The abdominal wall fat index (AFI) is the ratio of preperitoneal and subcutaneous fat layers as determined by ultrasound of the anterior abdominal wall. This correlates with the visceral fat area to subcutaneous fat area ratio (V/S ratio) at the umbilicus as determined from CT scans.



(1) The patient is placed in a recumbent position, lying face up.

(2) Ultrasound measurements are taken in the midline from xyphoid process to umbilicus.

(3) The probe is applied with minimal pressure to prevent fat compression.

(4) The minimal subcutaneous fat and maximal preperitoneal fat is located over the liver, while the maximal subcutaneous fat and minimal preperitoneal fat is located near the umbilicus.


abdominal wall fat index =

= (maximum thickness of preperitoneal fat layer in mm) / (minimum thickness of subcutaneous fat layer in mm)


correlation with V/S ratio: 0.746



• The AFI and V/S ratios are positively correlated with serum triglyceride and basal insulin levels.

• The AFI is negatively correlated with HDL cholesterol levels.


Correlation of AFI to V/S Ratio


body mass index (BMI) =

= (weight in kilograms) / ((height in meters)^2)


For BMI 20.3 to 25.7 (data from Figure 3, page 312, analyzed by JMP)


AFI (r value 0.67) =

= (1.00545 * (V/S ratio)) + 0.334182


V/S ratio =

= (0.99458 * (AFI)) – 0.33237


For BMI 26 to 42.9 (data from Figure 3, page 312, analyzed by JMP)


AFI (r value 0.66) =

= (0.9909 * (V/S ratio)) + 0.44545


V/S ratio =

= (1.009184 * (AFI)) – 0.44954


To read more or access our algorithms and calculators, please log in or register.