219 Pregnancy-Related Disorders
Ectopic Pregnancy
An ectopic pregnancy is implantation and development of the embryo outside the uterus, typically in the fallopian tubes.
Learning Objectives
Identify the factors involved in ectopic pregnancies
Key Takeaways
Key Points
- An ectopic pregnancy, or eccysis, is a complication of pregnancy in which the embryo implants outside the uterine cavity. With rare exceptions, ectopic pregnancies are not viable. Furthermore, they are dangerous for the mother, since internal haemorrhage is a life threatening complication.
- Most ectopic pregnancies occur in the Fallopian tube (called tubal pregnancies), but implantation can also occur in the cervix, ovaries, and abdomen. An ectopic pregnancy is a potential medical emergency, and, if not treated properly, can lead to death.
- If left untreated, about half of ectopic pregnancies will resolve without treatment and are called tubal abortions.
- A heterotopic pregnancy occurs when there are two fertilized eggs, one outside the uterus and the other inside.
- The mortality rate from ectopic pregnancies in Western countries is very low (less than one percent), but in underdeveloped countries, especially in Africa, the maternal death rate is extremely high and are a major cause of death among women of childbearing age.
Key Terms
- heterotopic pregnancy: A heterotopic pregnancy is a rare complication of pregnancy in which both extra-uterine (ectopic pregnancy) and intrauterine gestation occur simultaneously.
- ectopic pregnancy: A pregnancy in which the fertilized ovum is implanted in any tissue other than the uterine wall.
An ectopic pregnancy, or eccysis, is a complication of pregnancy in which the embryo implants outside the uterine cavity. With rare exceptions, ectopic pregnancies are not viable. Furthermore, they are dangerous for the mother, since internal haemorrhage is a life threatening complication that may result. Most ectopic pregnancies occur in the Fallopian tube (so-called tubal pregnancies), but implantation can also occur in the cervix, ovaries, and abdomen. An ectopic pregnancy is a potential medical emergency, and, if not treated properly, can lead to death.
In a normal pregnancy, the fertilized egg enters the uterus and settles into the uterine lining where it has plenty of room to divide and grow. About 1% of pregnancies are in an ectopic location with implantation not occurring inside of the womb; of these pregnancies, 98% occur in the Fallopian tubes.
Detection
Detection of ectopic pregnancy in early gestation has been achieved mainly due to enhanced diagnostic capability. Despite all these notable successes in diagnostics and detection techniques ectopic pregnancy remains a source of serious maternal morbidity and mortality worldwide, especially in countries with poor prenatal care.
Treatment
Ectopic pregnancy: schematic view of ectopic pregnancy
In a typical ectopic pregnancy, the embryo adheres to the lining of the fallopian tube and burrows into the tubal lining. Most commonly, this invades vessels and will cause bleeding. This intratubal bleeding hematosalpinx expels the implantation out of the tubal end as a tubal abortion. Tubal abortion is a common type of miscarriage. There is no inflammation of the tube in ectopic pregnancy. The pain is caused by prostaglandins released at the implantation site, and by free blood in the peritoneal cavity, which is a local irritant. Sometimes the bleeding might be heavy enough to threaten the health or life of the woman. Usually, this degree of bleeding is due to delay in diagnosis, but sometimes, especially if the implantation is in the proximal tube (just before it enters the uterus), it may invade into the nearby Sampson artery, causing heavy bleeding earlier than usual.
If left untreated, about half of ectopic pregnancies will resolve without treatment. These are the tubal abortions. The advent of methotrexate treatment for ectopic pregnancy has reduced the need for surgery; however, surgical intervention is still required in cases where the Fallopian tube has ruptured or is in danger of doing so. This intervention may be laparoscopic or through a larger incision, known as a laparotomy.
While a fetus of ectopic pregnancy is typically not viable, very rarely, a live baby has been delivered from an abdominal pregnancy. In such a situation the placenta sits on the intraabdominal organs or the peritoneum and has found sufficient blood supply. This is generally bowel or mesentery, but other sites, such as the renal (kidney), liver or hepatic (liver) artery or even aorta have been described.
In rare cases of ectopic pregnancy, there may be two fertilized eggs, one outside the uterus and the other inside. This is called a heterotopic pregnancy. Often the intrauterine pregnancy is discovered later than the ectopic, mainly because of the painful emergency nature of ectopic pregnancies. Since ectopic pregnancies are normally discovered and removed very early in the pregnancy, an ultrasound may not find the additional pregnancy inside the uterus. When hCG levels continue to rise after the removal of the ectopic pregnancy, there is the chance that a pregnancy inside the uterus is still viable. This is normally discovered through an ultrasound.
Risk Factors
There are a number of risk factors for ectopic pregnancies. However, in as many as one third to one half of ectopic pregnancies, no risk factors can be identified. Risk factors include: pelvic inflammatory disease, infertility, use of an intrauterine device (IUD), previous exposure to DES, tubal surgery, intrauterine surgery (e.g., D&C), smoking, previous ectopic pregnancy, and tubal ligation.
Prognosis
The prognosis in Western countries is very good; maternal death is rare. For instance, in the UK, between 2003 and 2005 there were 32,100 ectopic pregnancies resulting in 10 maternal deaths (meaning that 1 in 3,210 women with an ectopic pregnancy died). In the developing world, however, especially in Africa, the death rate is very high, and ectopic pregnancies are a major cause of death among women of childbearing age.
