Ultrasound - Sonogram

Ultrasonography used in Pregnancy

pregnancy ultrasound


Ultrasound Examination


What is an ultrasound scan?

An ultrasound scan involves transmitting high frequency sound waves through the uterus. These bounce off the baby and the returning echoes (sound waves) are translated by a computer into an image on a screen that reveals the baby's position and movements.

Hard tissues such as bone reflect as white in the image, and soft tissues appear grey and speckled. Fluids (amniotic fluid) do not reflect any echoes so appear black. The contrast between these different shades of white, grey and black allows your sonographer to interpret the images.

Ultrasound information :-    Who, Why, When?
What happens during an ultrasound examination?
Can the scan show the gender of my baby?

Examples of ultrasonography you may see used during your pregnancy.

Most parents look forward to their scan because it gives them the first glimpse of their baby. You will probably be give you a printout of your baby by the sonographer as a keepsake, it is important to remember the main purpose of the scan. It is not to provide the first photo for your baby album, or to find out your baby's sex. It is to check that your baby is growing and developing normally.


Who will do the scan?

Scans are usually performed by a doctors, midwives or radiographers who are specially trained in ultrasound, and are known as sonographers. Most have completed a post graduate Certificate, Diploma or Master's degree in Medical Ultrasound.

Why do I need an ultrasound scan?

Ultrasound has been used in pregnancy for about 30 years, it has progressively become an indispensible obstetric tool and plays an important role in the care of every pregnant woman.

The common reasons for your doctor to request an pregnancy ultrasound scan are:
  • To establish the date when the baby is due.
  • To check the number of babies.
  • To establish that the pregnancy is continuing normally.
  • To show the position of the placenta.
  • To check the physical development of the baby and to check for birth defects.
  • In later pregnancy, to see that the baby has grown appropriately for its stage of development.

When are scans usually carried out?

Five, six or seven weeks - If there is any need to check the viability of your pregnancy, you may have a early scan when you first visit your care provider. If you are experiencing pain or bleeding for example. This may rule out an ectopic pregnancy. You may have your first scan if unsure of the date of LMP.

10 to 14 weeks - It is recommended that all pregnant women have a dating scan in the first trimester at around 12 weeks of pregnancy to confirm their dates. First trimester ultrasonic scans may show 'soft' markers for chromosomal abnormalities, such as the absence of fetal nasal bone, an increased fetal nuchal translucency (back of the neck) to enable detection of Down syndrome fetuses.

About 18 - 20 weeks - Some women are offered a scan in the second trimester at around 18 to 20 weeks. Known as the anomaly scan or Level II to check that your baby is developing normally. A scan performed at 18 to 20 weeks the fetus is large enough for an accurate survey of the fetal anatomy. Congenital malformations, multiple pregnancies can be firmly diagnosed and dates and growth can also be assessed. Placental position is also determined. Further scans may be necessary if abnormalities are suspected.

28 to 40 weeks - Growth scans in the third trimester may be recommended if a previous baby was small, if you are having twins or when there are other complications of pregnancy, for instance if you are diabetic. Sometimes your midwife may suggest a growth scan if the baby feels and measures smaller or larger than expected.

There is no hard and fast rule for the number of scans you should have during pregnancy.
A scan maybe ordered when an abnormality is suspected on clinical grounds. Otherwise a scan is generally booked in the first trimester to confirm pregnancy, exclude ectopic or molar pregnancies, confirm cardiac pulsation and measure the crown to rump length for dating.


What happens during an ultrasound examination?

ultrasonologistUltrasound examinations are performed on your lower abdomen. Gel is spread on your stomach area to allow the ultrasound waves to pass from a transducer into your body. The waves reflect off internal organs and the fetus if you are pregnant, creating a moving picture on a screen. This is known as real time ultrasound, and you can view the picture on the monitor at the same time as the ultrasonologist.

