By Nicole Angemi
Getting pregnant is usually the most exciting time in a woman’s life. Having a child and being pregnant right now myself, I know all the emotions associated with the excitement of having a new baby. Most mothers become instantly attached to their new baby the moment they find out they are pregnant. Unfortunately many pregnancies will end up in miscarriage.
A miscarriage is the spontaneous loss of a pregnancy before the 20th week of pregnancy. Pregnancy losses after the 20th week are called preterm deliveries.It is estimated that up to half of all fertilized eggs die and are lost (aborted) spontaneously, usually before the woman knows she is pregnant. Among those women who know they are pregnant, the miscarriage rate is about 15-20%. Most miscarriages occur in the first trimester and the risk decreases the further along the pregnancy is.
The medical term for a miscarriage is abortion. The word abortion simply means a loss of a pregnancy. Abortion can occur in 2 ways, spontaneously and medically/surgically. A spontaneous abortion is one that occurs naturally and is what is commonly called a “miscarriage”. Spontaneous abortions can also be induced with medications such as the “abortion pill” for unwanted pregnancies. Under the category of spontaneous abortion falls a complete abortion, an incomplete abortion, a missed abortion, a blighted ovum, an ectopic pregnancy, and a molar pregnancy. A medical/ surgical abortion is done for 2 reasons: elective and therapeutic purposes. Elective abortions are surgically performed for unwanted pregnancies. Therapeutic abortions are performed for multiple reasons including problems with the pregnancy itself, the fetus and/or the mother.
To understand what to look for in these miscarriages upon arrival to the surgical pathology lab, you must understand the components of a normal pregnancy in the uterus. In the uterus is the embryo or fetus itself, an amniotic sac and some form of mature or immature placental tissue. A thin layer of membranous tissue is also present between the placental tissue and uterine lining called the decidua. Immature placental tissue or chorionic villi and/ or fetal components must be present in the specimen to prove an intrauterine pregnancy. Decidual tissue alone does not prove an intrauterine pregnancy. This tissue can still grow in the uterus even if the fetus is growing in an ectopic location such as the fallopian tube.
Complete/ Incomplete abortion
A completed abortion is when the embryo/fetus and/or products of conception have emptied out of the uterus. A completed miscarriage can be confirmed by an ultrasound. If the patient expels the products at home and saves it, or expels at the hospital, the products will be examined in pathology and decidual tissue, chorionic villi or placenta and/ or embryonic sac will be identified. This may be mixed with blood or mucous material. An incomplete abortion is incomplete expulsion of all products of conception.
This is the most common type of complete abortion we see in the lab. 1st trimester, so the embryo/fetus is small, sometimes too small to see. The photo below shows an intact fetal sac around 7 weeks gestation.
Here is another example of a first trimester complete spontaneous abortion. To the left of the photo is the decidual tissue, the center shows a fetus around 9 weeks gestation and to the right is the spongy chorionic villi tissue. Most spontaneous abortions happen within the first couple of weeks of pregnancy 5-8 weeks. Most products of conception specimens we receive to the lab just contain decidual tissue, chorionic villi and blood. It is not as common to find an embryo/fetus.
This is one type of example of a 2nd trimester complete spontaneous abortion. Before the second trimester, the fetus is usually difficult to identify. Here the fetal sac is intact. The placental tissue is the shaggy tissue surrounding the sac.
Opening the sac reveals a well formed, intact fetus, complete with attached umbilical cord. This fetus is grey and not the normal pink color. This is what we called macerated. This indicates this fetus died several days/weeks before it was spontaneously aborted.
Missed abortion
Women can experience this type of miscarriage without knowing it. A missed abortion is when embryonic death has occurred but there is not any expulsion of the embryo and/or products of conception. It is not known why this occurs. Signs of this would be a loss of pregnancy symptoms such as nausea and tender breasts and the absence of fetal heart tones found on an ultrasound.
Blighted ovum
Also called an anembryonic pregnancy. Basically no baby. A fertilized egg implants into the uterine wall, but fetal development never begins. Often there is a gestational sac with or without a yolk sac, but there is an absence of fetal growth.
Ectopic pregnancy
Extrauterine pregnancy, located outside the uterus, usually the fallopian tube. To read my post about ectopic pregnancies click here: http://iheartautopsy.com/?p=2042
Molar pregnancies
A hydatidiform mole or molar pregnancy is caused by a genetic error during the fertilization process that leads to growth of abnormal tissue within the uterus. This can happen if an egg with no genetic information is fertilized or if an egg is fertilized with 2 sperm. Molar pregnancies rarely involve a developing embryo, but often entail the most common symptoms of pregnancy including a missed period, positive pregnancy test and severe nausea. One clue to key off the physician that a patient has a molar pregnancy is rising hCG levels. hCG is the hormone that is present in all woman when they become pregnant. If the levels rise too fast it may be an indication of a problem.
This is what a molar pregnancy looks like grossly. The chorionic villi are hydropic or show cystic dilations. This specimen is said to look like a cluster of small grapes. These specimens can include fetal parts which would be considered a partial mole and the absence of fetal parts can indicate a complete mole.
Most molar pregnancies result in spontaneous abortion. If it is found by the physician, he may have to perform a D&C to remove the abnormal tissue. hCG levels are followed after the pregnancy has ended to ensure all of the abnormal tissue is removed. There is a small risk in the case of a complete mole that the tissue can become invasive and cancerous. This type of cancer is super rare and is called choriocarcinoma.It is important to avoid pregnancy and to use a reliable contraceptive for 6 – 12 months after treatment for a molar pregnancy. This allows for accurate testing to be sure that the abnormal tissue does not return. Women who get pregnant too soon after a molar pregnancy have a greater risk of having another one.
Risk factors
Most miscarriages are caused by chromosome problems that make it impossible for the baby to develop. Usually, these problems are unrelated to the mother or father’s genes. Other risk factors for miscarriage include drug and alcohol abuse, exposure to environmental toxins, hormone problems, infections obesity, problems with the mothers body including the uterus or immune response, systemic diseases such as diabetes, and smoking. The risk for miscarriage is higher in woman who are older,with increases beginning by 30, becoming greater between 35 and 40, and highest after 40 and woman with a previous history of miscarriage.
Treatment
The main goal of treatment during or after a miscarriage is to prevent hemorrhaging and/or infection. The earlier in the pregnancy, the more likely all the products of conception will expel by itself and will not require further medical procedures. If the body does not expel all the tissue, the most common procedure performed to stop bleeding and prevent infection is a dilation and curettage, known as D&C. A D&C is a procedure when the doctor dilates the cervix and places a tool in the uterus to scoop out the rest of the products of conception. The remainder of the products of conception will be sent to pathology to confirm an intrauterine pregnancy. The procedure is short and the recovery time is short.
All products of conception are sent to pathology when the products are available. All products get a microscopic evaluation, mainly to look for chorionic villi and confirm an intrauterine pregnancy. A molar pregnancy is also always ruled out. In some cases a portion of the specimen will be sent to cytogenetics for genetic testing. Unfortunately most of the time genetic testing is normal.