Fertility following ectopic pregnancy depends upon several factors, the most important of which is a prior history of infertility. The treatment choice, whether surgical or nonsurgical, also plays a role. For example, the rate of intrauterine pregnancy may be higher following methotrexate compared to surgical treatment. Rate of fertility may be better following salpingostomy than salpingectomy.
Infertility
Infertility, in both males and females, refers to the inability to contribute to conception.
Learning Objectives
Evaluate the factors involved in infertility
Key Takeaways
Key Points
- Several clinical and epidemiological guidelines exist to determine infertility, often based on regular sexual intercourse in the absence of contraception without conception.
- Infertility can result from genetic factors or more general factors such as endocrine disorders ( diabetes, thyroid disorders, etc.) and environmental factors.
- In the U.S., up to 20% of infertile couples have unexplained infertility. In these cases abnormalities are likely to be present but not detected by current methods.
- Medical treatment of infertility generally involves the use of fertility medication, medical device, surgery, or intrauterine insemination. If these treatments fail to achieve a full term pregnancy, in vitro fertilization or other assisted reproductive techniques (ART) can be used.
Key Terms
- contraception: The use of a device or procedure to prevent conception as a result of sexual activity.
- infertility: The inability to conceive children.
- conception: The fertilization of an ovum by a sperm to form a zygote.
Infertility primarily refers to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term. There are many biological causes of infertility, some which may be bypassed with medical intervention.
Definitions of infertility differ, with demographers tending to define infertility as childlessness in a population of women of reproductive age, while the epidemiological definition is based on “trying for” or “time to” a pregnancy, generally in a population of women exposed to a probability of conception. Existing definitions of infertility lack uniformity, rendering comparisons in prevalence between countries or over time problematic, and therefore data estimating the prevalence of infertility cited by various sources differs significantly. A couple that has tried unsuccessfully to have a child after a certain period of time (often a short period, but definitions vary) is sometimes said to be subfertile, meaning less fertile than a typical couple. Both infertility and subfertility are defined as the inability to conceive after a certain period of time (the length of which vary), so often the two terms overlap. Couples with primary infertility have never been able to conceive, while, secondary infertility is difficulty conceiving after already having conceived (and either carried the pregnancy to term or had a miscarriage).
Causes
Factors that can cause male as well as female infertility are:
- Genetic factors
- Chromosomal defects
- Diabetes mellitus, thyroid disorders, adrenal disease
- Hypothalamic-pituitary factors
- Hyperprolactinemia
- Hypopituitarism
- Environmental factors
- Toxins such as glues, volatile organic solvents or silicones, physical agents, chemical dusts, and pesticides. Tobacco smokers are 60% more likely to be infertile than non-smokers.
For a woman to conceive, certain things have to happen: intercourse must take place around the time when an egg is released from her ovary; the systems that produce eggs and sperm have to be working at optimum levels; and her hormones must be balanced. Some women are infertile because their ovaries do not mature and release eggs. In this case synthetic FSH by injection or Clomid (Clomiphene citrate) via a pill can be given to stimulate follicles to mature in the ovaries. Other factors that can affect a woman’s chances of conceiving include being over- or underweight, or her age as female fertility declines sharply after the age of 35. Sometimes it can be a combination of factors, and sometimes a clear cause is never established.
The main cause of male infertility is low semen quality. Another possible cause is a low sperm count. In some cases, both the man and woman may be infertile or sub-fertile, and the couple’s infertility arises from the combination of these conditions. In other cases, the cause is suspected to be immunological or genetic; it may be that each partner is independently fertile but the couple cannot conceive together without assistance.
Unexplained Infertility
In the U.S., up to 20% of infertile couples have unexplained infertility. In these cases abnormalities are likely to be present but not detected by current methods. Possible problems could be that the egg is not released at the optimum time for fertilization, that it may not enter the fallopian tube, sperm may not be able to reach the egg, fertilization may fail to occur, transport of the zygote may be disturbed, or implantation fails. It is increasingly recognized that egg quality is of critical importance and women of advanced maternal age have eggs of reduced capacity for normal and successful fertilization. Also, polymorphisms in folate pathway genes could be one reason for fertility complications in some women with unexplained infertility.
Treatment
Medical treatment of infertility generally involves the use of fertility medication, medical device, surgery, or a combination of the following. If the sperm are of good quality and the mechanics of the woman’s reproductive structures are good (patent fallopian tubes, no adhesions or scarring), physicians may start by prescribing a course of ovarian stimulating medication. The physician may also suggest intrauterine insemination (IUI), in which the doctor introduces sperm into the uterus during ovulation, via a catheter. In these methods, fertilization occurs inside the body. If conservative medical treatments fail to achieve a full term pregnancy, the physician may suggest the patient undergo in vitro fertilization (IVF). IVF and related techniques are called assisted reproductive technology (ART) techniques.
ART techniques generally start with stimulating the ovaries to increase egg production. After stimulation, the physician surgically extracts one or more eggs from the ovary, and unites them with sperm in a laboratory setting, with the intent of producing one or more embryos. Fertilization takes place outside the body, and the fertilized egg is reinserted into the woman’s reproductive tract, in a procedure called embryo transfer.
Causes of Infertility: Numerous factors may contribute to infertility.
