The efficacy of urethral stricture is significantly better than before. For anterior urethral strictures, the current clinical application of oral mucosal urethroplasty has satisfactory results and is recognized as the gold standard for the treatment of anterior urethral strictures. However, for long anterior urethral strictures, the oral mucosal graft selection is long and the procedure is quite complicated. For the treatment of posterior urethral stricture (or atresia), end-to-end anastomosis with stenosis segment excision is the standard procedure, but for complex posterior urethral strictures, the long stenosis segment, more local scarring, deeper field location, and unclear local anatomical levels increase the surgical difficulty. This article focuses on the considerations and technical points of the relevant techniques.
In recent years, the treatment of urethral strictures has entered a stage of rapid progress, and the efficacy has improved significantly compared to the previous ones. In the case of anterior urethral strictures, the lack of local replaceable tissues makes it more difficult to treat, and the use of oral mucosa for urethral repair is increasingly reported in clinical practice, with satisfactory recent follow-up results, and is recognized as the gold standard for the treatment of anterior urethral strictures. However, for long anterior urethral strictures, the selection of oral mucosal grafts is long and the procedure is quite complicated. For the treatment of posterior urethral stricture (or atresia), stenosis segment excision and end-to-end anastomosis is the standard procedure, but for complex posterior urethral strictures, the difficulty of surgery is increased by the long stenosis segment, more local scarring, deeper location of the operative field, and unclear local anatomical levels [1]. The technical problems of this complex type of surgery are briefly described in this paper.
1. Surgical treatment of anterior urethral stricture: oral mucosal urethroplasty
The epithelial layer of the oral mucosa is thick, rich in elastic fibers, and the intrinsic layer is thin and very tough, with good tissue elasticity and strong resistance to staining, suitable for survival in a wetter environment. At the same time, the oral mucosa is easy to retrieve, and the buccal mucosa, tongue mucosa and lower lip mucosa can be retrieved simultaneously on both sides, and these characteristics make it a more ideal alternative to the urethra [3].
The specific surgical steps are as follows [2].
(1) Anesthesia and position: general anesthesia with transnasal tracheal intubation in the flat or truncated position.
(2) Urethral stenosis incision: A straight incision was made through the penis, scrotum or perineum according to the site of urethral stenosis, and the fascia was incised layer by layer to the surface of the urethral corpus cavernosum of the stenosis, and an F5-7 ureteral stent tube was placed in the urethra as a guide to incise the urethra, and the urethra of the stenosis was incised ventral or dorsal longitudinally and extended to the normal urethral mucosa at 0 or 5 cm at both ends, and the length of the stenosis was measured with a scale. The urethral incision wound was covered with saline wet gauze. The surgery was transferred to the oral region to take the oral mucosa.
(3) Acquisition of oral mucosa: The oral mucosa is disinfected with III Anil iodine and marked on the buccal mucosa or lingual mucosa with a sterile marker according to the desired length and width, avoiding the opening of the parotid duct when selecting the buccal mucosa. The submucosa was injected with epinephrine saline (concentration 1:200000), the mucosal strip was cut and the oral wound was closed with interrupted 5-0 absorbable sutures. The removed mucosal strip was moistened with saline and trimmed of excess fat and fibrous tissue to make an oral mucosal strip for backup.
(4) Urethroplasty: F16~F18 silicone catheter was left in the urethra, and the oral mucosal strip was sutured to the incised urethral mucosa with 6-0 absorbable thread in a tension-free state, and the enlarged urethra was covered by multiple layers of the subcutaneous fascial layer of the penis.
1. 1 Buccal mucosa was obtained
The oral mucosa was disinfected with III Anil iodine and marked on the buccal mucosa with a sterile marker according to the desired length and width, avoiding the opening of the parotid duct. Oral buccal mucosa strips were cut and the oral wounds were closed with interrupted 5-0 absorbable sutures. The removed mucosal strip was moistened with saline and excess fat and fibrous tissue was trimmed to make an oral buccal mucosal strip for backup.
1, 2 Tongue mucosa acquisition
The oral mucosa was disinfected with III-Anil iodine, marked on the lingual mucosa with a sterile marker according to the desired length and width, injected with epinephrine saline (concentration 1:200000) under the mucosa, and the oral lingual mucosa strip was cut and the lingual mucosa trauma was closed with 5-0 absorbable sutures intermittently or continuously. The removed mucosal strip was moistened with saline and trimmed of excess fat and fibrous tissue to create a mucosal strip for backup.
Features and advantages of lingual mucosal urethroplasty: easy to retrieve, the tongue can be retracted outside the oral cavity after the tongue tip suture traction line, the left and right sides of the tongue can be well exposed and retrieved, and a long segment of lingual mucosa can be obtained by combining the mucosa below the tongue tip. For anterior urethral strictures larger than 5 cm, lingual mucosa is preferred.
