Free Fluid in the Abdomen
A 62-year-old male presents following a motor vehicle collision in which he was an unrestrained driver. He was intubated in the trauma bay for decreased mental status. A focused assessment with sonography for trauma (FAST) was performed, which did not reveal intra-abdominal fluid. Computed tomography (CT) of the head demonstrated minimal intra-cranial injury. CT of the abdomen and pelvis (see below) revealed decreased blood supply to the left kidney, small irregularity of the splenic contour, and a moderate amount of free fluid in the abdomen and pelvis. Hounsfield units are consistent with simple fluid.
CT of the abdomen and pelvis
What is the differential diagnosis for the free fluid in the abdomen?
Free fluid due to trauma can be urine, enteric contents (bowel injury with spillage of succus) or blood. It is possible to have fluid present prior to the trauma, such as ascites from chronic liver disease. In this case, the free fluid in the abdomen had characteristics of “simple fluid,” based on Hounsfield units, suggesting that the fluid was not blood. In females, free fluid in the pelvis can be normal (physiologic fluid). However, free fluid is NOT normal in a male, and it's concerning for hollow viscus injury.
What are the possible causes of decreased blood flow to the kidney?
The renal artery can be injured in blunt trauma. Blunt injury can disrupt the layers of the artery wall, leading to thrombosis and decreased blood flow beyond the injury.
He was admitted to the intensive care unit. A foley catheter was placed and demonstrated pink-tinged urine [NOT frank gross blood/ clots].
What are the possible causes of blood-tinged urine?
Bloody urine indicates a traumatic injury to the genitourinary tract, anywhere from the kidneys down to the urethra.
A CT cystogram was performed, which did not reveal any extravasation of contrast from the bladder.
CT Cystogram
Next steps?
Based on an unreliable physical exam and a normal CT cystogram, it is necessary to rule out bowel injury.
The patient was hemodynamically stable and had normal laboratory values. He remained with a decreased mental status, and therefore serial abdominal exams were not a viable management plan.
The patient was taken to the operating room and underwent diagnostic laparoscopy. His small bowel, colon, and mesentery were examined in there entirety and found to be completely normal. There was a small amount of clear thin fluid in the pelvis, but there was no evidence of bile staining or bleeding. After completing the evaluation of the gastrointestinal tract, we repositioned the patient in Trendelenburg. The pelvis was inspected, and it was quickly apparent that the patient in fact had a large defect in the dome of the bladder.
We elected to proceed with a low midline laparotomy. The bladder was easily mobilized, and the extent of the defect was defined. The edges were grasped, and the defect was closed in two layers with absorbable suture.
Postoperatively, we reviewed the preoperative CT cystogram. In retrospect, there was a suggestion of bladder irregularity. We reviewed the CT cystogram with the radiologist and there was no evidence of contrast extravasation. However, the bladder does not appear to have been completely distended with contrast. It is very atypical that a large bladder wall defect was not associated with contrast extravasation, and this highlights the importance and ensuring complete filling of the bladder with contrast.
Evaluation and Management of Bladder Injuries
Bladder injuries can occur from blunt or penetrating trauma. For example, bladder injuries can occur when blunt force is exerted on a full bladder or in the setting of a pelvis fracture.
Diagnosis
Gross hematuria is seen in most patients with bladder injuries. Cystography, either using plain x-ray or CT, is the diagnostic test of choice.
Management
The management of bladder injuries is based on location. Intra-peritoneal injuries require operative management. This is done in two or three layers with absorbable suture. A decompressive foley catheter is left following repair.
Extra-peritoneal injuries can typically be managed non-operatively with a foley catheter for 10-14 days. Exceptions include large bony segments protruding into the bladder wall, associated rectal or vaginal injuries, bladder neck injuries, or an associated pelvic fracture undergoing operative intervention to prevent hardware contamination. Current guidelines recommend a cystogram before foley removal, except for the most uncomplicated injuries.