SPLENIC LACERATION

A manifestation of the potential inaccuracy of CT is the entity of delayed splenic rupture. This is defined as bleeding due to splenic injury occurring more than 48 hours after blunt trauma following an apparently normal CT examination and must be differentiated from delayed presentation of splenic rupture. 

Spleen is most commonly injured organ in blunt abdominal trauma, accounting for approximately 40% of all solid organ injuries. Contributory factors include its potential for injury from fractured ribs, intra abdominal compression and its rich supply. The presence of splenomegaly or of splenic disease e.g. infectious mononucleosis increases this susceptibility to trauma.
Contrast CT is the definitive radiological investigation for detection of splenic injuries.
On contrast CT splenic laceration appear as linear low attenuation defects that contrasts well with high attenuation vascular spleen. Complex inter connecting lacerations may combine; appear as more diffuse hypo attenuating regions.
Splenic haematomas must be differentiated from more triangular peripheral non-enhancing regions that are characteristic of splenic infarcts. Sub capsular haematomas may occur alone or in combination with other injuries and result in low attenuation collections that indent the splenic margins.

Pitfalls: Uniform enhancement of spleen occurs approximately 50-60 seconds after contrast administration and is optimal timing for the detection of intrasplenic injuries. During earlier phase of arterial enhancement, the cord like geographical enhancement of splenic pulp may mimic intrasplenic lacerations, so delayed supplementary confirmatory images should be obtained whenever there is doubt.
Congenital splenic clefts may be distinguished from lacerations by their superior location and slightly lobulate contour, with absence of perisplenic haematoma and the clarity of surrounding perisplenic fat.