URORADIOLOGY


Case 16 :
What is the diagnosis?
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CYSTOGRAPHY

CLINICAL REASON:POST C-SECTION,SUSPECTED IATROGENIC BLADDER INJURY,FOR EVALUATION AND CONFIRMATION.
FINDINGS: FLAME SHAPED EXTRAVASATION OF CONTRAST SEEN FROM SUPERIOR WALL OF URINARY BLADDER JUST LEFT TO THE MIDLINE REPRESENT EXTRAPERITONEAL RUPTURE.

 

 

 

Introduction

Bladder injuries are caused by blunt or penetrating trauma. The probability of bladder injury varies according to the degree of bladder distention; therefore, a full bladder is more likely to become injured than an empty one.
Although uniformly fatal in the past, a timely diagnosis with appropriate medical and surgical management now offers an excellent outcome. Early clinical suspicion, appropriate and reliable radiologic studies, and prompt surgical intervention, when indicated, are the keys to successful diagnosis and management of bladder trauma.

History of the Procedure
Patients with signs and symptoms suggestive of a bladder injury have a history typical for pelvic trauma, which is fairly straightforward for motor vehicle collisions, deceleration injuries, or assaults to the lower abdomen. If the patient is unconscious, family members or, more often, emergency services personnel may be able to provide the history.

  • Bladder injury from a motor vehicle collision may occur from direct impact with the car or indirectly from the steering wheel or seatbelt.
  • Deceleration injuries of the urinary bladder usually result from falling from a great height and landing on unyielding ground.
  • Assault to the lower abdomen by a sharp kick or blow may result in a bladder perforation.
  • Penetrating injuries to the bladder usually result from high-velocity gunshots or sharp stab wounds to the suprapubic area.

Problem
Blunt trauma
Deceleration injuries usually produce both bladder trauma (perforation) and pelvic fractures. Approximately 10% of patients with pelvic fractures also have significant bladder injuries. The propensity of the bladder to sustain injury is related to its degree of distention at the time of trauma.
Penetrating trauma
Assault from a gunshot or stabbing typifies penetrating trauma. Often, concomitant abdominal and/or pelvic organ injuries are present.
Obstetric trauma
During prolonged labor or a difficult forceps delivery, persistent pressure from the fetal head against the mother's pubis can lead to bladder necrosis. Direct laceration of the urinary bladder is reported in 0.3% of women undergoing a cesarean delivery. Previous cesarean deliveries with resultant adhesions are a risk factor. Undue scarring may cause obliteration of normal tissue planes and facilitate an inadvertent extension of the incision into the bladder. Unrecognized bladder injuries may lead to vesicouterine fistulas and other problems.
Gynecologic trauma
Bladder injury may occur during a vaginal or abdominal hysterectomy. Blind dissection in the incorrect tissue plane between the base of the bladder and the cervical fascia results in bladder injury.
Urologic trauma
Perforation of the bladder during a bladder biopsy, cystolitholapaxy, transurethral resection of the prostate (TURP), or transurethral resection of a bladder tumor (TURBT) is not uncommon. Incidence of bladder perforation is reportedly as high as 36% following bladder biopsy.
Orthopedic trauma
Orthopedic pins and screws can commonly perforate the urinary bladder, particularly during internal fixation of pelvic fractures. Thermal injuries to the bladder wall may occur during the setting of cement substances used to seat arthroplasty prosthetics.
Idiopathic bladder trauma
Patients diagnosed with alcoholism and individuals who chronically imbibe a large quantity of fluids are susceptible to this type of injury. Previous bladder surgery is a risk factor. In reported cases, all bladder ruptures were intraperitoneal. This type of injury may result from a combination of bladder overdistention and minor external trauma (eg, a simple fall).
Frequency
Frequency of bladder rupture varies according to the following mechanisms of injury:

  • External trauma (82%)
  • Iatrogenic (14%)
  • Intoxication (2.9%)
  • Spontaneous (<1%)

