Periodic abstinence

It is known that if a woman has a menstrual cycle of normal duration, ovulation occurs 14 ± 3 days before the start of her next menstruation. It is also known that pregnancy is most likely to occur if intercourse takes place in the 5 days before ovulation or on the day of ovulation. This interval is called the fertile period. This has led to the idea of periodic abstinence during the fertile period as a method of birth control.

The woman is taught to detect the presence of mucus at the vaginal entrance each morning (before any sexual arousal). Three types of mucus can be detected and, from this, the days on which sexual intercourse can take place can be calculated while to some extent avoiding the chance of an unwanted pregnancy (Fig. 31.2). The compliance of the man is essential if pregnancy is to be avoided.

Fig. 31.2 Periodic abstinence: the mucus (ovulation) method.

Because of the difficulties in assessing the mucus and the need for the man to cooperate fully, the pregnancy rate varies from 10 to 30 per HWY for all couples, but for motivated couples it is 2.5–5.0 per HWY.

Coitus interruptus

Withdrawal, or coitus interruptus, is the oldest form of birth control apart from induced abortion. With the development of more modern contraceptives its frequency has declined, but it is still the preferred method in some sections of society. Its reliability for preventing pregnancy depends on the ability of the man to recognize the pre-ejaculatory phase and his agility in withdrawing his penis from the woman’s vagina before ejaculation. Because of these constraints, the efficacy of coitus interruptus in preventing an unwanted pregnancy is rather low (see Table 31.1).

Condom

Modern condoms, which are made of latex, prelubricated, and supplied in hermetically sealed aluminium sachets, are cheap, efficient and hardly noticeable to either partner. Their advantages are that they can be obtained from a variety of outlets without a doctor’s prescription, and that they offer some protection against sexually transmitted diseases, including the human papilloma virus, chlamydia and the human immunodeficiency virus (HIV). The disadvantage of condoms is that many younger men refuse to use them in the belief that they reduce sexual pleasure and may burst during use.

The pregnancy rate following condom use relates to usage, to the way the condom is put on the penis, and how it is held on after penile detumescence. If consulted by a woman or her partner the doctor should explain how a condom should be used (Fig. 31.3).

Fig. 31.3 Information for patients: how to use a condom, (A) Open the packet carefully, and do not unroll the condom before putting it on. (B) Semen can leak out soon after the penis becomes erect, prior to ejaculation. To prevent pregnancy or infection, the condom must be put on before any sexual contact takes place. (C) Ensure that the condom is the right way up. Squeeze the teat on the tip of the condom and hold it against the tip of the penis, (D), unroll the condom all the way to the base of the penis. (E) After ejaculation, the penis should be withdrawn before the erection is totally lost. When withdrawing, hold on to the condom. (F) Do not allow the condom or penis to come into contact with the woman’s genital area, and carefully dispose of the condom.

Barrier methods

Vaginal diaphragm and the cervical cap

The vaginal diaphragm and the cervical cap consist of a thin plastic or latex dome attached to a circular flat, coiled or arching spring rim. The vaginal diaphragm is easier to use than the cervical cap, as it fits diagonally across the vagina. The correct size of the diaphragm is determined by a medical practitioner examining the woman vaginally, by inserting the index and middle fingers as far as they will go into the posterior vaginal fornix and noting how far the index finger reaches behind the symphysis pubis. The diaphragm is made in sizes from 50 mm to 100 mm, in 5 mm steps. After measuring the vagina, the doctor inserts a series of diaphragms or fitting rings until the most appropriate size is found.

Using a diaphragm or a cervical cap requires practice, and after teaching a woman how to use it (Fig. 31.4) many doctors ask the woman to learn the technique at home and return with the diaphragm or cap in place for checking.

Fig. 31.4 The use of the vaginal diaphragm.

When the woman is confident about the technique, she inserts the diaphragm each day or at any convenient time before sexual intercourse is anticipated. It should not be removed for cleaning until at least 6 hours after the last ejaculation. Some women choose to smear a nonoxynol-9 spermicidal cream around the rim, but whether this adds to the effectiveness of the diaphragm in preventing pregnancy is uncertain. It is known to destroy HIV to some extent, which is a benefit.

