiccation Transurethral electrodesiccation can adequately remove the scar tissue around the urethra, but its thermal damage is large, the cutting accuracy is not high, and it is also easy to damage the urethra and normal tissues. Zhu Lijie et al [24] concluded that electrodesiccation with its high temperature of 300°C to 400°C produces deeper thermal penetration, which can cause different degrees of thermal injury to the periurethral tissues, resulting in tissue necrosis, which in turn induces the production of certain fibrous scar tissue, prompting tissue fibrosis and stricture recurrence, and the excessive necrotic tissue on its cutting surface is also not conducive to the crawling coverage of the urethral mucosa. Some scholars have placed urethral stent support at the stenosis site after endourethral incision or electrodesiccation, which can effectively prevent stenosis recurrence, but complications such as urinary incontinence, stent displacement or dislodgement, stent luminal obstruction and stone, urethral infection and bleeding may occur, and its effect remains to be observed.
4.3.3 Laser surgery and bipolar plasma cutting
(1) Laser surgery laser treatment of urethral stricture began in 1977. The basic principle is that the laser eliminates the stricture scar through the destruction of the thermal effect produced. At present, there are four main types of laser treatment for urethral strictures in China: neodymium: yttrium aluminum garnet laser (Nd: YAG), holmium: yttrium aluminum garnet laser (Ho: YAG), potassium titanium oxide phosphate: yttrium aluminum garnet laser (KTP: YAG), and semiconductor laser. Laser surgery has unique advantages over other intracavitary treatments in terms of performance and operation, i.e., good vaporization hemostasis, clear surgical field; easy control of the laser fiber handle, easy to master operating technique, few complications, low stenosis recurrence rate, and repeatability are considered as the preferred method for the treatment of urethral strictures. Liu et al. concluded that transurethral green laser scar vaporization for the treatment of urethral stricture, compared with endourethral stricture incision and electrodesiccation for the treatment of urethral stricture, has equivalent recent efficacy, but with high safety, low recurrence rate, and shortened patient hospital stay, but its long-term efficacy is yet to be further studied.
(2) Advantages of bipolar plasma cutting system As a new type of urological intracavitary low-temperature cutting system, this procedure not only makes up for the defects of incomplete removal of tissue by ordinary cold knife incision, but also overcomes the drawbacks of thermal damage by monopolar electrodes, and is superior to the treatment of urethral stricture in terms of high efficiency, safety, few complications and low recurrence rate of stricture. Dong Xuzhe et al. believe that it can be the preferred surgical method for the treatment of urethral strictures and atresia, and the bipolar plasma columnar electrode is small and has a certain hardness, which can be guided like a catheter to find the small stenosis or the central part of the atretic urethral stricture and move freely in the narrow urethra, and can reach into the narrow urethra to accurately vaporize and cut the scar tissue. Although laser beam and bipolar plasma cutting have many advantages, they cannot avoid scar regeneration and adhesion formation, and regular postoperative urethral dilatation is required to prevent recurrence of stenosis.
5. Summary and outlook
Urethral stricture, especially complex urethral stricture, is still a common and difficult disease in urology. The treatment level of urethral stricture varies around China and is not yet standardized. Improper treatment in the early stage often leads to increased difficulty in subsequent management and also results in a huge waste of medical resources. Therefore, it is significant to establish relevant guidelines for the diagnosis and treatment of urethral diseases as early as possible. In addition, there is a lack of case-control, prospective randomized controlled clinical studies on the treatment of urethral stricture, and there is no evidence of evidence-based medicine for its treatment, which is also an urgent issue to be addressed.