Blunt traumatic abdominal wall disruption with evisceration.

Blunt traumatic abdominal wall disruptions associated with evisceration are very rare. The authors describe a case of traumatic abdominal wall disruption with bowel evisceration that occurred after a middle-aged woman sustained direct focal blunt force impact to the lower abdomen. Abdominal exploration and surgical repair of the abdominal wall defect were performed, with good clinical outcome. A brief overview of literature pertinent to this rare trauma scenario is presented.

INTRODUCTION

Traumatic abdominal wall hernia (TAWH) associated with blunt injury mechanism is very rare, with an approximate prevalence of 0.2–1% in major reported series.[1-4] Abdominal evisceration (AE) associated with TAWH is even less common, with one study reporting an incidence of approximately 1 in 40,000 trauma admissions.[5] While the precise mechanism behind TAWHs is not fully understood, they are thought to result from simultaneous surge in abdominal pressure and the presence of shearing forces that synergistically lead to the disruption of the abdominal wall musculature and fascial layers.[6] This report describes a case of AE – an example of the most extreme clinical manifestation of TAWH – following blunt traumatic abdominal wall injury. The authors also review literature on abdominal wall injury grading in the context of the clinical problem presented herein.

CASE REPORT

A middle-aged female presented to a Level I Trauma center after being involved in a horse riding accident. The patient was thrown off the horse, which then fell and rolled partially onto the patient. During the process, the horn of the saddle briefly exerted direct pressure on the patient's lower abdomen before the horse recovered. Initially awake and alert, the patient became progressively more somnolent, requiring endotracheal intubation at the scene. En route to the hospital, the patient was noted to have a loop of small bowel protruding from an open lower abdominal wound. The bowel was easily reduced and saline-soaked gauze was used for temporary coverage over the wound.

Upon arrival to the trauma bay, her pulse rate was 92 beats/minute and the blood pressure was 164/86 mmHg. The patient's Glasgow Coma Score was 10T (Motor 6, Verbal 1T, Eyes 3) during the initial trauma bay evaluation. On further examination, she was found to have a 10-cm transversely oriented complex suprapubic abdominal wound [Figure 1a]. Upon reflection of the superior skin flap, the wound was found to involve full thickness of the abdominal wall as well as evisceration of bowel loops [Figure 1b]. Other positive findings on the physical exam included superficial skin abrasions and lower back pain. There was also trace hematuria present on urinalysis performed upon placement of urinary catheter, with no other signs of urinary system injury. Given continued hemodynamic stability, computed tomography (CT) was performed to rule out any potential associated skeletal and head injuries. The patient was then taken to the operating room for exploratory celiotomy, abdominal washout, and repair of the TAWH.

Figure 1

Photographs of the traumatic abdominal wall defect described in the current case. (a) Note the symmetric butterfl y-shaped defect, with the bowel not immediately apparent. (b) After lifting the upper wound fl ap, bowel evisceration became evident

In the operating room, the peritoneum was entered through a midline incision separate from the original traumatic suprapubic wound [Figure 1a and b]. The bowel, abdominal solid organs, and the retroperitoneum were inspected, with no additional injuries found. Subsequent examination of the TAWH showed the anterior abdominal fascia not amenable to complete primary reconstruction due to severe tissue fragmentation/disruption. Therefore, the patient's native fascia was closed using a combination of biologic mesh underlay combined with primary suture repair (where possible). Subsequent layered closure of the wound was performed and the patient was taken to the surgical intensive care unit. She was extubated within 24 hours and had an otherwise uneventful postoperative course. The patient was discharged from the hospital 1 week after the initial injury and did well in follow-up at 6 months, both from a cosmetic and a functional perspective. The patient returned to pre-injury activity levels and there was no evidence of recurrent hernia at the site of the traumatic defect.

DISCUSSION

The reported incidence of all abdominal wall injuries following blunt trauma is about 9%.[7] TAWHs associated with blunt injury mechanisms are uncommon, with an approximate prevalence of 1% in major reported series.[1-48] TAWHs have been linked to both high energy (i.e., traffic/pedestrian accidents, falls from a height) and low energy (i.e., “handlebar hernia”) mechanisms.[910] Diagnosis of TAWH can be difficult and requires a high index of suspicion.[11] Consistent with the mechanism reported in the current case, many TAWHs have been associated with the victim impacting on angled or curved surfaces/objects.[9] TAWHs are thought to result from simultaneous surge in abdominal pressure and the presence of shearing forces that synergistically disrupt the abdominal wall musculature and fascial layers.[6]

Associated AEs are even less common, accounting for approximately 1 in 40,000 trauma admissions.[5] AEs constitute an extreme form of TAWHs, with the main difference between the two being the amount of force that is focally delivered to the abdominal wall tissues, as well as the anatomic location of the force application (i.e., eviscerations tend to occur at anatomically weak points – the lateral rectus, lower abdomen, and inguinal regions).[2]

Traumatic AE is a clinically apparent injury. Due to the mechanism of injury and significant forces required to cause both TAWH and AE, further investigation to rule out other intra- and extra-abdominal associated injuries is required.[2] If the patient is hemodynamically stable, a CT scan is the preferred modality for diagnosis of any potential associated injuries.[2] The incidence of associated intra-abdominal injuries among patients with TAWH may be as high as 30%.[12]

Dennis et al. described an abdominal wall injury scale based on CT scan findings, with overall injury severity graded on a scale from I to VI [Table 1].[7] Of note, among the 140 patients with CT-diagnosed abdominal wall injuries in that study, only 3 had TAWH (grade V injury) and none of the patients had grade VI injury (i.e., complete abdominal wall disruption with evisceration). This report describes a case of grade VI injury - an exceedingly rare finding.

Table 1

Abdominal wall injury grading scale

Regardless of the presence of any associated injuries, prompt surgical repair of the TAWH and/or AE it is still required.[2713] At the time of surgical repair, the surgeon should perform a standard trauma laparotomy via separate midline abdominal incision, followed by either mesh and/or primary repair of the traumatic abdominal wall defect. At times, immediate abdominal wall reconstruction may not be possible and staged abdominal wall closure may be required.[67] Long-term follow-up is needed to ensure that both cosmetic and functional outcomes are satisfactory. It is also important to monitor the patient for the possibility of a recurrent hernia at the injury site.

CONCLUSIONS

Blunt TAWHs associated with AE are exceedingly rare. When encountered, blunt TAWH/AE should prompt an aggressive search for other associated injuries and prompt surgical repair of the abdominal wall defect. In more severe cases, staged abdominal wall closure/reconstruction may be required. Long-term follow-up is important and should include the assessment of cosmetic and functional outcomes as well as examination for any recurrent herniation at the site of the injury. The TAWH/AE outlined herein represents one of the very few cases of grade VI abdominal wall injury in the world literature.