# Abbrev help - Posterior Placenta



## sar35

On my 20week scan report it says "Leading edge of placenta covering os" what does os mean?
Im booked for another scan at 34weeks but just wondering if this is something to worry about, the sonographer said it should move up, would this cause an obstruction for baby to come out naturally?
Do you think its a common thing that sorts itself out
Thanks x


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## mamaofthree

os means the internal pubic bone (os pubis) and if placenta is partially covering this and it doesnt lift it can cause bleeding, and problems in delivery...however...the vast majority will lift as your uterus grows. I had an anterior placenta adjacent to os last time and delivered at fullterm naturally. They may want to give you an extra scan at around 34weeks just to make sure ur placenta is behaving!!!! This is what they did with me, and all was fine, so try not to worry hun. x x x


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## KandyKinz

Os actually refers to the opening of the cervix in this context. So the concern here is placenta previa. If the placenta remains over the cervical os (the opening into your vaginal canal) at term then the baby would not be able to exit without causing hemorrhaging.... not a good thing so c-section is required. 

However, it is actually quite common to have a low lying placenta in early pregnancy and to have it move up later on which is why they do repeat scans to check to see if it moves up. Just imagine your uterus as a balloon.... now stick a piece of gum close to the very bottom (the gum represents the placenta)... now blow up the balloon (which represents your uterus growing with the pregnancy).... as the uterus (balloon) grows the gum will typically start to rise away from the bottom (cervix)... and once that gum (placenta) is away from the os there is no problem at all for a vaginal delivery. 

Unfortunately in some situations.... a piece of the gum will still remain on or close to the os causing a problem. Hopefully this will not occur with you though!


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## mamaofthree

os always means pubic bone in any context actually! but the fact that the placenta is adjacent to the os will obviously mean it is also covering the cervix due to their being positions so close together. You will be fine, and they will look after you...try not to worry too much about the medical ins and outs just yet hun. x


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## KandyKinz

Actually in terms of low lying placentas.... When they refer to os they are referring soley to the cervical os. Meaning the opening of the cervix. 

Os in the medical word can refer to two different things... bone and opening.... you're referring to the pubic bone which has no relevance to the location of the placenta... the cervical opening does....

I would like to see the source where you have gained your information, as I've searched through all of my obstetrical, gynecological and midwifery texts and I cannot find anything to support what you are saying.


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## mamaofthree

I also gained information from an old (albeit)midwifery and adult nursingtextbook of mine passed down from my parents(RADIOLOGISTS, AND A MIDWIFE). I think the lady actually asked the meaning of 'os'. I then went on to also explain the risks of a low laying placenta without trying to unduly concern her. tHIS WAS NOT ONLY MY MEDICAL EXPERIENCE, BUT ALSO MY OWN PERSONAL EXPERIENCE AS I HAVE EXPERIENCED PLACENTA PREVIA ALONG WITH A LOW LAYING PLACENTA THAT MOVED BY THIRTY FOUR WEEKS. Besides why quibble so long as she has the information she needs, and is reassured (the whole purpose of medical knowledge is it not?)I don't think just because you believe yourself to be correct you should discount other peoples posts and opinions. I can see what you are saying , but saying the placenta is partially covering or adjacent to means the placenta is close to the cervix or may be fully/partially covering the cervix. Internal os is close in nature to os pubis, and the definition for os is small bone connecting to the hips...internal os also is used to refer to the cervix but neither is wrong hun!!!!

Sa35 i wish you all the luck with your pregnacy, and hope both our answers have gone some way to resolving your query despite a little dispute...lol x x x x x x


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## sar35

thanks ladies i appreciate your input ;) x


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## KandyKinz

You're right in that us arguing holds no benefits..... However, I still feel that it's appropriate to correct information posted on here if it is wrong... She did ask the question what the definition of os was referring to and you gave her the wrong definition. As I mentioned above os can mean two different things... opening and bone... Also os is not specific to the pelvic region... None the less you picked the wrong definition. 

I'm just 7 months shy of being a midwife myself. I have been studying midwifery for years and have take several anatomy and physiology courses as part of that... Several of my clients so far have had low lying placentas and I am quite familiar with the vocabulary and definitions surrounding this issue.

No one is right all of the time and it's good to learn new things...Even doctors learn make mistakes and learn new things all the time as do I..... For instance, yesterday I learned that uterine massage prior to delivery of the placenta was shown in a cochrane review to prevent hemorrhage when I had been previously taught that manipulating the uterus prior to completion of 2 stage actually increased risk of hemorrhage.... I took that as a moment of learning and growth and did not get defensive to the person who presented the new information to me despite that it conflicted with my previous knowledge of the issue. It was an excellent learning experience and I embraced it... 

Just food for thought....

And sorry Sar for taking over your thread....


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