Morbid Obesity’s Silver Lining: An Armor for Hollow Viscus in Blunt Abdominal Trauma

Background: Morbid obesity is usually accompanied by both subcutaneous and visceral fat accumulation. Fat can mimic an air bag, absorbing the force of a collision. We hypothesized that morbid obesity is mechanically protective for hollow viscus organs in blunt abdominal trauma (BAT). Methods: The National Trauma Data Bank (NTDB) was queried for BAT patients from 2013 to 2015. We looked at the rate of gastrointestinal (GI) tract injuries in all BAT patients with different BMIs. A subset analysis of BAT patients with operative GI tract injuries was performed to evaluate the need for abdominal operation. Multivariate analyses were carried out to identify factors independently associated with increased GI tract injuries and associated abdominal operations. Results: A total of 100,459 BAT patients were evaluated in the NTDB. Patients with GI tract injury had a lower proportion of morbidly obese patients [body weight index (BMI) ≥ 40 kg/m2)] (3.7% vs. 4.2%, p = 0.015) and instead had more underweight patients (BMI < 18.5) (5.9% vs. 5.0%, p < 0.001). The risk of GI tract injury decreased 11.6% independently in morbidly obese patients and increased 15.7% in underweight patients. Of the patients with GI tract injuries (N = 11,467), patients who needed a GI operation had a significantly lower proportion of morbidly obese patients (3.2% vs. 5.3%, p < 0.001). The risk of abdominal operation for GI tract injury decreased 57.3% independently in morbidly obese patients. Compared with underweight patients, morbidly obese patients had significantly less GI tract injury (6.0% vs. 13.3%, p < 0.001) and associated abdominal operation rates (65.2% vs. 73.3%, p < 0.001). Conclusion: Obesity is protective in BAT. This translates into lower rates of GI tract injury and operation in morbidly obese patients. In contrast, underweight patients appear to suffer a higher rate of GI tract injury and associated GI operations.