Barrier and Spermicidal Contraceptive Methods

Mechanism of Action

Barrier contraception prevents pregnancy by physically blocking sperm from reaching the ovum. Spermicidal agents, such as nonoxynol-9, act locally by disrupting sperm cell membranes, further reducing fertilization chances. Depending on the method, some protection against sexually transmitted infections (STIs) is also provided.

Types of Barrier Methods

1. Male Condoms

• Description: Penile sheaths, usually latex (alternatives: polyurethane, polyisoprene), worn over an erect penis. Semen is collected in a reservoir tip.

• Advantages:

• No medical contraindications except latex allergy.

• Reduces transmission of many STIs (e.g., chlamydia, gonorrhoea).

• Widely available, inexpensive, and easy to use.

• Disadvantages:

• May reduce sensitivity or interfere with erection.

• Requires consistent use; risk of breakage or slippage.

• Failure rates: Perfect use – 2%; typical use – 16%.

2. Female Condoms

• Description: Polyurethane tubular sheath with inner and outer rings; lines the vaginal canal before intercourse.

• Advantages:

• No contraindications; less likely to tear than male condoms.

• Can be inserted up to 8 hours before sex.

• Offers some STI protection.

• Disadvantages:

• May be noisy or uncomfortable.

• Can become dislodged or allow incorrect penetration.

• Failure rates: Perfect use – 5%; typical use – 21%.

3. Vaginal Diaphragm

• Description: Dome-shaped device (rubber or silicone) covering the cervix, used with spermicide. Held in place by vaginal tone and pubic bone support.

• Advantages:

• Can be inserted up to 3 hours before intercourse.

• Disadvantages:

• Requires individual fitting; size changes with weight change or pregnancy.

• Increased risk of urinary tract infections (UTIs).

• No STI protection; spermicide may cause mucosal irritation.

• Failure rates: Perfect use – 6%; typical use – 16%.

4. Cervical Cap

• Description: Small cup fitting directly over the cervix, creating a seal by suction. Used with spermicide.

• Advantages & Disadvantages: Similar to diaphragms.

• Failure rates:

• Nulliparous: Perfect use – 9%; typical use – 16%.

• Parous: Perfect use – 20%; typical use – 32%.

5. Spermicides

• Description: Jellies, foams, or films containing nonoxynol-9.

• Disadvantages: May cause genital irritation, potentially increasing STI risk.

General Considerations

• Barrier methods are less effective than long-acting reversible contraception (LARC) and require correct, consistent use.

• Male condoms remain the only contraceptive method with significant STI protection.

• Emergency contraception should be discussed in case of barrier failure.

• Contraception can be provided to under-16s if Fraser criteria are met.

Failure rates