Intro, efficacy, duration of use, choice of device and assessing suitability

Introduction

Cu-IUDs are non-hormonal and vary in size and shape (Table 1). They consist of copper and plastic and may contain barium for radio-opacity. They can be used for regular and emergency contraception (EC),(see Emergency Contraception Protocol), and are effective immediately following insertion.

Main mode of action of a Cu-IUD is inhibition of fertilisation through the effect of copper on the ovum and sperm. Copper also inhibits the passage of sperm into the upper reproductive tract, and causes an inflammatory response within the endometrium, which could impair implantation.

Efficacy, duration of action and choice of device

  • Cumulative pregnancy rates for Cu-IUDs with 380mm2 copper are between 0.1 and 1% after the first year of use.
  • Pregnancy rates are lowest for T-shaped devices which have a copper surface area of 380 mm2 with copper banding on both the arms and stem.
  • Cu-IUDs with longest duration of use should be used as they reduce the risk of infection, perforation and expulsion associated with reinsertion (see Table 1).
  • Contraceptive effectiveness is not affected by use of enzyme-inducing drugs or weight/BMI
  • The intrauterine ball is not available in the UK at the time of guideline publication

If a Cu-IUD with a copper surface area ≥300 mm2 is inserted in those ≥40 years old, the CoSRH supports extended use of the device, and the Cu-IUD can be used for contraception until menopause. It can be removed 1 year after the final menstrual period if this occurs after age 50 years.

Table 1: Types of copper intrauterine devices listed in the British National Formulary*Checked 11/9/25

(reproduced from https://www.fsrh.org/documents/ceuguidanceintrauterinecontraception/)

Assessing Suitability

Few medical conditions contraindicate use of IUC (see UKMEC)

UK Medical Eligibility Criteria for Contraceptive Use (UKMEC) | CoSRH

The use of the Cu-IUD is contraindicated if there is a known or suspected allergy or hypersensitivity to any of the components of the device.

Editorial Information

Last reviewed: 25/08/2023

Next review date: 01/10/2025

Author(s): West of Scotland Managed Clinical Network in Sexual Health Clinical Guidelines Group .

Version: 10.1

Approved By: West of Scotland Managed Clinical Network in Sexual Health

Reviewer name(s): George Laird.