The combined oral contraceptive. a practical guide
Miller, C.
Australian Family Physician 19(6): 897; 900 903-906
1990
ISSN/ISBN: 0300-8495 PMID: 2248582 Document Number: 376192
Low does pills have an effectiveness of 0.2-1.0 pregnancies/100 woman-years. The pill functions by multiple modes of action, namely: inhibition of ovulation by suppressing cyclic follicle stimulating hormone and luteinising hormone release; reducing sperm penetrability of cervical mucus; rendering the endometrium hostile to implantation; and probably affecting tubal transit time. Patients will no longer have their 'periods' but will experience hormone withdrawal bleeds. The greatest risk of ovulation is at the end of the pill-free week, not in the middle of the pack. Make sure you determine that it is an appropriate contraceptive: make sure the patient and her partner both want to use it and understand its advantages and disadvantages; is the risk of pregnancy high enough to justify its use (low coital frequency might indicate that a less effective method could be acceptable); how critical is pregnancy avoidance? (is it merely for child spacing?) Make sure you determine the medical appropriateness; absolute contraindications include pregnancy, undiagnosed vaginal bleeding, 1st 2-weeks postpartum, history of thromboembolic disease, CVAs, focal migraines, coronary artery disease, recent impaired liver function, and steroid-dependent tumors. Perform a physical examination including at least: blood pressure, weight, urine test for glucose and protein, heart, breasts, Papanicolaou smear and bimanual vaginal examination. Always choose the lowest possible dose pill. Often times this means a levonorgestrel-containing triphasic or low dose norethisterone-containing monophasic. Give the patient adequate information including: effectiveness, safety, how to start, possible side effect, what to do about late or missed pills, action to take in case of vomiting or diarrhoea, interactions with other drugs, postponed or missed periods, and special considerations for vegetarians. Offer preventative measures and give take home pamphlets.