Abdominal wall injury

Abdominal wall injuries comprise a set of injuries of the abdominal wall and include different forms of muscle injuries, traumatic hernias and injuries to the subcutaneous tissue.  They are often overshadowed by the attention to associated “more severe” abdominal visceral injuries.

Epidemiology

Non-penetrating abdominal wall injuries are more common than lacerations or stab wounds and are seen in patients suffering from blunt abdominal trauma in about 9% ¹.

Risk factors

Sports or behavioural patterns that increase the likelihood of sustaining an abdominal wall injury include:

• football (soccer)
• rugby / American football
• martial arts/wrestling
• motorsports

Associations

• polytrauma
• visceral injuries such as splenic trauma, liver trauma, pancreatic trauma or hollow viscus injury
• vascular injuries
• pelvic fractures
• rib fractures
• lumbar spine fractures

Clinical presentation

The main symptom will be abdominal pain and history will often reveal the mechanism of injury frequently a blunt and less often a penetrating abdominal trauma. The physical examination might reveal skin discolouration or ecchymosis in case of blunt trauma or a laceration, stab or gunshot wound in case of penetrating trauma. Other findings include a soft tissue mass or bulge. Typical seat belt injuries should raise the concern for traumatic abdominal wall hernias ².

Complications

Complications of abdominal wall injuries differ with the type of injury and include ¹:

• haematoma formation
• skin or muscle necrosis
• infection
• myositis ossificans
• incarceration or strangulation (in case of traumatic hernias)

Pathology

Mechanism

The most common mechanisms of non-penetrating abdominal wall injuries are direct impact with an elevation in intraabdominal pressure or a shearing injury caused by a collision e.g. in a road traffic accident or during a fall ¹. Penetrating injuries involve a piercing or slashing mechanism.

Subtypes / Classification

Abdominal wall injuries can be classified based on type and location into the following ¹:

• non-penetrating injury
  • muscle contusion
  • abdominal wall haematoma (e.g. rectus sheath haematoma)
  • muscle strain/tear
  • traumatic abdominal wall hernia
  • groin injury
  • Morel-Lavallée lesion
• penetrating injury
  • laceration
  • stab wound
  • gunshot injury

Radiographic features

Abdominal wall injuries can be depicted and assessed with ultrasound, CT and MRI and their appearance will vary with the type of injury. Acute injuries will be probably most frequently evaluated in CT in an emergency after blunt abdominal injury.

Muscular haematoma (e.g. rectus sheath haematoma) will appear as spindle-shaped or spherical muscular swelling in the affected abdominal muscle.

Muscle contusions or muscle strains will typically show fluid-signal along and around the muscle fibres.

Stab wounds and wounds from projectiles might show fluid, air and dirt along the wound track or trajectory.  

Traumatic abdominal wall hernias usually occur at various weak spots of the abdominal wall most frequent are lumbar hernias affecting the inferior lumbar triangle. Spigelian hernias can also occur in a traumatic event and rarely there are trans-diaphragmatic intercostal hernias.

Morel-Lavallée lesions affect mostly the subcutaneous tissue.

Ultrasound

Similar to the other cross-sectional imaging modalities ultrasound can be used for all types of abdominal wall injuries and is used best for haematomas, muscle injuries and Morel-Lavallée lesions.

CT

Nowadays CT will be often the first-line modality for the workup of penetrating but also non-penetrating abdominal wall injuries also due to its capability of fast and comprehensive imaging of associated vascular, visceral and osseous injuries ¹.  Besides, CT is highly sensitive in the detection of traumatic abdominal hernias.

MRI

Due to superior soft-tissue characterisation abilities MRI can depict and characterise abdominal wall injuries. However, in an emergency, it will be hardly needed due to its long examination time and might be even contraindicated in penetrating abdominal wall injuries.

MRI is considered the modality of choice in the workup and classification of Morel-Lavallée lesions ¹ and the preferred imaging technique in the workup of an acute groin injury.

Radiology report

The radiological report should include a description of the following:

• type of the abdominal wall injury
• location and extent of the lesion
• signs of active bleeding
• associated injuries (especially vascular, visceral injuries and associated fractures)

Treatment and prognosis

Treatment will depend on the type and extent of the injury.

Most muscle contusions, haematoma or muscle strains can be managed conservatively with rest and pain control. In some larger haematomas, patients might need a blood transfusion because of blood loss. A smaller percentage of rectus sheath haematomas with active bleeding might require surgery or endovascular treatment. In acute groin injuries affecting the rectus abdominis insertion surgery will probably be considered ¹.

Traumatic abdominal wall hernias may require surgery either as primary closure or with a mesh repair. Surgery might be done simultaneously for other trauma-related intraabdominal injuries or at a later stage ¹.

Treatment strategies for Morel-Lavallée lesions vary significantly, options include compression, aspiration, surgical evacuation and debridement and sclerotherapy. Surgical intervention is recommended in the setting of an underlying fracture or complications as skin necrosis or infection ¹.

Differential diagnosis

The differential diagnosis of abdominal wall injuries includes the following:

• costochondral injuries
• chest wall injury
• osteitis pubis

See also

• muscle injury
• groin pain