Abortion - Introduction

An abortion is a pregnancy that ends before the baby can survive outside the womb because it has not yet reached viability. An abortion may be early  - during the first 14 weeks of pregnancy, or late. The vast majority are early - only about 1% of abortions are late.

The definition of an abortion is a spontaneous loss of a pregnancy before 24 weeks: in the UK we calculate the duration of a pregnancy from the first day of the last period (LMP). An abortion - the medical term for an early pregnancy loss is abortion - tends to start with bleeding, and pain may then develop. Sometimes there may be bleeding early in the pregnancy but the pregnancy continues (threatened abortion). An inevitable abortion means that the pregnancy cannot be salvaged. It may be incomplete, with pregnancy products still in the cavity of the womb or complete with nothing remaining.

The combination of modern pregnancy tests and ultrasound will usually determine the situation quite quickly. Pregnancy tests these days should become positive within ten days of conception (i.e. even before the first missed period). Ultrasound begins to show a pregnancy within the uterus by five or six weeks (a week or two after the first missed period). On occasion, it may be too early to diagnose the situation accurately and tests may need to be repeated to see what changes occur.

Types of abortion

Table 12.1 indicates the various terms most frequently associated with abortion.

 
Type of Abortion Description
Spontaneous Abortion This is when the abortion occurs naturally as opposed to being induced.
Induced Abortion The pregnancy is terminated artificially.
Threatened Abortion There is bleeding and sometimes pelvic pain but the cervix is closed and ultrasound indicates an ongoing pregnancy within the uterus.
Inevitable Abortion The pregnancy is not continuing.
Complete Abortion An inevitable abortion and the uterus has completely emptied itself.
Incomplete Abortion An inevitable abortion with products of the pregnancy still present in the uterus.
Missed Abortion There are no reasons to have suspected that the pregnancy is not going to continue but the embryo has died.
Septic Abortion The abortion has been complicated by infection.
Recurrent or habitual Abortion Most authorities recommend that these terms should be used only for three or more consecutive abortions although there is a tendency towards two.
Early Abortion Abortion in the first few weeks of the pregnancy.
Late Abortion Abortion after the first few weeks.
First trimester Abortion Abortion before thirteen weeks of pregnancy.
Second trimester Abortion Abortion after thirteen weeks and before twenty four weeks.

Abortion symptoms

The first abortion symptom is vaginal bleeding, which can range from spotting to being heavier than a period. A little spotting may be an early sign of abortion although fortunately this may amount to no more than a threatened abortion and the pregnancy continues. The second abortion symptom is pelvic pain. The third abortion symptom is cessation of pregnancy symptoms including breast tenderness, morning sickness and having to pass urine more frequently than usual. Some women have no abortion symptom and the discovery is made at ultrasound examination.

Sometimes there may be no sign or symptom to suggest abortion and pregnancy symptoms continue, and the abortion is only discovered in a routine scan. This is a missed abortion. A threatened abortion occurs when there is vaginal bleeding but ultrasound confirms a viable pregnancy.

Cause of Abortion

Often the cause of an abortion remains unknown. The most common cause for abortion is a blighted ovum ? the afterbirth type tissues develop but there is no baby. Another common cause is a genetic defect and nature decides not to allow the pregnancy to continue. Smoking and obesity may contribute to abortion but do not cause abortion by themselves. Similarly,  stress may play a role in pregnancy loss, but it hasn't been shown to cause abortion on its own. Cause for recurrent abortions is discussed Q12.16 to Q12.21.

Prevalence Of Abortion

It is thought that between 10 and 20% of pregnancies miscarry. Most abortions occur in the early weeks of pregnancy. Ultrasound screening for fetal anomaly has shown the incidence of non-viable pregnancy at 10-13 weeks to be 2.8%

Blighted Ovum

Normally the fertilised egg divides and part becomes the embryo (future baby) and part becomes the afterbirth type tissue (trophoblast) and the membranes that form a fluid filled bag around the baby. When there is a blighted ovum, the afterbirth tissues develop alone without the development of the baby. Blighted ovum hasalso been referred to as an 'anembryonic pregnancy'. Nearly half of early abortions are associated with a blighted ovum. It is likely that abnormal chromosomes are more prevalent.

