2. Testimony of drug abuse
In order to avoid unintended pregnancy after unprotected sex, the specific indications for using emergency contraception are as follows:
No contraceptive measures were used.
Failure or improper use of contraceptive methods, including the following situations:
Condom is damaged, slipped or improperly used.
Two or more oral contraceptives were missed.
The injection time of pure progesterone contraceptive needle is delayed for more than two weeks, such as medroxyprogesterone acetate (DMPA) and norgestrel (NET-EN).
The injection time of estrogen and progesterone combined with contraceptive needle is delayed for more than three days, such as medroxyprogesterone acetate, estradiol 17- cyclopentane propionate)
Improper placement, rupture, tearing or premature removal of vaginal septum or cervical cap.
Failure to ejaculate in vitro (such as vaginal or vaginal ejaculation)
Sexual intercourse before the external spermicide takes effect
The calculation of safety period is wrong, which easily leads to the failure of abstinence during pregnancy.
The intrauterine device falls off.
Women who have no reliable contraceptive methods suffer from sexual violence.
Second, emergency contraception.
1, administration method
Levonorgestrel preparation
Take levonorgestrel 0.75mg (or norgestrel 1.5mg) as soon as possible within 72 hours after unprotected sex, and take it again after 12 hours.
Estrogen and progesterone complex (Yuzpe method)
Take ethinylestradiol 0. 1mg and levonorgestrel 0.5mg (or norgestrel 1mg) as soon as possible within 72 hours after unprotected sex, and take it again after 12 hours.
2. Mechanism of drug action
In a sense, the exact mechanism of emergency contraception is unknown, and its mechanism may change with different sexual intercourse time and different administration time. Some studies have shown that taking estrogen and progesterone complex before ovulation can inhibit or delay ovulation. Some studies have found that the endometrium has undergone histological or biochemical changes after using emergency contraception, which infers that the implantation of pregnant eggs is affected by endometrial changes. However, other studies have not found that emergency contraception has these effects on endometrium, and it is uncertain whether the observed endometrial changes are enough to inhibit the implantation of pregnant eggs. Other possible mechanisms are: cervical mucus thickening, limiting sperm activity; Changing the transport of sperm, eggs or pregnant eggs; Interfere with the function of ovarian corpus luteum; Directly inhibit sperm-egg binding. Although the existing clinical data may not fully confirm these mechanisms, the statistical evidence of the effectiveness of emergency contraception shows that there must be some mechanism at work besides delaying or inhibiting ovulation.
It can be seen from the data of high-dose oral contraceptives research that neither of these two conventional emergency contraceptives will cause abortion; After implantation, these two emergency contraceptives will not interfere with or damage pregnancy.
3. Clinical effect
Levonorgestrel
The study on the maximum clinical effect of levonorgestrel emergency contraception involved 14 countries, 2 1 center and * * * observation100/woman. The conclusion of this study is that levonorgestrel emergency contraception can prevent 85% of unwanted pregnancies. For example, among 100 women who have unprotected sex, usually 8 may get pregnant; If these 1 000 women take levonorgestrel, only1will get pregnant. It shows that taking levonorgestrel can reduce the pregnancy probability by 8 times.
Estrogen-progesterone complex
Eight studies on emergency contraception with estrogen and progesterone compound and the data of 3800 patients concluded that emergency contraception with estrogen and progesterone compound can prevent 74% of unintended pregnancy. For example, out of 65,438,000 women who have unprotected sex, 8 may get pregnant. If these 65,438+000 women take estrogen and progesterone compounds, only two will get pregnant. It shows that estrogen and progesterone complex can reduce the pregnancy probability by 4 times.
A large-scale randomized clinical trial directly comparing the two administration methods showed that the emergency contraception effect of levonorgestrel preparation was significantly higher than that of estrogen and progesterone compound preparation. The relative risk of pregnancy of women receiving levonorgestrel is 0.36, which is only 65,438+0/3 of that of women receiving estrogen and progesterone.
Three studies have shown that the earlier you take estrogen and progesterone compounds after sexual intercourse, the better the effect. One of the largest studies found that the pregnancy risk of taking emergency contraceptives on the third day after sexual intercourse is three times that of taking them on the first day after sexual intercourse. The early research did not put forward this time effect, which may be because the early research did not strictly follow the design scheme as the recent research did. Two studies found that the effect of levonorgestrel emergency contraception also decreased with the time from sexual intercourse to taking, but there were not many pregnant women, and the trend was not statistically significant.
