Traumatic Rupture of the Ureter: 10 Cases
A retrospective study was performed on eight dogs, one cat, and one ferret with ruptured ureters secondary to blunt trauma. The most common physical examination findings were abdominal distension/discomfort (in five of 10 animals) and gross hematuria (in five of six animals). Multiple organ injury was also common (in seven of 10 animals). Loss of retroperitoneal and peritoneal detail was the most common radiographic finding (in four of six animals). Ureteronephrectomy was the most common surgical procedure (performed in five out of seven procedures). Three of the five cases discharged were available for follow-up and have had no evidence of associated problems.
Introduction
Trauma to the urinary tract most commonly involves the urinary bladder, urethra, or kidneys. Urinary tract trauma is a relatively common entity in veterinary medicine, and several studies and reviews have been reported in the literature.1–4 Traumatic ureteral rupture is diagnosed less commonly and, to the authors’ knowledge, no information currently exists in the veterinary literature concerning prognoses or survival rates. Clinical signs of ureteral rupture are often nonspecific, resulting in a patient becoming severely compromised while awaiting a diagnosis. The purpose of this report is to describe the clinical parameters of a series of 10 patients with unilateral ureteral rupture secondary to blunt trauma, in order to aid in early recognition and treatment of this injury as well as to potentially minimize morbidity and optimize outcomes.
Materials and Methods
All cases of ureteral rupture from 1986 to 1999 in the medical records database at the Veterinary Hospital of the University of Pennsylvania (VHUP) were identified. Those cases with ureteral rupture secondary to blunt trauma were selected for review. Iatrogenic ureteral trauma as well as ureteral damage secondary to urolithiasis or neoplasia were excluded from this study.
The medical records of 10 cases of traumatic ureteral rupture were reviewed. Information collected included signalment, nature of injury, time between trauma and presentation, presenting complaint, presenting physical examination findings, concurrent injuries, diagnostic procedure(s) and clinical pathology results, presence of hematuria (gross or microscopic), initial treatment, surgical procedures, ureteral pathology, duration of hospitalization, follow-up at suture removal, and long-term outcome.
Results [see Table]
Signalment/Clinical Signs/Physical Examination Findings
Ten animals were included: eight dogs, one cat, and a ferret. There were six males and four females. The median age was 23 months, with a range of 3 months to 9 years. Eight animals suffered motor vehicle trauma, and two experienced blunt trauma from unknown causes. The median time from trauma to admission at VHUP was approximately 7 hours (range, 30 minutes to 2 months). The majority of the animals had relatively nonspecific clinical signs or signs related to other injuries. Only two animals had signs related to the urinary tract that included dysuria, anuria, hematuria, or a combination of these. Similarly, physical examination findings were consistent with those animals experiencing severe trauma with multiple injuries and included abdominal distention/discomfort (n=5); poor tissue perfusion indicated by weak peripheral pulses, pale mucous membranes, prolonged capillary refill time, tachycardia, or a combination of these (n=3); bone fractures (n=3); and subcutaneous emphysema (n=1).
Concurrent Injuries
Seven animals had concurrent injuries or compromise, including bone fractures (n=3), urinary bladder rupture (n=3), hemoabdomen (n=2), pulmonary contusions (n=2), and one each of splenic trauma, fractured liver, pneumothorax/pneumomediastinum/subcutaneous emphysema, perforation of the colon, mesenteric tear, and diaphragmatic hernia.
Clinical Pathology
Blood work included an emergency database (packed cell volume, total solids, dipstick blood glucose, and dipstick blood urea nitrogen [BUN]; n=6), complete blood count (n=5), serum biochemical profile (n=4), and urinalysis (n=6). Abnormalities included increased creatinine in four animals (three dogs with creatinine ranging from 1.7 mg/dL to 5.4 mg/dL [dog reference range, 0.5 to 1.0 mg/dL]; one cat with creatinine of 3.4 mg/dL [cat reference range, 0.5 to 2.0 mg/dL]); hyponatremia in three dogs (range, 127 to 136 mmol/L [dog reference range, 138 to 148 mmol/L]); increased BUN in two animals (one dog with BUN of 218 mg/dL [dog reference range, 5 to 30 mg/dL]; one cat with BUN of 30 to 40 mg/dL [cat reference range, 5 to 30 mg/dL]); and one dog with hyperkalemia (potassium, 5.9 mmol/L [dog reference range, 3.5 to 5.0 mmol/L]). The only consistent abnormality noted on urinalyses was gross hematuria in five animals.
Diagnostic Imaging of the Abdomen/Urinary Tract
Abnormalities noted on abdominal radiographs (n=6 dogs) included loss of both retroperitoneal and peritoneal detail (n=4), loss of retroperitoneal detail only (n=1), or loss of peritoneal detail only (n=1). Excretory urograms (n=4) identified ureteral leakage in all cases, although partial or complete tears could not be determined. Retrograde urethrograms (n=3) identified no abnormalities. Abdominal ultrasound identified retroperitoneal fluid in both cases where it was performed, but the precise location of the fluid was not recorded.
Ureteral Pathology
Ureteral pathology was described in nine animals. There were seven complete avulsions (six were of the right ureter) and two partial tears (both were of the left ureter). Four of the ureteral injuries were near the ureteropelvic junction (three right-sided, one left-sided), three were near the ureterovesicular junction (two right-sided, one left-sided), and two were midureter (one right-sided, one left-sided).
