Stabs (band cells) are immature neutrophils (leukocytes or white blood cells). Adult blood normally contains less than 1% of its leukocytes in the form of stabs. A higher percentage or ratio (stab %) generally indicates that the bone marrow has received a signal of low neutrophil count and is responding adequately by making more white blood cells. This is particularly the case in bacterial or viral infections.
The presence of an abnormally high percentage or absolute number of stabs may also indicate a disorder called Pelger-Huet anomaly or pseudo-Pelger-Huet anomaly. Pelger-Huet anomaly is a very rare, benign genetic disease in which the leukocytes cannot form a normal nucleus. There are often no symptoms. Pseudo-Pelger-Huet anomaly is not of genetic origin, but it has a greater significance. It can accompany myelodysplastic syndrome (bone marrow impairment) or certain types of leukemia.