Emergency contraception should not be used as a routine contraceptive method, the main reasons are as follows: First, emergency contraception is not as effective as most modern contraceptive methods used for a long time. This is because the pregnancy rate of emergency contraception is based on single use and cannot be directly compared with the failure rate of conventional contraception, which represents the long-term (such as one year) failure risk. If emergency contraception is used as a routine method, the cumulative pregnancy rate within one year will be higher than that of barrier contraception such as hormonal contraceptives and male condoms currently used. In addition, if you often take emergency contraception, the dose of hormones that come into contact with the human body will be higher than that of conventional contraception or simple progesterone contraception, and the side effects will be greater. At present, there is no information about the incidence of serious medical complications caused by women's long-term and frequent use of emergency contraception.
4. Side effects and their prevention and treatment
(1) Nausea and vomiting
The nausea rate of women who use levonorgestrel is about 23%, and the vomiting rate is about 6%. The incidence of nausea and vomiting was about 43% and 65438 06% respectively. The direct comparative study of the two preparations did not show that the nausea and vomiting caused by taking levonorgestrel were significantly lower than those caused by taking estrogen and progesterone complex. Nausea and vomiting usually appear within three days after taking the medicine.
prevent
The best way to reduce nausea and vomiting is to use levonorgestrel preparation as much as possible, instead of estrogen and progesterone compound. Nausea and vomiting caused by levonorgestrel preparation are not very common, so it is not necessary to take antiemetic drugs routinely and preventively. If estrogen and progesterone are used, preventive antiemetic drugs can be considered. It is observed that meclozine is a drug with this preventive effect. Oral administration of a single dose of chlorpromazine 50mg 65438+ 0 hours before the first combination of estrogen and progesterone can reduce the incidence of nausea and vomiting by 30% and 60%. When using chlorpromazine, users should be reminded of the possibility of drowsiness. Reducing the dosage of chlorpromazine or using other antiemetic drugs may also have the effect of preventing nausea and vomiting, but it has not been confirmed by clinical observation so far. At present, it is impossible to predict who will have nausea and vomiting after taking estrogen and progesterone compound, and who will benefit from taking antiemetic drugs before taking them. There is no evidence that taking estrogen and progesterone with food can reduce the risk of nausea.
deal with
Some experts believe that if you vomit within one hour after taking emergency contraception, you should take emergency contraception again; If vomiting occurs many times, vaginal administration should be used. Studies on traditional oral contraceptives show that hormones can be absorbed through vaginal mucosa.
(2) Irregular vaginal bleeding
A few women will have irregular vaginal bleeding or drip bleeding after taking emergency contraception. Such irregular bleeding is not menstruation. Users should know that emergency contraception does not directly induce menstrual cramps, but users of emergency contraception often have this illusion. After taking emergency contraception, most women will menstruate one week before or one week after the expected menstrual period.
deal with
After taking emergency contraception, if menstruation is not delayed for one week, the possibility of pregnancy should be considered, and women should have appropriate pregnancy tests and related tests.
(3) Others
Other side effects include abdominal pain, breast tenderness, dizziness and fatigue. These side effects usually occur within 1-2 days after taking the medicine, and the duration does not exceed 24 hours.
deal with
Headache and breast tenderness can be treated with over-the-counter painkillers.
Apart from these side effects, emergency contraception has no other known medical side effects on women, and there is no known teratogenic effect of taking emergency contraception in the first three months of pregnancy on the fetus. Emergency contraception does not increase the risk of ectopic pregnancy, nor does it increase the probability of pregnancy complicated with ectopic pregnancy after taking medicine.
5. Preventive measures
Women who have been diagnosed with pregnancy should not take emergency contraception because emergency contraception has no effect on the established pregnancy.
If a woman needs emergency contraception, but can't completely rule out pregnancy, she can be given emergency contraception, but it should be noted that if she is pregnant, emergency contraception can't do anything about it. Studies from high-dose oral contraceptives show that even taking emergency contraceptives by mistake in early pregnancy will not harm pregnant women and fetuses.
The history of using emergency contraception is not long, and there are no other medical conditions that are not suitable for using emergency contraception except conventional compound oral contraceptives and progesterone contraceptives. Women with a history of ectopic pregnancy can also use emergency contraception.
6, check before medication
Understand the last menstrual period and rule out possible pregnancy. If a woman has not menstruated recently, the reasons are unknown (for example, long-acting contraceptive injections, pregnancy, breastfeeding, irregular menstruation or long-term absence). ), or if a woman can't remember the exact date of her last menstruation, she can also use emergency contraception as long as the user understands that the possibility of pregnancy has not been completely ruled out.
Know the time of unprotected sex. If it has been more than 72 hours, you can still take emergency contraceptive measures, but let users know that it may not be effective.
Other health checks, such as pregnancy test, blood pressure measurement, laboratory tests, gynecological examination, etc. , only when the user has medical indications, and usually do not need routine. Emergency contraception providers should also be aware of the conventional contraceptive methods currently used by users. This problem can be used as a starting point to discuss the use of conventional contraceptive methods and how to use them correctly.