Urinary Tract Surgical Procedures
Seven animals had surgeries performed specifically for the urinary tract, with a median time from trauma to surgery of 3 to 4 days (range, <24 hours to 2 months). Initial surgical procedures included ureteronephrectomy (n=5), ureteroneocystostomy (n=2), and ureteral repair with nephrostomy tube placement (n=1). Failure of ureteral repair in this latter animal resulted in a ureteronephrectomy being performed 2 days later. Other urinary tract surgical procedures included cystotomy performed in two animals. Reasons for these cystotomies included examination of the urinary bladder lumen in one animal and partial cystectomy in another for a compromised portion of the bladder wall.
Outcome
There were five survivors and five nonsurvivors. Of the nonsurvivors, two dogs were euthanized for acute renal failure 1 and 4 days after ureteral surgery, one was dead on arrival, one died under anesthesia before surgery, and one was euthanized upon admission for financial reasons. Of the survivors, all five had initial ureteronephrectomies performed, and the median time for discharge after urinary tract surgery was 5 days (range, 1 to 8 days).
Discussion
This paper describes the clinical parameters of 10 animals with unilateral ureteral rupture secondary to trauma. The signalment of these animals is similar to previous reports of animals that have experienced motor vehicle trauma. Traumatic ureteral rupture appears to be a rare event, accounting for 0.01% of the authors’ hospital population.
There are a number of proposed mechanisms by which blunt trauma can result in ureteral rupture in humans. These include crushing of the ureter into the transverse process of the lumbar vertebrae, excessive tension on the ureter due to severe stretching between the relatively fixed ends, sudden craniad movement of the kidney against a relatively immobile uteropelvic junction, or a combination of spinal hyper-extension and sudden acceleration/deceleration.56 It has been suggested that the hyperextension places such extreme tension on the ureter that a snap or lash against the vertebral column could cause rupture at the ureteropelvic junction where the tension is the greatest.5 This theory might preselect for children, as less-compliant adults might not survive the extreme hyperextension necessary to produce such a lesion. This may explain why blunt traumatic ureter rupture occurs clinically more frequently in children, as noted in some studies.7 Domestic animals might be similar to children in the degree of lateral flexion that they can tolerate. In fact, the extreme lateral flexion tolerated by cats and dogs may actually reduce the incidence of this type of injury, as similarly severe ureteral tension may not occur due to anatomical differences.
The small number of cases precludes the authors from making strong conclusions regarding the consistency of ureteral rupture location. Two studies in humans report that ruptures occur in the upper half of the ureter >84% of the time, compared to approximately 50% in this study.78 In the authors’ study, six of seven complete tears occurred on the right side. These results seem striking but could still be due to chance. More cases would be required to confirm this predilection. There is no apparent side predilection reported in humans.78
Shock or multiple organ injuries were present in the majority of the animals (70%) in this study. This result is consistent with the findings in humans and is in agreement with the hypothesis that severe trauma is required to cause ureteral rupture. The concurrent injuries, nonspecific signs, sheltered location of the ureters, and rarity of this condition make early diagnosis a challenge.
The mild to moderate increases in creatinine concentration and hematuria should alert the clinician to the possibility of ureteral rupture, but further diagnostic and clinical studies would be required to confirm the sensitivity or specificity of these findings.
Loss of retroperitoneal detail on abdominal radiography combined with ultrasound findings of free retroperitoneal fluid warrants a suspicion of ureteral rupture, although retroperitoneal hemorrhage can have similar findings.
Definitive presurgical diagnosis is best achieved by iodinated contrast studies. Excretory urography provided a diagnosis in all four animals in which it was performed. In humans, the diagnostic rates range from 33% to 100%.57 The lower diagnostic rates in humans have been attributed to incomplete studies or poor urine output. Currently, the techniques most commonly used in human medicine include direct inspection during exploratory surgery with or without dye injection, excretory urography/intravenous pyelography, retrograde (or anterograde) pyelography, computer-aided tomography, or magnetic resonance imaging.
The basic surgical options available include ureteral reanastomosis, ureteroneocystostomy, stenting across the defect until the ureter heals, and ureteronephrectomy. Due to the retrospective nature of this study, it is difficult to determine why particular techniques were chosen for individual cases. Six ureteronephrectomies were ultimately performed. In humans, this technique is a salvage procedure that reduces the clinical complications associated with ureteral repair, including dehiscence, stricture formation, urine extravasation, fistula formation, and calculi formation.17–10
For the animals that underwent initial ureteronephrectomy, the prognosis appears good. The two animals that did not receive initial ureteronephrectomies died of acute renal failure postoperatively. Five of the seven surgical patients were discharged from the hospital. Of the three animals available for follow-up, one dog and one cat died of unrelated causes 6.5 years and 20 months postoperatively, respectively, and one dog continues to do well 5 months postoperatively.
Conclusion
Traumatic ureteral rupture is a rare condition in veterinary medicine. Nonspecific clinical signs and concomitant multiple organ injuries often result in a delayed diagnosis. Imaging studies, including contrast radiography and ultra-sonography, consistently aided in the diagnosis of this condition and should be considered when an animal receiving significant blunt trauma develops an elevated creatinine, hematuria, or evidence of retroperitoneal effusion on abdominal radiography. Animals undergoing initial ureteronephrectomy appear to have a good prognosis.
Contributor Notes
