Comparable to patients with other general trauma, patients with traumatic colorectal injury should be first evaluated and treated for injury that may threaten life, sufficient resuscitation by fluid and transfusion is required, and efforts should be made to reduce hypothermia, hypotension, shock, and acidosis, all of which can influence the morbidity and the mortality rates. Next, tests and evaluation that assess colorectal injury are required. For critical patients, movement of the patient should be limited; thus, physical examination cannot be performed efficiently.

Injuries from the back-side can be missed easily due to the patient's condition, so more a thorough physical examination needs to be carried out. Also, accurate assessment is required to see whether other injuries are present, to diagnosis underlying diseases, and to clearly evaluate the mechanism of trauma. In addition, it is necessary to understand the interval from trauma time to surgery. In operating rooms, in order to achieve an objective evaluation of the level of fecal contamination within the abdominal cavity, accurate exploratory open abdominal surgery including other organs is required, and an evaluation of the possibility of injury to the colon located in the retroperitoneum is required.

To select treatment methods for colon injury, first, colon injury grading scales that evaluate the level of colon injury should be accurately understood. As grading scales limited to colon injury, two systems, the Flint scale prepared by Flint et al. [19] and the colon injury scale (CIS) of the American Association for the Surgery of Trauma (AAST) [20, 21], are frequently applied (Table 1). The two scales are applied to quantify and objectify the level of colon injury. Based on them, the level of colon injury can be objectified by classifying colon injuries as destructive colon injuries or non-destructive colon injuries. Other evaluation tools, such as the Penetrating Abdominal Trauma Index (PATI), show address associated injuries to other organs and are helpful in evaluating the overall seriousness of the trauma [20, 21].

Generally, colorectal injuries can be categorized as penetrating, blunt, and iatrogenic injuries, and treatment methods may differ depending on the mechanism of colon injuries. Most traumatic colon injuries have been reported to be caused by penetrating trauma, and colon injury is associated in 20% of abdominal penetrating traumas [12]. Penetrating traumas are gunshots and stabs in most cases. Gunshots can be divided into injuries caused by high-speed bullets and by low-speed bullets. High-speed bullets are known to be related with more associated organ injuries and wider soft tissue damage. During war times, injuries caused by high-speed bullets and explosives are more frequent, and during peace times, injuries are caused by low-speed bullets primarily. In recent trends, even during peace times, high-speed-bullet injuries have been increasing. In case of gunshot injury, the ascending colon and the transverse colons are more frequently injured, and multiple colon injuries may be associated.

Comparing the gunshots to the stabbings in cases of penetrating injuries, in the United states, gunshot injuries are predominant (gunshot wounds:stabbings = 10:1) [22], but in Korea, out of 47 penetrating injuries, only a single gunshot wound was noted, making stabbings absolutely the dominant injury mechanism [23-27]. In gunshot injuries, exploratory open abdominal surgery is required because 95% of the cases involve intra-abdominal organ injuries. In stabbing injuries, selective surgical observation can be used because only 50% of the cases involve intra-abdominal organ injuries, although exploratory open abdominal surgery can be performed as well [12].

In the treatment of the colon injuries, whether the primary repair and the proximal diversion is selected will depend on the severity of the colon injury. Maxwell and Fabian [28] classified colon injuries as non-destructive colon injuries and destructive colon injuries. Non-destructive colon injuries correspond to Flint grades 1 and 2 and to CIS grades 1-3, and in many cases, primary repair can easily be done.

In 1979, Stone and Fabian [14] provided evidence for the first time that the primary repair was superior to the colon diversion through a prospective randomized study conducted on selective patients, excluding risk factors. Since then, several prospective studies and prospective randomized studies have been conducted. Chappuis et al. [29] reported that in a prospective randomized study without exclusion of risk factors conducted on 28 patients in the primary repair group and 28 patients in the proximal diversion group, the primary repair showed less intra-abdominal sepsis, regardless of risk factors (the number of associated injuries, the level of fecal contamination, with or without shock, and transfusion volume). Demetriades et al. [30] conducted a prospective, non-randomized study involving the treatment of 100 cases of gunshot colon injury in which the primary repair was performed on all cases except cases requiring resection of the colon or cases with severe intra-abdominal contamination, without considering other risk factors, and they showed that the primary repair group presented good treatment outcomes compared to the proximal diversion group (11.8% vs. 29.2%, respectively).

