Penetrating Traumatic Injuries of the Diaphragm: how much can we rely on pre-operative imaging findings to detect them?

Background: The diagnosis of penetrating isolated diaphragmatic injuries (DI) can be challenging because they are usually asymptomatic and may be missed on initial evaluation. Chest X-ray (CXR) may not be reliable for the diagnosis of penetrating DI, whereas CT scan has been reported to be more valuable in detecting them, with better sensitivity and specificity. This study’s aim was to review the radiological findings of the CXR and CT scan and to define the accuracy of these imaging in patients with an operative diagnosis of DI. Materials and Methods: Patients with penetrating DI who were admitted to a level I trauma center in the US (Los Angeles County Medical Center, University of Southern California, Los Angeles) between January 2009 and June 2019 were retrospectively identified from the trauma registry of the hospital. Patients without pre-operative imaging, non-operatively managed or with missing operative data were excluded. Demographics, injury data and outcomes were collected and analyzed; CXR, CT scan findings and operative notes were reviewed. Results: 230 patients with an intra-operative diagnosis of penetrating diaphragmatic injury (DI) met the inclusion criteria. 27.0% of the population (62 patients) had an “isolated DI”, while 168 patients (73.0%) had an associated injury (AAST grade ≥ 3) in the abdomen or in the chest. The overall mean age was 27 (IQR 21 - 36). Two-hundred and seventeen patients (94.3%) were male. CXR detected a traumatic diaphragmatic hernia in 4 cases (1.8%) while was normal in 86 patients (38.9%). The presence of a diaphragmatic injury was detected at the CT scan in 56 patients with a sensitivity of 44.4%. This was slightly higher (48%) in the group of patients with an isolated diaphragmatic injury. Conclusions: In patients who sustained a penetrating thoraco-abdominal trauma and without clinical indications for a laparotomy, CT scan findings may help narrowing down the population that needs to undergo further evaluation with diagnostic laparoscopy, that remain the gold standard for the detection of these injuries. Nevertheless, a highly grade of suspect and an aggressive policy in patients with positive or equivocal clinical and radiographic signs of DI is recommended in order to avoid delayed complications associated with diaphragmatic herniation