Failure rates of nonoperative management of low-grade splenic injuries with active extravasation: an Eastern Association for the Surgery of Trauma multicenter study

Introduction

In recent decades, the clinical management of splenic injuries has transitioned from immediate operative intervention to watchful waiting and a minimally invasive approach with angioembolization for hemodynamically stable patients.1–7 The 2012 Eastern Association for the Surgery of Trauma (EAST) Practice Management Guidelines recommend nonoperative management (NOM) as the preferred treatment in hemodynamically stable patients regardless of injury grade.8

The management is less clear, however, when there is an active arterial bleed, described as active extravasation or contrast blush (CB), on a CT scan.9–11 While evaluating all patients who present with CB, prior studies have demonstrated that splenic injuries with CB increase the risk of splenectomy,12 13 in some studies by 20-fold.14 However, very few studies evaluate the risk of failure of NOM in patients with low-grade splenic injuries (grade I–II) with CB, with some asserting that low-grade splenic injuries with CB require no intervention.15 16

In contrast, the most recent American Association for the Surgery of Trauma (AAST) 2018 guidelines now suggest treating prior grade I/II splenic lacerations with a CB as grade IV injuries. However, there is little evidence in the literature to support this recommendation due to the low numbers included in prior studies. Furthermore, angioembolization of these injuries could lead to patients undergoing an unnecessary procedure with inherent risks such a splenic infarction, abscess, arterial access injury, contrast nephropathy, coil migration17 as well as an increased risk of venous thromboembolism18 and postsplenectomy sepsis.19

To date, there have been no large-scale studies to evaluate the failure of NOM for traumatic grade I–II splenic injuries with CB on a CT scan. Therefore, this multicenter study aimed to analyze the frequency of failure of NOM (defined as nonangiographic or surgical intervention) of grade I–II splenic injuries with CB in hemodynamically stable patients.

Methods

This is a retrospective cohort study of 21 institutions from January 1, 2014, to October 31, 2019. Centers were enrolled through the EAST website. Study data were collected and managed using a centralized Research Electronic Data Capture electronic data capture tool hosted at the lead center.20 21 A standard data dictionary was developed and used by all sites to ensure use of the same nomenclature based on Trauma Quality Improvement Program (TQIP) definitions.

Inclusion criteria were patients 18 years of age or older with an AAST grade I or II splenic injury secondary to blunt trauma with CB on a CT scan. All mechanisms of blunt trauma were included. Patients were excluded for hemodynamic instability, known bleeding disorders, or medication-induced coagulopathy, including antiplatelet therapy. We excluded patients who were taking warfarin, rivaroxaban, apixaban, dabigatran, clopidogrel, and ticagrelor. Patients on aspirin were not excluded in this study. Hemodynamic instability was defined as a systolic blood pressure (SBP) less than 90 mm Hg within 1 hour of arrival to the emergency department (ED). The primary outcome was failure of medical management requiring angioembolization or surgical intervention resulting in splenectomy. Medical management was defined as hospital admission without planned operative or angiographic intervention. Secondary outcomes included mortality, length of stay (LOS), intensive care unit (ICU) LOS, and need for blood transfusion. Data collection included demographics such as age, sex, mechanism of injury, comorbidities, transfer data, admission SBP, highest SBP within 1 hour on arrival to ED, amount of fluid (all volumes, including crystalloid, blood, blood products) in milliliters received within 1 hour of arrival, location of blush (outside spleen, within the spleen, or outside and within the spleen), need for blood transfusion and massive transfusion, splenic injury grade, and outcome data such as discharge disposition and death (table 1).

Patients who failed NOM were compared with patients who were successfully managed nonoperatively. Statistical analysis was performed, with continuous variables reported as median and IQR. Discrete variables were reported as N (%). P values <0.05 were considered indicative of statistical significance. Continuous variables were analyzed using the Wilcoxon rank-sum test and discrete variables were analyzed using Fisher’s exact test. Direct standardization was used to calculate the failure rate of NOM, adjusting for center-specific rates and volumes. All analyses are performed using SAS Enterprise Guide 8.3 statistical software (SAS Institute).

Results

There wasere a total of 209 patients from 21 institutions enrolled in this study. Of these, 64 (30.6%) patients were excluded from the study: 44 due to no documentation of CT evidence of CB, 9 due to hemodynamic instability at admission, 9 patients who underwent a prophylactic/planned intervention, and 2 patients who underwent exploratory laparotomy for other injuries. Thus, 145 patients were analyzed in the study (figure 1), which was comprised of 65 (66%) men and a mean study population age of 47 years. The median Injury Severity Score was 17 with motor vehicle collision being the most common mechanism of injury (67%) followed by falls (12.3%). All patients in the study received a CT scan within 24 hours of being admitted. The mean time to admission CT was 48 min (SD 60), and the median time was 30 min (IQR 13–60 min). There were 55 (37.9%) patients with grade I splenic injuries with CB and 90 (62.1%) grade II injuries with CB.

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The combined rate of failure for both grade I and II injuries was 20.0% (29 patients, 20.0%–95% CI=13.8 to 27.4); the standardized rate to adjust for center-specific volumes was 22.1% (95% CI=14.4 to 29.8). There was a statistically similar rate of NOM failure for grade I versus grade II injuries (18.2% vs 21.1%, p=0.831, 95% CI=9.1 to 30.9 and 13.2 to 31.0, respectively). There was also no difference in NOM failure based on the location of the splenic blush (see table 2). Of the 29 patients who failed medical management, 11 (37.9%) required operative splenectomy whereas the remaining 18 were managed with IR embolization (see table 3). There were no patients who underwent angioembolization that then required splenectomy.