7. Special circumstances
(1) lactating women
Breast-feeding completely after delivery, menstruation has not come yet, the possibility of ovulation is very small, there is no need to take emergency contraceptives. If breastfeeding increases complementary food or menstrual cramps, it is possible to get pregnant. A medical emergency contraception will not have a great impact on the quality and quantity of breast milk. Some hormones can enter the milk, but it is impossible to have a bad influence on the baby.
(2) More than 72 hours after sexual intercourse
Studies have shown that taking emergency contraception after 72 hours of sexual intercourse reduces the contraceptive effect and has limited effect. Recent research on taking medicine after 72 hours of sexual intercourse shows that it still has a certain contraceptive effect. Because the use of emergency contraception is not dangerous to women or embryos, if users insist on and fully understand the possibility of pregnancy after using it, they can give emergency contraception. In this case, if women are suitable for taking mifepristone or placing intrauterine devices, taking mifepristone or placing copper-containing intrauterine devices is more effective.
(3) unprotected sex more than once
If users have unprotected sex more than once, they should not be denied emergency contraception unless they have been diagnosed with pregnancy. However, users should be aware that the effect of emergency contraception may decrease due to the prolonged interval between the first medication and unprotected sex. Users should take emergency contraceptive measures as soon as possible after unprotected sex, and should not wait until after multiple sexual intercourse. No matter how many times you have sex during emergency contraception, you can only take one dose at a time.
(4) Can it be reused?
Although the frequent use of emergency contraception is not advocated, it is unlikely to cause harm if it is used repeatedly occasionally. Women who have taken emergency contraception before or in the same cycle can still use it again. All women who take emergency contraception, especially repeat users, should get information about other contraceptive methods and guidance on how to avoid contraceptive failure.
(5) Take emergency contraceptive measures before sexual intercourse.
There is no data to determine the duration of contraceptive effect after taking emergency contraception. If you have sex immediately after taking emergency contraception, the contraceptive effect is the same as taking it immediately after sexual intercourse. However, if women can consider contraception before sexual intercourse, then other contraceptive methods such as condoms or other barrier contraception are preferable.
(6) Take emergency contraceptive measures when "pregnancy is difficult"
Studies have shown that sexual intercourse can only be conceived within 5-7 days before and after ovulation in the menstrual cycle. Theoretically, if unprotected sexual intercourse occurs in other periods of menstrual cycle, even if emergency contraceptive measures are not taken, you will not get pregnant. But in fact, it is difficult to determine whether a sexual intercourse occurs in "easy pregnancy" or "difficult pregnancy". Therefore, usually at any time after unprotected sex, women should consider the possibility of pregnancy and take emergency contraceptive measures. Even if unprotected sex takes place on a day when pregnancy is unlikely, a decision should be made after comprehensive consideration of women's anxiety, the availability of emergency contraceptives and other information of users.
(7) Drug interaction
There is no specific information about the interaction between emergency contraception and other drugs. However, drugs that interact with conventional oral contraceptives will have similar effects as emergency contraceptives. Drugs that may reduce the effectiveness of oral contraceptives (including rifampicin, some anticonvulsants, etc. ) may also reduce the effectiveness of emergency contraception. If women take emergency contraceptive measures when taking these drugs, they should consider increasing the hormone dose of emergency contraception, either in one of the two conventional drugs or once.
(8) Other formulations
Recent studies have shown that the contraceptive effect and side effects of oral contraceptives containing estrogen and progesterone complexes containing levonorgestrel are similar to those of estrogen and progesterone complexes containing levonorgestrel where there is no levonorgestrel and standard estrogen and progesterone complexes.
8. Consultation
Like other contraceptive methods, emergency contraception should provide users with advice and information that respects individuals and suits their needs. After unprotected sex, women may feel particularly anxious because they are afraid of pregnancy, may worry about missing more than 72 hours to take emergency contraceptive measures, may feel embarrassed because of contraceptive failure, and may be afraid of contracting AIDS because of sexual violence or complicated factors. When discussing with users, consultants should support users' choices as much as possible, and restrain the judges' remarks to avoid some unpleasant body language and facial expressions. The supportive attitude helps to promote the discussion on the use of conventional contraceptive methods and the prevention of sexually transmitted diseases during the follow-up period. In the process of consultation, it may be more effective to guide women to participate by whether they have heard of emergency contraception, discuss the experience of using contraceptive measures (especially the details that lead to emergency contraception) and the existing methods to protect themselves from sexually transmitted diseases (especially the use of condoms), and then convince them with appropriate affirmation or correction, which may be more effective than simply providing information.