Hydatidiform Mole

This is a benign tumour of the trophoblast (afterbirth tissues) characterised by vesicles which look like small grapes. Usually a hydatidiform mole develops without an embryo but this is not always the case. As hydatidiform moles produce a relatively high level of the pregnancy hormone HCG, there tends to be an increased incidence of excessive vomiting in early pregnancy. The diagnosis is usually made from the typical ultrasound picture. The womb will need to be carefully emptied by suction. Very rarely, there is subsequently evidence of malignancy (choriocarcinoma). It is therefore essential that you are carefully monitored for a few months by hormone tests on your urine. These days choriocarcinoma can be treated successfully by chemotherapy (Q32.33).

Pictures of a hydatidiform mole from www.hmole-chorio.org.uk

Picture of Hydatidiform Mole

Pregnancy Tests

Pregnancy tests are designed to determine the presence of the pregnancy hormone HCG. Until twenty years ago, pregnancy tests were biological, relying on the affects of the hormone on animals. There could be a cross-reaction with other hormones, notably LH. Many women reaching the menopause could have a false alarm as LH levels rise at the menopause and when they missed their periods their pregnancy tests could be falsely positive. Modern pregnancy tests are monoclonal they react only with the specific hormone they are designed to detect. In the early weeks of pregnancy, the HCG level doubles every two days. Whereas the old pregnancy tests would become positive with a concentration of 3,000 IU (about two weeks after the missed period) the monoclonal tests show a positive result at between 25 and 50 IU and these levels are reached before a period is missed.

The accuracy of modern pregnancy tests are not only useful in the early detection of pregnancy but also in assisting in the management of early pregnancy problems such as threatened abortion or possible ectopic pregnancy.

A lady presented with vaginal bleeding and left sided pelvic pain. Her pregnancy test was positive and ultrasound did not show any sign of a pregnancy either within or outside the uterus (ectopic pregnancy). Her beta HCG level was 365 units suggesting a very early pregnancy at most. Two days later the level had fallen to 180 units which indicated that the pregnancy was not continuing. We could not say for certain whether this had been an intra-uterine pregnancy that miscarried or a possible ectopic pregnancy that was being resolved by nature but no operative intervention was required.

Treatment of Abortion

The options for managing abortion are outlined in Figure 12.1. If abortion is threatened, you will usually be advised to rest for a few days and a repeat scan will confirm whether the pregnancy is continuing. There have been several important developments in the management of abortion in recent years. The combination of highly sensitive pregnancy tests and ultrasound will usually assist in providing an accurate diagnosis. Many hospitals now have an early pregnancy assessment unit that specialise in these problems. This should allow you to see an expert in a dedicated area where you can receive sympathetic assistance away from busy, and often fraught, accident and emergency departments.

;

 

Flowchart showing a flowchart for the treatment  management for abortion.

At one time, we believed that if you miscarried between seven and thirteen weeks, there were likely to be retained products of pregnancy and an ERPC (evacuation of retained products of conception) was indicated to reduced the risk of infection and bleeding. In the days before legal termination of pregnancy (Chapter 19) infection with induced abortion was relatively common. These septic abortions could be life threatening. Current opinion is that the risk of infection and bleeding has been overstated and a conservative approach now seems safe. From your point of view, this means that you may not need an operation which, as always, carries an element of risk (surgery risks) and furthermore delays waiting for an operation slot are avoided. A repeat scan about ten days after the diagnosis of incomplete abortion will usually confirm that nature has solved the problem for you and the womb has completely emptied itself. If an abortion is incomplete, oral misoprostol 600 micrograms may be as safe as surgical evacuation.

If you are Rhesus negative you should be offered an injection of Anti-D to reduce the chance of rhesus problems in a future pregnancy. Guidelines for the administration of Anti-D are currently under review.