Discussion

Splenic injury is a common solid organ injury after blunt force trauma. However, the management has changed significantly as CT imaging has improved and the field of interventional radiology progresses. Historically, splenectomy was the treatment of choice for splenic lacerations. Sclafani1 first described the role of angiography in treating blunt splenic trauma in the early 1980s. Although grade I–II injuries are often thought to be mild, when they occur with a CB there is an unclear definition of the severity of these injuries (eg, AAST consideration to make this a grade IV injury) and the management. This large multicenter study found that grade I–II splenic injuries with CB fails in 20% of patients.

CB has been identified as a predictor of NOM failure,22 and grade of injury correlates with an increased incidence of CB.23 However, grade I–II splenic injuries with CB are relatively rare. There has been debate regarding the management of low-grade splenic injuries with CB in hemodynamically stable patients. A study by Omert et al24 in 2012 concluded that the presence of CB was not an absolute indication of angioembolization. However, this was a small study at only two institutions and thus may lack generalizability as interventional radiology practices are variable throughout the country. In addition, only 138 patients had grade I–II injuries and only 5 of them had CB (3.2%). Another single institution study in 2013, reported good outcomes with NOM in low-grade injuries with CB, but this was a small population consisting of only 40 patients.15 This is the largest multicenter study to date evaluating the outcomes of NOM of grade I and II splenic injuries with CB.

Despite a lack of studies describing the natural history of NOM for grade I–II splenic injuries with CB, many authors consider signs of CB as an indication for angioembolization in stable patients. In 2015, Brillantino et al prospectively evaluated NOM of both minor (grades I–II) and severe (grades III–V) splenic injuries based on the 2008 AAST grading system. Although they found that NOM was successful in all grades, this study excluded patients with CT-documented vascular injury at admission, as all patients with CB underwent diagnostic angiography and splenic embolization.25 Recently, Zarzaur et al26 described the natural history of splenic injury and the current management of splenic pseudoaneurysms and CB in 2017 and discovered that active bleeding vascular injuries were associated with a 40.9% risk of splenectomy. Similar to other studies in the literature, they did not delineate the risk of failure of NOM with CB based on injury grade.

The most recent 2018 AAST splenic trauma guidelines have been updated to consider any splenic injury with vascular involvement or active bleeding within the splenic capsule as a grade IV injury.27 Although there have been two retrospective studies suggesting that the newer 2018 AAST guidelines better predicted the need for operative management than the previous guidelines,28 29 it is unclear whether the consideration of CB in patients with grade I–II injuries as grade IV injuries improved this prediction. The anticipated failure rates of NOM based on AAST splenic grades are as follows: AAST grades I (4.8%), II (9.5%), III (19.6%), IV (33.3%), and V (75.0%).3 After ruling out patients who were admitted to the hospital hypotensive, the failure rate of NOM of patients with CB and grade I or II splenic injuries more closely aligned with grade III injuries than grade IV injuries.

Our data indicates that when patients failed NOM of low-grade splenic injuries with CB, patients expectedly had increased hospital LOS and need for blood transfusion but did not increase ICU LOS nor did they have an increase in mortality. Our findings suggest that all grade I–II splenic lacerations that were normotensive on arrival to the ED with CB should be classified as grade III. This downgrade in splenic injury grade will likely decrease splenic embolization in many institutions and its associated complications.

The type and rate of complication of splenic embolization depends on whether the spleen is embolized proximally or distally. In general, patients who undergo splenic embolization more proximally are more susceptible to infection, whereas those who are embolized more distally are more susceptible to infarction. Schnüriger et al30 performed a meta-analysis evaluating the rate of complications of splenic embolization performed proximally and distally. In their study, the patients whose spleens were embolized more proximally, 0.5% of patients developed an infarction that ultimately required splenectomy whereas 1.9% developed infection requiring splenectomy. In patients who underwent distal embolization, 2.7% developed infarction that required splenectomy whereas 0% developed infection that required splenectomy. Many of the patients in the study developed splenic infarction but did not ultimately require splenectomy (5.8% of patients embolized proximally and 18.3% of patients embolized distally). Trauma surgeons must weigh these risks of splenic embolization with the risk of failure of NOM with low-grade splenic injuries with CB.

There are several limitations to this study including those inherent to its multicenter retrospective design. Also, the presence or absence of CB was determined by the attending radiologist report, which may not have been available at the time of injury for the practicing trauma surgeon and was not verified by a blinded panel of expert radiologists for this study. Although CB may be mistaken for pseudoaneurysms or calcifications on some CT imaging, by assuming the best practice of radiologists and trauma surgeons at each participating institution, we think this makes our study more generalizable to the typical trauma center. Additionally, our study did not address the use of anticoagulant therapy in low-grade splenic injuries with CB and we chose to only evaluate patients with no preexisting bleeding diatheses, thus this data is not generalizable to these relatively common populations of trauma patients. Also, it must be reiterated that this data only applies to patients who are hemodynamically normal.

Conclusion

NOM of grade I–II splenic injuries with CB fails in 20% of patients.