Since first it was my fate to know thee

Just a quick update to highlight a case report I find particularly important when considering the origin of endometriosis. This case report from the US is of a pregnant woman who, after a scan at 35 weeks, was told that her unborn child had a large abdominal mass measuring roughly 6.5 x 4.8cm, a mass which there was no sign of at the 20 week scan. A further scan at 37 weeks revealed that the mass, which had all the hallmarks of a large cyst, had grown to 7.8 x 6.8cm. No doubt fearing for the health of both mother and unborn child, the decision was made to induce the pregnancy at 38 weeks. After delivery the infant was operated on, the cyst removed and was otherwise perfectly healthy.

Analysis of the cyst revealed the tell-tale signs of an ovarian endometriotic cyst i.e. a thin walled cyst filled with reddish-brown fluid, which the pathologist later confirmed. Ovarian cysts in unborn females foetuses are not unheard of, but are extremely rare and endometriotic cysts even rarer, in fact this is the first case I’ve seen reported.

I have though, seen reports on microscopic endometriosis being found unborn female foetuses and talked about them here. However, these findings usually describe very small areas of endometriosis, hardly what you could call ‘mature’ disease. This most recent case is particularly unusual then as it represents what’s is termed ‘advanced’ stage endometriosis (although in reality there is some contention as to whether endometriosis is a progressive disease and therefore whether words like ‘early’ and ‘advanced’ stage endometriosis are even relevant). Certainly this case casts doubt on the assumed notion that endometriosis progresses to further stages as you get older.

Furthermore, this raises more questions about the origin of endometriosis. The accumulating evidence suggests that endometriosis is a dormant developmental disorder; something with which you are born that becomes active around the time of puberty. How, when and why the symptoms associated with endo come into being is another matter altogether. How endometriosis arises during development is another big question. Displacement of stem cells? Abnormal growth of portions of the reproductive organs? Early menstrual influences before birth? Yes, you read that last part right. The uterus of new-born females is capable of undergoing something akin to menstrual changes and menstruation. Of the very few studies that have looked into this, the general finding was that visible bleeding was observed in around 5% of new-born females, caused by exposure to, and withdrawal from, the mothers hormones. This may lead to a sort of prenatal retrograde menstruation of endometrial cells, planting the seeds of endometriosis in the pelvis before birth. Of course, there are still many stumbling blocks to overcome before any theory on the origin of endometriosis is widely accepted, some of which I’ve touched upon previously. 

Title from Thomas Hardy’s poem ‘How Great my Grief’