Whenever possible, the consultation should be conducted in confidence. In places without privacy conditions such as pharmacies, users should be informed to contact medical and health care institutions or family planning service institutions to obtain information and suggestions on conventional contraceptive methods. In order to reassure all users, they tell the service provider all the information, such as age, marital status and so on. The treatment they receive will be kept confidential.
If possible, users should be provided with written and oral instructions on how to take emergency contraception. For users with low educational level, instructions on the use of the map should be given.
9. Information to be provided
Users should be informed of the effectiveness, side effects and mechanism of emergency contraception, and how to prevent re-emergency contraception and conventional contraception to prevent pregnancy after emergency contraception. But we should pay attention to avoid giving too much information for users to absorb. In addition, some users may not need to consult some questions when accepting emergency contraception, such as other contraceptive methods or the mechanism of emergency contraception. At this time, the service provider should let users know the minimum information on how to use emergency contraception correctly. The following key messages should be conveyed to users as far as possible:
Users who have unprotected sexual intercourse should take the first dose of emergency contraception as soon as possible to obtain the maximum emergency contraceptive effect; Note to repeat after 12 hours. Users should know how to correctly calculate the interval of 12 hours. Normally, the dose should not be increased. If you vomit after taking the medicine for one hour, you need to take another dose.
After taking emergency contraception, if menstrual cramps are delayed for more than a week, we should consider the possibility of pregnancy and go to the corresponding service institutions for further examination and diagnosis.
Emergency contraception has no contraceptive effect on sexual intercourse after taking medicine; Emergency contraception has high hormone content, low contraceptive efficiency and high incidence of side effects, so it cannot be used as routine contraception. Users should be provided with information about other contraceptive methods and where to obtain them. If possible, users should be provided with contraceptive methods that can be used directly, such as condoms.
Emergency contraception does not have the function of anti-AIDS and sexually transmitted diseases, and the risk of these infections may still exist when using emergency contraception in unprotected sex. Information on where to get the diagnosis and treatment of sexually transmitted diseases should be provided; If possible, also introduce how to reduce the risk of sexually transmitted diseases.
10, follow-up
Mainly solve the following problems for users.
Routine contraceptive counseling and guidance on the implementation of contraceptive measures;
Measures to be taken to delay menstruation for more than one week;
How to deal with pregnancy or other related problems?
1 1, to deal with pregnancy after taking the medicine.
There may be three situations of pregnancy after emergency contraception: failure of emergency contraception, pregnancy before taking medicine or sexual intercourse after taking medicine. Once pregnant:
Inform the above three possible pregnancy situations, analyze the most possible pregnancy factors, respect and support the user's choice, and provide suitable places for further treatment.
If users choose to continue pregnancy, they should ensure that there is no evidence that emergency contraceptives have teratogenic effects; Existing data show that emergency contraception will not increase the possibility of ectopic pregnancy after pregnancy.
12. Start time of routine contraception after emergency contraception.
Whenever possible, conventional contraceptive methods, such as condoms, should be provided when distributing emergency contraceptives so that users can use them immediately. However, this kind of consultation is not suitable for all cases, because users may not need this information when receiving emergency contraceptives; At the same time, this should not be a prerequisite for providing emergency contraception. Users who need or want to know this knowledge but are unwilling to consult when receiving emergency contraception should be given the earliest and humanized follow-up appointment.
After taking emergency contraceptive measures, users may want to use the previous contraceptive methods again, or want to use new contraceptive methods. If this kind of emergency contraception is caused by conventional contraceptive mistakes, such as condom breakage or missed use of contraceptives, we should discuss with users the causes of the mistakes and how to prevent similar mistakes in the future.
Women infected with sexually transmitted diseases, such as young people or women living in areas where sexually transmitted diseases are prevalent, should receive special guidance on how to prevent sexually transmitted diseases when receiving pregnancy prevention services, and should emphasize the use of condoms as the main contraceptive method.
The time to start routine contraception after emergency contraception is as follows:
Both male and female condoms can be used immediately.
Vaginal diaphragm or cervical cap can be used immediately.
External spermicidal foam, tablet, jelly, cream or film can be used immediately.
There are two methods to choose from for oral contraceptives.
① At the beginning of the next menstrual cycle, start a new cycle according to the instructions of the contraceptive. Women who use this method should use barrier contraception or abstinence during taking emergency contraception.
(2) After taking emergency contraception, take a new cycle of contraception. If the user uses emergency contraceptives because he missed them, he can continue to take the remaining contraceptives until he finishes taking them. Women who use this method may have irregular bleeding before their next menstrual cramp, so they should use barrier contraception within 7 days of starting or restarting taking contraceptives.