The emotional aspects of abortion can be difficult to deal with particularly if you have had difficulty conceiving or if this is not your first abortion. There is inevitably a time of grieving. A trained counsellor with a special interest in abortion can provide support and help you come to terms with your loss.

What is meant by recurrent abortion?

Abortion is an emotionally challenging ordeal accompanied by all the feelings of bereavement. When it occurs more than once it may, understandably, be a devastating experience. Most experts suggest that investigations to detect the cause of recurring abortion should begin after three consecutive pregnancy losses. Regional centres have difficulty coping with referrals even for women who have miscarried three times. For those who have miscarried twice, this seems harsh. If we are pedantic, when something recurs it has happened more than once so the second abortion is obviously a recurrence. Some departments, have revised their criteria so that consultation and some investigations can commence after two consecutive abortions.

As the majority of pregnancies, even after three abortions, are likely to be successful, it is particularly difficult to scientifically prove that a particular treatment is effective. The one cause of abortion that can be detected and for which there is effective treatment is increased levels of antiphospholipid antibodies. The blood tests are for lupus anticoagulant and anticardiolipin. If these prove to be positive, Aspirin (75mg daily) particularly in combination with heparin, significantly reduces the likelihood of abortion.

The incidence of early pregnancy loss doubles from the age of 20 to 40 years and evidence from IVF with egg donation suggests that increased abortion problems in older women may be partly attributable to the state of the uterus. A recent study in Bologna, Italy compared implantation and pregnancy rates in an oocyte donation programme with women of different ages sharing oocytes from the same donor: clinical pregnancy rates and ongoing pregnancy rates were twice as likely in recipients of less than forty years old compared to older recipients.

Can abortion and recurrent abortion result in symptoms of anxiety and depression?

It is more than understandable that abortion is frequently associated with depression and anxiety for both the female and male partners. An abortion can be associated with all the symptoms associated with bereavement and reactive depression is a common feature. There may be anxiety that there may be difficulty achieving a family particularly if abortion has occurred before.(Q12.20).

Pregnancy after Abortion.

If you are pregnant after a previous abortion, the chances are that the pregnancy will be successful. Even after three abortions, your chance of a successful pregnancy is 55%.


Usually nature has detected some problem such as a chromosome abnormality (genes - chromosomes) and decides that it is in your interests to discontinue this pregnancy and give you an early chance to start a successful one. A blighted ovum (Q12.4), or an embryo with an abnormality would be reasons for spontaneous abortion. Occasionally there may be a different and perhaps remedial cause which would need consideration if you have three abortions.


What is the chance of a successful pregnancy after recurrent abortion?

This depends on the number of consecutive abortions that you have had (Table 12.2).

Table 12.2 The chance of subsequent abortion related to previous number of consecutive abortions.

Two 75
Three 55
Four 45
Five 42

 

Whilst this is to some extent reassuring, it means that the potential value of a new treatment is difficult to determine as a healthy baby could be as much due to chance as to the treatment. Large numbers of patients are required in controlled trials to demonstrate any true benef

Why do I keep miscarrying?

It is sad enough to lose one pregnancy but it is particularly devastating when this problem recurs; you will have the sympathies of all concerned.

Pregnancy may fail at any time from implantation to childbirth. The majority of unsuccessful pregnancies will fail in the first four months first trimester. About one pregnancy in five or six will result in a first trimester pregnancy loss about the same chance as rolling a 1 with a dice. When an abortion occurs the question to be answered is Was this just chance?

. If you roll the dice once and get a 1 it seems reasonable to assume this is chance. A second 1 may still be chance but by the third consecutive 1 there is more than a suspicion that the dice is weighted. The investigation of recurrent abortion is really designed to check in the first instance whether the dice has been weighted and whether it is possible to get a new and fairer dice (Q12.6).

