Midwife Matters

Pregnancy preparations, women's health, and care options

Ultrasound in the 2nd trimester

The second trimester ultrasound is routinely performed on every pregnant women to look at the overall well being of the baby.  It  looks for confirmation of your due date, any possible birth defects, and where the placenta is located.

Due Dates:

Sometimes there is a difference between the size of your baby and the expected size based on your last period.  If the difference is great (more than 10 days) your midwife may adjust your due date.  Only your midwife can do this and will explain why at your next appointment.


Limitations of the ultrasound:

Not all birth defects can be seen.  About 5% of babies are born with some birth defect.  Often these are not seen due to position or size of the baby, where the placenta is located, the amount of amniotic fluid or the size of the mother (obese).


Follow-up exam:

Sometimes you might need a follow-up exam.  Common reasons for this are:  inability to see all the parts of the baby, placenta is too close to the cervix, other “minor markers”.

Minor markers: 

There are some very common markers that are seen on ultrasound that are rarely associated with birth defects.  However, one of these markers is not a birth defect, they do not pose any risk if your baby is otherwise perfectly normal.   They are more common in certain ethnic groups. 

Choroid Plexus Cyst (CPC): A collection of fluid in part of the brain that makes the fluid that circulates in the brain and spinal column.  These cysts almost always disappear by 24 week as the brain grows.  They do not harm the baby’s brain function.

Echogenic intracardiac focus:  A bright spot under the heart valves.  It is NOT associated with heart disease.

Pyelectasis:  A collection of urine as it leaves the kidneys.  Caused by urine backing up from the kidneys throught the ureter into the bladder.  Is usually dissapears as the baby grows.  For a small percentage of babies it continues and can cause kidney damage after birth so ultrasounds may be performed throughout the pregnancy to follow this.

Echogenic bowel:  The bowel appears brighter than usual.  Is associated with an increaed risk of cystic fibrosis and growth problems.  However, it is most commonly seen in babies who swallow blood-stained amniotic fluid.  You may require another ultrasound.

« Healthy Pregnancy Care 16-18 weeks

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