1,3 Comparison of ventral mucosal inlay and dorsal inlay urethroplasty
Ventral mucosal onlay urethroplasty is a longitudinal incision of the urethra on the ventral side of the urethra, enlarging the urethra at the stenosis, suturing the oral mucosal strip to the incised urethral mucosa with 6-0 absorbable thread in a tension-free state, and then covering the formed urethra with multiple layers of the subcutaneous fascial layer of the penis. In contrast, dorsal mucosal inlay urethroplasty is performed by first circumcising the foreskin, decapping it to the root of the penis, then freeing the narrow segment of the urethral corpus cavernosum to the dorsal side, cutting the urethra longitudinally on the dorsal side of the urethra, fixing the oral mucosal strip to it with the white membrane of the penile corpus cavernosum as the vascular bed, and then suturing it to the incised urethral mucosa.
There is no significant difference in the success rate of dorsal/ventral mosaicplasty of the oral mucosa [3]. The disadvantage of ventral mosaicplasty, which is relatively simple to perform and has satisfactory therapeutic results, is that it lacks a solid bed, making the growth of mucosal neovascularization relatively difficult and graft survival relatively poor; due to the lack of good mechanical support, the donor area tends to protrude ventrally to form small sacs and diverticulae under pressure during voiding, further producing symptoms such as urinary drip and ejaculation disorders [4]. Dorsal plication can provide better support and conditions for neovascularization, which can reduce the occurrence of related complications. Urethral freeing during dorsal plication is more complicated and slightly more traumatic than ventral plication [5]. Therefore, when technical conditions allow, we still advocate that the graft should be placed on the dorsal side of the urethra when oral mucoplasty is applied to treat urethral strictures in the penile region.
1,4 Postoperative management
The urethral repair of the penile segment was wrapped with elastic bandages, and those in the scrotum and perineum were wrapped with pressure for 4-5 d. Later, the normal gauze wrapping was used instead, and the catheter was removed for urination 4 weeks after surgery. For 3 days after surgery, mouth opening and closing movements were prohibited, cold saline or mouthwash was used 3 times a day, and a liquid diet until general diet was available 4 days after surgery. Apply broad-spectrum antibiotics for 5-7 days postoperatively to prevent infection.
1.5 Key points of surgical technique
The key to successful surgery is the survival of oral mucosal grafts. Therefore, whether the graft can establish new blood circulation as soon as possible and whether there is infection in the wound are crucial. During the operation, it should be done as follows.
① Establish a flat and good blood supply receiving bed as much as possible. For the ventral mosaic style, it is important to cover the mucosal graft with subcutaneous fascia tightly and in multiple layers;
② Minimize the ischemic time of the mucosal graft, which is the time interval between the removal of the mucosal strip and the suturing of the mucosa on the urethral mucosa;
③No local infection, prophylactic antibiotics need to be applied for 5-7 days after surgery.
In order to improve the success rate of the operation, the technical points of the operation are specified as follows:
(1) Requirements for oral mucosal strip: Obtain the mucosal width generally around 1, 5 to 2, 0 cm, and the mucosal length is selected according to the long segment of urethral stricture. Oral buccal mucosa. The thickness of the oral mucosal strip is the full epithelial tissue, and the subcutaneous fat and fibrous tissue need to be removed cleanly, leaving only the thicker epithelial layer, which is conducive to mucosal vascularization and early mucosal viability.
(2) Technical points of obtaining mucosal strips: aseptic marker marks the site of extraction, submucosal injection of adrenal saline is used to obtain oral mucosa, the site of free mucosa is fully elevated to facilitate the separation of mucosa and facilitate trauma hemostasis, electrocoagulation is required to stop bleeding where trauma is obviously active, and absorbable thread is used to intermittently or continuously close the trauma.
(3) Prevention of anastomotic stenosis: In order to avoid stenosis at the anastomosis between the mucosa and normal urethral mucosa, first of all, the urethrotomy of the stenotic segment must be in place.
(4) Fistula prevention: For the ventral mucosal mosaic style, the subcutaneous fascial layer can be multilayered to cover the enlarged formed urethra. The purpose of covering the mucosa with “multiple layers of alternating sutures” is to provide a good mucosal receiving bed to facilitate mucosal survival and to effectively prevent the occurrence of urethral skin fistula. For dorsal onlay, circumcision to the root can prevent the occurrence of postoperative urethral fistula.
(5) Postoperative pressure bandaging of the graft area for 4-5 days to eliminate dead space by tightly bonding the graft to the receiving bed is essential to ensure graft survival.
2. Posterior urethral stricture: stenosis segment excision and end-to-end anastomosis
(1) Anesthesia and position: epidural anesthesia is used for adults, and general anesthesia is used for children. The over-truncated position is used, with the buttocks padded in an oblique ladder position.
