Delayed Iatrogenic Bladder Rupture Diagnosed by POCUS in the Emergency Department

Abstract Bladder rupture is an uncommon injury that leads to significant morbidity and mortality. Though occurring mostly due to trauma, this life-threatening pathology may also occur spontaneously or after a procedure such as transurethral resection of bladder tumor (TURBT). Computed tomography (CT) cystography is the standard imaging modality for diagnosis. However, this test is unlikely to be ordered in a patient with undifferentiated abdominal pain unless there is specific suspicion for this diagnosis. In our emergency department, a 48 year-old male with history of bladder cancer and TURBT two weeks prior to arrival presented with severe abdominal pain and difficulty urinating for 3 days. Point of care ultrasound (POCUS) revealed an irregularly shaped bladder, likely site of bladder rupture, and large amount of abdominal free fluid with sediment. These findings prompted an expedited diagnostic CT scan with cystography. Emergent exploratory laparotomy ultimately confirmed a small bladder defect with 2.5 L of urinary ascites. The diagnosis of non-traumatic bladder rupture can be overlooked in patients presenting with a peritonitic abdominen. The typically ordered test for such patients is standard CT, which carries a high false-negative rate for bladder rupture. This case highlights the utility of POCUS in facilitating a rapid diagnosis.

The American Urological Association (AUA) reports that computed tomography (CT) cystography (using retrograde contrast instillation through a urethral catheter) is the diagnostic imaging test of choice to evaluate for bladder injury [19], with 94.7% sensitivity and 100% specificity in blunt trauma [20]. However, to order this test requires a high level of suspicion for the rare diagnosis of bladder rupture. Furthermore, this timeconsuming test requires bringing a potentially unstable patient outside the patient care area. Additionally, patients with an undifferentiated acute abdomen typically undergo conventional CT imaging, but the sensitivity for bladder injury is only 60% using this modality [20].
Here we present the first known case of an iatrogenic bladder rupture diagnosed by point of care ultrasound (POCUS), as well as the first known case where delayed diagnosis of any bladder rupture was made using POCUS. This rapid bedside diagnosis led to prescient ordering of CT cystography and expedited definitive surgical management.

Case Report
A 48 year-old male with history of bladder squamous cell carcinoma was triaged to the ED with worsening abdominal pain and difficulty urinating for 3 days. Triage vitals signs were notable for an elevated blood pressure of 178/89 mmHg and tachycardia to 110 beats per minute. Otherwise, the patient was afebrile with a temperature of 99.1°F, breathing at 20 breaths per minute, with an oxygen saturation of 98% on room air. As the patient looked uncomfortable upon arrival to the patient care area, he was attended to immediately by the physicians, while the nurse obtained intravenous access and blood tests. A brief history revealed that he had undergone TURBT six weeks earlier for initial evaluation and treatment of his bladder cancer, then another repeat TURBT two weeks prior to arrival for restaging and removal of the remaining tumor.
On physical examination, the patient was ill-appearing, tachycardic, and in significant distress due to abdominal pain. His abdomen was diffusely distended, tense, and tender to palpation with involuntary guarding. The rest of the physical examination (including genitourinary) was unremarkable.
An electrocardiogram from triage showed beginnings of a sine wave pattern, prolonged QRS interval to 160 msec, and peaked T waves altogether suggestive of hyperkalemia, for which appropriate medications were ordered. Given the patient's urinary retention and history of prostate cancer, immediate foley catheter insertion was planned in order to drain an expected markedly distended bladder. However, POCUS performed at the bedside in the supine position revealed an irregularly-shaped, non-distended bladder containing anechoic fluid and floating sediment ( Figure 1, Video S1). Disruption of the hyperechoic bladder dome was seen superiorly leading directly to intra-abdominal free fluid, indicating a likely site of bladder rupture ( Figure 2, Video S2). The patient was then tilted into the Trendelenburg position to increase POCUS sensitivity for gravitationally-dependent free fluid. This evaluation revealed large volume of heterogenous free fluid throughout the right upper quadrant, as well as moderate bilateral hydronephrosis ( Figure 3, Video S3). Altogether, this raised concern for intraperitoneal bladder rupture.  The Urology service was consulted immediately and reviewed the POCUS images. Placement of a foley catheter drained cloudy yellow urine, and both services expedited CT scan of the abdomen and pelvis with cystography ( Figure 4, Video S4). The suspected diagnosis was confirmed, and the patient was emergently taken directly from CT to operating room prior to any laboratory tests having resulted. During exploratory laparotomy, 2.5 liters of urinary ascites were evacuated from the peritoneal cavity, and the bladder wall defect was sutured closed. By this time, the initially drawn blood samples resulted with blood urea nitrogen of 180 mg/dL, creatinine of 12.4 mg/dL, potassium of 7.5 mEq/L, and anion-gap metabolic acidosis with pH of 7.23. Postoperative course was uneventful, acute kidney injury improved, and the patient followed up in clinic five days later for pelvic drain removal.

