This is a large descriptive study from a single center that reports clinical presentations, management and outcomes of blunt liver injuries based on the injury grade, hemodynamic status and management approach. The study showed a higher rate of liver injuries in young males which occurred in more than one third of patients with blunt trauma. Conservative treatment was the option of treatment in more than a three-quarter of cases.
The mechanism of liver injury differs geographically due to socio-demographic and community factors [21, 22]. In the state of Qatar, the rate of blunt poly-trauma associated hepatic injury is high secondary to the increase in the trend of motor vehicles crashes over the recent decades .
Earlier studies on blunt hepatic trauma showed an association with extra-abdominal injuries involving chest and head regions as well as fractures of the long bones and pelvis .
It has been well established that around 80% of patients with liver injuries can be successfully managed non-operatively . However, this approach could fail in up to 25% of cases due to re-bleeding, bile leak, liver necrosis or secondary sepsis. Our study demonstrated that the vast majority of patients were successfully treated conservatively. Consistent with our findings, an earlier study from Kuwait showed an 80% success rate of NOM in patients who sustained blunt liver trauma and only 4 patients (4%) failed NOM. A recent study from Albania reported a similar rate of successful conservative management (83%) . Another study from Turkey  included 300 patients (63% stable and 37% unstable), of them 192 patients treated conservatively and 108 received surgery. In this study, 13% died and the main determinants of mortality were hemodynamic instability on admission and type and grade of liver injury .
In our study, conservative treatment failed in six patients mainly due to delayed bleeding from hepatic hematoma, associated splenic rupture or small bowel injury. These findings reflect the improvement of the NOM approach as compared to earlier study by Bernardo et al.,  where 60.8% of cases were treated non-operatively with a failure rate of 15%. In our series; one patient failed NOM which later successfully treated with angioembolization. Recent literature suggests that NOM in higher grade of liver injury can be considered using selective angioembolization in the absence of active bleeding. Despite the fact that angioembolization is promising adjunct for increasing the success of NOM in blunt liver injury, it could be associated with serious complications such as liver necrosis, secondary infection, liver abscess, bile leak and biloma .
In the present study, 23% cases underwent emergent surgery where the major indications for surgery included hemodynamic instability, acute peritonitis and associated other surgically correctable intra-abdominal injuries. Failure of NOM was related mainly to high grade liver injury. Although the failure rate was low, three cases had re-bleeding due to development of pseudoaneurysm. Current reports have suggested the rate of successful NOM to be 60–70% for high-grade liver injuries (i.e. III and above) .
Østerballe et al.  reported a 4% of pseudoaneurysm on radiological follow-up for 188 patients. The authors observed no correlation between the development of pseudoaneurysm and severity of liver injury; therefore they recommended a follow-up CT angiogram after 4–5 days to rule out such complications. As the high grade injury is the mainstay of failure, we have changed our institutional protocol to repeat the CT scan in patients with higher liver injuries grades with intravenous contrast to pick up early pseudoaneurysm development and to plan angioembolization (coiling) aiming to reduce the rate of NOM failure.
In the present study, complications related to liver injury were very few in terms of biloma in two cases and pseudoaneurysm related rebleeding in three patients. Much less to Carrillo et al. series ; who reported biloma of 2.8% in cases with complex blunt hepatic injuries. Bala et al. analyzed 398 patients with liver trauma and identified complications in 16 patients with high grade injury which included biloma and bile leak that was treated with drainage and endoscopic retrograde cholangiopancreatography, while three patients developed re-bleeding from pseudoaneurysm that required angioembolization .
Generally, in about 10–20% of severe hepatic injuries, the decision for surgery poses a difficult challenge for surgeons. Non-operative management of high grade liver injuries may carry risk of complication which can be related to the amount of blood transfusion, associated injuries, age and/or liver related complications . The concept of damage control in patients with abdominal trauma is currently a valuable operative approach in unstable patients with liver injury as well as polytrauma .
Similar to our findings, few studies have suggested that the need for blood transfusion is lesser in patients who are managed non-operatively than those who underwent surgery [5, 21]. Notably, an earlier study from Egypt reported blood transfusion in 70.5% cases managed non-operatively  which is much higher than that of our study (18%). It is worthy to mention that the need of blood transfusion was not dependent on the liver injury alone.
The conservative treatment group showed no significant difference in the length of hospital stay as compared to OM group in our study which is similar to the observation from the Ghnnam et al. study .
In our study, the overall mortality rate was 7.8%, and most deaths accounted for significant injuries involving head or chest region and exsanguinating hemorrhage at presentation. The reported mortality rate in hepatic injury patients varies from 9 to 42%, and mostly close to 20% among the admitted patients. However, an earlier study from Saudi Arabia showed a lower rate of motility (3.5%) . The observed high mortality in mild liver injury patients was mainly related to the associated head injury.
Recently, WSES classification for liver injury has been published , however, in our center; we still rely on the AAST for grading of solid organ injuries. According to WSES, stable patients should be treated non-operatively in grade I-III whereas WSES grade IV patients should be treated surgically without having initial CT scanning due to patients’ instability. In the present study, there were 189 mild AAST cases, of them 13 patients were classified as WSES grade IV, indicating that surgical intervention was based on the patient instability due to other associated injuries. One-quarter of severe AAST cases was treated surgically and grouped as a WSES IV.
The main limitation of the present study is the retrospective analysis of data which may limit its generalizability in addition to potential selection bias. Patients with incomplete data, prehospital or on arrival death were excluded from the current analysis which may underestimate the blunt liver injury rate. The sample size in the higher grade liver injury groups was small for reliable comparisons. The design of the study makes it difficult to carefully assess the management approach. Moreover, we lack information regarding the time to CT scan and follow-up for patients post-discharge from the hospital.