A successful pregnancy requires a healthy egg and a healthy sperm. The resulting embryo must be perfect and the womb capable of sustaining the pregnancy. There is a requirement for a series of appropriate changes in hormone production. When evaluating the potential value of the numerous tests that can be considered we need to determine how relevant the result may be to determining the likelihood of a further abortion and particularly whether the result would influence treatment. During investigation, observations may be made that are incidental and not necessarily the cause of recurrent abortion (Q4.3). We are looking for a cause for which there is evidence based effective treatment (Q33.24).

Before considering the possible causes of recurrent abortion it should be emphasised at the outset that there is only one investigation that may identify a problem for which there is effective treatment, the antiphospholipid antibody tests (Q12.17). A diagnosis of polycystic ovary syndrome may lead to treatment with metformin which looks promising but it will take time before controlled trials have been undertaken to determine whether it is effective in reducing recurrent abortion.

The causation of a clinical problem may be reviewed under the headings identified in Q3.2. In Table 12.3 this grouping has been applied to recurrent abortion. Recurrent abortion is one of the most difficult clinical problems to identify the cause as it involves eggs, sperm, embryos, uterus and hormones.

Table 12. 3

DISEASE PROCESS

Examples

Congenital

Congenital uterine abnormality; Fetal abnormality

Trauma

Cervical incompetence.

Inflammation/infection

'TORCH' infections; Endometrial Infection; Syphilis.

Metabolic

Mineral deficiencyObesity

Hormonal

Hormone deficiency; LH excess (PCOS)

Autoimmune

Antiphospholipid antibodies;Alloimmunity

Tumour

Fibroids

Degenerative

Maternal age

Psychological

Anxiety / depression

Idiopathic

 

Could A Congenital Abnormality Cause Recurrent Abortion?

It is now recognised that some inherited defects in the normal anticoagulant mechanism of the blood may be related to recurrent abortion. When tissues are cut they bleed and the blood should clot (coagulation) to stop the bleeding. There is a cascade of chemical changes in the blood that lead to this coagulation. The body also produces a set of chemicals that prevent the blood clotting inappropriately - these are anticoagulants. There is increasing interest in a number of inherited defects in these anticoagulants including activated protein C resistance, which is usually due to Factor V Leiden gene mutation, deficiencies of Protein C or S, antithrombin III, hyperhomocystinaemia, and prothrombin gene mutation. About 10% of women with recurrent abortions will prove to have inherited thrombophilia compared to 3% of controls. It is believed that anticoagulation treatment with aspirin 75 mg daily or injections of heparin may improve the prognosis but more research is required in this area.

Congenital structural abnormality may relate to the uterus or the fetus. Congenital uterine abnormalities are discussed in Q3.3 . It is not uncommon to find evidence of a congenital uterine abnormality during investigation of recurrent abortion. Many women with congenital uterine abnormality seem to have uneventful pregnancies. It is not certain whether there is an increased incidence of congenital uterine abnormality in association with recurrent abortion. There have been many women who have conceived whilst awaiting corrective uterine surgery and these pregnancies have proceeded uneventfully suggesting that the abnormality was not preventing a successful outcome. Controlled studies (placebo & controlled trials) are awaited to determine whether surgery reduces recurrent abortion.

Genetic evaluation of the embryo or placental tissue is only possible in about 60% of cases even in dedicated university departments. It would appear that in 50-60% of abortions there is evidence of chromosome defects. Recent developments in DNA analysis may indicate that an even higher proportion of abortions may be genetic. At this time there is no known treatment that would reduce the incidence of genetic disorders.

Parental chromosome abnormalities may be found in about 6% of couples with three abortions or more. These families require counselling from geneticists (doctors who specialise in gene disorders). Advice can be given on the chance of successful pregnancy and the risk of producing a child with a genetic disorder. On rare occasions, it may be appropriate to consider donated gametes, i.e. donor insemination (23) if the problem is with the male partner and IVF/ donated ova (IVF - egg donation) if the problem is with the woman.

