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Fruit of the Womb
Fruit of the Womb

Molar Pregnancy vs. Hydropic Degeneration

As detailed in the reader's comment below, she had an early pregnancy loss and her doctors were concerned that she had a molar pregnancy. Sometimes it is very difficult to differentiate by ultrasound a true molar pregnancy from simple 'hydropic degeneration' of a pregnancy that did not get beyond the early stages of embryonic development. However, as I point out in my response, because of the risks of choriocarcinoma it is very important that the diagnosis under these circumstances is ascertained by histopathologic assessment of the products of conception. Many women who miscarry early in pregnancy may be placed in a similar situation, so I thought the reader's story and my response will be of general interest. I have taken the liberty of editing the reader's original comment.

• At Wed Dec 05, 08:20:00 AM 2007, Daisy said…

On Nov 5th, I suffered a missed miscarriage at 11wks 5days which required an emergency D&C due to a suspected molar pregnancy. This is my 1st pregnancy. I am 36years old, have regular 28 day cycles, periods that last 4 days with medium flow, and nothing significant to note other than 5 sisters - all very very fertile.

Besides the obvious shock at facing what I was told at the early pregnancy clinic, I now want to ensure I understand what the histology report says. The histology report results presented "no atypical features", but there are things I do not understand.

The clinical details: "Missed abortion @ 10/40. No foetal pole on ultrasound scan. ??Hydropic changes seen on scan."

The macroscopic report reads: "a bulky amount of haemorrhagic products, 70x40x20mm's. No membranes seen. No foetal tissue seen."

The Microscopic report reads: Chorionic villi, inflamed and degenerate decidua, blood and fibrin, in keeping with retained products of conception. No atypical features seen"

Can you tell me in plain english what this means? We desperately want to have a baby and I'm concerned about maximising my success rates given the gynaecological challenges I could face at my age.
Thank you for any help.

At Thu Dec 13, 02:31:00 PM 2007, Kenneth F. Trofatter, Jr., MD, PhD said…

Hi Daisy, sorry for your loss. From what you describe, you had a 'blighted pregnancy' that did not get past the very early stages of embryonic development, although the placental tissues continued to grow for awhile (which is not all unusual) and make pregnancy hormone (hCG) so that your body did not know the baby did not make it.

It is very unlikely that you actually had a 'molar pregnancy', although that is what your doctors were concerned about based on the ultrasound findings prior to your D&C. Hydropic degeneration (enlarged, fluid-filled, balloon-like) of the placental villi is characteristic of molar pregnancies, but also of pregnancies undergoing spontaneous abortion if it has been awhile from the time the baby was lost to the time of miscarriage or if the baby is chromosomally abnormal. First pregnancies have a high rate of miscarriage for reasons I have detailed in my posts, but at your age, there is also a greater chance that the baby had a chromosomal abnormality. These are not uncommon and most babies with aneuploidy are lost in the first trimester.

Your pathology report is not unusual under these circumstances - you had blood clot and the placental tissues were inflamed. The latter does NOT mean you lost this pregnancy as the result of an infection. It simply means that your immune system was reacting to the pregnancy tissues - that might be a good sign and increase your chance for success with a subsequent pregnancy.

True molar pregnancies occur in about 1 in 1000 to 1 in 1500 pregnancies. They are more common in very young women under the age of 15 and in women over the age of 40. Complete molar pregnancies usually result from a sperm fertilizing an egg in which the maternal chromosomes are either inactivated or lost. Occasionally, this results from two sperm fertizing the egg simultaneously. In most cases the maternal chromosomes do remain so the pregnancy tissues end up with three sets of chromosomes (a total of 69 chromosomes rather than the normal 46). No baby or fetal membranes develop in these situations, just the placental tissues. The placental villi may grow at a very fast rate and eventually become 'hydropic.' The uterus is usually enlarged for the gestational age expected for the pregnancy and the ultrasound appearance of the abnormal placental tissues is that of multiple small cysts, giving the classic 'grape-like appearance' of a molar pregnancy. Partial molar pregnancies in which there is an embryo, but also molar changes in the placental tissues can also occur, but these are less common.

Molar pregnancies can be accompanied by heavy bleeeding, very high levels of the pregnancy hormone (hCG), severe nausea and vomiting, hypertension (preeeclampsia-like, but prior to 20 weeks), abdominal pain/cramping and occaionally very large multicystic ovaries (theca lutein cysts) resulting from stimulation by the high levels of hCG. Women can have signs and symptoms of hyperthyroidism as well.

The primary concern of your doctors related to the possibility of a molar pregnancy is that as many as 20% can turn into choriocarcinoma (whereas simple hydropic degneration of placental tissues in a blighted pregnancy does not). Choriocarcinoma can be a very serious and rapidly progressing cancer, but today, almost all cases are entirely treatable if caught early enough. If a molar pregnancy is confirmed on the pregnancy tissues, we usually recommend serial measurements of hCG for at least six months (and in some cases a year) and also recommend that you do not get pregnant over that same time period. That will confuse the opportunity to make the diagnosis of choriocarcinoma and could delay early therapy. Women who have had a molar pregnancy are at increased risk (about 1%) for that to happen again.

Anyway, Daisy, I know you are sad over the loss of your pregnancy, but it appears you did not have a molar pregnancy - and that is good news. Once you have had a chance to recover, it should be safe to try again in a short period of time. Because of youir age, and this recent loss, I would recommend that when you do get to the latter part of the first trimester, you have 'combined first trimester risk assessment for aneuploidy' because you are at greater risk for having a baby with a chromosomal abnormality - but remember the odds are still in your favor that you will not!

Hope this helped. Thanks for reading and good luck to you!

Dr T
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