A-The challenge of diagnosis and missed injuries
Diagnosis of DI can be challenging and several imaging modalities may participate in diagnosis. Chest x-ray may give a clue to diagnosis by showing air-fluid level consistent with hollow viscera (with or without coiled nasogastric tube) in the chest cavity. However, x-ray may not be conclusive either due to delayed herniation of viscera or improper technique. Also, on the right side it is difficult to differentiate between elevated diaphragm and herniation of the liver [4].
Although Focused Assessment with Sonography for Trauma (FAST) is widely used for initial evaluation in trauma settings, its usefulness in diagnosis of DI is scarcely reported [5].
Importantly, the advent of multiple detector computed tomography (MDCT) with coronal and sagittal multiplanar reformation represent a great advances. This technique allows better demonstration of DI with high sensitivity, specificity, and accuracy [6]. However, missed diagnosis of DI is still frequently reported; the reasons could be due to clinically occult DI or the presentation is dominated by other associated major injuries [7]. This leads some authors to utilize laparoscopy or video-assisted thoracoscopic surgery (VATS) or both for diagnosis. Both modalities allow assessment and possible repair of the diaphragm especially when open surgery is not required [8, 9]. Laparoscopy could have identified occult diaphragmatic injuries in up to 24% of the patients with penetrating injuries of the left lower chest [9].
Early diagnosis of DI and surgical intervention are important, as the repair will be easy before development of fibrosis and atrophy of the diaphragm. Moreover, missed DI may result in herniation of intra-abdominal viscera into the thoracic cavity and subsequent strangulation [7, 10].
The delay in diagnosis in our series can be attributed to one or more of the following reasons. Delay in transfer process as less priority is given to stable patients without clear indications for surgical intervention. Secondly, subtle radiological findings can be missed by junior staff and subsequently detected by a more experienced radiologist at higher centers. Another possibility is that, stable patients referred to subspecialty usually are not subjected to routine multidisciplinary assessment of acute trauma cases in emergency department and diagnosis is discovered later when the patient starts to complain or during evaluation for general anaesthesia.
B- Choice of surgical approach
The choice of surgical approach in acute situations is mainly determined by the presence of associated injuries requiring immediate intervention. Other factors are the surgeon choice, and availability of specialized trauma surgery unit [1].
Only few authors reported the use of thoracic approach (usually in selected patients among their series) in absence of abdominal injuries [4, 11]. But there are no studies with matched patient populations comparing abdominal and thoracic approaches for repair of DI whether in the acute or chronic phase; this leads to difficulty to formulate a clear recommendation regarding the preferred approach especially in elective chronic visceral herniation. In these situations, whatever the approach used, it is wise to anticipate and prepare for a second cavity approach (thoracotomy or laparotomy) due to potential difficulties in dealing with hernia contents from the initial approach [12].
Abdominal exposure of the diaphragm requires one or two assistants for retraction of abdominal wall and the mobilized abdominal organs. With maximal assistance, viewing and access to some areas of diaphragm is still difficult. Moreover, the presence of the liver on the right side adds more obstacles. All these factors may explain missing some of diaphragmatic injuries during exploratory laparotomy for trauma [13]. On the contrary, thoracotomy and entering the chest through lower intercostal space gives direct access to the target operative site and the whole diaphragm can be accessed easily without much assistance especially with the use of single lung anaesthesia. The herniated viscera can be returned to the abdomen more easily and safely particularly in situations of small diaphragmatic rent and hour-glass herniation of the stomach or gut. Moreover, the operative field is in alignment with direction of surgeon’s vision; accordingly repair can be done more safely and efficiently. (Figs. 1, 2)
Computed tomography has lower sensitivity in diagnosis of pancreatic, mesenteric and colon injuries [14]. Accordingly, some authors advised to keep patient with suspected abdominal injury under observation for at least 24 hours even if primary abdominal CT is free [15]. Others follow a similar policy before minimal invasive laparoscopic repair in stable cases with penetrating diaphragmatic injury [16]. This period of observation allows for occult injuries to manifest. If this principle is applied to our cases, the short time delay in diagnosis can be considered as unplanned observation period during which any occult abdominal injuries would have manifest. The latent period between time of injury and surgical intervention whether planned or unplanned gives more confidence to surgeon’s choice.
Recently, there are several reports of either 3-port or single port VATS repair of traumatic diaphragmatic hernia. This technique shares many of the advantages of open thoracic approach in addition to the advantage of being less invasive. In comparison to laparoscopic repair, VATS is safer as it avoids the risk of tension pneumothorax due to escape of the CO2 gas through the diaphragmatic rent to the pleural space. In experienced hands VATS may be the proper management approach [8, 17].