**5. Hepatic injury grading**

One of the most widely accepted injury grading scale to grade hepatic injuries is the American Association for the Surgery of Trauma (AAST) classification system. A study done using the National Trauma Data Bank (NTDB) in 2008 about the solid organ injuries showed that about 67% of hepatic injuries are Grade I, II, or III [26].

The nonoperative management (NOM) can give rise to higher successful outcome for lowgrade injuries (Grades I, II, and III) and less success in cases of high-grade injuries (Grades IV and V). The major benefit of AAST grading system is for predicting the likelihood of success with NOM (see Figure 3).

**Figure 3.** CT scan images show (A) Grad II Subcapsular, nonexpanding, 10-50% surface area; intraparenchymal nonex‐ panding <10 cm diameter; (B) Grad III liver injury with >3 cm laceration in the left lobe; (C) CT showing Grade IV liver injury with parenchymal disruption involving more than 25% of the liver.

Patients with Grade VI injuries are universally hemodynamically unstable and surgical intervention is required. The grades of hepatic injury are described in Table 4 [27-29].


**Table 4.** Grading of liver injury based on the American Association of Surgery for trauma (AAST; 1994 revision) (data adopted from Moore EE, Cogbill TH, Gregory JJ, Shackford SR, Malangoni MA, Howard CR. Organ injury scaling: spleen and liver. J Trauma 1995;38:323-4)

In high-grade liver injury patients, liver-related complication rates are 11-13%. These can be predicted by the volume of packed red blood cells transfused at 24 hours post-injury and the grade of liver injury [30, 31].
