Penetrating gluteal injuries in North West London: a retrospective cohort study and initial management guideline

Chronological distribution

The chronological distribution of patients remained relatively static across the study period, as outlined in table 1. Analysis of the temporal distribution demonstrates three clear peaks at 17:00, 19:00, and midnight, which was consistent across the 3 years studied (figure 1). However, subset analysis of the under-18 cohort reveals that the majority of these injuries occur earlier in the afternoon, soon after the school day finishes, between 16:00 and 17:00 (figure 2).

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Table 2 compares the number and percentage of PGI in the 3-year study period with the preceding 3 years. This revealed an increase of 43% in total penetrating trauma and 87% in the number of presentations with PGI.

Anatomic distribution

Although there were 125 patients in the data set, several of them were injured multiple times, giving a total number of wounds of 141. A significant structure was defined as a confirmed injury to the rectum, urethra, prostate, sciatic nerve, or named blood vessel. The overall absolute risk (AR) of injury to a significant structure was 27.2% per patient over the entire cohort (table 3).

There were 22 vascular injuries (20.00% of all patients), 6 (4.80%) rectal injuries, 1 (0.80%) mesorectal laceration, and 2 (1.60%) urethral injuries, with 1 (0.80%) of these urethral injuries extending to the prostate. There were two (1.60%) possible sciatic nerve injury suggested on CT; however, one was ruled out after a normal clinical examination and the second patient absconded before this could be confirmed operatively. The distribution of the injuries according to the quadrant of the buttock can be found in figure 3.

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Although the vascular injuries were spread relatively evenly across the quadrants, five out of the six confirmed rectal injuries were found in patients who had entry wounds in the lower inner quadrant (p=0.0577). The patients stabbed in the lower inner quadrant of the buttock had an AR of rectal injury of 18.52% and an AR of 55.56% for injury to any significant structure.

Investigations

The vast majority of our patients received neither a digital rectal examination (DRE) nor a rigid sigmoidoscopy (RS) in the ED (table 4), and the percentage of patients receiving either of these examinations in the ED declined during the study period, from 26% in 2017 to 10% in 2019.

A total of 113 CT scans were performed for 111 patients, meaning 88.80% of patients received a CT scan. The remaining 14 patients (11.20%) were discharged after thorough clinical assessment, with the trauma team leader (TTL) deciding that there was no need for CT. Rectal contrast was only used in two patients (1.60%). There was equal split in the type of CT used to assess these patients, with dual-phase or triple-phase contrast CT being used with almost the same frequency as a single-phase combi CT scan (table 5). There were eight false positive CT findings and four false negative CT findings, giving an overall sensitivity of 50.00% and specificity of 92.38% in identifying rectal injury on initial assessment. From this data, combi CT had a sensitivity of 50% and a specificity of 94.55%, whereas dual-phase or triple-phase CT had a sensitivity of 50% and a specificity of 90.00%.

Management

The most common procedure required for these injuries was debridement, washout, and delayed primary closure of the entry wounds. This was performed in 26 patients by a variety of specialties. The median time from arrival to the hospital to operative intervention was 724 minutes (293–1047), or 12 hours and 4 minutes.

As displayed in table 6 there were 13 vascular injuries, 69.23% (9) were treated conservatively, 30.77% (4) underwent embolization, and 7.69% (1) also underwent an endovascular repair of an arteriovenous fistula. When assessing vascular injuries, major bleeding was considered present if the patient was alerted as a ‘code red’ by prehospital ambulance teams or if the patient received at least one unit of blood product in the ED.

Of the six rectal injuries shown in table 7, 16.67% (1) were primarily repaired during an examination under anesthetic (EUA), with a drain left in situ, 33.34% (2) were treated with washout and packing only, and 50.00% (3) were treated with proximal diversion, 2 of which were colostomies and 1 an ileostomy due to congenital adhesions affecting the sigmoid colon. There was one additional patient who suffered an injury to the mesorectum with no injury to the rectal wall; this patient was managed with oversewing of the mesentery during trauma laparotomy.