A woman of 30 was investigated for recurrent abortion and was found to have a balanced translocation between chromosomes 8 and 14 (genes - chromosomes). This causes no difficulties for the lady as she has all the required genetic material, albeit in an incorrect order. The problem is that her gametes (eggs) may contain an incorrect amount of chromosomes 8 and 14, which almost certainly accounts for recurrent abortion. A pregnancy could continue with a 5% risk of physical or intellectual problems for the baby. The options open to this couple were to continue trying for a pregnancy and in the event of success to accept CVS or amniocentesis (Q19.3) to check the baby's chromosomes. A second option would be IVF with donated eggs (IVF - egg donation).

Preimplantation genetic diagnosis can be beneficial for three major subgroups of patients with recurrent pregnancy loss:

  • couples carrying chromosomal translocations
  • women more than 35 years of age
  • women of any age whose previous abortions were due to fetal aneuploidy.

It is likely that the rate of abortion will be further reduced with the new advances in methods of performing preimplantation genetic diagnosis for more chromosomes.0801

What traumatic conditions might be associated with abortions?

The cervix (neck of the womb) should remain closed through pregnancy but in labour it must stretch to allow the baby through. Cervical incompetence is characterised by weakness of the cervix allowing it to open without the typical labour pains, expelling the fetus during the middle weeks of pregnancy (mid-trimester abortion). For the cervix to be incompetent the internal os (top end of the cervix) must be weak. It is possible for the cervix to be weak from the outset particularly in association with congenital uterine abnormality. Cervical incompetence can result from outmoded traumatic obstetric delivery but we now resort to Caesarean section rather than difficult forceps delivery. Stretching the cervix beyond 10mm to terminate pregnancy may be a factor in cervical incompetence and every care is taken to avoid damage to the cervix during these procedures. Cone biopsy of the cervix (Q12.14) could theoretically damage the cervix but again care is taken to avoid the internal os and studies of the outcome of pregnancy following the modern loop cone procedures provide reassurance. 

The diagnosis of cervical incompetence is not easy. Painless abortion may occur when there was no apparent reason to predict that this would occur. Serial ultrasound assessment of the cervix looking for evidence of the internal os opening may be a reasonable approach. The treatment of cervical incompetence is a special stitch (cervical cerclage), which acts as a purse-string. No operation is without complication (surgery risks). Controlled studies (Q33.24) have not demonstrated that cervical cerclage is as beneficial as we originally believed. An interesting recently published concept is that the stitch may work by preventing bacteria ascending from the vagina into the uterus rather than as a mechanical barrier stopping the cervix from opening.

Can Infection Cause Recurrent Abortion?

Any acute infection in pregnancy can sometimes result in abortion.

Listeriosis is caused by the Listeria bacterium which has the unusual ability to grow over a wide range of temperatures. Some abortions have been associated with this infection which can be acquired from undercooked foods and soft cheeses. Appropriate care with food preparation is particularly important during pregnancy.

The 'TORCH' infections (Toxoplasmosis, Rubella, Cytomegalovirus and Herpes may be associated with abortion. Each of these infections, however, can occur on one occasion only as immunity is then acquired. It is, therefore, not possible for any one of these infections to be responsible for recurrent abortion. Toxoplasmosis is an infection acquired from the domestic cat. It has been shown that one woman in five in the UK has evidence of infection prior to pregnancy and this compares to 80% in France. The incidence of infection during pregnancy in the UK is low. Rubella is also known as German measles. Rubella infection can be prevented by immunisation. Cytomegalovirus can produce a flu-like illness. About 50% of women will have had this infection before pregnancy. Herpes infection is discussed in 3.

There has recently been increasing interest in the role of bacterial infection in relation to abortion and premature labour. Bacterial vaginosis (Q 22.7) has been implicated in some studies but not all. The difficult question that remains to be answered is whether the bacteria that may be found in association with some abortions are the cause of the problem or whether they are opportunistic and proliferate as a result of the abortion.

Can a Metabolic condition cause recurrent abortion?

