The diaphragm is a muscular structure which separates the high-pressure abdominal cavity from the negative pressure of the thoracic cavity. Traumatic diaphragmatic injury occurs in 0.8 to 8% of all thoraco-abdominal traumas. Seventy-five percent of TDIs are due to blunt trauma and 25% to penetrating .
When the abdomen is impacted by a strong enough blunt force, a sudden increase in intrabdominal pressure occurs. If this increase in pressure is greater than the tensile strength of the diaphragm, then the diaphragm ruptures, typically resulting in defects larger than those caused by penetrating injuries, which reflect the size of the penetrating agent [2, 4].
Only 20% of blunt traumatic diaphragmatic injuries occur on the right side [2, 3, 5,6,7]. The functional anatomy of the diaphragm is the reason behind both the rarity and the diagnostic difficulty of right-sided traumatic diaphragmatic injury. The close proximity of the liver to the inferior aspect of the right hemidiaphragm creates a physical barrier which protects the diaphragm from injury and acts as a cushion to attenuate the transmitted force from a blunt trauma to the abdomen [2, 4]. Furthermore, when right-sided diaphragmatic ruptures do occur, the dome of the liver can act as a seal of the diaphragmatic defect. This poses significant challenges to the early radiological visualization of the injury and, in association with a lack of immediate symptoms, can be falsely reassuring [6, 8].
When the diagnosis of diaphragmatic rupture is missed at the time of the inciting event, the pressure gradient between the abdominal and thoracic cavities causes a gradual migration of intrabdominal viscera into the thoracic cavity, resulting in delayed diaphragmatic hernia formation .
The clinical presentation of delayed blunt traumatic diaphragmatic hernias is variable and reflects the anatomical progression of each case. Patients may present weeks, months, or even many years after the initial trauma. When hernial orifices are smaller, creating narrow-necked hernia sacks, there is more risk of obstruction or strangulation of the hernial contents . In many cases, the first presentation of a delayed diaphragmatic hernia may be due to symptoms of obstruction of herniated hollow viscera or strangulation and compromised blood supply to contents of the hernia, the latter often requiring urgent surgical intervention [2, 9]. Patients may also present with cardiopulmonary symptoms due to compression of intrathoracic structures by the hernial sac. In chronic hernias, abundant adhesion formation can further interfere with the normal function of both intrathoracic structures and the contents of the hernia sac . In some cases, the anatomy of the hernia could allow relatively normal physiological function, and the diagnosis can be made completely incidentally on routine check-ups or while investigating other conditions . The broad clinical and pathophysiological spectrum of delayed diaphragmatic hernias necessitate that each case be managed uniquely. Some cases, such as this one, may present in stable condition and can undergo an elective procedure, while some require much more urgent surgical intervention [3, 9]. A high index of clinical suspicion for delayed traumatic diaphragmatic hernia should be maintained for all patients with a history of trauma, but occasionally patients may present with a diaphragmatic hernia without a history of significant trauma . Chest radiographs have a low sensitivity for detecting delayed diaphragmatic hernias, so even the slightest suspicion should be confirmed with thoracoabdominal CT as it is much more reliable for diagnosis of diaphragmatic hernias .
No matter what the presentation, all cases of delayed diaphragmatic hernia will need surgery to be corrected . The specifics of the procedure however, much like the presentation, can vary greatly. If there is minimal herniation of abdominal viscera, a purely thoracic approach is often viable to repair the defect . In some cases, an abdominal approach, either laparoscopically or via laparotomy, is sufficient. The chronicity of the hernia is also important to consider while planning for surgery as longstanding hernias can result in significant adhesion formation, further complicating the procedure. In these cases, excessive adhesions may necessitate a combined thoracoabdominal approach to satisfactorily lyse all adhesions, reduce the contents of the hernia to anatomical position, and repair the defect . This further stresses the importance of early diagnosis in delayed traumatic diaphragmatic hernias.