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Urethrostomy is a surgical procedure that creates a permanent opening in the urethra, commonly to remove obstructions to urine flow. The procedure is most often performed in male cats, where the opening is made in the perineum. [1]
For many years perineal urethrostomy has been used in cattle, sheep and goats, especially young males that have been castrated at a young age, for obstruction by uroliths. However, the anatomy of the male cat is quite different and the urethra is very small in diameter.
Perineal urethrostomy in the male cat was developed in 1962 and published in the Journal of the American Veterinary Medical Association in 1963. [2] It was modified in 1967, [3] and further modified in 1971. [4]
Since animals are potentially suffering from severe metabolic derangements at the time of initial presentation, animals need to be stabilized prior to surgery. Common physiologic derangements noted on bloodwork are elevated kidneys values (azotemia) and elevated potassium levels (hyperkalemia). The presence of profound sedation, low body temperature, and/or a slow heart rate (bradycardia) are usually associated with more severe blood derangements.
Ideally, the urethral obstruction is removed or temporarily bypassed with urethral flushing (urohydropulsion) and the placement of an in-dwelling urinary catheter prior to surgery. This catheter allows urine to be removed from the body, and, along with fluid therapy, help normalize blood derangements to resolve prior to anesthesia. There are many types of catheters commonly used, including common red rubber catheters, stiff Tomcat catheters, soft and flexible Cook catheters or semi-rigid "Slippery Sam" catheters.
Sedation is usually required for urohydropulsion and the placement of a urinary catheter due to the associated pain with the procedure. A combination of injectable ketamine and diazepam is a safer option for sedation considering its reduced cardiopulmary depression effects compared to other anesthetics. A combination of etomidate and diazepam would be an even safer anesthetic consideration, but etomidate is not commonly carried by general veterinary practitioners due to its cost.
Fluid therapy is equally essential for correcting derangements. Commonly, a fluid low in potassium, such as 0.9% NaCl, is selected. If 0.9% NaCl is not available, any other crystalloid fluid is realistic even if it contains some level of potassium. Insulin is sometimes used intravenously to temporarily reduce high potassium levels. Calcium gluconate can also be used to protect the myocardium (heart muscle) from the negative effects of hyperkalemia.
Rarely, an urethral obstruction cannot not be removed on initial presentation and emergency surgery must be performed immediately to return urethral patency and save the animal's life. These animals are at a much higher risk under anesthesia.
The cat can be placed in either dorsal or ventral recumbency. An elliptical incision is made around the base of the cat's penis and scrotum. If the cat has not been neutered previously, it must be neutered before the perineal urethrostomy can be performed. A combination of sharp and blunt dissection is started ventrally (the underside of the penis) to expose the penis' muscular and soft tissue attachments to the pelvis. After removing these soft tissue attachments to the pelvis, dissection is continued dorsally (on top of the penis) to remove the dorsal retractor penile muscle and other soft tissue covering the site of the required urethral incision.
All of these dissection steps are necessary to free the penis from the pelvis, allowing the veterinarian to move the significantly wider pelvic urethra caudally (or rearward) so it can be attached to the skin.
After the penile body is freed, a dorsal incision is started at the tip of the penis using either a small scalpel blade or fine ophthalmic scissors. This incision is extended to a level at or above the bulbourethral glands. At this level, the urethra is considered wide enough to create an adequate stoma, or urethral opening. The urethra is sutured to the skin for approximately 2 cm using a fine suture on a taper needle (i.e. 4-0 PDS). The remainder of the penis is amputated and any remaining skin defect is closed.
As the surgery site heals, the urethral mucosa and skin will heal together creating a permanent stoma. This stoma (opening) is much larger than the original penile urethra making it unlikely for the animal to obstruct in the future.
A urinary catheter may be placed following surgery for the initial 12–24 hours of recovery. This catheter should not be left in longer than this though, as it will increase the likelihood of stricture formation at the surgery site. Animals should wear an e-collar until sutures are removed in 10–14 days.
Initial post-operative complications include wound infection and excessive pain or bleeding. These can be controlled commonly with appropriate prescription medications or ice packs if the animal will tolerate them. A more concerning, though not common, complication is stricture, or narrowing, of the surgery site. The formation of a stricture will require additional procedures to either try and salvage the initial surgery site or create a new urethral opening (or stoma) under the floor of the pelvis (subpelvic urethrostomy) or immediately in front of the pubic bone (prepubic urethrostomy).
The most common long term complication associated with this surgery is an increased incidence of urinary tract infections.
The urethra is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra connects to the urinary meatus above the vagina, whereas in marsupials, the female's urethra empties into the urogenital sinus.
The prostate is both an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and physiologically. Anatomically, the prostate is found below the bladder, with the urethra passing through it. It is described in gross anatomy as consisting of lobes and in microanatomy by zone. It is surrounded by an elastic, fibromuscular capsule and contains glandular tissue as well as connective tissue.
