Understanding the mechanical behavior of intrauterine devices during simulated removal.

Objective: To evaluate differences based on intrauterine device (IUD) frame geometry in force, and stress, and strain at the stem/arms junction during simulated IUD removal.

Study Design: We manufactured injection-molded frame models for three Nova-T IUDs (Mirena [model M]; Liletta [model L]; Kyleena [model K]) and a Tatum-T IUD (Paragard [model P]) at two-times scaling. We created a custom fixture to simulate the uterus and used a screw-driven machine to pull models at various displacement rates through the 10 cm fixture cavity to measure force and strain and calculate stress at the IUD stem/arms junction.