Teaching Case

A 33-year-old male is brought to the emergency room (ER) following a moderate speed motorcycle accident. The patient presented with constant thoracolumbar pain and clinical examination revealed a left flank ecchymosis.
An abdominopelvic computed tomography (CT) examination was performed for further investigation.

Admission CT examination detected non-displaced fractures of the 10-11th left ribs (Fig. 1a), with a spleen AAST grade II injury at the lower pole (Fig.1b-c) and a small amount of perisplenic fluid.
CT also depicted an iliac crest avulsion fracture (Fig.1d-e) and a posterior left-sided detachment of the abdominal wall musculature at the level of the inferior lumbar triangle (Fig.2a), with herniation of retroperitoneal fat (Fig2b-c). A sizeable adjacent haematoma was also noted.
The patient was considered for conservative treatment as he was clinically and haemodynamically stable.
Within 36 hours after admission, the patient developed acute abdominal pain and nausea with elevated inflammatory parameters, and a new abdominopelvic CT was performed. It depicted the presence of small bowel dilatation (Fig.3a) and a significant amount of retroperitoneal free air (Fig.3b-c). These findings were related to acute bowel entrapment at the inferior lumbar hernia with perforation, probably caused by the iliac bone fragment (Fig.3d).

A lumbar hernia is a rare type of posterior abdominal wall hernia. It describes the protrusion of abdominal content through a defect in the lumbar muscles or the posterior fascia. It can be divided into two types, according to its anatomical location: Grynfeltt-Lesshaft hernia when it occurs through the superior lumbar triangle and Petit’s hernia when the hernia neck is located in the inferior lumbar triangle [1].
Lumbar hernias may be congenital(20%) or acquired(80%). The latter may be subdivided as primary(55%) or secondary(25%). Primarily acquired hernias occur spontaneously in older patients with extreme weight-loss and secondary hernias when they are related to trauma, prior surgical procedure or lumbar abscess. Studies suggest that when related to trauma, inferior lumbar hernia are far more common (70%) [2].
Clinical manifestations are usually non-specific, particularly in the immediate postinjury period, delaying the diagnosis in at least 27% of cases. Physical examination may expose a reducible painful mass just superior to the iliac crest or a flank ecchymosis/haematoma. However, these findings may be overlooked or even missed [2, 4].
Computed tomography (CT) has become a crucial element in the decision-making algorithm for haemodynamically stable trauma patients. It is the most accurate imaging test for identifying traumatic abdominal wall disruption [5]. It is depicted as a disruption of thoracolumbar fascia at insertion of aponeurosis of internal oblique and transverse abdominal muscles [6]. It may contain extraperitoneal fat, colon, kidney, small bowel or ascites. It is also the best imaging method to detect other associated injuries (in up to two-thirds of patients). Mesenteric injury is the most common associated injury, followed by solid organ and bowel injury. Pelvic and thoracolumbar spine fractures are frequently associated with traumatic abdominal wall disruption, purporting the energy required to produce this injury [2].
Although incarceration and strangulation are uncommon because of the large size of this hernias neck, it is more frequent when related to trauma (10%) [3]. Bowel wall thickening, fat straining and pain at the site of hernia suggest strangulation and ischaemia [7].
When an acute lumbar hernia is found, the timing of the repair is controversial. The decision of when to repair should be made according to clinical course. When there is a post-operative high-risk of infection, secondary to traumatic bowel perforation, delayed reconstruction of the abdominal wall may decrease the risk of infection and subsequent failure of the repair. On the other hand, when a hernia enlarges, repair becomes technically more difficult. This repair can be performed via open surgery or laparoscopic approach [2, 3].