In four prospective or prospective, randomized studies [29-32], the primary repair group presented better results than the proximal diversion group (10.7% vs. 23.3%, respectively) (Table 2). By reviewing other prospective and retrospective studies, Maxwell and Fabian [28] reported that the primary repair group presented better results compared to the proximal diversion group not only for complications (14% vs. 31%) but also for intra-abdominal sepsis (5% vs. 12%) and mortality rate (0.11% vs. 0.14%). Therefore, based on several prospective and retrospective studies, one can conclude that in non-destructive colon injuries, primary repair should be the standard treatment regardless of associated risk factors. Nevertheless, despite such a scientific basis, as shown by a survey of 317 Canadian surgeons conducted in 1999 [33], even in cases of colon injuries caused by low-speed bullets, 75% of the surgeons still performed proximal diversion to treat colon injuries. This fact implies that surgeons are still being driven by a past preference for the proximal diversion.

Destructive colon injuries are injuries corresponding to Flint grade 3 or CIS grades 4-5, and such injuries require resection. The causes of such injuries are high-speed bullets and explosives; safety belts cause abdominal blunt injuries. During the peace time, 80-90% of colon injuries are non-destructive colon injuries [12]. In contrast, in war time, 72% of colon injuries are destructive injuries [34]. In most cases (60-93%) [35] of non-destructive colon injuries caused by penetrating trauma, the primary repair is the standard treatment without considering the risk factors, but guidelines for the treatment of destructive colon injuries are still controversial due to their lower incidence rate and the lack of definitive data.

Maxwell and Fabian [28] reviewed two prospective studies and three prospective, randomized studies and found the incidence rates of overall complications, intra-abdominal abscess, and anastomosis leakage to be 35%, 23%, and 3.1%, respectively. In addition, no mortalities were reported for the 65 patients who underwent end-to-end anastomosis after the colon resection. According to the guideline of the Eastern Association for the Surgery of Trauma (EAST guidelines, 1998) [36], even in destructive colon injury cases, if patients are hemodynamicaly stable during surgery, have fewer associated injuries (PATI < 25, Injury Severity Score < 25), do not have severe peritonitis, and have with no prior underlying medical diseases, the end-to-end anastomosis after the colon resection is recommended without the proximal diversion. In cases of shock or severe associated diseases with severe peritonitis and with prior underlying medical diseases, the colon resection and the proximal diversion are the standard treatments. However, the guideline is not based on sufficient evidence (class III evidence), and it has clear limitations. Demetriades et al. [37] conducted a multicenter, randomized, prospective study to augment the guideline. Out of 297 destructive colon injuries, on 197 patients, anastomosis was done after the colon resection, and on 100 patients, proximal diversion was performed. The results showed that in the patient group receiving anastomosis after the colon resection, 13 cases (6.6%) developed anastomosis leakage, and in the patient group receiving proximal diversion, 1 case presented with anatomosis leakage. In the univariate analysis, intra-abdominal complications were increased in cases treated with a single prophylactic antibiotic, in cases with severe intra-abdominal fecal contamination, and in cases with transfusions of more than 4 units. In the multivariate analysis, the mortality rates and the incidences of intra-abdominal sepsis between the two groups, without regarding the risk factors, were not different. Thus, even for destructive colon injury cases, the colon resection followed by anastomosis without the proximal diversion has been recommended as the standard treatment. Therefore, even though in cases of destructive colon injury, the primary repair or the end-to-end anastomosis after the colon resection is usually performed in selected patients, the selection of the correct treatment for destructive colon injuries is still a subject of controversy and depends on associated risk factors, injury mechanism, anatomical site, and severity. In the future, more studies are required to address this debate.

