Video Lecture (10 Minutes):
Audio Lecture:
Spontaneous abortion or miscarriage is the unplanned loss of a pregnancy prior to 20 weeks of gestation.
Spontaneous abortion is common, occurring in about 15% of all documented pregnancies. It’s likely more common than that, since many undocumented pregnancies occur and spontaneously abort very early, before the woman even recognizes that she’s pregnant. All she notices is a somewhat unusual menstrual period, occurring more or less at the proper time in her cycle.
The risk of a miscarriage is greatest during the first trimester, during which time 80% of the pregnancy losses occur. The risk of miscarriage decreases with advancing gestational age past the 1st trimester.
Spontaneous abortion is strongly associated with abnormal pregnancies. Half or more of these pregnancies have abnormal chromosomes. About 30% have some identifiable placental abnormality. Approximately 10% are associated with miscellaneous factors, including intrauterine bacterial or viral infections, significant exposure to teratogens, endocrinopathies, and catastrophic trauma, although non-catastrophic trauma is not associated with first trimester pregnancy loss. Some losses are unexplained.
Increasing maternal age is a significant risk factor for first trimester pregnancy loss. The lowest risk is between ages 20 and 30, with steadily rising loss rates of 40% by age 40 and 80% by age 45.
Some other maternal factors that increase the risk of miscarriage are cocaine use, cigarette smoking, and moderate to heavy alcohol intake. But for the most part, 1st trimester pregnancy losses are not predictable and not preventable.
Miscarriage is the layman’s term for spontaneous abortion, an unexpected 1st trimester pregnancy loss. Since the term “spontaneous abortion” may be misunderstood by laymen, the word “miscarriage” is sometimes substituted.
Abortions are further categorized according to their degree of completion. These categories include:
• Threatened
• Inevitable
• Incomplete
• Complete
• Septic
Threatened Abortion
A threatened abortion means the woman has experienced symptoms of bleeding or cramping.
About one-third of all pregnant women will experience these symptoms. Half will go on to abort spontaneously. The other half will see the bleeding and cramping disappear and the remainder of the pregnancy will be normal. Those women who go on to deliver their babies at full term can be reassured that the bleeding in the first trimester will have no effect on the baby and that you expect a full-term, normal, healthy baby.
Treatment of threatened abortion should be individualized. Many obstetricians recommend bedrest in some form for women with a threatened abortion. There is no scientific evidence that such treatment changes the outcome of the pregnancy in any way, although some women may feel better if they are at rest. Other obstetricians feel that being up and active is psychologically better for the patient and will not change the risk of later miscarriage.
Among these active women, strenuous physical activity is usually restricted, as is intercourse. Remember that most of the causes for miscarriage, if present, cannot be altered. If the chromosomes are abnormal, bedrest will not make the chromosomes normal.
Evaluation of a 1st trimester patient with cramping or bleeding usually consists of an examination and transvaginal ultrasound scan. The purpose of this evaluation is to differentiate a threatened abortion from the other, relatively common causes of 1st trimester bleeding and cramping, including:
• Complete abortion
• Incomplete abortion
• Septic abortion
• Ectopic pregnancy
• Gestational Trophoblastic Disease
• Other miscellaneous causes for bleeding, such as cervical or vaginal trauma, infection, and polyps
Complete Abortion
A complete abortion means that all tissue has been passed through the cervix.
This is the expected outcome for a pregnancy which was abnormal from the outset. Often, a fetus never forms. This is sometimes called a blighted ovum.
Complete abortions can present in a variety of ways, but one common presentation is with several days to weeks of intermittent vaginal bleeding and pelvic cramping. The bleeding and cramping steadily increases, leading up to an hour or two of fairly intense cramps. Then the pregnancy tissue is passed into the vagina and the cramping stops.
If you examine the patient at this point, you’ll see the active bleeding has slowed or stopped, there is no tissue visible in the cervix, and the passed tissue appears complete. Save any tissue for pathologic exam, and if desired by the patient, chromosome studies.
RH negative women should receive an injection of Rhogam (hyperimmune Rh globulin) within 3 days of the abortion, although It may still be effective in preventing Rh sensitization if given within 7-10 days.
It may be difficult to determine clinically whether all the pregnancy tissue has been expelled or not in this situation. I rely on the presence or absence of significant continuing bleeding, and a post abortion transvaginal ultrasound scan to guide me. If there appears to be retained products of conception, I’ll intervene. If the endometrial cavity appears empty or virtually empty and there is not significant bleeding, I usually do not intervene.
