Hydatidiform mole: Description, Causes and Risk Factors:
A vesicular or polycystic mass resulting from the proliferation of the trophoblast (the mesectodermal cell layer covering the blastocyst that erodes the uterine mucosa and through which the embryo receives nourishment from the mother; the cells do not enter into the formation of the embryo itself, but contribute to the formation of the placenta. The trophoblast develops processes that later receive a core of vascular mesoderm and are then known as the chorionic villi; the trophoblast soon becomes two-layered, differentiating into the syncytiotrophoblast, an outer layer consisting of a multinucleated protoplasmic mass (syncytium), and the cytotrophoblast, the inner layer next to the mesoderm in which the cells retain their membranes), with hydropic degeneration and avascularity of the chorionic villi; the abnormal tissue typically results from expression of paternally derived chromosomes and a loss of maternal chromosomes.
A hydatidiform mole is a growing mass of tissue inside your uterus (womb) that will not develop into a baby. It is the result of abnormal conception.
Chromosomes are found in the nucleus (the centre) of the cells in your body. They carry genetic information in the form of genes. Most of the cells in your body contain 46 chromosomes arranged in 23 pairs. One chromosome from each pair is inherited from your mother and the other is inherited from your father. These 46 chromosomes make up your genetic code. This code determines what you look like, how your body functions, whether you are male or female and sometimes even whether you will get certain diseases.
However, the reproductive cells (eggs, or ova, in women and sperm in men) only have 23 chromosomes. This is so that, when a sperm fertilises an egg during normal conception, the child that is produced has 46 chromosomes in each cell, 23 from their mother and 23 from their father. The fertilised egg, or ovum, has a complete set of genetic material.
After fertilisation, some cells from the fertilised ovum (called the trophoblast cells) develop into the placenta and membranes that form around the developing baby and some cells develop into the embryo from which the baby grows. As the placenta develops, the trophoblast cells grow into and attach to the lining of the uterus (womb), allowing the pregnancy to implant in the uterus.
A hydatidiform mole is a growing mass of tissue inside the uterus that will not develop into a baby. It is the result of abnormal conception. Sometimes, during conception, a sperm fertilises an 'empty' ovum (an ovum not carrying any chromosomes or genetic material). Under normal circumstances, the fertilised empty ovum would die and not implant in the uterus. But rarely, the ovum doesn't die and implantation takes place. The trophoblast cells grow and develop as a disorganised mass of tissue but the embryo does not develop. This is a complete hydatidiform mole. There is no tissue resembling a fetus (an unborn baby) at all.
A hydatidiform mole may be either complete or partial.
Complete Mole: This condition results when the sperm fuses with an egg that does not carry any genetic material. These complete moles are derived entirely from the cells of the father. When this fertilised egg grows, no embryo is present in the pregnancy sac, only the placenta.
Partial Mole: These are much more common and usually mimic the appearance of an incomplete miscarriage. In this condition the egg allows two sperms to fertilise it. The embryo has 3 sets of chromosomes instead of the usual two so the baby would be abnormal and could never survive. Very rarely a partial mole develops into an invasive mole, but seldom develops into a cancer.
Hydatidiform mole is rare in the UK. There is about 1 molar pregnancy for every 714 live births. This works out to be less than 1,000 hydatidiform moles diagnosed per year in the UK.
Any woman of childbearing age can develop a molar pregnancy but women who are aged under 16 and over 40 have a higher risk. For some reason, women of Asian backgrounds are also more likely to have a molar pregnancy.
Symptoms usually occur in first 20 - 24 weeks of gestation.
- Toxemia (25%).
- Hyperemesis (25%).
- Absent fetus, LGA, SGA.
- Hyperthyroidism (7%).
- Passage of tissue with vesicles.
- Bilateral thecalutein cysts (30%).
If you do not have bleeding or other symptoms, the diagnosis of hydatidiform mole is usually suspected when you have a routine pregnancy ultrasound scan. The further through the pregnancy you are, the more characteristic the ultrasound picture of a molar pregnancy becomes.
The ultrasound diagnosis of a complete mole is often reliable. Thediagnosis of a partial molar pregnancy is more complex. Thefinding of multiple cystic spaces in the placenta is suggestive of apartial molar pregnancy. When there is diagnostic doubt about the possibility of acombined molar pregnancy with a viable fetus then ultrasoundexamination should be repeated before intervention.
You will be admitted to hospital to have a D&C (Dilatation and Curettage) - a scrape of the womb under general anesthetic.
If your admission is planned for the Day Surgery Unit you will be discharged the same day. However, an overnight stay is sometimes necessary.
Blood levels of the pregnancy hormone hCG (human chorionic gonadotropin) are measured weekly following a molar pregnancy. The normal level of the pregnancy hormone hCG in the blood is less than 5 IU/l. Once the blood tests are normal, only urine samples will be needed. Remember that urine samples should always be the first urine of the day.
There is a small risk that you can develop GTN after a hydatidiform mole. There is a risk that this can spread (metastasise) to other parts of your body including your lung, liver or brain. Therefore, you need close follow-up after a hydatidiform mole to monitor for this.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.