The urinary system, also known as the renal system or urinary tract, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine. The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary system are very similar, differing only in the length of the urethra.
A urethral stricture is a narrowing of the urethra caused by injury, instrumentation, infection, and certain non-infectious forms of urethritis.
Phalloplasty is the construction or reconstruction of a penis, or the artificial modification of the penis by surgery. The term 'phalloplasty' is also occasionally used to refer to penis enlargement.
Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include loss of bladder control, mild lower abdominal pain, and a weak urine stream. Those with long-term problems are at risk of urinary tract infections.
Prostatectomy as a medical term refers to the surgical removal of all or part of the prostate gland. This operation is done for benign conditions that cause urinary retention, as well as for prostate cancer and for other cancers of the pelvis.
Feline lower urinary tract disease (FLUTD) is a generic category term to describe any disorder affecting the bladder or urethra of cats.
A suprapubic cystostomy or suprapubic catheter (SPC) is a surgically created connection between the urinary bladder and the skin used to drain urine from the bladder in individuals with obstruction of normal urinary flow. The connection does not go through the abdominal cavity.
Radical retropubic prostatectomy is a surgical procedure in which the prostate gland is removed through an incision in the abdomen. It is most often used to treat individuals who have early prostate cancer. Radical retropubic prostatectomy can be performed under general, spinal, or epidural anesthesia and requires blood transfusion less than one-fifth of the time. Radical retropubic prostatectomy is associated with complications such as urinary incontinence and impotence, but these outcomes are related to a combination of individual patient anatomy, surgical technique, and the experience and skill of the surgeon.
A urethrotomy is an operation which involves incision of the urethra, especially for relief of a stricture. It is most often performed in the outpatient setting, with the patient (usually) being discharged from the hospital or surgery center within six hours from the procedure's inception.
Posterior urethral valve (PUV) disorder is an obstructive developmental anomaly in the urethra and genitourinary system of male newborns. A posterior urethral valve is an obstructing membrane in the posterior male urethra as a result of abnormal in utero development. It is the most common cause of bladder outlet obstruction in male newborns. The disorder varies in degree, with mild cases presenting late due to milder symptoms. More severe cases can have renal and respiratory failure from lung underdevelopment as result of low amniotic fluid volumes, requiring intensive care and close monitoring. It occurs in about one in 8,000 babies.
Bladder stones or uroliths are a common occurrence in animals, especially in domestic animals such as dogs and cats. Occurrence in other species, including tortoises, has been reported as well. The stones form in the urinary bladder in varying size and numbers secondary to infection, dietary influences, and genetics. Stones can form in any part of the urinary tract in dogs and cats, but unlike in humans, stones of the kidney are less common and do not often cause significant disease, although they can contribute to pyelonephritis and chronic kidney disease. Types of stones include struvite, calcium oxalate, urate, cystine, calcium phosphate, and silicate. Struvite and calcium oxalate stones are by far the most common.
Urethral cancer is a rare cancer originating from the urethra. The disease has been classified by the TNM staging system and the World Health Organization.
Urethroplasty is the repair of an injury or defect within the walls of the urethra. Trauma, iatrogenic injury and infections are the most common causes of urethral injury/defect requiring repair. Urethroplasty is regarded as the gold standard treatment for urethral strictures and offers better outcomes in terms of recurrence rates than dilatations and urethrotomies. It is probably the only useful modality of treatment for long and complex strictures though recurrence rates are higher for this difficult treatment group.
A prostatic stent is a stent used to keep open the male urethra and allow the passing of urine in cases of prostatic obstruction and lower urinary tract symptoms (LUTS). Prostatic obstruction is a common condition with a variety of causes. Benign prostatic hyperplasia (BPH) is the most common cause, but obstruction may also occur acutely after treatment for BPH such as transurethral needle ablation of the prostate (TUNA), transurethral resection of the prostate (TURP), transurethral microwave thermotherapy (TUMT), prostate cancer or after radiation therapy.
Feline idiopathic cystitis (FIC) or feline interstitial cystitis or cystitis in cats, is one of the most frequently observed forms of feline lower urinary tract disease (FLUTD). Feline cystitis means "inflammation of the bladder in cats". The term idiopathic means unknown cause; however, certain behaviours have been known to aggravate the illness once it has been initiated. It can affect both males and females of any breed of cat. It is more commonly found in female cats; however, when males do exhibit cystitis, it is usually more dangerous.
Bulbar urethral necrosis is a problem that can occur after a pelvic fracture associated urethral distraction defect (PFUDD).
A penile injury is a medical emergency that afflicts the penis. Common injuries include fracture, avulsion, strangulation, entrapment, and amputation.
Penis clamp is an external penis compression device that treats male urinary incontinence. Incontinence clamps for men are applied to compress the urethra to compensate for the malfunctioning of the natural urinary sphincter, preventing leakage from the bladder with minimal restriction of blood flow.