An FAQ Question re "Pregnancy" after UAE

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Q: I have a fibroid uterus which I would prefer having treated by UAE. Are there any problems that UAE is known to cause in future pregnancies? How long after the procedure should I wait before attempting pregnancy?

The Source of Information about Pregnancy following UAE (12/31/99)

Most of the data about the successes of UAE has been developed by following women who were not planning pregnancy. Most embolizations done on women who subsequently became pregnant and had normal deliveries, were done as emergencies to control bleeding - not for the treatment of infertility resulting from fibroids. An example of such an emergency would be severe hemorrhage after delivery.

Unfortunately, the whole issue of whether or not UAE potentially compromises the next pregnancy - is unresolved. There are about 21 cases of pregnancy reported following Uterine Artery Embolization. In all fairness, only one of the pregnancies was unsuccessful, and this loss occurred for reasons unrelated to UAE.

As to the actual pregnancies, it is our understanding that (1) All were spontaneous conceptions, (2) None were post-IVF, and (3) They were not primarily Infertility Patients. (However, the observation has been made that there was a very high incidence of Twinning in these patients. As we cannot see a connection between UAE and multiple ovulations, we must wonder whether fertility drugs were involved in at least some of the cases??)

It is wonderful that there have been no observed pregnancy complications related to UAE. Yet with only 21 cases thus far, this is not enough of an experience to prove without doubt that prior UAE is without an adverse effect on pregnancy. The main reason for this dearth of information is because no one is focusing on the pregnancy-post-UAE question, as the safety data is not worked out.

At the same time, there is little doubt that there are pregnancies currently out there in post-UAE patients. We suspect that there will be data before too long reporting outcomes of pregnancies which patients began voluntarily with full knowledge of the uncertainties. Hence there is the possibility that even now world-wide, the actual number of pregnancies post-UAE may well exceed 21?

Yet until such time the questions can be answered with experience, the jury is still out on whether UAE is an appropriate treatment if pregnancy is anticipated.

Do the Embolizing Particles injure normal uterine wall muscles?

The most useful piece of information about wall damage comes from a 1998 European study done on a hysterectomy specimen taken within the week following UAE. Though all fibroids showed marked tissue damage (the expected effect of embolization), the uterine muscles - even those immediately adjacent to the fibroid - showed no signs of injury. No embolizing particles were seen in the smaller uterine wall vessels, whereas they were easily seen within fibroid tissue. This is especially significant as our European counterparts tend to use smaller PVC particles (often 300 microns), making it more likely they would have entered smaller vessels, but did not. The limiting factor in drawing conclusions from this study is obvious - it is an analysis of but one case.

Obstetrical Concerns?

One of the things Obstetricians question about UAE is a concern about damage to the uterine wall. For if the blood supply to the wall was hurt in some way, the placenta could conceivably get less blood supply than usual. This is turn might decrease birth weight or even cause pre-term labor. Despite these concerns, these side-effects have not yet been found in the pregnancies followed thus far.

Theoretically it would seem . . .

That UAE causes no significant changes in the normal myometrium partly because few particles enter the smaller vessel system, and partly because there is adequate collateral supply (from the ovarian supply) to give additional protection.

That the interlacing musculature of the uterus remains intact and is not weakened as the fibroid (which developed within the wall and pushed normal myometrium aside) decreased in size post UAE. Pregnancy itself could (?) be a model of expanding uterine musculature with its subsequent recovery to normal size, configuration and strength. (Only in the patient with parity exceeding 5 does the concern about a weakened uterine wall - without prior C-Section - become an issue to Obstetricians.)

That in contrast, myomectomy does interrupt the strong interlacing fibers by replacing the incision site with scar tissue. It is well known that this can put the wall at risk for rupture during labor or even ante-partum. Hence UAE might seem even safer than myomectomy??

Given all of these facts - it would appear that one could make a good case that nothing is liable to happen to the wall during embolization. And, yes, the theory appears sound. However, as more and more cases go on to pregnancy we will soon learn if there is any subtle unknown that will become apparent. The hope is obvious, i.e., that the original theory will be valid and no impediment will be introduced by the procedure to compromise future pregnancies.

Because of the above, it then would appear that there is no information about timing of conception following UAE!

For the most part this is correct. We must still approach UAE in women planning pregnancy with caution. It is so important that the patient understands clearly the unknowns in this situation, and realize that science cannot at this time give guarantees.

The best that can be offered - and this is only a theoretical suggestion - is to let healing be completed before attempting pregnancy. A rough estimation of this time frame - for patients who strongly wish to begin conception - is to wait 3-6 months.

At the 2nd International Conference on UAE (1999) it was interesting to hear Dr. Ravina (the originator of the procedure with undoubtedly the longest followup experience in the world) speak on this question. When asked what sort of a delay was appropriate after UAE to attempt pregnancy, his answer was "As soon as the patient cares to begin." Hence, as one might expect, there is no universally accepted plan.

Is anything known about the success of conception after UAE?

If the fibroid was definitely the cause of the infertility, there is the possibility that good things will happen. But the multiplicity of factors which interfere with conception are still being worked out, and they far exceed just the issue of Fibroids. Thus - without some marker unequivocally identifying the cause of the problem - it is impossible to accurately predict outcome. There is much we have yet to learn about conception issues, and in areas well beyond fibroids.