Tucker, a 3-year-old border collie, was rushed to your hospital after getting hit by a car at 9 a.m. He is lucky, as he escaped without any fracture or major laceration. He only seems to have a few skin scrapes.
You stabilize Tucker throughout the day, and he looks much better by that evening. He is kept overnight for IV fluids and pain medications. By the next morning, you are disappointed to see that Tucker’s condition has worsened overnight. Blood work and abdominal X-rays make you strongly suspect a bladder rupture. Ultrasound confirms it without a doubt.
Fortunately, Dr. Jennifer Stafford, a double-boarded colleague in critical care and internal medicine at VCA Veterinary Referral Associates in Gaithersburg, Md., comes to the rescue with a full write-up on uroabdomen (JR Stafford, et al. “A clinical review of pathophysiology, diagnosis, and treatment of uroabdomen in the dog and cat.” J Vet Emerg Crit Care 2013, Vol 23, N 2, p. 216-229).
As in Tucker’s case, most uroabdomen cases are caused by blunt trauma to the abdomen, such as getting hit by a car. The chances of this happening depend on the degree of bladder distention at the time of the trauma.
Uroabdomen also can be seen in cats with a urethral blockage who receive manual bladder expression (causing the bladder to rupture) or traumatic urethral catheterization (causing a tear in the urethra).
Kidneys and ureters are less likely to be damaged because of their anatomic location behind the caudal ribs and muscles of the body wall. However, fractures to the spine or ribs in this area increase the likelihood of ureteral or renal lesions.
Abdominal ultrasound is a useful diagnostic modality; an empty bladder with a thick wall and poor definition may indicate rupture. Radiographic studies may show peritoneal effusion, loss of detail, difficulty visualizing the bladder or a fractured pelvis.
Contrast studies are helpful to confirm uroabdomen. Approximately 10 ml/kg of contrast agent can be used to infuse the bladder. If the patient is female and urethral catheterization is difficult, a vaginourethrogram can be performed.
“With heavy sedation or anesthesia, a large balloon-tipped catheter is inserted into the vagina rather than the urethra and the balloon is inflated to prevent loss of contrast medium,” write the authors. “The contrast is injected through the catheter and will fill the vagina initially until a noticeable amount of resistance is met during the injection as the contrast refluxes into the urethra” and into the bladder.
Signs and Lab Findings
Clinical signs are typically nonspecific and can include vomiting, anorexia, weakness and abdominal pain. Lethargy occurs secondary to progressive azotemia.
Other lab findings include hyperkalemia and metabolic acidosis. It is critical to remember that some patients may not show clinical signs right away. Later clinical signs may include a palpable fluid wave, inguinal or perineal bruising, hematuria, stranguria, dysuria or anuria.
Most importantly, “a palpable urinary bladder does not rule out a rupture of the urinary tract (including the bladder itself), and voiding of urine without gross hematuria does not exclude a diagnosis of a ruptured bladder,” the authors note.
Confirming uroabdomen requires abdominocentesis. Potassium is excreted into urine faster than the body can reabsorb it, so an indicator for uroabdomen is an increased potassium level in the abdominal tap. Cardiac abnormalities can also be seen secondary to hyperkalemia.
In addition, an increase in creatinine occurs. Unlike urea, creatinine is too large of a molecule to equilibrate across the peritoneum. A creatinine level in the abdominal fluid greater than twice the level in the blood is considered a pathognomonic indicator of uroabdomen.
Fluids are required in case of shock, hypovolemia or hemorrhage. Orthopedic injuries and head trauma should be assessed and treated accordingly.
Calcium gluconate or chloride may be administered to treat effects of hyperkalemia on the heart but will not effectively decrease serum potassium levels.
Pain management must be included in the initial treatment. Chemical peritonitis is considered very painful. Constant rate infusions with a reversible opioid can be used as long as hypotension is not a major issue.
Urinary diversion may be necessary if the patient is not stable enough for surgical repair because of concurrent injuries. Urethral catheterization or placement of a cystostomy tube to drain the bladder and placement of a peritoneal catheter to drain the abdomen may be necessary to buy time before definitive surgery can be performed.
DR. PHIL ZELTZMAN
A Poole suction tip is inserted into Tucker’s bladder through the tear.
Overly aggressive fluid therapy in patients with a ruptured bladder can exacerbate potassium excretion by improving the glomerular filtration rate.
Medications like dexmedetomidine may worsen cardiac toxicity because of its usual side effects: bradycardia, peripheral vasoconstriction and decreased cardiac output.
If ketamine is used as a component of a CRI, it is important to remember that it is excreted unchanged by the kidneys. Therefore, ketamine can increase sedation because of its reabsorption through the peritoneum.
As long as the diversion of urine is established, it is important to remember that a uroabdomen is a medical emergency and not a surgical one. It is preferable to stabilize a patient before surgery to minimize anesthetic risk.
Lacerations or ruptures of the bladder are most common and surgical repair is relatively straightforward. Debridement of necrotic tissue and a double layer closure are recommended. Up to 75 percent of the bladder can be sacrificed while maintaining its normal function.
Urethral lacerations or ruptures are less common. They can benefit from various surgical repairs, depending on the location of the tear and the integrity of the surrounding tissue—debridement and anastomosis, placement of a cystostomy tube, urethrostomy (prescrotal, scrotal, perineal or prepubic). A prepubic urethrostomy is technically demanding and is considered a salvage procedure.
Ureteral tears and avulsions are rare and difficult to repair. The best surgical solution may be a nephrectomy.
Severity of the urinary injuries, success of the surgical repair and concurrent pathology influence the prognosis. The owner may, of course, choose euthanasia rather than treatment.
The authors conclude: “In a study of 26 cats with uroperitoneum, the prognosis for those cats treated for uroabdomen with no concomitant injuries was fairly good with 62 percent discharged from the hospital. To the authors’ knowledge, there is no study to date that discusses the prognosis of dogs with uroabdomen. However, without treatment, death will usually occur within three days in dogs.”
Remember Tucker, our hit-by-car patient? He was successfully diagnosed and stabilized by his veterinarian. Surgery was successful, and he made a full recovery.
Katie Kegerise, a certified veterinary technician in Reading, Pa., contributed to this article.