There are two forms of intervention, surgical and medical. A D&C or dilatation and curettage can remove most of the retained products of conception, but requires anesthesia and minor surgery. Medically, uterotonic agents such as methergine or misoprostol can be effective in helping squeeze out much of the remaining pregnancy tissue. Each approach has pluses and minuses, but they are different pluses and minuses, so you need to individualize your treatment plan.
Women who have just sustained a complete abortion are encouraged to have a restful day or two and a follow-up examination in a week or two. Bleeding similar to a menstrual flow will continue for a few days following the miscarriage and then gradually stop completely. A few women will continue to spot until the next menstrual flow (2-6 weeks later). A pregnancy test is not helpful in these situations, as clinically significant levels of HCG will remain in the mother’s bloodstream for weeks following a complete abortion. The mean time to HCG washout is about 30 days.
Women seeking another pregnancy as soon as possible are often advised to wait a month or two to allow them to re-establish a normal uterine lining and to replenish their reserves. Prolonged waiting before trying again is not necessary.
If fever is present, then this may not be a simple complete abortion, but an infected, septic abortion, which I’ll discuss in a minute.
If continuing bleeding is present, this suggests an “incomplete abortion” rather than a “complete abortion” and your treatment should be reconsidered.
Incomplete Abortion
With an incomplete abortion, some tissue remains behind inside the uterus. That definition is simple enough to state, but there are some complexities to consider. Even following clinically “complete” abortions, there is usually some tiny fragments of placental tissue left inside the uterus. This tissue deteriorates over time and is sloughed out, usually unnoticed, mixed with the small amount of bleeding that we typically see for a few days following the abortion. Even if a D&C is used to complete an abortion, there will still be a few fragments of pregnancy tissue left behind. So a complete abortion doesn’t literally mean that all pregnancy tissue is gone, just that the vast bulk of it has been passed.
These patients typically present with continuing bleeding, sometimes very heavy, and sporadic passing of small pieces of pregnancy tissue. The uterus is usually still soft and enlarged.
Ultrasound may reveal the presence of identifiable tissue within the uterus. Serial quantitative HCG levels can be measured if there is doubt about the completeness of a miscarriage.
Left alone, many of these cases of incomplete abortion will eventually resolve spontaneously, but so long as there are large, non-viable pieces of tissue inside the uterus, the risks of bleeding and infection will continue.
Treatment consists of converting an incomplete abortion into a complete abortion. This can be done surgically with a D&C (dilatation and curettage). This can also be done medically with uterotonic agents such as misoprostol or methergine.
If fever is present and the uterus is markedly tender, then infection may be complicating the abortion and antibiotics are usually employed.
Any tissue fragments visibly protruding from the cervical os can be grasped with a ring or dressing forceps and gently pulled straight out. This simple and safe procedure will have a beneficial effect on the bleeding.
Inevitable Abortion
Inevitable abortion means that a miscarriage is destined to occur, but no tissue has yet been passed. This is sometimes called a “missed abortion.”
This diagnosis is best made by ultrasonic visualization of the fetal heart and noting no movement. Alternatively, demonstrating no growth of the fetus over a one week period in early pregnancy confirms an inevitable abortion. A single measurement showing disparities in size between the gestational sac, yolk sac and fetal pole are suggestive but probably not diagnostic of a missed abortion. Falling levels of HCG are an ominous sign and strongly suggest the pregnancy is no longer living.
Three alternative approaches can be considered for treating an inevitable abortion: D&C, awaiting a spontaneous abortion, or inducing an abortion with medications. Each approach has its own merits and limitations:
• Performing a D&C has the advantage of quickly resolving the issue of a missed abortion, but commits the patient to a surgical procedure associated with some risks. For some patients, this will be the preferred approach, particularly those with other significant commitments. Many of my patients with small children will prefer this approach because it can be scheduled at a time convenient for child-care arrangements.
• Awaiting a spontaneous abortion offers the benefit of avoiding surgery, but commits the patient to a day or more of heavy bleeding and cramping. A few of these women will experience an incomplete abortion and will need to have a D&C anyway.
• Inducing the abortion with medication has most of the same constraints as awaiting spontaneous abortion, but moves up the time frame, to enable the patient to more quickly move past the pregnancy loss.
Septic Abortion
During the course of any abortion, spontaneous or induced, infection may set in.
Such infections are characterized by fever, chills, uterine tenderness and occasionally, peritonitis. The responsible bacteria are usually a mixed group of Strep, coliforms and anaerobic organisms. These patients display a spectrum of illness, ranging from mild, to very severe.
Usual treatment consists of bedrest, IV antibiotics, uterotonic agents, and complete evacuation of the uterus. If the patient does not respond to these measures and is deteriorating, surgical removal of the uterus, tubes and ovaries may be life-saving.
