Clinics in diagnostic imaging (221)

CASE PRESENTATION

A 55-year-old man with benign prostatic hyperplasia was on follow-up at the urology outpatient specialist clinic and complained of persistent lower urinary tract symptoms despite medical therapy (xatral XL and finasteride). He subsequently underwent elective transurethral vaporisation of the prostate (TUVP). One day postprocedure, the patient developed a fever and complained of abdominal pain with bloating. Clinical examination revealed lower abdominal tenderness. Initial laboratory tests performed showed an elevated C-reactive protein level of 138.0 mg/L (reference range: <10.0 mg/L) with mild neutrophilia of 8.2 × 10⁹/L (reference range: 1.9–6.0 × 10⁹/L). Computed tomography (CT) was then performed to evaluate the cause of the patient’s symptoms [Figure 1]. What does the image show? What is the diagnosis?

Figure 1.

Delayed-phase axial CT image of the pelvis.

IMAGE INTERPRETATION

Delayed-phase CT in the axial plane [Figure 1] showed perivesical contrast extravasation extending to the right hemipelvis, right inguinal canal and perineum. Iodinated contrast extravasation around the urinary bladder showed a classic ‘molar tooth’ configuration (long arrows). Free gas (short arrow) and presacral fluid (*) were also noted.

DIAGNOSIS

Extraperitoneal bladder perforation.

CLINICAL COURSE

Extraperitoneal bladder perforation was likely secondary to perforation during TUVP for benign prostatic hypertrophy. The patient underwent cystoscopy with insertion of an indwelling catheter (IDC), was treated conservatively with a 2-week course of ciprofloxacin and discharged uneventfully. Repeat fluoroscopic cystogram (not shown) after 2 weeks showed complete healing with no evidence of contrast extravasation.

DISCUSSION

Bladder ruptures are usually secondary to trauma. This can be due to direct impact, shearing injury, or perforation from pelvic fracture or penetrating trauma. Bladder ruptures are classified as extraperitoneal (80%–90%), intraperitoneal (10%–20%) or combined (intraperitoneal and extraperitoneal) (5%–12%,).[1,2] The American Association for the Surgery of Trauma has subclassified bladder trauma into five grades based on severity of injury [Table 1].

Table 1.

AAST classification system for bladder injury.

Grade	Injury type	Description
I	Haematoma Laceration	Contusion, intramural hematoma Partial thickness
II	Laceration	Extraperitoneal (<2 cm)
III	Laceration	Extraperitoneal (≥2 cm) or intraperitoneal (<2 cm)
IV	Laceration	Intraperitoneal (≥2 cm)
V	Laceration	Intraperitoneal or extraperitoneal extending to the bladder neck or ureteric orifices/trigone

AAST: American Association for the Surgery of Trauma

Extraperitoneal bladder ruptures are often associated with pelvic bone fractures.[3,4,5] On imaging, they may be subdivided into simple (where contrast extravasation is limited to the perivesical area) and complex (with contrast extravasation extending into the scrotum, perineum or thighs).[2,3] Intraperitoneal bladder ruptures are more often associated with direct impact on a fully distended bladder, classically at the bladder dome, where it is structurally the weakest.[3] Intraperitoneal ruptures are more common in the younger population, as the bladder tends to lie more superiorly in an intra-abdominal location before adolescence.[3] Combined ruptures show the imaging features of both intraperitoneal and extraperitoneal bladder ruptures and are usually a result of penetrating injuries.

Distinguishing between extraperitoneal and intraperitoneal bladder ruptures is crucial, as management is vastly different. Based on the American Urological Association guidelines, extraperitoneal rupture may be treated conservatively, whereas the standard of care for intraperitoneal rupture is surgical.[5] Without surgery, patients are at high risk of developing peritonitis, severe sepsis and fistulas.[5] Uncomplicated extraperitoneal bladder rupture (without concomitant urethral injury) is typically managed with bladder catheterisation (for 10–14 days) and prophylactic antibiotics.[4] Before IDC removal, a fluoroscopic cystogram is performed to demonstrate bladder wall healing.

