Surgery, sepsis, and nonspecific immune function in neonates.

An audit of 143 neonatal surgical operations identified low birth weight infants as being at particular risk of developing post-operative sepsis following major surgical trauma. Activity of the nonspecific immune system was examined pre- and post-operatively in order to elucidate the susceptibility to post-operative sepsis of these infants. A chemiluminescence micro-method was developed specifically for this purpose. Neonatal plasma was shown to have significantly impaired opsonising activity, and activity was further reduced in low birth weight infants. Levels of immunoglobulin and complement factors were also reduced, particularly in the low birth weight infant. Following major surgical trauma polymorph activity was significantly lower in low birth weight infants than in mature neonates.