Discussion
Traumatic abdominal wall hernias (TAWHs) are defined as the disruption of the abdominal wall musculature and/or fascia, without skin penetration, associated with blunt trauma. These injuries can be secondary to blunt trauma; however, the term "handlebar hernia" was coined in 1980.1 There have been several published case reports and case series of handlebar hernias in the pediatric population. Of these, the vast majority were diagnosed via abdominal imaging. In all prior reports, patients with TAWHs who received imaging had suspicious ultrasound (US) or CT scan findings. TAWHs can be diagnosed via US, but CT scans are being increasingly utilized to diagnose herniae and evaluate for other intraabdominal injuries.
A PubMed search for "traumatic abdominal wall hernia" or "handlebar hernia" since 1990 revealed 43 cases of TAWH as a result of handlebar injuries from bicycles or motorcycles in the pediatric population (Table 1).2‒35 Of these children with "handlebar hernias," the mean age was 10.8 years. (range 4 to 16 years) and 97.4% were male (38/39). The majority (65.7%) of handlebar TAWHs were diagnosed with CT scan (25/38),2–5,8,12–15,17,20,21,23,24,28,29,32,34 23.7% via abdominal ultrasound (9/38),7,11,18,25–27,30,33,35 and only 10.5% with physical exam alone (4/38).6,9,10,22 The majority of patients had some findings on physical exam, either ecchymosis, swelling, or bulging. All four cases diagnosed via physical exam alone had a bulge with Valsalva.6,9,10,22 All other patients in our literature review with skin changes or swelling were evaluated further with abdominal imaging. Importantly, all patients with a TAWH who received abdominal imaging, either CT scan or ultrasound, had positive imaging findings revealing either a fascial defect or herniation of abdominal contents. The case we presented above is unique. A CT scan was done on presentation yet revealed no acute findings related to the abdominal wall, only mild subcutaneous tissue stranding. This, therefore, highlights the critical need for clinical suspicion and a thorough physical exam in patients with blunt handlebar trauma to the abdomen. The majority (94.8%, 37/39) of TAWHs occur in the lower abdomen, with only two cases revealing hernias in the upper abdomen.11,20 This has been speculated to be due to the tension of the abdominal wall musculature between the bony prominences of the pelvis, leading to increased susceptibility to traumatic disruption in that area.29
When blunt trauma has enough impact to cause a traumatic abdominal wall hernia, there must also be a clinical concern for underlying intraabdominal injury, including to the bowel, mesentery, and pancreas. A recent retrospective review from a Level I pediatric trauma center revealed an overall incidence of TAWH of 0.1% following blunt abdominal trauma.31 In this series, only 27.3% identified a hernia on physical exam, whereas 80% of hernias were visible on CT (8/10). Only two of these were related to handlebar injury. At this institution, 65% of patients with TAWHs had a concurrent intraabdominal injury requiring operative intervention, including five bowel injuries, four mesenteric injuries, and two urologic injuries.31 In our literature review, 31.6% (12/38) of patients with a handlebar hernia had an underlying intraabdominal injury; two patients had a mesenteric disruption,14,20 five patients had bowel hematomas,21,28,32 and five patients had bowel perforations.8,15,17,18,21 Additionally, one patient developed bowel incarceration within the first 24 hours after injury.26 Almost all patients were treated operatively. Four patients were treated nonoperatively,4,7,23,24 three patients underwent delayed open repair,2,9,35 and the remainder were repaired immediately. One delayed repair was planned, and the other two occurred because the patients presented weeks after their traumatic injury. Of the hernias repaired immediately, 91.4% (32/35) were repaired via open technique.
