An ultrasound study of 80 children from 5 pre-determined age groups showed that the femoral veins increased their diameter in the frog-leg compared with straight-leg positions. Left and right femoral veins were the same size. There was significant overlap of the femoral arteries and veins which increased with distance distal to the inguinal ligament.
The Anatomic Relationship between the Common Femoral Artery and Common Femoral Vein in Frog Leg Position Versus Straight Leg Position in Pediatric Patients.
Acad Emerg Med. 2009 Jul;16(7):579-84