surgical danger zone
A highly nonspecific user- and context-determined term.
In 1891*, the pregnant uterus was considered a surgical danger zone due to the risk of air embolism.
*The Medical Standard, Volumes 9-10, GP Engelhard & Co, 1891, p137
A more recent usage* of the term “surgical danger zone” refers to anatomic regions rife with vessels and nerves in which only the foolhardy would willingly venture without a map, pith helmet and a malpractice attorney on speed dial.
Other danger zones include the nasal and periorbital regions.
The term is probably best not used.