Of all bladder injuries, 60%-85% are from blunt trauma and 15%-40% are from a penetrating injury. The most common mechanisms of blunt trauma are motor vehicle collisions (87%), falls (7%), and assaults (6%). In penetrating traumas, the most frequent culprit is gunshot wounds (85%), followed by stabbings (15%).
Approximately 10%-25% of patients with a pelvic fracture also have urethral trauma. Conversely, 10%-29% of patients with posterior urethral disruption have an associated bladder rupture.
Traumatic bladder ruptures
Of traumatic ruptures, extraperitoneal bladder perforations account for 50%-71%, intraperitoneal accounts for 25%-43%, and combined perforations account for 7%-14%. The incidence of intraperitoneal bladder rupture is significantly higher in children because of the predominantly intra-abdominal location of the bladder prior to puberty.
Combined intraperitoneal and extraperitoneal ruptures account for approximately 10% of all traumatic bladder-perforating injuries. Mortality rates in these patients approach 60%, as compared to 17%-22% overall, reflecting the severity of concomitant injuries associated with combined bladder ruptures.
Associated bowel injuries
Among patients with bladder trauma due to a gunshot, the incidence of associated bowel injuries is reportedly as high as 83%. Colon injuries are reported in 33% of patients with stab wounds, and vascular injuries are reportedly as high as 82% in patients with a penetrating trauma (with a 63% mortality rate).
Etiology
Main causes of bladder injury are penetrating and blunt trauma. Iatrogenic causes include surgical misadventures from gynecologic, urologic, and orthopedic operations near the urinary bladder. Less common causes involve obstetric trauma. Spontaneous or idiopathic bladder injuries without an obvious underlying pathology constitute the remainder.
Pathophysiology
Bladder contusion is an incomplete or partial-thickness tear of the bladder mucosa. A segment of the bladder wall is bruised or contused, resulting in localized injury and hematoma. Contusion typically occurs in the following clinical situations:

  • Patients presenting with gross hematuria after blunt trauma and normal imaging findings
  • Patients presenting with gross hematuria after extreme physical activity (ie, long-distance running)

The bladder may appear normal or teardrop-shaped on cystography. Bladder contusions are relatively benign, are the most common form of blunt bladder trauma, and are usually a diagnosis of exclusion. Bladder contusions are self-limiting and require no specific therapy, except for short-term bedrest until hematuria resolves. Persistent hematuria or unexplained lower abdominal pain requires further investigation.
Extraperitoneal bladder ruptures
Traumatic extraperitoneal ruptures are usually associated with pelvic fractures (89%-100%). Previously, the mechanism of injury was believed to be from a direct perforation by a bony fragment or a disruption of the pelvic girdle. It is now generally agreed that the pelvic fracture is likely coincidental and that the bladder rupture is most often due to a direct burst injury or the shearing force of the deforming pelvic ring.
These ruptures are usually associated with fractures of the anterior pubic arch, and they may occur from a direct laceration of the bladder by the bony fragments of the osseous pelvis. The anterolateral aspect of the bladder is typically perforated by bony spicules. Forceful disruption of the bony pelvis and/or the puboprostatic ligaments also tears the wall of the bladder. The degree of bladder injury is directly related to the severity of the fracture.
Some cases may occur by a mechanism similar to intraperitoneal bladder rupture, which is a combination of trauma and bladder overdistention. The classic cystographic finding is contrast extravasation around the base of the bladder confined to the perivesical space; flame-shaped areas of contrast extravasation are noted adjacent to the bladder. The bladder may assume a teardrop shape from compression by a pelvic hematoma. Starburst, flame-shape, and featherlike patterns are also described.
With a more complex injury, the contrast material extends to the thigh, penis, perineum, or into the anterior abdominal wall. Extravasation will reach the scrotum when the superior fascia of the urogenital diaphragm or the urogenital diaphragm itself becomes disrupted.
If the inferior fascia of the urogenital diaphragm is violated, the contrast material will reach the thigh and penis (within the confines of the Colles fascia). Rarely, contrast may extravasate into the thigh through the obturator foramen or into the anterior abdominal wall. Sometimes, the contrast may extravasate through the inguinal canal and into the scrotum or labia majora.

Intraperitoneal bladder rupture
Classic intraperitoneal bladder ruptures are described as large horizontal tears in the dome of the bladder. The dome is the least supported area and the only portion of the adult bladder covered by peritoneum. The mechanism of injury is a sudden large increase in intravesical pressure in a full bladder. When full, the bladder's muscle fibers are widely separated and the entire bladder wall is relatively thin, offering relatively little resistance to perforation from sudden large changes in intravesical pressure.
Intraperitoneal bladder rupture occurs as the result of a direct blow to a distended urinary bladder. Resulting increase in intravesical pressure causes a horizontal tear along the intraperitoneal portion of the bladder wall. This is the weakest part of the bladder, since its muscle fibers are most widely separated. This type of injury is common among patients diagnosed with alcoholism or those sustaining a seatbelt or steering wheel injury.
Since urine may continue to drain into the abdomen, intraperitoneal ruptures may go undiagnosed from days to weeks. Electrolyte abnormalities (eg, hyperkalemia, hypernatremia, uremia, acidosis) may occur as urine is reabsorbed from the peritoneal cavity. Such patients may appear anuric, and the diagnosis is established when urinary ascites are recovered during paracentesis.
Intraperitoneal ruptures demonstrate contrast extravasation into the peritoneal cavity, often outlining loops of bowel, filling paracolic gutters, and pooling under the diaphragm. An intraperitoneal rupture is more common in children because of the relative intra-abdominal position of the bladder. The bladder usually descends into the pelvis by age 20 years.

