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Pregnancy and Pelvic Imaging

Pregnancy and Pelvic Imaging


Our sonographers have extensive experience in performing all branches of ultrasound including Obstetric and Pelvic Imaging. Obstetric imaging is overseen by Radiologists with a special interest in obstetric ultrasound.

Pelvic/Gynaecology Ultrasound Scan 

What is a pelvic or gynaecological ultrasound?

This is an ultrasound that examines the organs of the female pelvis. This includes the ovaries, the cervix, the uterus/womb and the lining of the uterus (referred to as the endometrium) It is completely safe and uses sound waves, not ionising radiation such as that used for x-rays or CT scans.

Why might I need a pelvic ultrasound?

Common reasons for this are;

  • Pelvic pain or painful periods

  • Heavy periods or abnormal bleeding

  • Pelvic mass

  • Infertility

  • Postmenopausal bleeding

  • Pain or bleeding following delivery of a baby or after a miscarriage

  • Assessment of IUCD/Mirena position


What can be seen on the scan?

  • Abnormalities with the uterus such as fibroids

  • Ovarian cysts, masses or polycystic ovaries

  • Abnormalities with the endometrium like polyps or abnormal thickening

  • Abnormal fluid adjacent to the uterus or ovaries

How is it performed?

Both transabdominal and transvaginal scanning is recommended for adequate views of your pelvic structures.

Transabdominal scanning is performed by placing a probe and gel on the skin of your lower abdomen. This provides a good overall assessment of pelvic organs and not a lot of detail. A transvaginal scan involves a sterilised, covered probe being gently placed into the vagina whilst you are covered. This usually provides clearer images of the pelvic structures as this probe lies closer to the uterus, ovaries and cervix.  It is less uncomfortable than a PAP smear. You will always have the choice about whether this is performed.

Do I need a full bladder?

Fluid in the bladder allows clearer images to be obtained during transabdominal scanning. It allows a “window” for the scan and moves your bowel out of the pelvis helping better visualisation. Your bladder needs to be partially filled (your bladder should not be so full that it causes you pain). Empty your bladder 2 hours before your appointment time and drink 1L of a litre of water and do not empty again until after the test. You will be allowed to empty your bladder before the transvaginal scan begins.

What if I am bleeding/have my period at the time of the scan?

It is not always possible to time your appointment after your period or when you are not bleeding, particularly if you have irregular bleeding or periods. A pelvic ultrasound can be performed at any stage of the menstrual cycle. Ideally, make an appointment just after you expect your period to finish. This is a good time of the cycle to assess the lining of the uterus/endometrium. Your doctor will let you know if there is a particular time in the cycle that you should attend.

First Trimester/Dating Ultrasound

What is a dating scan?

This scan is performed in early pregnancy to determine the age of the pregnancy (also known as the gestational age) using measurements. The measurements are from one end of the fetus to the other, known as the crown-rump length, or CRL.

When is it performed?

This scan is usually done if you are unsure about the dates of your last menstrual period (LMP) or have irregular periods. If you have been breast feeding or have recently stopped the oral contraceptive pill you may have had an unusual cycle so you may not be sure of your LMP.

This scan may also be performed also if you have an early pregnancy and have bleeding or pain (even if you have already had a scan or are sure of your last menstrual period) to assess if the pregnancy progressing normally.

How accurate is the pregnancy dating?

A scan performed between 7-11 weeks pregnancy/gestation is accurate to within 3 days.

What else does it show?

  • The number of babies

  • The presence of the baby’s heart beat

  • The position of the pregnancy (check it is in the uterus and not outside, known as an ectopic pregnancy)

  • The appearance of the uterus and ovaries

How is it done?

Most of the images can be obtained by transabdominal ultrasound (this involves scanning through your lower abdomen) using a probe and gel on your skin.  This requires a full bladder. Sometimes if the pregnancy is early or better images of your uterus or ovaries is required a transvaginal ultrasound scan is required. This involves an internal probe being gently placed into the vagina with a sterile protective sheath (usually less discomfort than a PAP smear) This allows better images as the probe lies closer to these structures.

Are there some occasions where I will have to return for a repeat early pregnancy scan?

This depends how far along your pregnancy is. Even if you have a positive pregnancy blood or urine test it may be too early to see signs of a pregnancy on ultrasound. Before 5.5 weeks a small fluid sac may be seen in the uterus without sign of a fetus or a fetal heart beat. In these situations a repeat scan one to two weeks later may be necessary to confirm a viable pregnancy and provide accurate dating. Your doctor will also usually correlate the results with blood tests (serum BHCG)

By 6-7 weeks the fetus is usually seen clearly (often requires transvaginal scanning) and its heart beat can be visualised.

Second Trimester/Morphology Scan

This ultrasound examination (also known as an anomaly scan) provides a detailed scan of your developing baby and is considered to be routine practice for all pregnant women in Australia. At Spectrum, we recommend booking your morphology scan from 19 weeks 4 days gestation.

What is the purpose of the scan?

At this stage the sonographer and doctor are able to look at the baby’s anatomy (this involves a detailed examination of the baby’s head/brain, face, heart, stomach, kidneys, bladder, spine and limbs). They can also check the position of the placenta in relation to your cervix, the length of the cervix and fluid around your baby.

Why is this scan carried out after 19 weeks 4 days gestation?

This is thought to be the optimal time to visualise the baby’s anatomy, allowing accurate assessment of the internal organs and limbs. The timing of the scan also allows further testing should an abnormality be found.