Investigation of PGI

The decrease in proportion of patients receiving DRE and RS in the ED is reflective of international consensus, moving away from mandating these tests in all patients and instead using RS in selected cases as a useful adjunct. RS is used at our institution to confirm or refute the presence of a rectal injury and to identify the anatomic location of any injury that can affect further management, and can be done as part of an EUA in the theater rather than performed in the ED. This is considered more likely to yield identification of rectal injury due to the controlled theater environment and be more acceptable to the patient who may find this intolerable in the ED.

There are widespread, and justifiable, reservations about the utility of DRE in assessing for rectal injury, with a previous 2007 study reporting a sensitivity of only 33% (specificity 99%) based on a retrospective analysis of over a thousand patients.16 In another study from 2005, the DRE was shown to give ‘useful information’ in only 5% of cases and changed management in only 4%.17 RS, on the other hand, has been found to have a much higher sensitivity of 94% in one large-scale retrospective study of 22 level 1 trauma centers, which was better than CT in identifying both intraperitoneal and extraperitoneal injuries. The same study found that RS in combination with CT gave an overall sensitivity of 97%.18 RS can be useful in determining the anatomic location of a rectal injury which, given the trend toward managing intraperitoneal injuries and extraperitoneal injuries differently, can aid decision-making for surgical teams.4

The decision on which patients underwent CT was made by the TTL at the time of presentation after a thorough clinical examination. The choice of CT protocol was inconsistent across the study period, with an almost 50:50 split between triple-phase or dual-phase CT and ‘combi’ CT scan. The specificity of CT in detecting rectal injury improved during the study period, which could reflect growing familiarity and experience among reporting radiologists during the time since this unit was established as an MTC in 2010.

Although contrast-enhanced CT is the default imaging in the severely injured trauma patient, penetrating injury to the bowel can be difficult to confirm on CT and is most commonly identified by locules of gas or inflammatory stranding in adjacent soft tissue.1 The gold standard non-invasive investigation is a ‘triple contrast’ CT (with oral, intravenous, and rectal), being quoted with a sensitivity of 97% and a specificity of 98% for diagnosis of peritoneal breach in penetrating torso injury; this is, however, impractical in the acute setting and seldom used at our center.1 19–21 The authors of one military case series of 19 patients with no missed rectal injuries concluded that a CT scan can be a useful screening tool to help identify which patients warrant further investigation.22

Given that in our population CT had a sensitivity of 50.00% and specificity of 92.38% in identifying rectal injury on initial assessment, these data support having a low threshold for assessing any patients at high risk of rectal injury with direct visualization, either with an EUA (±RS) in the operating theater for an extraperitoneal injuries or with a diagnostic laparoscopy for intraperitoneal injuries. Although the decision of what constitutes a high-risk patient for rectal injury will vary from clinician to clinician, the authors suggest that those with rectal bleeding or radiological evidence of bowel wall breach or thickening, presence of a wound tract extending to the bowel or mesentery, or adjacent mesenteric hematoma or stranding should be investigated with an EUA in the theater as these indications are supported by recent literature.18 19 21 While noting that no individual CT finding can be considered both sensitive and specific to bowel injury, the authors also suggest that patients with presence of air or fluid near the bowel wall on CT should also be considered for either observation, serial clinical examination and repeat imaging, or an EUA in the theater at the discretion of the responsible clinician.19 21

Management of colorectal trauma

The management of rectal trauma has traditionally centered on ‘the Four D’s’ of debridement, diversion, drainage, and distal washout. However, this was based on the Allied military experience during World War II and the US military experience during the Vietnam War, where the pattern and mechanism of injury were vastly different from that seen in UK civilian trauma practice outside of major terrorist incidents.2 4 23 One of the few prospective studies on colon trauma by Demetriades et al24 recommended considering primary anastomosis in all patients with colon trauma and identified severe fecal contamination, transfusion of >4 units of blood products within the first 24 hours, and single-agent antibiotic prophylaxis as the only independent risk factors for abdominal complications.