There has been a suggestion that deficiencies of minerals such as zinc may be a cause of abortion but there are no controlled trials to demonstrate the efficacy of supplements.

Obesity has been shown to increase the risk of recurrent abortion but it is not known whether it is a direct effect or if PCOS underlies the obesity and recurrent abortion. Smoking increases the risk of abortion but it is not known how the body chemistry is affected. One study in Italy found that the risk of abortion is increased by 40% in smokers.

Can a hormonal problem cause recurrent abortion?

It is tempting to assume that administration of the pregnancy hormones HCG and progesterone would increase the chance of a successful outcome but there is no definite evidence to demonstrate that these treatments are effective. Some women have heard anecdotal stories of hormones being successful. Most IVF centres advocate hormone supplements in pregnancy and there is no evidence of any adverse effects. Gestone (progesterone) 100 mg injections, HCG 5000 units by injection, Crinone (progesterone) 4 or 8% on alternate days and Cyclogest pessaries 400mg each night until about 14 weeks are typical regimens.

An elevated FAI appears to be a prognostic factor for a subsequent abortion in women with recurrent abortion and is a more significant predictor of subsequent abortion than an advanced maternal age (> or =40 years) or a high number (> or =6) of previous abortions in this study.0801

PCOS (Q7.2) and high levels of LH are thought to be associated with abortion. It may be that metformin will prove to be effective, if there is evidence of such problems, but it will be some while before we have evidence.

Can an autoimmune problem cause recurrent abortion?

An autoimmune disease is an illness that occurs when the body tissues are attacked by its own immune system. The immune system is a complex organization within the body that is designed normally to "seek and destroy" invaders of the body, including infectious agents. Patients with autoimmune diseases frequently have unusual antibodies circulating in their blood that target their own body tissues. Examples of autoimmune diseases include:-

  • systemic lupus erythematosus,
  • Sjogren syndrome,
  • Hashimoto thyroiditis,
  • rheumatoid arthritis,
  • juvenile (type 1) diabetes,
  • polymyositis,
  • scleroderma,
  • Addison disease,
  • vitiligo,
  • pernicious anemia,
  • glomerulonephritis, and
  • pulmonary fibrosis.

There are two issues to consider in the context of a possible autoimmune causation of recurrent pregnancy loss the antiphospholipid antibodies and alloimune pregnancy loss.

Lupus anticoagulant and anticardiolipin are two antiphospholipid antibodies that have been associated with abortion. They increase the chance of the blood clotting (throbophilia - Q12-12) and this may damage the placenta . When they are present, and not treated, a live birth can only be expected in 25-50% of subsequent pregnancies. Scientifically controlled trials have demonstrated that low-dose aspirin in combination with heparin will increase the chance of a live birth in women with antiphospholipid antibodies. Many women have taken low dose aspirin in pregnancy apparently without problems. There is no evidence so far that low dose aspirin treatment will improve the outcome if there is no increased antiphospholipid antibodies although in one study involving IVF, low dose aspirin enhanced treatment outcome even in the absence of these antibodies.

In the era of blood transfusion and organ transplantation, we have all become aware of the importance of tissue typing and the problems of the immune response, which limits our choice of donors. In general, tissue typing is likely to show that a child could not donate an organ to its mother. In this context, it is remarkable that during pregnancy the baby is not rejected by the immune system even though the baby's blood comes into direct contact with maternal tissue in the placenta (afterbirth). The immune system is known to change in pregnancy and there must be some adaptation to allow the majority of pregnancies to continue. It has been suggested that some women who recurrently miscarry have a defect in this normal immune adaptation (alloimune pregnancy loss).

One method of treating women with recurrent abortion seeks to alter their immune response by immunising them with white blood cells obtained from their partners. It is still uncertain whether this treatment increases the live birth rate. One meta-analysis (Q33.23) suggests that there may be a 10% improvement. If it has a benefit it may be appropriate only for those who are deficient in the relevant antibody (APCA) and also those with a relatively high number of pregnancy losses.



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