Traumatic supra-iliac hernia: a case series
Traumatic Abdominal Wall Hernia (TAWH) is a rare cause of abdominal wall herniation that usually occurs as a result of blunt force trauma to the lower abdomen, causing a shearing action as the abdominal wall comes into contact with a static object, usually a seatbelt or handlebar. The result of this, plus raised intraabdominal pressure as a result of rapid deceleration, causes musculature and fascia to come away at their attachments, and allows herniation of fat, peritoneum and occasionally intraabdominal contents to occur(1, 2) . The commonest site for this to happen is the lumbar region (3) . Supra-iliac traumatic herniaehave yet to be described in a case series.
Due to the high energy mechanism required to achieve this, patients often present with a combination of serious injuries, meaning recognition and management of TAWH may be delayed or missed altogether (2).
We present a case series of 4 patients suffering from traumatic supra iliac abdominal wall hernias, and discuss options for the management thereof.
Background and pathophysiology
Herniation following blunt trauma is a rare occurrence, and was first reported by Selby in 1906, and since then there have only been around 250 recognisedcases in literature (4)(5).
Herniationcan occur at any point through the abdominal wall, and is not located to the site of injury, rather to sites of anatomic weakness, either in the lumbar region, in the lower abdomen lateral to the rectus sheath, inguinal region and superior to the iliac crests(3)(6) .
Due to the mechanism required to produce TAWH, it is often associated with other injuries, as in all 4 cases presented above. It is estimated that the incidence of associated intraabdominal injuries may be up to 30%(7), although this varies depending on location, with flank and supra iliac hernias having higher risk of concomitant visceral injuries (8) .
The increased use of CT imaging in major trauma has improved detection rates, and now up to 72% of TAWH are detected on first admission (13)(14) .
Emergent vs delayed repair
Surgery remains the primary modality of treatment for TAWH, however there is no clear guidance regarding whether this should be performed emergently or electively.
Nettoet al carried out a retrospective review of 34 cases and made three recommendations. Firstly, the mechanism of injury should dictate the need for urgent laparotomy. Secondly, clinically apparent anterior abdominal wall hernias have a higher rate of associated intraabdominal injuries and therefore required urgent laparotomy. Thirdly, occult TAWH, diagnosed on CT may not require emergency laparotomy or hernia repair (2). Care should be taken, however, to ensure that timely follow up for TAWH and consideration of elective fixation is made to reduce risk of strangulation or incarceration (15) .
Operative techniques vary, with most preferring to use open mesh repair(16). Closure of the defect can be performed with non-absorbable sutures with or without mesh (7) , and laparoscopic approaches are increasingly being undertaken in those with suitable hernias (17) .
When muscle avulsion occurs from the iliac crest, as in three of our cases, primary repair is usually difficult due to muscle retraction or lack of remaining fascia to which to suture. In these cases, the use of bone anchors is being increasingly used. Söderlundet al described an open, mesh-free repair in these patients using suture anchors, commonly seen in orthopaedicsurgery, to allow tension free repair of a large supra iliac defect. This mesh free approach, in theory, leaves the patient more at risk of recurrence (18) .
Bone anchors have been used successfully in laparoscopic mesh repairs for traumatic lumbar hernias, and appear be particularly effective in managing recurrent herniae, whereby mesh repair has failed due to a paucity of tissue still attached to the iliac crest (18) .
Despite this, there is still a lack of high quality evidence for this surgical approach, and more studies are needed before any guidelines can be developed.