Contemporary lines of evidence tell us that cervical insufficiency is apoorly defined entity, lacking objective and reproducible criteria. It maybe more effectively conceptualized as one factor in the complex syndromeof spontaneous preterm birth. Deciding whether an individual patient hasa significant (and treatable) component of insufficiency requires significantclinical judgment. Herein we have presented (as currently available)evidence-based guidelines for the selection of patients who would reasonablybenefit from cerclage. © 2010 Blackwell Publishing Ltd.