Part one of this series looked at how to perform an abdominal focused assessment with sonography for trauma (AFAST) – this week looks at how to interpret abdominal fluid scores (AFS) in a clinical setting.

To recap – the score is out of a possible 4, with each site allocated a 0 or 1 based on the presence of fluid.

Haemoabdomen

It has been shown the ASF correlates well with markers of injury, such as lactate and alanine transaminase (ALT) – in that the higher the score, the higher the lactate and ALT values.

Also the higher the AFS, the more likely the requirement for a blood transfusion. Patients with an AFS of 1 or 2 are unlikely to develop an anaemia, while patients with an AFS of 3 or 4 are very likely to develop an anaemia and require a blood transfusion.

This is not the case in cats as, likely due to their lower blood volume, they often die before they reach an AFS of 3 or 4.

Post-surgical bleeding

If, during surgery, efforts are made to remove as much of the lavage fluid and blood as possible, AFAST can be performed to get post-surgical baseline.

If the AFS goes from 0 of 1 then monitor. If the AFS progresses to a 3 or 4, consider repeat surgery as it either means a large bleed or major gut breakdown.

Always assess fluid cytology to assist in decision-making – for example, look for bacteria. Remember, the abdominal fluid glucose is not accurate post-surgery, so a drop in abdominal fluid glucose is not specific for gut breakdown.

Blunt trauma

Medical management with fluids and blood transfusions is generally indicated first, regardless of the AFS.

Possibly consider low end-point resuscitation variables, to not dislodge clots. Otherwise, if the AFS keeps rising, surgical intervention may be indicated.

Penetrating trauma

If any free fluid is found associated with a skin wound, it most likely means a foreign body has penetrated into the abdomen. Therefore, exploratory surgery is indicated.