Sexual and reproductive health
Contraception and termination of pregnancy
Artificial methods of contraception act predominantly by the following pathways:
• prevention of implantation of the fertilized ovum
• barrier methods of contraception, whereby the spermatozoa are physically prevented from gaining access to the cervix.
The effectiveness of any method of contraception is measured by the number of unwanted pregnancies that occur during 100 women years of exposure, i.e. during 1 year in 100 women who are normally fertile and are having regular coitus. This is known as the ‘Pearl index’ (Table 19.1).
Table 19.1
Failure rates per 100 women for different methods of contraception
USA data used by WHO: % of women having an unintended pregnancy within the first year of usea | Oxford/FPA Study (all women married and aged above 25)b | ||||
Typical use* | Perfect use† | Overall (any duration) | Age 25–34 (≤2 years use) | Age 35+ (≤2 years use) | |
Sterilization | |||||
Male (after azoospermia) | 0.15 | 0.1 | 0.02 | 0.08 | 0.08 |
Female (Filshie clip) | 0.5 | 0.5 | 0.13 | 0.45 | 0.08 |
Subcutaneous implant | 0.05 | 0.05 | – | – | – |
Nexplanon® | |||||
Injectable (DMPA) | 3 | 0.3 | – | – | – |
Combined pills | |||||
50 µg oestrogen | 8 | 0.3 | 0.16 | 0.25 | 0.17 |
<50 µg oestrogen | 8 | 0.3 | 0.27 | 0.38 | 0.23 |
Evra® patch | 8 | 0.3 | – | – | – |
NuvaRing® | 8 | 0.3 | – | – | – |
Cerazette® progestogen-only pill | 0.17‡ | – | – | – | |
Old-type POP | 8 | 0.3 | 1.2 | 2.5 | 0.5 |
IUD | |||||
Levonorgestrel-releasing intrauterine system (LNG-IUS) | 0.2 | 0.2 | – | – | – |
T-Safe® Cu 380 A | 0.8 | 0.6 | – | – | – |
Other >300 mm copper-wire IUDs (Nova-T 380®, Multiload® 375, Flexi-T® 300) | ≈1‡ | ≈1‡ | – | – | – |
Male condom | 15 | 2 | 3.6 | 6.0 | 2.9 |
Female condom | 21 | 5 | – | – | – |
Diaphragm (all caps believed similar, not all tested) | 16 | 6 | 1.9 | 5.5 | 2.8 |
Withdrawal | 27 | 4 | 6.7 | – | – |
Spermicides alone | 29 | 18 | 11.9 | – | – |
Fertility awareness | 25 | ||||
Standard days method | – | 5 | 15.5 | – | – |
Ovulation (mucus) method | – | 3–4 | – | – | – |
Persona | 6‡ | – | – | – | |
No method, young women | 80–90 | – | – | – | |
No method at age 40 | 40–50 | – | – | – | |
No method at age 45 | 10–20 | – | – | – | |
No method at age 50 (if still having menses) | 0–5 | – | – | – |
Other Notes (1) Note influence of age: all the rates in the fifth column being lower than those in the fourth column. Lower rates still may be expected above age 45. (2) Much better results also obtainable in other states of relative infertility, such as lactation. (3) Oxford/fpa users were established users at recruitment – greatly improving results for barrier methods (Qs 1.19, 4.9). (4) The Nexplanon, Cerazette and Persona results come from pre-marketing studies by the manufacturer, giving an estimate of the Pearl ‘method-failure’ rate.
bVessey M, Lawless M, Yeates D (1982) Efficacy of different contraceptive methods. Lancet 1(8276):841–842.
*Typical use: Among typical couples who initiate use of the method (not necessarily for the first time), the percentage who experience an accidental pregnancy during the first year if they do not stop use for any other reason.
†Perfect use: Among typical couples who initiate use of the method (not necessarily for the first time), and who then use it perfectly (both consistently and correctly), the percentage who experience an accidental pregnancy during the first year if they do not stop use for any other reason.
‡Data not available from Trussell, so best alternative data given, e.g. from manufacturer’s studies.
(This Table was published in Guillebaud J, MacGregor A (2013) Contraception 6e. ©Elsevier. Reproduced from Trussell J, Wyn LL (2008) Reducing unintended pregnancy in the United States. Contraception 77(1): 1–5, with permission.)
Barrier methods of contraception
Diaphragms and cervical caps
The modern vaginal diaphragm consists of a thin latex rubber dome attached to a circular metal spring. These diaphragms vary in size from 45–100 mm in diameter. The size of the diaphragm required is ascertained by examination of the woman. The size and position of the uterus are determined by vaginal examination and the distance from the posterior vaginal fornix to the pubic symphysis is noted. The appropriate measuring ring, usually between 70 mm and 80 mm, is inserted. When in the correct position the anterior edge of the ring or diaphragm should lie behind the pubic symphysis and the lower posterior edge should lie comfortably in the posterior fornix (Fig. 19.1).
Intrauterine contraceptive devices
Intrauterine contraception is used by 6–8% of women in the UK. A wide variety of intrauterine devices (IUDs) have been designed for insertion into the uterine cavity (Fig. 19.2). These devices have the advantage that, once inserted, they are retained without the need to take alternative contraceptive precautions. It seems likely that they act mainly by preventing fertilization. This is a result of a reduction in the viability of ova and the number of viable sperm reaching the tube.
Types of devices
The devices are either inert or pharmacologically active.
Devices containing progestogen
The levonorgestrel-releasing intrauterine system or Mirena® contains 52 mg of levonorgestrel (Fig. 19.2) which suppresses the normal build up of the endometrium so that, unlike most IUDs, it causes a reduction in menstrual blood loss. However, there is a high incidence of irregular scanty bleeding in the first 3 months after insertion of the device. Unlike previous progestogen-containing devices it does not appear to be associated with a higher risk of ectopic pregnancy. The superior efficacy of third-generation copper IUDs and the levonorgestrel-releasing system means that these are now considered the devices of choice.
Complications
The complications of IUDs are summarized in Figure 19.3.
Perforation of the uterus
• The device has been expelled.
• The device has turned in the uterine cavity and drawn up the strings.
• The device has perforated the uterus and lies either partly or completely in the peritoneal cavity.
If there is no evidence of pregnancy, an ultrasound examination of the uterus should be performed. If the device is located within the uterine cavity (Fig. 19.4A), unless part of the loop or strings is visible, it will generally be necessary to remove the device with formal dilatation of the cervix under general or local anaesthesia. If the device is not found in the uterus, a radiograph of the abdomen will reveal the site in the peritoneal cavity (Fig. 19.4B). It is advisable to remove all extrauterine devices by either laparoscopy or laparotomy. Inert devices can probably be left with impunity, but copper devices promote considerable peritoneal irritation and should certainly be removed.
Hormonal contraception
Contraindications
There are various contraindications to the pill, some being more absolute than others.
The occurrence of migraine for the first time, severe headaches or visual disturbances, or transient neurological changes are indications for immediate cessation of the pill. There are a series of minor side effects that may sometimes be used to advantage or may be offset by using a pill with a different combination of steroids (Table 19.2).
Table 19.2
Minor side effects of combined oral contraception
Oestrogenic effects | Progestogenic effects |