Insertion forces with intrauterine devices: implications for uterine perforation

Area of Science:

• Gynecology
• Biomedical Engineering
• Medical Devices

Background:

• Intrauterine devices (IUDs) are common contraceptives.
• Uterine perforation is a rare but serious complication of IUD insertion.
• Understanding insertion forces is crucial for device safety.

Purpose of the Study:

• To measure the insertion forces of three IUD models: Copper 7, Multiload Copper, and Nova T.
• To compare these forces with the forces required to perforate uterine tissue in vitro.
• To assess the risk of uterine perforation during IUD insertion.

Main Methods:

• Measured insertion forces for Copper 7, Multiload Copper, and Nova T IUDs in 197 successful and 25 unsuccessful attempts.
• Compared IUD insertion forces with in vitro fundal perforation forces using uterine sounds and Dalkon shields.
• Calculated mean insertion forces and pressures for each IUD type.

Main Results:

• Mean insertion forces: Copper 7 (1.502 N), Nova T (2.134 N), Multiload Copper (4.041 N).
• Mean insertion pressures: Copper 7 (0.203 N/mm²), Nova T (0.209 N/mm²), Multiload Copper (0.122 N/mm²).
• All tested IUDs generated forces significantly lower than in vitro perforation forces, indicating a low risk of perforation.

Conclusions:

• The insertion forces and pressures for Copper 7, Multiload Copper, and Nova T IUDs are well below the forces required to perforate uterine tissue.
• Primary uterine perforation during the insertion of these IUDs appears unlikely.