Only 33 (31%) patients had both a positive CT and positive RP and in three (3%) patients both diagnostic tests were negative (Fig. 1). Two patients with false-negative results on both studies had high grade (≥III) IP injuries resulting from penetrating trauma that were identified on laparotomy and received a proximal diversion for treatment. Although neither of these patients had a direct CT finding of rectal injury, they both had pneumoperitoneum on CT. The third patient with dual false negative studies had a grade II IP injury after a blunt trauma mechanism and received a proximal diversion. Unlike the previous two described patients, the only other CT findings were pelvic fractures and a perineal soft tissue injury.
Despite the frequent use of both RP and CT for the evaluation of possible rectal injuries, there is no clear evidence supporting a diagnostic strategy. We sought to evaluate a multicenter retrospectively collected data set to evaluate the utility of these diagnostic studies. Our data show that the combination of both RP and CT will identify 97% of rectal injuries.
In one of the few existing comparisons between RP and CT, Leaphart et al.11 retrospectively identified 24 pediatric patients with a rectal injury. Of 18 patients who underwent either CT or RP (nine in each group), three patients had a missed injury. Two were missed by initial evaluation with RP, and the other by CT without contrast. Based on these results, the authors concluded that CT was at least as accurate at RP, and recommended selective use of RP, specifically in combination with CT when a high suspicion for injury exists. In contrast, our results show that the sensitivity of RP (94%) far exceeds that of CT (34%) for rectal injury. However, when used in combination, CT does add diagnostic value, raising the diagnostic accuracy to 97%.
The majority of injuries were identified on RP, with false-negative CT results in approximately two thirds of patients. This is interesting, as the reported sensitivity of CT for hollow viscous injuries this is 53% to 86% in recent studies.5–7 One previously published study in a military population including 10 patients with rectal injuries, the authors reported a 100% sensitivity of CT.12 Unlike our study design, this study included perirectal air as a positive radiographic finding, and this was seen in all 10 patients with a rectal injury. Findings we considered as indicative of a rectal injury, such as rectal wall thickening and fat stranding, were seen in only half of their study population. Although findings such as pneumoperitoneum and free fluid are suggestive of hollow viscous injury, they are not specific to rectal injures, and we chose to only consider direct CT findings of rectal injury as having positive results. While perirectal air may arguably be a convincing sign of a rectal injury, our data set was inconsistent in distinguishing this finding from pneumoperitoneum. Therefore, we were unable to include this radiographic finding in our evaluation. Future studies evaluating these diagnostic tests should aim to investigate its value in the CT diagnosis of rectal injuries.
Furthermore, CT was especially poor at identifying extraperitoneal (EP) injuries. One potential explanation for this finding may be a lack of rectal contrast administration. Our data set did not specifically require the details of CT scanning protocols, and therefore we are unable to account for the effect of contrast in our analysis. On the other hand, RP identified 94% of all injures, 75% of intraperitoneal (IP) injuries, and 98% of the EP injuries. While more recent literature detailing the sensitivity and specificity of RP for rectal injuries is lacking, this is consistent with previously reported diagnostic accuracy rates of 80% to 100%.13–15
As mentioned above, one the limitations of our study is secondary to the retrospective design and inability to account for specific variables outside of those collected within our data set. Moreover, the variables we were able to collect are also subject to data recording and entry errors. While the complete AAST multicenter data set includes a large number of patients with rectal injuries, we were only able to identify a small percentage that met our inclusion criteria, and therefore our study is further limited by a small sample size. Additionally, our entire cohort includes patients with known rectal injuries, and therefore we are unable to calculate specificity, and positive and negative predictive values. Future studies should be designed with a patient population that would allow determination of these values, as this would better add to our understanding of our diagnostic options.
In conclusion, our findings show that, although standard in the workup of hemodynamically stable trauma patients, CT has a poor sensitivity for rectal injuries. Practitioners should perform RP when there is a concern for rectal trauma, as the combination of these two tests will identify 97% of injuries. When a high index of suspicion remains, a low threshold to perform a laparotomy is necessary to avoid morbidity from a delayed diagnosis, as there is a small subset of intraperitoneal injuries that will be missed.
