The vast majority of bladder injuries result from external trauma. Most cases result from blunt trauma, such as motor vehicle accidents, whereas a smaller number result from penetrating trauma, such as gunshot or stab wounds. A minority of bladder injuries not associated with external trauma are iatrogenic. The highest risk procedures include transabdominal hysterectomy, Cesarean section, transurethral resection of a bladder tumor, and bladder biopsy.
Bladder trauma may lead to contusions (partial-thickness mucosal tears resulting from blunt forces), interstitial injuries (partial-thickness lacerations that involve the serosa), and ruptures. The remainder of this section will focus on ruptures, which can be classiﬁed as either extraperitoneal or intraperitoneal based on the region of the bladder wall that tears, which determines the consequent site of urine collection. Overall, approximately 60% of ruptures are extraperitoneal, 30% are intraperitoneal, and 10% are combined.
Extraperitoneal ruptures involve the lateral or inferior surfaces of the bladder, which are not in contact with peritoneum. Urine extravasates into the pelvis and collects around the base of the bladder. This type of rupture almost always occurs in the setting of a pelvic fracture, resulting from the shearing forces of the pelvic fragments, rather than from perforation by bony spicules. If additional fascial planes are disrupted, urine may extend into the abdominal wall, thigh, and genitals.
Intraperitoneal ruptures, in contrast, involve the superior surface (dome) of the bladder, which is covered with peritoneum. As a result, urine extravasates into the intraperitoneal space. This type of rupture occurs when a full bladder is subject to a sudden and dramatic increase in pressure. The bladder’s superior surface has the most widely spaced muscle ﬁbers and is thus most likely to rupture. A common victim is a person with a full bladder who is wearing a seatbelt during a motor vehicle accident.
PRESENTATION AND DIAGNOSIS
Hematuria is a nearly universal feature of bladder rupture. Other signs include suprapubic tenderness, lower abdominal bruising, and low urine output. On laboratory assessment, patients may be found to have elevated serum creatinine concentration, acidosis, hyperkalemia, and azotemia secondary to reabsorption of extravasated urine. Women should receive a careful pelvic examination to assess for possible vaginal injuries, which can result in vesicovaginal ﬁstulae. In addition, patients should be assessed for urethral injuries, which can lead to difﬁculty with voiding.
After blunt trauma, an absolute indication for imaging the bladder is the combination of pelvic fracture and gross hematuria. Relative indications include gross hematuria without pelvic fracture, as well as microhematuria with or without pelvic fracture, occurring with any of the following: the clinical signs and symptoms listed previously, free intraperitoneal ﬂuid on abdominal imaging, or known prior bladder abnormality.
In most patients, computed tomographic cystography is the initial imaging test of choice. After urethral injury has been excluded, a Foley catheter is placed and the bladder is retrograde ﬁlled with 350 to 400 mL of dilute contrast. This imaging modality is highly sensitive for the detection of tears and also permits evaluation of other abdominopelvic organs. The previous gold standard was conventional cystography; however, this test often requires more time and may fail to detect subtle tears. In addition, post drainage ﬁlms must be obtained. Of note, neither ultrasound nor CT scan without bladder contrast is sensitive enough to be an effective screening tool.
Using the appropriate imaging techniques, bladder ruptures may be characterized based on the location and extent of contrast extravasation. As previously noted, extraperitoneal ruptures lead to contrast extravasation into the pelvis. Meanwhile intraperitoneal ruptures cause contrast extravasation around loops of the bowel and into the paracolic gutters. Injuries less severe than a complete rupture may also be detected. Interstitial injuries cause contrast accumulation within the bladder wall with minimal extravasation. Contusions often do not cause any radiographic abnormalities but may, in some cases, result in an abnormal bladder contour.
If an iatrogenic bladder injury is suspected during a surgical procedure, a Foley catheter should be placed, and the bladder should be ﬁlled with either methylene blue (in open cases) or contrast (in endoscopic cases) to determine if there is extravasation into the abdomen.
Most blunt extraperitoneal bladder ruptures can be successfully managed with catheter drainage alone and do not need to be explored. In most cases, the bladder will heal spontaneously over the course of several weeks, which can be conﬁrmed with a follow-up cystogram. If the abdomen is explored because of other injuries, however, extraperitoneal ruptures can be repaired at the same time.
In contrast, blunt intraperitoneal ruptures require open repair. Delayed management often results in signiﬁcant morbidity, including metabolic acidosis, ileus, abdominal/pelvic pain, sepsis, and possibly peritonitis.
Penetrating bladder injuries mandate surgical exploration to assess for other intraabdominal injuries and to determine if there is damage to the ureters or trigone. To explore injuries, the bladder should be exposed through a midline abdominal incision and opened at the dome. This precaution minimizes the risk of incising a pelvic hematoma, which can cause brisk, difﬁcult-to-control bleeding. All tears should be repaired from within the bladder. The bladder neck and ureteral oriﬁces should be inspected for possible damage. Bladder neck injuries must be surgically repaired or patients may experience stress urinary incontinence. Injuries to the ureteral oriﬁces require ureter reimplantation. After formal bladder repair, the urine is diverted using a large-bore Foley catheter and/or suprapubic tube.