Talk to me about low-lying placentas...

[BraveLilBear]

So yesterday, had 20-week scan and all looks to be really good with baby which is fab news.

But it seems I have a low and anterior placenta - low enough to need a dildocam additional scan yesterday (thank god I knew these occasionally happened and had had a long shower that morning ahem) which revealed it's 8mm from cervix.

Sonographer wasn't very bothered by this (I know now it could have been much worse ie covering cervix) and said they move up and away as uterus grows in 90% of cases, so it'll probably be fine.

But... how do they know it's fine later on? Will I need another scan? Thought it was odd not to mention that, but then realised that there can't be any other way of knowing.

So - have you had this? How was it for you? Is 8mm away at 20 weeks far enough away to not need additional scans? Am having a bit of a worry wobble...

TIA

Hi, yes, you will most likely need another scan - usually around 36 weeks. Mine had moved by then so I am not sure what happens in the event of it not having moved! They don't usually give much info out at the ultrasounds (ime!) so your midwife will discuss it with you at your next appointment I imagine.

I had a second scan at 32 weeks. Ask your mw what they will do.

You need a gap of 20mm to be ok for vaginal delivery. Ish, measuring is a bit tricky, obv.

The fact that it isn't overlapping the os now is very good news. Something like an 80% chance of it being far enough away by 38 weeks I think.

Think of your uterus as a balloon. While it was deflated you put a pen mark right next to the opening of the balloon. Then you start to inflate. At 20wks, only the top part of the balloon is inflated - the bit by the neck hasn't stretched very much yet, so the pen mark is still very near the opening. In the last trimester, the bottom part of the balloon starts to stretch. That little pen dot could end up a long way from the opening. The further in the pen dot is at the beginning, the more it will 'move'.

Sometimes the stretching causes a tiny bit of the placenta to break away. Think of the placenta as a jelly fish, with hundreds of little tentacles hanging down to attach it to the womb. As the womb stretches, some of those can detach, and you get a bit of bleeding.

Any sign of blood, phone the midwife. If she doesn't take you seriously, hotfoot it to hospital and demand a scan.

I had this with ds1. Rescanned at 35 weeks and it had moved. Completely wasted my time worrying about it.

Hi, LilBear. I'm a midwife and preggers and when we had our 20 week scan the sonographer told me something that I didn't know: If your placenta is anterior and low, it will always move away from the cervix, so much so that in my area, they no longer do a second scan to check. If it is posterior and low, then its a bit more likely that it may not move. This is because the anterior (front) side of the uterus grows and stretches WAY more than the posterior side (which has the fallopian tubes coming off it etc).

So its worth checking, you may be offered a follow up scan at 36/40 but if your trust is the same as mine, then although it was found to be low, as long as it is anterior, you have nothing to worry about and it will be alot further away than 8mm by the time you deliver.

HTH and good luck for the rest of your pregnancy!

Hi all - thanks for the insight! Love the analogies bertha and the extra special insight merrygiant - thinking about it it does make sense, but I somehow figured that low and anterior would be 'worse' than low and posterior.

I have been very lucky so far and haven't had any bleeding at all - sonographer actually asked and seemed surprised at that (before revealing that it was low), but then she was also surprised that I've been feeling movements for best part of 4 weeks already (again, not revealing that it was anterior) - so maybe she was in an easily surprisable place!

I will ask midwife about it when I next have an appointment - but as it won't be for 8 weeks (they don't have enough funds for total mw care in my area so GPs fill in the gaps) thought I'd ask in the meantime.

Much less worried now already - hope everyone's pregnancies continue well!