Makindo Medical Notes

The Combined Oral Contraceptive Pill (COCP) contains two hormones—oestrogen and progestogen—and is widely used for birth control.
Note: There is an increased risk of thromboembolism, particularly in smokers, women over 35, or those with a history of clotting disorders.

About

• Contains synthetic forms of oestrogen (usually ethinylestradiol) and progestogen.
• Highly effective when taken correctly:
  • Typical use failure rate ~7%.
  • Perfect use failure rate <1%.

Mechanism of Action

• Inhibits ovulation by suppressing follicle-stimulating hormone (FSH) release, preventing follicular maturation, and blocking the luteinising hormone (LH) surge.
• Thickens cervical mucus, making it more difficult for sperm to enter the uterus.
• Alters the endometrium, reducing the likelihood of implantation.

Benefits

• Contraceptive effectiveness — highly reliable if used properly.
• Reduces dysmenorrhoea and menorrhagia.
• Helps regulate periods and can lessen menstrual cramps.
• Decreases heavy menstrual bleeding.
• Reduces risk of ovarian and endometrial cancer.
• Can be helpful in PCOS, PMS, and endometriosis.

Risks

• Thromboembolism (especially in smokers >35 years, obesity, history of clotting disorders).
• Increased cardiovascular risk with smoking, obesity, age, diabetes, hypertension, and dyslipidaemia.
• Possible weight gain, reduced libido, breast discomfort.
• Mood changes, breakthrough bleeding.
• Association with cervical intraepithelial neoplasia, slightly increased risk of breast cancer.

Contraindications

• Acute porphyrias
• Atrial fibrillation
• Benign hepatocellular adenoma
• Budd–Chiari syndrome
• Cardiomyopathy with impaired cardiac function
• Complicated congenital heart disease
• Complicated valvular heart disease
• Current breast cancer
• Hepatocellular carcinoma
• Hypertension (systolic ≥160 mmHg or diastolic ≥100 mmHg)
• Hypertensive retinopathy
• Ischaemic heart disease
• Known thrombogenic mutations (e.g., factor V Leiden, prothrombin mutation, protein S, protein C, antithrombin deficiency)
• <3 weeks postpartum in non-breastfeeding women with other VTE risk factors
• <6 weeks postpartum if breastfeeding
• Major surgery with prolonged immobilisation
• Migraine with aura
• Peripheral vascular disease with intermittent claudication
• Positive antiphospholipid antibodies; previous or current venous thrombosis
• Smoking ≥15 cigarettes/day in women aged ≥35 years
• Stroke
• Systemic lupus erythematosus with antiphospholipid antibodies
• Transient ischaemic attack

Advice & Monitoring

• Assessment: Check blood pressure, take a detailed medical and family history to identify contraindications. Discuss risks, benefits, and side effects. Monitor side effects and adherence.
• Missed Pills:
  • If one pill is missed, take it as soon as possible and continue the next pill at the usual time (this may mean taking two pills in one day).
  • If two or more pills are missed, use additional contraception (e.g., condoms) for the next 7 days.
• Drug Interactions: Some medications (e.g., certain antibiotics, anticonvulsants, St. John’s Wort) can reduce COCP effectiveness. Consider additional contraceptive methods in these cases.

Causes of Contraceptive Failure

• Gastrointestinal issues (e.g., severe diarrhoea, malabsorption).
• Poor compliance (missed doses).
• Liver enzyme induction (e.g., with some antiepileptics).
• Broad-spectrum antibiotics (alter gut flora and possibly reduce hormone reabsorption).

References

• COMBINED HORMONAL CONTRACEPTIVES at BNF