Recent literature has proposed a more nuanced approach to the management of colon and rectal injuries based on the degree of injury and the anatomic location of the injury, in conjunction with other patient factors such as comorbidity, presence of hemorrhagic shock, and concurrent injuries.2 4 25 Clemens et al4 have proposed a treatment algorithm based on the size and location of rectal injury in relation to the peritoneal reflection. In this pathway, an injury affecting greater than 25% of the circumference of the rectum is considered ‘destructive’ and those affecting less than 25% ‘non-destructive’. Non-destructive extraperitoneal injuries are treated either by primary repair if accessible or conservatively with admission and observation. Destructive extraperitoneal injuries are treated with proximal fecal diversion without presacral drainage. Rectal washout is recommended for selected, high-energy injuries only. Intraperitoneal injuries are treated by primary repair if non-destructive and with primary resection and anastomosis if destructive.4 26 27

Of particular importance when considering repair of colorectal injury is the presence of concomitant vascular injury. These cases have reported mortality as high as 36%. This supports a lower threshold to treat these patients with proximal diversion rather than anastomosis; however, this evidence originates from a military case series of high-energy battlefield injuries.4 28

The more nuanced approach is supported by a recent meta-analysis that recommends primary repair or resection with anastomosis in colon trauma unless patients are critically unwell or undergoing damage control surgery (DCS) as these patients have a significantly higher rate of anastomotic leak.29

Given all the injuries in our data set were low-energy wounds from sharp objects and all extraperitoneal injuries, it is perhaps surprising that half of these injuries were managed with fecal diversion. Two (33.34%) of these patients were recognized to have a potentially destructive extraperitoneal injury during EUA and so were appropriately managed with a defunctioning stoma. It could be argued that the one remaining rectal injury treated with a defunctioning stoma could have been initially managed with either primary repair or conservative management following current international guidance.4 24 29 This may represent unfamiliarity with the international guidelines, or there may have been other patient-related or surgeon-related factors that were beyond the remit of this study.

A suggested pathway for management of PGI

Based on the findings of this study, we have identified a need for a pathway providing a systematic and consistent approach to the assessment and initial management of patients presenting with a PGI. A pathway was designed to address the areas of greatest variation and based on previous literature, the evidence from this study, and expert opinion of surgeons, emergency medicine physicians, and radiologists from our MTC. This pathway (figure 4) describes the assessment and initial management, whereby following primary survey and resuscitation, or DCS where required, all patients are imaged with a dual-phase CT scan to assess the risk of rectal, vessel, and nerve injury. The quadrant of injury is useful to help identify high-risk patients for rectal and urethral injury, but is one component of a thorough clinical assessment in combination with judicious use of radiological investigations. As part of the algorithm the authors use CT as a screening tool to identify any immediate life-threatening injuries, such as major hemorrhage or intra-abdominal visceral injury. Those patients deemed to be at high risk of an injury to a vessel, the rectum, or sciatic nerve are then referred to the appropriate specialty for further investigation and management. The data from this study suggest that a CT scan cannot be used to confidently rule out a rectal injury; therefore, where there is clinical suspicion of rectal injury, an EUA, RS, and/or a diagnostic laparoscopy should be performed depending on the suspected anatomic location of injury. The authors recommend the use of a dual-phase CT (with arterial and portal venous phases) to allow for accurate assessment of any vascular injury and allow for efficient planning of any interventional radiological procedure without the need for a return to CT. The pathway has created a clear tool that various specialties feeding into a multidisciplinary trauma team can refer to. This ensures optimized investigation and treatment, minimizing the likelihood of missed injury or unnecessary use of resources. It therefore represents a potential pathway other centers receiving a high proportion of low-energy PGIs could also consider incorporating into practice.

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