Approximately 4% of colon injuries are caused by blunt trauma, mostly traffic accidents [38]. Blow out injuries by seat belts and wheels are the most common, ischemia is developed due to vascular injuries, and delayed colon perforation may occur. Therefore, the possibility of delayed colon perforation should be kept in mind. The injuries caused by blunt trauma frequently occur in the movable areas of the colon, such as the cecum, the transverse colon, and the sigmoid colon, and secondary injuries caused by mesenteric devascularization frequently happen in the right-side colon. Blunt injuries to the perineum may cause detachments of the rectosigmoid junction and the surgical anal canal from the levator muscle sling [39, 40]. The possibility of delayed diagnosis of colon injury caused by blunt trauma is higher than it is for colon injury caused by penetrating trauma, and associated organ injuries are severe; thus, high morbidity and mortality rates are shown [35]. In penetrating injury cases, 60-93% are treated with primary repair or with resection and anastomosis [35]. Regarding treatments for colon injuries caused by blunt trauma, according to the study reported by Miller and Schache [41], primary repair could be performed only in 39% of the cases; thus, for colon injury cases caused by blunt trauma, proximal diversion is performed more frequently.

In blunt traumatic colon injuries, delayed perforations may found a few days later, and in case of severe fecal contamination during the operation and septic conditions, resection and diverting colostomy are preferred rather than the primary repair [12]. In cases with destructive colon injuries, hypovolemic shock, severe intra-abdominal fecal contamination, old age, associated severe underlying medical disease and less experienced trauma centers, the proximal diversion is performed more frequently for blunt-trauma colon injuries [18, 42]. Carrillo et al. [40] reported that complications between the group who received end-to-end anastomosis after resection and the group who received proximal diversion after resection were not different. Nevertheless, for patients with unstable vital signs, cases with severe fecal contamination, and cases with severe associated extra-abdominal organ injuries, proximal diversion is recommended. Fallon [42] explained that the proximal diversion would be performed on the abdominal blunt trauma patients rather than on penetrating trauma patients because the former has more associated organ injuries.

Since the Second World War, the fundamental principles of treating rectal injuries have been the proximal colon diversion, the primary repair, and the presacral drainage (PSD) [43]. Two more treatments, distal rectal washout (DRWO) and primary repair without proximal colon diversion, were introduced afterward. However, controversy still exists [44, 45]. Shannon et al. [46] reported that the DRWO showed promising results and was most effective in cases with high-energy pelvic crush or large-caliber handgun injuries. A study by Burch et al. [47] and other studies provided no definite evidence for the efficacy of the DRWO [45, 48, 49]; a small number of cases required only primary repair without proximal diversion for rectal injuires.

Depending on the anatomical location of the rectal injury, such injuries can be classified as intraperitoneal and extraperitoneal rectal injuries. The former can be treated with the standard treatment for colon injuries, which is the primary repair, while the latter may be treated with the primary repair without proximal diversion, and no anastomotic leakage has been reported [28, 45, 48, 50]. However, because of the small number of cases, its effectiveness needs to be confirmed by follow-up studies in near future. The PSD is also a subject of debate. For example, there are numerous studies proving the advantages of PSD, but only Burch et al. [47] reported statistically significant results. In contrast, Gonzalez et al. [51] reported in a prospective, randomized study that in only the proximal colon diversion without PSD group, did the mortality and the morbidity rates not increase. This raises the question whether PSD is really required. In cases of destructive rectal injuries, where the presacral area is severely contaminated, PSD would be the effective treatment [35]. Cleary et al. [35] proposed a treatment algorithm for penetrating trauma cases; in this algorithm, when the rectal injury site cannot be treated with the primary repair or cannot be identified in cases of destructive extraperitoneal rectal injuries, the proximal colon diversion and PSD seem to be the appropriate treatments. However, in less severe cases without serious associated injuries or with no underlying medical diseases, the primary repair without proximal colon diversion is the more appropriate treatment.

Rectal injuries caused by blunt trauma are associated with pelvic blood vessel injuries and with bladder or ureter injuries; thus, high mortality and morbidity rates are shown. When complex injuries, such as severe pelvic injuries, injuries in the peritoneal area, pelvic vascular injuries, and pelvic bone injuries, occur, multidisciplinary treatment is required.

Because the mortality rate of rectal injuries caused by blunt trauma is more than 50%, which is higher than the mortality rate of colon injuries caused by blunt trauma (17%) and because the possibilities of associated rectal injuries is higher, more attention needs to be paid to patients with pelvic fractures or peritoneal injuries [52]. In regard to the principle of treatment and to existing controversies, intraperitoneal rectal injuries are similar to colon injuries. Treatments for extraperitoneal rectal injuries caused by blunt trauma follow the treatment principle for extraperitoneal rectal injuries caused by penetrating injuries, and the points of controversy are similar.