If a woman chooses a cervical cap she must have a healthy, short cervix. Fitting is carried out by a medical practitioner. The technique of insertion and removal is the same as that for the vaginal diaphragm.

Hormonal contraceptives

Hormonal contraceptives contain oestrogen and a progestogen (combined oral contraceptives) or progestogen alone. Oestrogen suppresses follicle-stimulating hormone (FSH) secretion and reduces luteinizing hormone (LH) secretion, and in this way prevents ovulation. The progestogen further suppresses LH release, alters the quality of the cervical mucus, rendering it less penetrable to sperm, and produces endometrial changes culminating in glandular exhaustion. Importantly, the progestogen also permits a withdrawal bleed, which is regular in onset, short in duration and light in amount.

Non-oestrogen hormonal contraceptives

Progesterone-only pill (POP) – the mini-pill

This oral contraceptive is a good choice for women who have contraindications for COCs, or who are breastfeeding. It is an alternative for some diabetic women, women who have risk factors for cardiovascular disease, women who have hypertension related to COCs or who need control by antihypertensives, and some migraine sufferers. The POP is associated with BTB and unpredictable menstruation in about one in four users. The failure rate (pregnancy rate) is shown in Table 31.1.

Long-acting injectable progestogens

This formulation contains medroxyprogesterone acetate (DMPA) 150 mg, injected 3-monthly, or norethisterone oenanthate (NET-OEN) 200 mg, injected every 2 months. The advantage of the injectables is that they remove the need to take a pill every day. Their disadvantage is that during the first 4–6 months of use menstruation tends to be irregular. After this initial period amenorrhoea is usual and may lead to osteopenia.

Subdermal implants

The synthetic progestagen etonorgestrel (Implanon) is placed under the skin of the inner aspect of the non-dominant upper arm under local anaesthetic. The 68 mg implant is effective for 3 years and ovulation usually returns within 1 month of removal. It is a highly effective contraceptive agent with a Pearl Index of <0.07/100 woman years (Fig 31.5). As with other progestogen formulations such implants may provoke irregular episodes of uterine bleeding; oligomenorrhoea 26%, amenorrhoea 21%, frequent or prolonged bleeding 18% and normal menstrual cycle in 35%. Weight gain, breast tenderness and mood changes occur in 5–10% of women, and acne may be improved. If it is inserted in the first 5 days of the woman’s cycle then it is effective immediately, otherwise it is important to make sure the woman is not already pregnant before insertion and then to use other contraception for 7 days.

Fig. 31.5 Implanon.

Vaginal ring

This novel contraceptive, currently under study, has been developed in two forms:

• A ring containing an oestrogen and a progestogen, mimicking the COCs

• A ring containing levonorgestrel.

The ring fits in the upper vagina around the cervix. Its advantage is that it is the only long-acting method that is under the woman’s control. The woman removes the ring at will but generally replaces it at once after it has been washed. The disadvantage is that the ring may be associated with irregular bleeding in the first months of use and may be expelled from the vagina.

Postcoital contraception

If a woman has unprotected sexual intercourse at ovulation time she has two choices. The first is to wait and see if she misses a menstrual period and then have an immunological pregnancy test. If this is positive, she can then choose to continue with the pregnancy or to have an induced abortion (see p. 105). The second choice is to use a form of postcoital contraception, provided she seeks help within 72 hours. Four methods are available:

Pregnancy is prevented in 75% with Yuzpe, 88% with levonorgestrel and over 90% with an IUCD. It is important that the woman is given careful instructions to return a week after the time of her expected period for a pregnancy test if she fails to menstruate.

Intra-uterine device

Intra-uterine devices (IUCDs) were used in humans in the last years of the 19th century, but had so many adverse side-effects that their use was abandoned. The development of a polyethylene IUCD in 1950, which had a memory for its shape, revived interest.