While spontaneous rupture of the bladder is rare (<1%, with a reported incidence of 1 in 126,000), it has a high morbidity and can be potentially fatal.[6,7] These patients often present with vague symptoms and are often only diagnosed on surgical laparotomy. Predisposing factors include pelvic radiotherapy, chronic urinary retention, tumour, calculi and other causes that result in underlying weakness in the bladder wall. In our patient, the cause of bladder rupture was iatrogenic, a complication of TUVP. Apart from urological procedures, the bladder may also be injured during gynaecological and obstetric surgeries.[8]

There are two main imaging modalities that are used to diagnose bladder rupture: CT imaging and fluoroscopy. In the context of trauma, CT is the modality of choice. Therefore, a delayed-phase CT of the bladder should be performed if there is evidence of significant pelvic trauma, to evaluate for bladder injury [Figures 2 & 3]. If a delayed-phase CT does not demonstrate a leak but bladder injury is still strongly suspected, usually due to multiple pelvic fractures or the presence of a pelvic haematoma, CT cystography can be performed. In CT cystography, contrast is infused directly into the urinary bladder through an IDC. A 1:10 dilution of iodinated contrast is preferred, where typically 50 mL of iodinated contrast is diluted with 450 mL of normal saline.[9] Adequate bladder distension is needed for diagnosis, and usually, at least 250–300 mL of contrast is required to confidently exclude a bladder tear.[9] Higher intravesical pressures also allow for more homogeneous mixing of the contrast, which aids in the demonstration of contrast extravasation, although this increases the overall scan time of up to 10–15 min and may not be feasible for unstable trauma patients.[2]

Figure 2.

Extraperitoneal bladder rupture. A 53-year-old man presented to emergency department with severe pelvic injuries after a road traffic accident. Portovenous followed by 5-min delayed-phase axial CT image shows a urinoma in the left perivesical space, with contrast extravasation likely from the left lateral wall of the urinary bladder (*). Left iliac bone fractures are also seen (arrows).

Figure 3.

Extraperitoneal bladder rupture. A 33-year-old man had a fall from height. (a) Delayed-phase axial CT image at 5 min shows pelvic fractures (white circle) and a pelvic haematoma (*), but did not show contrast extravasation. (b) Delayed-phase axial CT image of the pelvis at 15 min, with the urinary catheter clamped, eventually shows contrast extravasation near the bladder neck at 3 o’clock, suggestive of an extraperitoneal bladder rupture (arrow).

Fluoroscopic cystogram can also be used to diagnose bladder rupture. Similar to CT cystography, this is performed by infusion of contrast into the urinary bladder via an IDC, with the benefit of real-time visualisation of bladder filling and extravasation under fluoroscopy. This allows for the estimation of rate and detection of the site of leakage. However, it is a generally time-consuming procedure and does not allow for the evaluation of surrounding structures.

Imaging findings of bladder rupture are similar for both CT and fluoroscopy. In extraperitoneal rupture, contrast extravasation remains confined around the perivesical space [Figures 4 & 5]. Layering of contrast along the perivesical space and the pelvic side walls can give rise to the classic ‘molar tooth’ configuration. In intraperitoneal rupture, contrast extravasation is usually seen arising close to the bladder dome and spreading cranially along the paracolic gutters and the mesentery [Figure 6]. The key differences between extraperitoneal and intraperitoneal bladder ruptures are summarised in Table 2.

Figure 4.

Extraperitoneal anastomotic leak. A 70-year-old man underwent robot-assisted prostatectomy. (a) Routine postoperative sagittal fluoroscopic cystogram shows extraperitoneal contrast extravasation confined to the perivesical space posteriorly (*). (b) Follow-up sagittal fluoroscopic cystogram 1 month later shows reduction in the extent of contrast extravasation (arrows).

Figure 5.