The AAST Contemporary Management of Rectal Injuries Study Group is composed of the following: Richard H. Lewis, MD, S. Rob Todd, MD, Rachel E. Hicks, MD, Greg Victorino, MD, Tom Scalea, MD, Oscar Guillamondegui, MD, Vaidehi Agrawal, MD, Julia R. Coleman, MD, Kenji Inaba, MD, Matt Martin, MD, Cullen K. McCarthy, MD, Dennis Kim, MD, Zach M. Bauman, DO, Joseph Galante, MD, Kelly Lightwine, MD, Martin Schreiber, MD, Ladonna Allen, RN, Barbara U. Okafor
M.D.T., J.V., C.V.R.B. participated in the literature search. M.D.T., J.V., C.V.R.B. participated in the study design. M.D.T., J.V., C.V.R.B., J.P.S., T.M., J.H., E.B., B.B., H.A.H., M.T., C.B., M.S., J.S., J.V., B.E., A.C., R.V., G.V., E.C., J.H., R.C., P.B., S.G., P.G.B. participated in the data collection. M.D.T., J.V., C.V.R.B. participated in the data analysis. M.D.T., J.V., C.V.R.B. participated in the data interpretation. M.D.T., J.V., C.V.R.B. participated in the writing. M.D.T., C.V.R.B. participated in the critical revisions.
The authors have no funding or conflicts of interest to disclose.
1. Ahl R, Riddez L, Mohseni S. Digital rectal examination for initial assessment of the multi-injured patient: can we depend on it? Ann Med Surg (Lond)
2. Ahern DP, Kelly ME, Courtney D, Rausa E, Winter DC. The management of penetrating rectal and anal trauma: a systematic review. Injury
3. Grasberger RC, Hirsch EF. Rectal trauma. A retrospective analysis and guidelines for therapy. Am J Surg
4. Goodman CS, Hur JY, Adajar MA, Coulam CH. How well does CT predict the need for laparotomy in hemodynamically stable patients with penetrating abdominal injury? A review and meta-analysis. AJR Am J Roentgenol
5. Joseph DK, Kunac A, Kinler RL, Staff I, Butler KL. Diagnosing blunt hollow viscus injury: is computed tomography
the answer? Am J Surg
6. Bhagvan S, Turai M, Holden A, Ng A, Civil I. Predicting hollow viscus injury in blunt abdominal trauma with computed tomography
. World J Surg
7. Matsushima K, Mangel PS, Schaefer EW, Frankel HL. Blunt hollow viscus and mesenteric injury: still underrecognized. World J Surg
8. Leaphart CL, Danko M, Cassidy L, Gaines B, Hackam DJ. An analysis of proctoscopy
vs computed tomography
scanning in the diagnosis of rectal injuries
in children: which is better? J Pediatr Surg
9. Brown CVR, Teixeira PG, Furay E, Sharpe JP, Musonza T, Holcomb J, Bui E, Bruns B, Hopper HA, Truitt M, et al. Contemporary management of rectal injuries at level I trauma Centers: the results of an American Association for the Surgery of Trauma multi-institutional study. J Trauma Acute Care Surg
11. Leaphart CL, Danko M, Cassidy L, Gaines B, Hackam DJ. An analysis of proctoscopy
vs computed tomography
scanning in the diagnosis of rectal injuries
in children: which is better? J Pediatr Surg WB Saunders
12. Johnson EK, Judge T, Lundy J, Meyermann M. Diagnostic pelvic computed tomography
in the rectal-injured combat casualty. Mil Med
13. Morken JJ, Kraatz JJ, Balcos EG, Hill MJ, Ney AL, West MA, Van Camp JM, Zera RT, Jacobs DM, Odland MD, et al. Civilian rectal trauma: a changing perspective. Surgery
14. Levine JH, Longo WE, Pruitt C, Mazuski JE, Shapiro MJ, Durham RM. Management of selected rectal injuries by primary repair. Am J Surg
15. Bostick PJ, Johnson DA, Heard JF, Islas JT, Sims EH, Fleming AW, Sterling-Scott RP. Management of extraperitoneal rectal injuries. J Natl Med Assoc
Keywords:© 2018 Lippincott Williams & Wilkins, Inc.
Proctoscopy; computed tomography; diagnosis of rectal injuries