Observation Vs Embolization in Severe Splenic Injury: a Randomized Controlled Trial

Background

The spleen is the most commonly injured organ in patients who sustain blunt abdominal trauma.[1] Splenic trauma management has evolved significantly over the past 40 years, with non-operative management (NOM) considered the standard of care due to the decrease in morbidity, shorter length of hospitalization, and preservation of splenic function.[2] There are several controversial topics in the management of blunt splenic injuries (BSI) but the utilization of splenic artery embolization (SAE) in NOM is perhaps the biggest one.[3] Proponents of SAE cite higher success rates for NOM and some have even advocated that it should always be used in the following situations: 1) presence of contrast ¨blush¨ or extravasation on CT or angiography, 2) AAST Grade 3 injuries associated with moderate amount of hemoperitoneum, or 3) Patients with AAST Grade 4-5 injuries.[4] These criteria have never been validated prospectively and are simply associated with a higher risk for NOM failure. Opponents to SAE cite that this invasive approach has no effect on successful observation and that it is associated with higher complication rates (splenic infarction, splenic abscess, puncture site issues) when compared to observation alone.[5-7] There is limited evidence to guide the decision regarding SAE vs observation in patients sustaining high-risk BSI. Numerous observational studies on the role of SAE in splenic injury management have been published but their findings are inconclusive and often contradictory.[8, 9] Considering the inconsistent evidence and the lack of any high-quality data to inform best practice, clinical equipoise is achieved and a randomized controlled trial comparing observation to SAE is justified. Data from our own institution has shown that the presence of a contrast blush is associated with a much higher NOM failure rate (unpublished data). Based off that finding the investigators hypothesize that prophylactic SAE will improve NOM success in patients with high-risk BSI.

The contemporary management of splenic injury

The contemporary management of BSI began in the mid-1980's when the surgeons began publishing their data on NOM of splenic trauma in children. The adult trauma surgeons subsequently began using this approach when CT technology allowed for identification and classification of solid organ injuries.[10] The American Association for Surgery of Trauma (AAST) developed and subsequently validated a splenic injury grading scale, which provided a standardized nomenclature for those treating patients with BSI.[11, 12] In addition, the AAST grade was shown to correlate with risk of NOM failure and also allowed institutions to benchmark their splenic salvage rates. With increased success in NOM there were subsequent improvements in other clinical outcomes including lower rates of blood transfusion and decreased length of stay.[13]

NOM does carry some risks, the most significant of which is delayed splenic rupture. Typically occurring within 72-hours, delayed splenic rupture is a potentially life-threatening event that usually requires splenectomy.[14] Failure of NOM also occurs because of persistent bleeding, an ongoing transfusion requirement, or worsening abdominal pain that prompts the surgeon to perform a splenectomy. Since the advent of NOM, researchers have worked to identify the risk factors associated with failure. Increasing age, amount of hemoperitoneum, grade of organ injury, and presence of contrast extravasation have all been associated with NOM failure.[14, 15] While none of these are absolute contraindications to NOM they are used by some institutions as criteria for which to use prophylactic SAE in an attempt to improve splenic salvage.[16] When employed in a prophylactic manner, the splenic artery is embolized, which decreases the amount of blood flowing to the injured areas within the spleen.[17] Splenic infarction is not inevitable since some perfusion occurs through collateral circulation and splenic immune function is maintained even after embolization.[18] Despite the potential benefit, prophylactic SAE has not been universally adopted. In a multi-center retrospective study, Lee et al noted that there was a wide variation of SAE utilization in Level 1 trauma centers, ranging from 5.1% to 33%.[19] This finding is not unexpected considering that, in 2012, only 30% of trauma centers had a written guideline for the management of splenic injury.[20] Despite these issues, NOM has been the standard of care for more than 30 years and currently >85% of patients undergo an attempt at NOM.[2] In a recent meta-analysis, the success rate of NOM is ~8.3% of all patients but the role of SAE in improving NOM success rates is still unclear.[21]