Extraperitoneal bladder rupture. A 67-year-old man was involved in a road traffic accident. Delayed-phase axial CT image did not show evidence of bladder rupture. However, as there was evidence of significant pelvic trauma, CT cystography was performed. Axial CT cystogram shows contrast extravasation limited to the perivesical space, suggestive of an extraperitoneal rupture (arrows).

Figure 6.

Intraperitoneal bladder rupture. A 69-year-old man underwent transurethral vaporisation of the prostate for benign prostatic hyperplasia. Intraoperatively, there was inadvertent perforation of the bladder. (a) Intraoperative cystogram shows contrast extravasation from the region of the bladder dome (*). (b) Coronal CT cystogram shows a perforation at the bladder dome, with contrast extravasation extending cranially into the abdominal cavity, suggesting intraperitoneal bladder rupture (arrows). There are also large amounts of intraperitoneal free fluid in the paracolic gutters, peri-hepatic and peri-splenic spaces.

Table 2.

Key differences between extraperitoneal and intraperitoneal bladder ruptures.

Variable	Extraperitoneal	Intraperitoneal
Aetiology	Pelvic fractures; spontaneous; iatrogenic	Direct impact on distended bladder; spontaneous; iatrogenic
Imaging (CT)	Contrast pools around the perivesical space (molar tooth sign)	Contrast extends along the paracolic gutters and the mesentery
Management	Conservative	Surgical

In conclusion, bladder rupture is commonly associated with trauma. In the presence of significant pelvic fractures, additional phases such as delayed pelvic CT should be performed to evaluate for bladder injury. If this does not demonstrate contrast extravasation, further evaluation with CT cystography or fluoroscopy should then be performed. It is important to differentiate between extraperitoneal and intraperitoneal ruptures on imaging, as their clinical management is distinctly different.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

SMC CATEGORY 3B CME PROGRAMME

Online Quiz: https://www.sma.org.sg/cme-programme

Deadline for submission: 6 pm, 10 December 2024

Question: Answer True or False
1. Regarding bladder rupture in the setting of trauma:
(a) A standard computed tomography (CT) trauma angiogram allows for adequate assessment for bladder injury.
(b) An intramural bladder haematoma is classified as an American Association for the Surgery of Trauma grade III bladder injury.
(c) Before inserting an indwelling catheter, urethral injury should be excluded first.
(d) A delayed-phase CT should be performed when bladder injury is suspected.
2. Regarding intraperitoneal bladder rupture:
(a) Intraperitoneal bladder ruptures typically occur at the bladder neck.
(b) Intraperitoneal bladder ruptures are more common in the elderly.
(c) The CT images show contrast extravasation in the paracolic gutters and the mesentery.
(d) Intraperitoneal bladder ruptures can occur from direct impact on a full bladder.
3. Regarding extraperitoneal bladder rupture:
(a) Extraperitoneal bladder ruptures account for the majority of bladder ruptures.
(b) Extraperitoneal bladder ruptures are closely associated with pelvic bony fractures.
(c) The CT images for extraperitoneal bladder rupture show contrast in the perivesical space, which has a ‘molar tooth’ configuration.
(d) Extraperitoneal bladder laceration of 1 cm is a grade II bladder injury.
4. Regarding management of bladder rupture:
(a) Intraperitoneal bladder ruptures can be managed conservatively.
(b) Repeat cystography must be performed before catheter removal to ensure bladder wall healing.
(c) For extraperitoneal ruptures, the indwelling catheter may be removed after 24–48 h if the patient is clinically well.
(d) Spontaneous rupture of the bladder can be managed conservatively.
5. Regarding imaging of bladder rupture:
(a) The main imaging modalities for diagnosis of bladder rupture are ultrasonography and CT.
(b) An additional benefit of fluoroscopic cystogram is the real-time visualisation of contrast extravasation, and thus the site and rate of leakage.
(c) Bladder injury can be excluded if delayed-phase CT shows no evidence of leak.
(d) Even if initial imaging findings are negative, CT cystography should be performed if there is persistent suspicion of bladder injury.