UROGENITAL TRAUMA

Proposed mechanisms of lower urinary tract injury in fractures of the pelvic ring
Andrich DE, Day AC, Mundy AR
Institute of Urology, UCL, London, UK
BJU Int. 2007; 100: 567-73

• Objective: To investigate whether the observation of particular pelvic fracture patterns enables the clinician to predict the presence and type of injuries to the lower urinary tract, as the mechanisms of injury to the lower urinary tract in association with fractures of the pelvic ring are unclear.
• Patients and Methods: The case-notes and radiographs of 168 patients with either pelvic ring or acetabular fractures were reviewed; 108 pelvic ring fractures (81 men, 27 women) and 60 acetabular fractures (46 men, 14 women). The pelvic fractures were classified according to the system described by Tile and were correlated with the incidence and type of lower urinary tract injury (LUTI).
• Results: Overall, of the 108 men and women with pelvic ring fractures, 27 (25%) had a LUTI documented either radiologically or as an intraoperative finding. Of the 81 men with pelvic ring fractures, 24 (30%) had a LUTI, of whom six (7%) had an isolated bladder laceration, 14 (17%) a partial urethral injury (PUI) and four (5%) a complete urethral disruption (CUD). Five of the 18 men with urethral injuries also had bladder injuries and in three of these, the bladder neck was also injured. Three of 27 women (11%) had a LUTI, all of whom had isolated bladder lacerations. Of the 46 men with an acetabular fracture, one (2%) had a CUD, and three (7%) had a PUI. One of 14 of women with an acetabular fracture sustained a bladder laceration. None of the three men with a Tile Type-A pelvic ring fracture sustained a LUTI. Of the 28 men with ‘open-book’ (Tile Type-B1) fractures, 21 (75%) had no associated LUTI and seven (25%) had a LUTI (five partial urethral injuries and two bladder lacerations). Of the 10 men with ‘lateral compression’ (Tile Type-B2) fractures, six had no LUTI and four had a LUTI (two partial urethral injuries and two bladder lacerations). Of the 40 men with ‘vertical shear’ (Tile Type-C) fractures, 27 (68%) had no LUTI and 13 (32%) a LUTI (four complete urethral disruptions, seven partial urethral injuries, and two bladder lacerations) including all of the combined bladder and urethral injuries and all of the bladder neck injuries.
• Conclusion: The pelvic fracture pattern alone does not predict the presence of a LUTI. When it occurs, the type of LUTI appears to be related to the fracture mechanism. The pattern of injury to the soft tissue envelope and specifically to the ligaments supporting the lower urinary tract offers the best correlation with the observed LUTI. We propose a mechanism for this.
  
  
• Editorial Comment
  The above article by Mundy clearly deserves a closer look, particularly at the illustrative images and figures. Pelvic fractures are typically classified by fracture pattern and mechanism of injury. The two most commonly used schemas are the Young-Burgess and the Tile classifications. They divide the fracture patterns more by mechanism into Type A, anterior compression (AP) injury, Type B, lateral compression (LC) and Type C vertical shear and conformationally unstable. Bladder injuries in the male with pelvic fractures are primarily due to shearing forces and not to bladder penetration from a bony spicule. This is illustrated by publications from the SF General Group where half of bladder injuries occurred on the opposite side of the bony fracture. Intuitively, a pelvic fracture that results in the most shearing forces, then should also give the highest likelihood for bladder injury. Urethral injuries have been classically described by Turner Warwick as prostato-membranous disruption injuries. It is my observation, and that of others, most injuries to the urethra from pelvic fracture are at the bulbomembranous junction and not at the level of the prostate. Again, in the male, it appears that shearing forces are the cause of urethral injury and not direct compression or penetration. In other words, the injury that causes the most shearing forces to the urethra should cause an injury.
  

Dr. Steven B. Brandes
Associate Professor, Division of Urologic Surgery
Washington University in St. Louis
St. Louis, Missouri, USA