A satisfactory IUCD should be easy to introduce, easy to remove, and have few side-effects and a high degree of efficiency in preventing pregnancy. In the 1980s, a series of legal actions against manufacturers led to the removal from the market of most IUCDs, and today only three types remain. Two of the devices have fine copper wire surrounding the stem, which permits a smaller device to be used and reduces some of the side-effects (Fig. 31.6). The third type contains levonorgestrel in its stem (Fig. 31.7). In the first 4 months of use some women have unpredictable episodes of spotting or bleeding, and may develop the unacceptable side-effects of negative mood change, acne and, sometimes, weight gain. After this time the levonorgestrel IUCD reduces the menstrual flow, controlling menorrhagia in women who have this menstrual disturbance; it may also cause amenorrhoea. This device may be chosen by women in their 40s who would otherwise consider tubal ligation.

Fig. 31.6 Copper 375 multiload IUCD.

Fig. 31.7 The levonorgestrel IUCD.

Copper IUCDs prevent pregnancy by incapacitating the sperm, making them dysfunctional for fertilization. The progestogen IUCD releases 20 µg of levonorgestrel a day and acts in the same manner as the progesterone-only pill.

The 5-year cumulative pregnancy rate for the levonorgestrel IUCD is 0.5–1.0%, whereas that of the copper-containing IUCDs is between 2.0 and 5.5%.

Vasectomy

The vasectomy operation is simple to perform, effective, and attended by little pain or inconvenience, particularly if the no-scalpel technique, developed in China, is used (Fig. 31.8). A few men develop scrotal swelling, bruising or a small haematoma, all of which settle quickly.

Fig. 31.8 In a no-scalpel vasectomy the vas (dotted line) is grasped by special ring forceps and the skin and the vas sheath are pierced by sharp-tipped dissecting forceps (A). The forceps then stretches an opening (B) and the vas is lifted out (C).

It is important that the medical practitioner discusses the procedure with the man and answers his questions. Many men equate vasectomy with castration; others are concerned that as sperm continues to be produced it will accumulate in the testes and swell them; others are anxious that after the vasectomy a man’s desire and performance will diminish. None of these beliefs has any basis in fact. The man needs reassurance that vasectomy does not increase his risk of developing cardiovascular disease, prostatic disease, cancer, erectile failure or autoimmune disease.

He must be made aware that following vasectomy he is not immediately sterile, as the sperm in the epididymis proximal to the vasectomy are still potent. Until these have been ejaculated, which takes on average 12 ejaculations, contraception must continue. The man should also be made aware that vasectomy should be considered a permanent method of birth control. Although the operation can be reversed by microsurgery and patency obtained in 70% of cases, the pregnancy rate is less than 50%.

Tubal ligation

In most cases tubal ligation – or, more accurately, tubal occlusive clipping – is performed through a laparoscope. A few women have the operation via a small suprapubic incision (minilaparotomy).

Although a failure rate of 2 per 1000 procedures at 5 years is often quoted, a study in the USA of 10 700 women who had had a tubal ligation showed a failure rate of more than 7 per 1000. The highest rate was 36 per 1000 procedures following clip sterilization, and the lowest 7.5 per 1000 after unipolar procedures. The failure rate is three times lower if the operation is performed as an interval procedure, that is, not immediately postpartum or after an abortion. A woman should be made aware of this before she decides to have the operation.

In the discussion before recommending the operation, the alternative methods of permanent birth control, including vasectomy, should be mentioned. Also, the stability of the current relationship should be explored.

Provided the woman has made an informed decision that she wants the operation and is aware that tubal ligation should be considered a permanent method of birth control, adverse reactions are few. As in the case of vasectomy, tubal patency can be restored by microsurgery and about 60% of women treated will conceive. In general, tubal ligation should not be performed immediately after childbirth, as 5% of women who have the operation at this time later regret their decision.

Hysteroscopically placed tubal occlusive device

The Selective Tubal Occlusive Device (Essure; Fig. 31.9) is a microcoil that is placed hysteroscopically directly into the tubal ostia under local anaesthesia. The localized inflammatory response causes tubal occlusion. The device appears to be well tolerated and clinical trials are reporting 85% successful placement and 99.8% efficacy.

Fig. 31.9 Essure device placed hysteroscopically in the uterine ostium.