Should pregnant women go for scan? Find out in this well written article titled Ultrasound by Dr. Chin Akano.

ULTRASOUND

Today's topic is about ultrasound scan for pregnant women. I want to explain what ultrasound is, how it works, the safety, why and when it should be done and also to possibly correct some myths about it.



WHAT DOES ULTRASOUND MEAN?



Ultrasound is a sound of high frequency that one cannot hear and is emitted and received by the special machine known as ultrasound machine.These sound waves create images of organs and structures inside your body which the scan machine picks up. Ultrasound is used for both diagnosis and treatment.In diagnosis, it is used in various spheres of medicine including obstetrics, gynaecology, surgical, medical, foetal (new born babies), musculo-skeletal, cardiac, neurological etc etc.
Today i shall focus on obstetric scans which applies to pregnant women only.


WHAT IS REQUIRED FOR THE PROCEDURE:


* an air conditioned room to reduce heating from the machine
* an ultrasound machine
* a couch where the woman will lie
* a gel 
* a light dimmer to dim the light before the procedure takes place
* Paper towels to clean the woman after the procedure and also to protect her clothings from being soiled by the gel



WHAT IS THE USE OF ULTRASOUND IN PREGNANCY?



Ultrasound is used in pregnancy to monitor the baby for well being and to plan the pregnancy . It is not used for diagnosing pregnancy . Diagnosis of pregnancy is by either urine or blood test. It is only when one has confirmed that they are pregnant that they go for scan to check out their babies.



WHEN WAS ULTRASOUND FIRST USED IN PREGNANCY MONITORING?


Early 1960s and since then it has been improved and remodelled.

IS IT SAFE?
Yes ultrasound scan is largely safe for the mother and baby. However there may be a little rise in temperature known as heating effect to the baby especially when the mother is running a temperature or when doppler scan is being used. Therefore it is advisable for pregnant women as much as possible to avoid ultrasound scan when running a temperature (fever) or for the operator not to use the doppler for a very long time on the baby.

TYPES OF SCANS IN PREGNANCY

In pregnancy a woman can be scanned in two ways as follows:
* Transabdominal scan where the procedure is done on the abdomen . This is shortened as TA
* Trans-vaginal scan where it is done through the vagina shortened as TV

Does one type have an advantage over another?
Yes TV has some advantage over TA in early pregnancies. In TV, the ultrasound probe is inserted into the vagina to release and receive ultrasound beams. So since the vagina is close to the womb and other reproductive organs, the images produced are clearer than a TA where the beam has to pass through skin, fat, muscles etc before getting to the reproductive organs. So the image seen via a TV scan is more optimum and clearer than one seen via a TA scan.
TV is therefore better than TA in early pregnancies for dating (booking) the pregnancy, in diagnosing miscarriages, ectopic pregnancies and other early pregnancy problems. It is also better in non pregnant women for gynaecological diagnosis.
However TV is not advised in virgins for obvious reasons and some women do find it unpleasant.



DOES A WOMAN NEED TO DRINK WATER BEFORE A SCAN?


In the first instance, let us understand why pregnant women are sometimes asked to drink water before being scanned. It is not to fill up her stomach but to fill up her bladder with urine.
Why does the bladder need to be filled up?
A full bladder is necessary to push the womb out of the pelvis to prevent shadows from pelvic bones. If not these shadows will prevent the visualisation of images. A full bladder also acts a window for proper visualisation of the ultrasound images
Do all pregnant women going for a scan need a full bladder?
Answer is capital NO
For a TV scan, the bladder must be completely empty. So the woman needs to empty her bladder before being scanned because urine in the bladder will affect the image quality.
For an abdominal scan in pregnancy (TA), a full bladder is not necessary in most of the cases.
A full bladder is only necessary:
1) if the pregnancy is still quite early or young. I mean pregnancies younger than about 13 weeks. After that the woman does not need a full bladder to be scanned.
2) If the reason for the scan is to check the location or position of the placenta (after birth)
In all other cases, the woman does not need to drink water or have a full bladder before being scanned.



IS ULTRASOUND SCANNING A MUST IN PREGNANCY?


Absolute yes. Sometimes i wonder how obstetricians and midwifes coped before the advent of ultrasound in diagnosis.



WHAT ARE THE REASONS FOR ULTRASOUND SCANNING IN PREGNANCY?


In normal pregnancies, the woman is expected to be scanned only twice.
When?
1) when dating or booking the pregnancy
This means assigning an age to the pregnancy known as gestational age and also estimating date of delivery known as expected date of delivery (EDD). This is known as a dating or booking scan
When should this be done?
Between 6 weeks and 15 weeks of pregnancy. Beyond 15 weeks, the dating becomes unreliable.
2) when checking the baby for anomalies or abnormalities. This is known as anomaly scan. This is a very important scan because this is when any physical abnormality in the baby can be diagnosed.
When should this be done?
This scan is done only when the baby is fully formed and the organs and parts are fully developed. This is between 20-22 weeks
. In essence for every pregnant woman, only two scans are necessary if pregnancy is normal. That is
* dating (booking)
* anomaly scan

. Dr Chin Akano