What is the next indicated test for a patient with hypotension, tachycardia, gross hematuria, and lower abdominal bruising after a high-speed motor vehicle crash?

CT Scan with IV Contrast and Delayed Urographic Phase is the Next Indicated Test

For a hypotensive patient with gross hematuria and lower abdominal bruising after a high-speed motor vehicle crash, a contrast-enhanced CT scan with delayed urographic phase is the next indicated diagnostic test.

Rationale for CT Imaging in This Patient

• The patient presents with classic signs of potential urinary tract trauma: gross hematuria, lower abdominal bruising, and hemodynamic instability (BP 85/50, P 120) following a high-energy mechanism (high-speed MVA) 1
• While FAST examination was negative, it has low sensitivity (56-71%) for detecting specific intra-abdominal injuries, particularly those involving the urinary tract 1
• The combination of hypotension and gross hematuria strongly indicates significant genitourinary tract injury requiring immediate evaluation 1, 2
• The negative FAST does not exclude retroperitoneal bleeding or specific organ injuries, particularly to the kidneys or bladder 1

Diagnostic Algorithm for Suspected Urinary Tract Trauma

1. Initial Assessment:

   • The patient has already undergone chest X-ray and FAST examination (both negative) 1
   • Despite the negative FAST, the patient remains hypotensive with gross hematuria, indicating ongoing bleeding 1, 3

2. Next Step:

   • Contrast-enhanced CT scan with delayed urographic phase is indicated for:
     • Hemodynamically unstable patients with suspected urinary tract injury 1
     • Patients with gross hematuria after blunt trauma 4, 2
     • Patients with lower abdominal bruising suggesting possible bladder injury 1, 5

3. Specific CT Protocol:

   • IV contrast-enhanced CT of abdomen/pelvis in portal venous phase (70 seconds after contrast administration) 1
   • Addition of delayed urographic phase to evaluate the collecting system and ureters 1
   • No oral contrast is necessary as it delays diagnosis and does not improve sensitivity 1

Clinical Considerations and Caveats

• While some guidelines suggest immediate surgical exploration for hypotensive patients with positive FAST, this patient has a negative FAST but clear signs of genitourinary trauma 1
• CT cystography may be considered if bladder rupture is specifically suspected, as the lower abdominal bruising and gross hematuria suggest possible bladder injury 1, 5
• Single hematocrit measurements should not be used in isolation to assess bleeding severity, as initial values may be normal despite significant blood loss 3
• In this setting, rapid CT imaging is preferable to other modalities like IVP or ultrasound due to higher sensitivity and the ability to evaluate multiple organ systems simultaneously 1
• Studies show that 93% of patients with blunt bladder trauma have associated pelvic fractures, which may not be apparent on initial examination 5

Important Pitfalls to Avoid

• Do not rely solely on FAST examination to exclude significant injury in this patient, as it has low sensitivity for specific organ injuries 1
• Do not delay definitive imaging in a hypotensive patient with gross hematuria, as this combination indicates severe injury requiring prompt diagnosis 2, 6
• Do not perform non-contrast CT, as it has significantly lower sensitivity for detecting both visceral organ and vascular injuries 1
• Do not assume that a negative FAST excludes the need for further imaging in a patient with gross hematuria and hypotension 1