Discussion
This is the first known case report in which an iatrogenic bladder rupture, and also a delayed rupture from any etiology, was diagnosed at bedside using POCUS. Based on POCUS findings, the clinicians specifically ordered CT cystography due to its higher sensitivity for bladder injury, instead of standard CT with intravenous contrast. This decision expedited definitive diagnosis and subsequent exploratory laparotomy by the Urology service. ED management saved the patient from significant risk of morbidity and mortality. In the large retrospective study of patients who underwent TURBT, two of the fifteen patients with bladder perforation who died from septic shock and multiorgan failure had prolonged time of 21 days from TURBT to diagnosis [17].
Most prior cases of bladder rupture diagnosed by ultrasound occurred in the setting of trauma using the Focused Assessment with Sonography for Trauma (FAST) examination [21][22][23]. A 2019 systematic review and meta-analysis reported that POCUS was 74% sensitive and 98% specific for intra-abdominal free fluid in trauma [24]. Interestingly, these values did not differ greatly between hypotensive and normotensive patients.  Abdominal free fluid was also reported in all traumatic and atraumatic case reports of intraperitoneal bladder rupture evaluated with radiologist-or technicianperformed ultrasound [14,[21][22][23][25][26][27]. Similarly, our case showed large volume of free fluid in Morison's pouch and the rectovesical pouch with the patient reclined in Trendelenburg position, which increases sensitivity for free fluid [28].
The contour of a distended bladder would appear using 2D ultrasound as a roughly anechoic ellipsoid (not a circle), which explains why estimated bladder volume obtained from three dimensions is often multiplied by a correction coefficient factor of 0.72 [29]. Unexpectedly, our patient's bladder appeared non-distended and irregularly-shaped, while containing anechoic fluid and floating sediment. In two other case reports of traumatic bladder rupture, the bladder also appeared irregularlyshaped using POCUS, with intraperitoneal free fluid as well [22,25].
Intraperitoneal bladder ruptures most commonly occur at the bladder dome, the weakest and most mobile part of the bladder [2]. In one blunt trauma case, POCUS was used to identify the precise site of rupture at the bladder dome, leading directly to peritoneal free fluid [23]. In our case, POCUS similarly identified a purported site of bladder rupture. Additionally, the Foley catheter balloon has also been shown to approximate anatomy using POCUS. In one atraumatic case of bladder rupture, the catheter was visualized using POCUS even though the bladder walls were not [27]. In another bladder rupture case occurring after a fall, POCUS revealed that saline flushed through a catheter (with its bulb residing within the bladder) continued through a bladder dome defect directly into the peritoneum [21].

Why Should an Emergency Physician be Aware of This?
A bladder rupture occurs rarely and even less often from a non-traumatic etiology. A conventional CT scan ordered for a patient with an undifferentiated acute abdomen carries a high false-negative rate for this diagnosis. To order the gold standard CT cystography in the ED thus requires having a high level of suspicion. This case report highlights the utility of POCUS for rapidly identifying a bladder injury at the bedside, thereby leading to expedited appropriate follow-up imaging and transition to definitive surgical evacuation of free fluid and bladder wall repair.
Informed consent was obtained for use of the associated images and clips.

Conflicts of Interest
HL, EL, and SA have no conflicts of interest to disclose.