Isolated free fluid in trauma may or may not represent a significant injury, and this creates a diagnostic dilemma in determining appropriate treatment for these patients.
The presence of isolated free fluid in trauma occurs in 3-5% of blunt trauma patients 1-4.
The concern is that this free fluid represents a sign of occult traumatic abdominal organ injury such as:
- bowel injury (most common)
- liver injury
- splenic injury
- intraperitoneal bladder rupture
- pancreatic injury
- bile duct injury
The location, volume and attenuation of free fluid can be helpful in determining its significance 1-4:
- trace volume free fluid in females
- often within the pelvis, and described as physiological with no clinical significance 1
- known as physiological pelvic intraperitoneal fluid
- trace volume free fluid in males
- low volume of pelvic free fluid below the level S3 that was low-attenuating (mean 8.1 HU) was not associated with undiagnosed bowel or mesenteric injury in one study 4
- larger volume (i.e. more than trace) of higher-attenuating free fluid (30-35 HU), especially if mesenteric, present in more than one or more peritoneal compartments or pelvic free fluid above the level of S3 is more indicative of occult injury 2,4
Treatment and prognosis
Isolated free fluid in trauma can often present a diagnostic dilemma and options for management are based on clinical conditions; options include proceeding for diagnostic laparotomy (becoming less common) or repeat CT scan in 12-48 hours with the consideration for oral contrast 1-2.
- 1. Soto JA, Lucey B. Emergency Radiology: The Requisites. Mosby. ISBN:0323054072. Read it at Google Books - Find it at Amazon
- 2. Rodriguez C, Barone JE, Wilbanks TO et-al. Isolated free fluid on computed tomographic scan in blunt abdominal trauma: a systematic review of incidence and management. J Trauma. 2002;53 (1): 79-85. Pubmed citation
- 3. Drasin TE, Anderson SW, Asandra A et-al. MDCT evaluation of blunt abdominal trauma: clinical significance of free intraperitoneal fluid in males with absence of identifiable injury. AJR Am J Roentgenol. 2008;191 (6): 1821-6. doi:10.2214/AJR.07.3347 - Pubmed citation
- 4. Yu J, Fulcher AS, Wang DB et-al. Frequency and importance of small amount of isolated pelvic free fluid detected with multidetector CT in male patients with blunt trauma. Radiology. 2010;256 (3): 799-805. doi:10.1148/radiol.10091903 - Pubmed citation