Why do I need a full bladder? - In the early weeks of pregnancy, the uterus and the ovaries lie deep in the pelvis. So if you are having a scan in early pregnancy, you will need to drink several glasses of water beforehand so that your uterus is pushed out of your pelvis by your bladder, allowing the sonographer to get a good picture of your baby. If you have any bleeding complications in pregnancy, the lower part of the uterus needs to be viewed carefully to make sure that the afterbirth (placenta) is not in the way. Under these circumstances, a moderately filled bladder is need for a proper examination. For most of the other ultrasound examinations, a small amount of urine in your bladder is adequate. If you are not sure whether you can empty your bladder before the examination, ask the attending staff before your ultrasound scan.

pregnancy ultrasoundWill an ultrasound scan hurt? - An abdominal scan is painless except for the discomfort of the transducer pressing on your tummy if you have a very full bladder. A full bladder is not necessary for scans done later in pregnancy, though some hospitals may still request it. The gel used may feel slightly cold and wet. There will be no sensations from the ultrasound waves.

Are ultrasound scans safe? - Ultrasound has been in clinical use since 1960 and medical research has found no side effects. Most experts agree that the procedure should not be done without clear medical reasons, and limited to the minimum needed to make a diagnosis.

Transvaginal probeWhat are Transvaginal scans? - Ultrasound scanning can be done with the probe placed in the vagina of the patient. This method usually provides better images in the early stages of pregnancy or in patients who are overweight. Fetal cardiac pulsation can be clearly observed as early as 6 weeks of gestation and vaginal scans are also becoming indispensible in the early diagnosis of ectopic pregnancies. The sonographer will use a cover similar to a condom and will lubricate this with plenty of gel so it slides in easily. The sonographer will cover you with a sheet, and, if you relax your muscles so that the transducer can slide in easily, it should not be in the least bit uncomfortable. It is not necessary to go in very deeply, and it will not harm you or your baby in any way. You would usually be asked to empty your bladder before vaginal scanning.


Can the scan show the gender of my baby?

It can show the gender of the baby from about 14 weeks, but if your baby is lying in the wrong position it may be difficult to tell. The ability to assign gender increases with increasing gestational age.

[Fetal age 14 weeks]
[16 weeks Gestational]

[Fetal age 18 weeks]
[20 weeks Gestational]
   [Fetal age 18 weeks]
    [20 weeks Gestational]
phallusboy scan  girl 3 lines3 lines sign
The male fetus may show a round bulbous area within the genital area which is the scrotum and penis. This sometimes can be seen on screen as an appearance similar to the profile of a small snail. The absence of the penis must not be taken as sufficient evidence of the fetus being a girl. Using ultrasound the 3 lines sign which denotes the labia in the fetus is a good indication of the female gender.

Most of the time they should be able to tell the sex of the baby by about 22 weeks. The correct visualization of any fetal part depends on many factors such as fetal position, amount of amniotic fluid and thickness of the abdominal wall. Some hospitals have a policy of not telling women the sex of the baby, as it is not usually possible to be 100 per cent certain.

Boy 3DGirl 3D
35 weeks Scan

Ultrasound scans done in later pregnancy or 3D scans can make it easier to see the gender of a baby. The sonographer may not always get a good view of the private parts of the fetus for many reasons and therefore may not be able to give you an accurate answer.

Details of Embryo genital development

You will only know for sure when you, your midwife, or physician inspects the genitalia when the baby is delivered, sees ordinary male or female genitalia, and declares, "it's a girl" or "it's a boy"

Week by week scan pictures:   First Trimester

Examples of ultrasonography you may see used during your pregnancy.


Week By Week Pregnancy Progress Calendar

First Trimester
Week 1   Week 2   Week 3   Week 4   Week 5   Week 6   Week 7  
Week 8   Week 9   Week 10   Week 11   Week 12   Week 13
Second Trimester
Week 14   Week 15   Week 16   Week 17   Week 18   Week 19   Week 20  
Week 21   Week 22   Week 23   Week 24   Week 25   Week 26
Third Trimester
Week 27   Week 28   Week 29   Week 30   Week 31   Week 32   Week 33  
Week 34   Week 35   Week 36   Week 37   Week 38   Week 39   Week 40



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