What abnormalities can be detected?

Despite advanced technology and the very experienced medical professionals at our practice ultrasound does not detect all abnormalities a baby can have. There are some abnormalities that are only evident later in the pregnancy such as some cardiac defects and bowel abnormalities. There are conditions such as cerebral palsy and chromosomal abnormalities that cannot be detected at all. This scan provides reassurance for you and your doctor however does not guarantee a normal baby or that you will have no pregnancy complications.

What will I be able to see on the scan?

All of our Women's Imaging ultrasound rooms have a second screen mounted on the wall so you can watch your baby whilst the scan is being performed. The sonographer will point out your baby’s heartbeat and various parts of its body such as its hands and feet and face. The bones will appear white and the soft tissue grey and the fluid surrounding the baby will appear black.

What if there is a problem on the scan?

Approximately 95 % of babies will have a normal ultrasound can. If there is a problem with your scan you will be informed of this at the time of your scan by a doctor and informed of what the next step will be. Sometimes a repeat scan is required at our practice or in a tertiary referral centre. These results will also be discussed with your referring doctor/midwife. In most cases of repeat scanning no serious abnormality is present.

Do I need a full bladder?

Fluid in your bladder provides a “window” to get better images on your scan. It also helps push the uterus (womb) up from your pelvis and bowel out of the way to better visualise your baby, uterus and cervix. We suggest you empty your bladder an hour before your appointment and drink ¾ of a litre of water and then try not to empty your bladder until after your appointment (your bladder does not need to be so full that it is painful)

Is ultrasound safe for my baby?

Yes ultrasound is safe. Ultrasound scans have been used for over 50 years. They use sound waves and not ionizing radiation like that used in x-rays and CAT scans. Long term studies have shown that there is no adverse effect on the baby from an ultrasound scan performed before birth. Follow-up has shown normal growth and development, normal eyesight and hearing and a normal range of school performance.

Can I find out the sex of my baby?

Please let us know at the beginning of the examination if you would like to know the gender of your baby (also if you do not want to know please let us know). It must be remembered that ultrasound is not 100% in determining the sex of your baby. Sometimes it is not possible to determine the sex due to the position of the baby.

Establishing the sex of your baby is an exciting time for parents, however please remember that the purpose of this scan is to ensure your baby is developing normally and that there are no signs of structural abnormalities.  

Will I need any more scans after this?

Usually everything can be assessed on one scan, however in 5-10% cases another scan later that day or on another day may need to be performed when the baby is in another position or when the baby is bigger.

Some women may be required to return for a scan in the third trimester to check the growth of the baby, reassess the position of the placenta or review findings from the morphology scan. Your doctor or midwife will refer you for this ultrasound.


If you have any further questions do not hesitate to call us or ask the sonographer on the day of the scan.

Third Trimester/Fetal Growth and well-being Ultrasound

When is this scan usually performed?

A third trimester scan is carried out after 22-24 weeks gestation.

What is the purpose of this scan?

This scan is to look at;

  • Size and growth of the baby

  • Position of the baby

  • volume and fluid around the baby

  • Placental position

  • Review findings from a prior ultrasound

We can also assess blood flow through the umbilical cord (umbilical cord Doppler), Activity and movement of the baby (often termed biophysical profile) and the length of the cervix.

Why might I require this scan?

  • If you have a medical condition (such as diabetes, increased blood pressure/pre-eclampsia, or heart disease)

  • if you have a twin pregnancy

  • if your baby is suspected to be large or small for your dates

  • if your baby may be breech

What does the scan involve?

This scan takes around 20-30 minutes. It is performed by placing a probe and gel on the skin of your lower abdomen. Occasionally you will need a transvaginal scan (where a sterilised, covered probe is gently placed into the vagina whilst you are covered) This is sometimes required to more accurately assess the length of the cervix or the position of the placenta. It is less uncomfortable than a PAP smear.

Do I need a full bladder?

Your bladder needs to be partially filled (your bladder should not be so full that it causes you pain). Emptying the bladder an hour before the examination and drinking ¾ of a litre of water before your appointment is advised.

What if there is something wrong?

If there is a problem with your scan you will be informed of this at the time of your scan by a doctor and informed of what the next step will be. Occasionally a repeat scan is required at our practice or in a tertiary referral centre. These results will also be discussed with your referring doctor/midwife.

Will I have to return for further scans?

If a problem with your baby’s growth or the fluid around your baby is detected then a further scan/scans may be required to monitor this prior to delivery.

If you have any further questions do not hesitate to call us or ask the sonographer on the day of the scan.

Nuchal Translucency

This scan is ideally performed at 12 weeks 4 days - 13 weeks 5 days and involves assessing the baby's anatomy and taking specific measurements of the baby. These are entered into software developed by the Fetal Medicine Foundation along with the mother’s age and the results of the associated blood test. This program then allows us to calculate an individual risk of chromosomal abnormalities for each pregnancy.


Pregnancies considered high risk (less than 1:300) are referred to specialist centres for further counselling and testing.


This test is a risk assessment. It does not tell us which pregnancies are affected by chromosomal abnormalities. Approximately 5% of pregnancies will return as high risk and most of these will be normal, just as low risk does not entirely exclude an abnormality.

This screening method will detect approximately 88-93% of affected pregnancies.

If you meet certain criteria you may get a rebate from Medicare.

We perform Nuchal translucency evaluations in pregnancy at our Bankstown, Liverpool and Randwick practices.

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