About urethral stricture disease
A urethral stricture is a scar that forms in the urethral channel that connects the bladder to the outside world. In the male patient, the average adult urethral length is 22.3 cm with a range of 15 cm to 29 cm. In the adult female patient, the average urethral length is 4.9 cm to 5.1 cm. When discussing treatment for urethral strictures, it is helpful to further understand the anatomy and to describe accurately exactly where the stricture is located. We will first discuss the male anatomy.
The male urethra is divided anatomically into two broad segments: the posterior urethra and the anterior urethra. In strict anatomical terms, the posterior urethra begins at the bladder neck and extends through the prostate and terminates at the distal membranous urethra. However, from a surgical standpoint, the posterior urethra also includes the proximal bulbar urethral segment, which requires the same approach in the operating room via a perineal incision. The perineum is the area between the base of the scrotum and the anus. The anterior urethra includes the bulbar urethra and penile urethra all the way to the end of the urethra, which is the meatus. These strictures are corrected surgically with the patient lying down in the supine position and are approached by making a penile or scrotal incision (or both). Again, from a surgical standpoint, the anterior urethra describes the distal or latter one half of the urethra that is repaired with the patient lying down flat on their back.
There are many causes of male urethral strictures, but most urethral scars are related to some sort of trauma, either accidental or surgical. Straddle injuries, which are common in boyhood, involve an event where the patient straddles a hard object and the urethra is damaged by straddling the firm object such as a bicycle bar, tree limb, fence post, four-wheeler or motorcycle gas tank, saddle horn or handle bar. The urethra is soft tissue that is protected by a surrounding spongy layer. During the straddle injury event, the urethra is torn and bruised as the firm object pins the urethra between the outer object and the underlying bony pelvis. Often times, the patient will have bleeding from the meatus and trouble voiding but is afraid to tell his parents for fear of getting a good whooping. Then many years later, the scar forms and the young man cannot void with a good stream and presents with urinary retention as the scar closes down the urethral channel completely. Pelvic fractures can cause urethral disruption immediately at the time of the accident. The urethra tears apart as the bony pelvis shifts with the injury taking part of the urethra with it and leaving the rest of the urethra (distal segment) behind. These injuries are usually managed with a suprapubic tube and then the urethral is reconstructed 6 months later. A direct blow to the urethra can also cause strictures such as a kick, punch, tackle, flying baseball, slide, rollover or altercation. Surgeries that can cause urethral strictures are most commonly related to prostate disease and surgical treatments. Robotic or open radical prostatectomy surgery for caner can leave the patient with a scar between the urethra and bladder neck, or an anastomotic stricture. Transurethral resection of the prostate (TURP) can cause strictures at most any location along the entire urethra. Long-term Foley catheters can also cause urethral strictures. Certain urethral infections such as gonorrhea can cause strictures at multiple levels. Inflammatory diseases of the meatus and urethra can cause strictures and balanitis xerotica obliterans (BXO) is the most common associated disease. Radiation treatments for prostate cancer may cause strictures of the bladder neck, prostate, membranous and bulbous urethra and can also cause fistulas (abnormal communication) between the urethra and the rectum or other organs. Radiation strictures are some of the most difficult urethral problems to repair and certain patients will require permanent urinary diversion.
Female urethral strictures are often difficult to diagnose and are easily missed. The female urethra is divided into three segments: the bladder neck/proximal urethra, the external sphincter mid-urethra/middle 1/3 and the distal 1/3 urethra including the meatus. Many of these strictures are caused by the same straddle events that occur in the male patients and they can occur at any level. Childhood or adult urethral dilations with sounds (metal rods) can cause strictures later in life. Some infections and radical pelvic surgery are associated with female urethral strictures. Radiation damage to the urethra to treat pelvic malignancies is another risk factor. Finally, some female patients may develop strictures related to prior urethral diverticulum surgery or other vaginal surgeries. Most strictures are located at or near the meatus or in the mid portion of the urethra. Bladder neck and membranous strictures may occur in female patients secondary to pelvic fracture.
Evaluation of urethral stricture disease
The work up for urethral strictures is very basic but is extremely important to map out the stricture completely. This is accomplished by looking on both sides of the stricture whenever possible. RUG (retrograde urethrogram) is usually the first test. Contrast or dye is injected into the urethra using a special syringe and multiple images are obtained of the entire urethra in an oblique view, ie from the side. Next, a small feeding tube catheter (8F) is passed through the stricture and the bladder is filled with contrast. Then the patient is instructed to void and more images of the urethra are recorded. This test is called a VCUG (voiding cystourethrogram). We then compare the two sets of films to get an idea of the exact length and location of the stricture. Finally, cystoscopy is performed with either a flexible, fiberoptic, cystoscope or a very small pediatric scope to assess the depth of the scar, length of the stricture, and general appearance of the urethra including any other scars. Some patients will have a suprapubic (SP) tube in place which greatly aids in the evaluation. We can inject contrast into the bladder via the SP tube and/or pass a flexible cystoscope down the SP tract to assess the bladder, bladder neck and urethra. If the urethra is obliterated from the stricture (pelvic fracture distraction injury), we may perform a simultaneous RUG and VCUG or combine a RUG with flexible CYSTO via the SP tract to assess the exact length of the defect.
Many patients who suffer from traumatic urethral strictures also experience damage to the blood vessels and nerves that travel to the penis and pelvic organs. Pelvic fracture urethral disruption injuries are frequently associated with decreased blood flow to the penis and urethra. Many of these men suffer from erectile dysfunction and may have numbness to part or all of the penis. We will perform a blood flow test to assess these injuries prior to any type of urethral reconstruction. Duplex Doppler ultrasound of the penis is a test that will screen for these types of vascular injuries. The penile Doppler measures blood flow in the dorsal arteries and the cavernosal arteries of the penis and also evaluates venous outflow. We first inject a vasodilator drug ( Caverject/Trimix) directly into the corpus cavernosum of the penis then measure the blood flow after a wait time of 15-30 minutes. If this test is abnormal, the next step is a formal pelvic arteriogram.
Treatment options for urethral stricture disease
There are both endoscopic and open surgical procedures for the treatment of urethral strictures. Endoscopic procedures are usually performed with a rigid cystoscope and a cold knife blade that extends out from the scope and the stricture is cut at different points to open the scar. The scar can be incised with the laser, as well, using the same rigid scope or a flexible cystoscope. Another minimally invasive technique is to use a flexible scope to pass a wire through the stricture and then dilate the stricture sequentially using dilators of various sizes that pass over the wire. If the surgeon cannot get past the stricture then a suprapubic tube is inserted. If the stricture recurs after a scope procedure, then the patient should consider an open repair.
Open surgical repair implies that there is an incision somewhere along the path of the urethra and the stricture is repaired directly by sharp dissection and suturing. The most effective surgery with the best long term results is the excision with primary anastomosis procedure (EPA) and we always prefer this technique over any form of substitution urethroplasty (grafts or flaps). With the EPA, the strictured segment of the urethra is excised (removed), and the two healthy ends are sewn back together, tension free, mucosa to mucosa anastomosis. If the stricture is too long for an EPA, then we will perform either a local skin flap (penis or scrotum) or a buccal mucosa graft (taken from the mouth) to repair the urethra. This is like putting a new roof on the house, or an onlay procedure. We augment the diameter of the urethra by splitting it open and widening the narrow part. Two stage urethroplasty is generally used for longer, inflammatory strictures of the penis and bulbar urethra. Also known as a Johanson urethroplasty, this operation has a definite roll in the treatment of complex and recurrent strictures.