The term "segs" is laboratory shorthand for segmental neutrophils. "Segs" are part of a white blood cell differential test and are responsible for fighting infection within the body.
Neutrophils are also called polymorphonuclears or PMNs. The nucleus of mature white blood cells appear segmented, while immature white blood cells are rod-shaped and known as "bands."
Neutrophils are the first white blood cells to fight off an infection and appear within minutes after a wound is detected. They are predominantly found in the pus of a wound or injury and are responsible for the yellow-whitish color. A high neutrophil count on a white blood cell differential is a sign of acute infection.