(2) Incision and exposure of posterior urethral stricture site: Inverted U incision in the perineum, reaching the anterior border of the sciatic ridge on both sides and the superior border of the incision to the anterior bend of the pubic bone of the penis. The skin and subcutaneous tissue are incised layer by layer to expose the bulbocavernosus muscle (in case of reoperation, it is difficult to isolate the structural level of the bulbocavernosus muscle, which is replaced by scar tissue). The bulbocavernosus muscle is incised in the midline with an electric knife to reveal the bulbourethra, and the gap between the posterior margin of the urethra bulb and the penile corpus cavernosum is first freed with a vascular clamp, and the bulbourethra is freed on its deep side and lifted in a sling to facilitate the operation, and the midline non-vascular attachment between the posterior margin of the urethra and the penile corpus cavernosum is cut with tissue scissors, taking care not to damage the corpus cavernosum tissue during the operation. When freeing the urethra, it can be found that the bulbous urethra is significantly enlarged, and then the urethra gradually becomes thinner after entering the urogenital diaphragm, suggesting that it may have been free to the stenosis or atresia, if it cannot be identified, the “urethral probe rod” is used as a guide to accurately identify the stenosis with the aid of “feel”.
(3) Removal of the urethral stricture: The urethra is dissected with tissue scissors at the stricture or atresia, as close to the atresia as possible. Through the suprapubic cystostomy, a urethral probe rod is passed through the bladder neck into the prostatic urethra, and the head of the probe rod is easily palpated from the incised perineum. Using the probe rod as a guide, the dense fibrotic scar around the proximal urethra is completely excised. The distal urethral scar is also trimmed.
(4) End-to-end urethral anastomosis: A tension-free anastomosis between the urethral mucosa of the bulb and the prostate is ensured. The anastomosis can be applied with 4-0 or 5-0 absorbable sutures with 6-stitch sutures or 8-stitch sutures.
(5) Local application of antibiotics and placement of drainage sheet: suturing or electrocoagulation to stop bleeding, placement of drainage sheet located on the side of the anastomosis, suturing of the bulbocavernosus muscle, and suturing of the subcutaneous fascial layer. Vertical mattress sutures were applied to the skin, and the drainage piece was removed at 48 hours.
2. 1 Common postoperative complications
Common postoperative complications are bleeding, wound infection, and wound dehiscence. The main causes of surgical failure in complex urethral strictures are anastomotic infection leading to poor healing, anastomotic dehiscence, and proliferative paralytic tissue formation. The key to preventing infection is proper preoperative anti-infection measures, good flushing and sterilization of the bladder and waste urethra. Cystostomy tubes and catheters that have been left in place for a long time should be replaced in a timely manner. In addition, low drainage of the incision and pressure bandaging of the perineal incision are important measures to prevent infection.
2. 2 Technical points
There are three technical points: complete excision of the scar, tension-free anastomosis of the mucosa, and avoidance of damage to the anterior rectal wall.
(1) Complete excision of scar tissue around the urethra: How to complete excision? The “hand touch method” is used to determine and remove the scar. When removing the scar tissue, touch the local urethra and surrounding tissue bed with fingers, if there is a hard feeling, it indicates that the scar removal is not complete, and the anastomosis should be performed again when the local touch tissue is soft and free of scar.
Proximal urethral scar excision and exposure of normal urethral mucosa: the key point of surgical operation is the role of “internal guidance of the probe rod”.
One of the key points of the operation is the “internal guidance of the probe rod”: to guide the excision of the scar tissue. Through the suprapubic cystostomy, the urethral probe rod is passed through the bladder neck and into the urethra of the prostate. The finger can touch the position of the urethral probe rod, and the scar tissue around the posterior urethra is removed layer by layer using an electric knife, and the distance between the scar and the urethral probe rod is touched while cutting the scar until the posterior urethral mucosa is revealed and incised. The F22-24 probe rod was allowed to pass smoothly. The scar around the posterior urethra is excised, and “touching while excising” is used to determine whether the excision is complete. Be careful not to do too much freeing and excision away from the urethra, as this may easily damage the anterior rectal wall.
(2) The second part of “internal guidance of the probe rod”: to guide the exposure of normal posterior urethral mucosa. After the removal of scar tissue, the posterior urethral opening is soft to the touch, and at this time, the normal urethral mucosa can be clearly revealed by using the urethral probe rod to stretch freely and local saline flushing. It is able to lift the mucosa very easily with medium-sized forceps to facilitate anastomosis.
(2) Tension-free anastomosis is performed. How is it achieved? If there is tension during the anastomosis of the two urethral segments, the distance between the two segments can be shortened by fully freeing the distal urethra, splitting the cavernous septum of the penis, and wedge excision of the inferior border of the pubic symphysis.