Intra Uterine Devices
கருப்பை உள் சாதனங்கள் (IUDs)
Stop confusing IUDs with barrier methods. Barrier methods block sperm; IUDs actively destroy them or alter the uterine environment. If you don't distinguish between phagocytosis and mechanical obstruction, you will lose 4 marks on a simple matching question.
The idea
Intra Uterine Devices (IUDs) are inserted by doctors into the uterus. They are categorized into non-medicated (Lippes loop), copper-releasing (CuT, Cu7, Multiload 375), and hormone-releasing (Progestasert, LNG-20). These devices increase phagocytosis of sperms within the uterus, suppress sperm motility, and decrease their fertilizing capacity. Additionally, hormone-releasing IUDs make the uterus unsuitable for implantation and the cervix hostile to sperm.
Why it matters
To provide a highly effective, long-term, and reversible contraceptive method for women who want to space children.
NEET lens
NEET focuses on the mechanism of action for each type. Memorize that copper ions suppress motility, while hormones make the uterus unsuitable for implantation. Expect 'Match the following' questions linking the device type to its specific function. Do not confuse the mechanism of LNG-20 with that of CuT.
Clinical significance
IUDs are the most effective reversible contraceptives. Failure often results from improper placement or spontaneous expulsion. If an IUD fails and pregnancy occurs, there is a significantly higher risk of ectopic pregnancy, where the embryo implants outside the uterus, typically in the fallopian tube.
Introduction
Intrauterine devices (IUDs) are highly effective, long-acting reversible contraceptives (LARCs) placed inside the uterine cavity, working by creating a hostile uterine environment for fertilization and implantation.
Core concept
Types: (1) Copper IUDs (CuT-380A, CuT-380 — e.g. Copper-T): copper ions → toxic to sperm → inhibit sperm motility + viability. Also prevent fertilization. Endometrial inflammation → hostile to implantation. Non-hormonal. Lasts 10+ years. Can be used as emergency contraception (within 5 days). (2) Hormonal IUDs (LNG-IUS, e.g. Mirena): releases levonorgestrel (progestin). Thickens cervical mucus (blocks sperm). Thins endometrium. May suppress ovulation (partially). Lasts 5-8 years. Reduces menstrual bleeding (useful for heavy periods + contraception). Effectiveness: >99% — among the most effective reversible contraceptives. NEET commonly tests: Copper-T mechanism = copper ions → spermicidal + anti-implantation. Lippes Loop = older IUD type.
Go deeper
Emergency contraception with copper IUD: most effective emergency contraception (>99% effective if inserted within 5 days of unprotected intercourse). Mechanism: spermicidal + prevents fertilization + anti-implantation. After emergency use, can be left in for ongoing contraception (10 years). Superior to levonorgestrel emergency pill (Plan B) in efficacy and in women with higher BMI.
From Class 10
Intrauterine devices (IUDs) are small contraceptive devices inserted into the uterus by a healthcare provider to prevent pregnancy for several years.