Abdominal Trauma

The abdomen is the third most injured body part in children, after the head and the chest.

There is a medscape e-learning module here, and a good pdf overview here, here, and another overview here with a summary on page 13. There is some discussion around a case here and some good CT images here. There is an excellent summary about abdominal trauma in children here, which introduces us to some guidelines for careful imaging in children.The anaesthetists at Lewisham wrote a very thorough overview here. There's a good summary of common injuries and their management here.

There is a good CT scan with some SAQs from the PMJ here.

Anatomical differences in children:
- The abdomen is square and becomes more rectangular as the child matures.
- Muscles are thinner, so there is less protection for underlying structures.
- Ribs are more flexible so they are less effective at energy dissipation, so less effective at protecting the upper abdominal structures.
- Solid organs are comparatively larger so are at more risk for injury.
- Attachments are more elastic.
- The intestine is not fully attached within the peritoneal cavity so is more vulnerable to injury due to sudden deceleration and/or abdominal compression.
- The bladder is more exposed.
- Children's spines are exposed to chance fractures, especially if they are restrained with a lap belt only.
- Abdominal distension from aerophagia is common
- Hypothermia is more likely

Clinical Features
The Seatbelt Sign
The seat belt sign is a good indicator of serious injury. In one review, 78% of patients with a seat belt contusion had intra-abdominal injuries, although all children with injuries also had abdominal pain - not just a seat belt sign.
Lap belts are designed to be worn at or below the anterior superior iliac spine level. In smaller children the belts are in the wrong place, and children can move out of them very easily. The introduction of booster seats has helped to improve this. You are up to 3 times more likely to be injured if you are not properly restrained.

Haematuria
The most common indication for abdominal imaging after trauma in children is reported to be haematuria. Non–urinary tract injury is observed more frequently than urinary tract injury in children with haematuria and asymptomatic hematuria is a low-risk indicator for abdominal injury.

80% of injuries are from blunt mechanism.

Holmes 2012 - decision Rules
Holmes looked at children with blunt torso trauma, and suggested some decision rules for when we should be CTing these patients. The paper has been reviewed on PEMLit. He has listed seven factors that make the injury low risk:

Most patients I've seen with trauma do complain of some abdominal pain -so maybe one or two CTs might be saved! This has a 99.9% negative predictive value.

If we do CT it's pretty good at picking up pathology.  If the patient is stable, ultrasound and serial observation is probably sufficient. There's a suggestion of an algorithm here. In a verbal patient, normal obs, normal examination and no abdominal pain is a pretty good indicator of no abdominal injury.