 

 

 

Combination of intraperitoneal and extraperitoneal ruptures
Cystogram reveals contrast outlining the abdominal viscera and perivesical space. External penetrating injuries deserve special mention. A penetrating injury of the urinary bladder results from a high-velocity bullet traversing the bladder, knife wounds, or impalement by various sharp objects. These may result in intraperitoneal, extraperitoneal, or a combined bladder injury.

The high incidence of associated injury to abdominal viscera and vascular structures mandates surgical exploration in virtually every case. Often, cystography is bypassed, and the diagnosis is made during an exploratory laparotomy. Cystography results may be falsely negative in patients with penetrating bladder injuries secondary to small-caliber bullet wounds. In such patients, these injuries may not be appreciated until exploratory surgery is performed.

Presentation
Clinical signs of bladder injury are relatively nonspecific; however, a triad of symptoms is often present (eg, gross hematuria, suprapubic pain or tenderness, difficulty or inability to void).
Most patients with bladder rupture complain of suprapubic or abdominal pain, and many can still void; however, the ability to urinate does not exclude bladder injury or perforation. Hematuria invariably accompanies all bladder injuries. Gross hematuria is the hallmark of a bladder rupture. More than 98% of bladder ruptures are associated with gross hematuria, and 10% are associated with microscopic hematuria; conversely, 10% of patients with bladder ruptures have normal urinalysis results.
An abdominal examination may reveal distention, guarding, or rebound tenderness. Absent bowel sounds and signs of peritoneal irritation indicate a possible intraperitoneal bladder rupture. A rectal examination should be performed to exclude rectal injury and, in males, to evaluate prostate position. If the prostate is "high riding" or elevated, it may further suggest proximal urethra and bladder disruption.
In the setting of a motor vehicle collision or a crush injury, bilateral palpation of the bony pelvis may reveal abnormal motion, indicating an open-book fracture or a disruption of the pelvic girdle.
If blood is present at the urethral meatus, suspect a urethral injury. Perform retrograde urethrography to assess the integrity of the urethra before attempting to blindly pass a Foley catheter.


Indications

Foley catheter
Blood at the urethral meatus is an absolute indication for retrograde urethrography. Approximately 10%-20% of men with a posterior urethral injury have an associated bladder injury; therefore, do not place a urethral catheter in these patients. Passage of a urethral catheter may convert a partially disrupted urethra into a complete tear.
Place a Foley catheter only after urethral injuries are excluded. In the setting of a posterior urethral injury, insert a percutaneous suprapubic catheter.
CT scanning
This is often the first test performed in patients with blunt abdominal trauma. The CT scan of the pelvis provides information on the status of the pelvic organs and osseous pelvis and has replaced conventional cystography as the most sensitive test for bladder perforation. Once the urethra has been cleared by a retrograde urethrogram, a urethral catheter can be placed. Dilute Cysto-Conray is then passed through the urethral catheter, and an abdominal/pelvic CT scan is performed. Subtle perforations are often revealed, and the intraperitoneal and extraperitoneal nature of these ruptures can be determined.
Cystography
The criterion standard for imaging a suspected bladder injury is a well-performed cystography. Although it is preferable to perform the examination under fluoroscopy, clinical circumstances often do not permit this. A static cystography is satisfactory, even when performed at the bedside with portable equipment.
Most patients with bladder trauma have multiple injuries and require abdominal or pelvic CT scans as part of their trauma evaluation. This does not preclude obtaining a separate contrast cystogram if the bladder findings of the CT scan are equivocal.
A properly performed cystography consists of an initial kidney-ureter-bladder (KUB) followed by anteroposterior (AP) and oblique views of the bladder filled with contrast, plus another AP film obtained after drainage. The following procedure is recommended:

  • Obtain a scout radiograph.
  • Place a urethral catheter in the bladder.
  • Using a diluted contrast medium, slowly fill the bladder by gravity (approximately 75 cm above the pelvis) to a volume of 300-400 mL. (Diluted contrast media are usually 50% contrast and 50% sterile saline or water). Use a contrast media suitable for absorption.
  • Obtain a single AP film of the pelvis and lower abdomen after the first 100 mL of contrast is instilled.
  • If gross extravasation is noted, discontinue the procedure. If extravasation is absent, give the patient the remainder of the contrast.
  • Obtain a KUB, followed by a postdrainage film of the pelvis.
  • Obtain the postdrainage film after a complete drainage of the contrast. This is the most critical part of the study because it checks for extravasation that may be hidden by the distended bladder.
  • If possible, obtain lateral and oblique films of the bladder. In children, obtain the estimated filling for the cystogram based on the following formula:

    Bladder capacity = 60 mL + (30 mL X age in years)

The importance of proper filling and drainage films cannot be overemphasized. A significant number of injuries may be missed if the cystogram is not performed correctly.
As oblique films may be difficult to obtain in a trauma patient with pelvic fractures, they may be omitted in selected cases. The volume infused is less important than achieving an adequate bladder pressure to demonstrate small bladder injuries that may go undetected. Small puncture wounds or lacerations may be self-sealing because of mucosal edema. Overlying hematomas, omentum, a sigmoid colon, or a small bowel may seal the wound. Full distention helps to prevent this false-negative result, and the accuracy of a well-performed static cystogram ranges from 85%-100%.
If the patient is immediately taken to the operating room for an exploratory laparotomy and/or placement of a formal suprapubic cystostomy, the bladder is inspected at the time of surgery and the bladder injury is repaired. If surgery is delayed or an exploratory laparotomy is not contemplated, perform the cystogram via a percutaneous suprapubic tube (SPT) so that no bladder injury is overlooked.
Although static cystography is used to accurately diagnose a bladder injury, the same cannot be said of intravenous pyelography (IVP). The inaccuracy of IVP stems from incomplete bladder distension, poor opacification, or a combination of both.


Relevant Anatomy

The adult bladder is located in the anterior pelvis and is enveloped by extraperitoneal fat and connective tissue. It is separated from the pubic symphysis by an anterior prevesical space known as the space of Retzius. The dome of the bladder is covered by peritoneum, and the bladder neck is fixed to neighboring structures by reflections of the pelvic fascia and by true ligaments of the pelvis.
In males, the bladder neck is contiguous with the prostate, which is attached to the pubis by puboprostatic ligaments. In females, pubourethral ligaments support the bladder neck and urethra.
The body of the bladder receives support from the urogenital diaphragm inferiorly and the obturator internus muscles laterally.
The superior fascia of the urogenital diaphragm is continuous and includes the pelvic, obturator, and endopelvic fasciae. The inferior fascia of the urogenital diaphragm fuses with the Colles fascia. It continues as the Scarpa fascia anteriorly, the dartos muscle and fascia in the scrotum, and the fascia lata of the thigh.
The type of extravasation (intraperitoneal or extraperitoneal) depends upon the location of the laceration and its relationship with the peritoneal reflection.

  • If the perforation is above the peritoneal reflection, the extravasation is intraperitoneal.
  • If the injury is below the peritoneal reflection, the extravasation is extraperitoneal.

With an anterosuperior perforation, urinary extravasation may be intraperitoneal, extraperitoneal (space of Retzius), or both. If the tear is posterosuperior, fluid can spread intraperitoneally and/or retroperitoneally.
In a bladder rupture, the superior fascia of the urogenital diaphragm, when intact, prohibits extravasation from escaping the pelvis. Inferior fascia of the urogenital diaphragm, when intact, also prevents urinary extravasation from flowing into the perineum.

 

Contraindications

Posterior urethral injury is a specific contraindication to insertion of a urethral Foley catheter. Suspect a posterior urethral injury if blood is present at the meatus, in all pelvic fractures, or if a high-riding prostate is found on digital rectal examination.
When posterior urethral injury is suspected, perform a retrograde urethrogram before attempting to insert a Foley catheter. Perform a retrograde urethrogram as follows:

  • Gently stretch the penis and hold it at an obtuse angle from the pelvis.
  • Insert a 16F Foley catheter into the distal urethra, and inflate the balloon (3 mL) within the fossa navicularis. Alternatively, if available, a Brodney clamp may be used, which allows a better seal at the urethral meatus.
  • Inject a diluted x-ray contrast medium suitable for intravenous infusion into the catheter using a 60-mL piston syringe.
  • Obtain radiographic images of the urethra and the bladder. Oblique views are usually the most helpful. An extravasation indicating urethral injury will be readily apparent.

Alternatively, the tip of a 60-mL piston syringe may be engaged into the urethral meatus and contrast injected directly into the urethra. Lead-lined gloves must be worn when contrast is injected directly into the urethra to prevent radiation exposure to the examiner's hands.
After excluding posterior urethral injury, radiographic evaluation of suspected bladder injury may commence. In the presence of a documented urethral injury, a percutaneous SPT must be placed and primary urethral realignment attempted once the patient is stable; this is often efficacious in the prevention of severe urethral stricture formation. Primary realignment may often be attempted with flexible cystoscopy at the bedside and may help to obviate the need for a formal urethroplasty at a later date.

 

 

 

 

 

References

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Dr Sushila Ladumor