An ultrasound scan is one of the most commonly used investigations in women's healthcare. It is a safe, painless and non-invasive way of examining the uterus, ovaries, fallopian tubes and, during pregnancy, the developing baby.
Whether you have been advised an ultrasound for irregular periods, pelvic pain, infertility or pregnancy monitoring, it is natural to wonder what happens during the scan and what the doctor is looking for.
Modern ultrasound technology allows doctors to obtain detailed information without using radiation. Depending on the reason for the examination, different types of ultrasound scans may be recommended.
What is an ultrasound scan?
An ultrasound scan uses high-frequency sound waves to create images of structures inside the body.
Unlike X-rays and CT scans, ultrasound does not use ionising radiation. It can therefore be used extensively in pregnancy when clinically indicated.
During the examination, an ultrasound probe sends sound waves into the body. The returning echoes are processed by the machine to create images that the doctor can interpret.
The type of probe and approach used depends on the area being examined.
Pelvic ultrasound
A pelvic ultrasound is commonly used to evaluate the uterus, ovaries and surrounding pelvic structures. It may be recommended for:
- Irregular or painful periods
- Heavy menstrual bleeding
- Pelvic pain
- Suspected fibroids or ovarian cysts
- Endometriosis or adenomyosis
- Abnormal uterine bleeding
- Fertility evaluation
- Monitoring ovarian follicles
A pelvic ultrasound can provide information about the size and shape of the uterus, thickness and appearance of the endometrium, ovarian structure and the presence of conditions such as fibroids or ovarian cysts.
Transabdominal ultrasound
A transabdominal ultrasound is performed by moving the probe over the lower abdomen.
You may be asked to have a reasonably full bladder before the scan. A full bladder can provide a useful acoustic window and may help visualise the pelvic organs.
The doctor or sonographer applies ultrasound gel to the abdomen and gently moves the probe over the skin. The procedure is generally painless.
Transvaginal ultrasound
A transvaginal ultrasound (TVS) uses a specially designed ultrasound probe inserted gently into the vagina.
It provides high-resolution images of the uterus, endometrium, cervix and ovaries and is particularly useful in gynaecology and fertility care.
You will usually be asked to empty your bladder before a transvaginal scan. A protective cover and ultrasound gel are used on the probe. The probe is inserted carefully and only to the extent required to obtain the necessary images.
Some women may experience mild discomfort, but the examination should not usually be painful. If you are anxious or uncomfortable, let your doctor know.
Follicular monitoring scan
Women undergoing fertility treatment may be advised follicular monitoring.
This involves a series of ultrasound scans performed at different stages of the menstrual cycle to monitor ovarian follicles and determine whether ovulation is occurring or developing appropriately. The scan can help assess:
- Follicle growth
- Development of the dominant follicle
- Endometrial thickness
- Evidence of ovulation
- Response to ovulation-induction medication
Follicular monitoring can be particularly useful when timing intercourse, IUI or certain fertility treatments.
Early pregnancy ultrasound
An early pregnancy scan is often performed during the first trimester.
Depending on the gestational age, it can help confirm that the pregnancy is located inside the uterus, assess viability and estimate gestational age.
In very early pregnancy, a transvaginal ultrasound may provide clearer images than an abdominal scan. The timing of the scan matters because the structures visible on ultrasound change rapidly during the first few weeks of pregnancy.
Dating scan
A dating scan is used to establish or confirm gestational age and estimate the expected date of delivery.
An ultrasound measurement of the embryo or fetus during early pregnancy can provide a more reliable estimate of gestational age than menstrual dates in some circumstances.
Knowing the gestational age accurately helps doctors plan subsequent screening and pregnancy care.
First-trimester screening and NT scan
The nuchal translucency (NT) scan is usually performed between approximately 11 and 13+6 weeks of pregnancy.
It measures the fluid-filled space at the back of the fetal neck and assesses several other ultrasound markers.
The NT scan is generally part of a broader screening assessment for chromosomal conditions. Depending on the pregnancy and the screening strategy being used, it may be combined with maternal blood tests or cell-free DNA screening such as NIPT.
It is important to understand that screening estimates the chance or risk of a condition; it does not by itself provide a definitive diagnosis.
Anomaly scan
The anomaly scan, also called the detailed fetal anatomy scan, is usually performed around 18–22 weeks.
It is one of the most important ultrasound examinations during pregnancy.
The doctor examines the baby's anatomy, including structures such as the brain, spine, heart, abdomen, kidneys and limbs. The placenta, amniotic fluid and other relevant features are also assessed.
The scan is designed to identify many structural abnormalities, although no ultrasound can detect every possible condition.
Growth scan
A fetal growth scan may be recommended later in pregnancy when clinically indicated.
The baby's measurements are assessed to estimate fetal growth and weight. Amniotic fluid, placental location and other parameters may also be evaluated.
Growth scans may be particularly useful in pregnancies where there are concerns about fetal growth, maternal medical conditions, previous pregnancy complications or other risk factors.
Not every pregnant woman requires repeated growth scans. Your obstetrician will recommend them based on your individual pregnancy.
Doppler ultrasound
Doppler ultrasound assesses blood flow through blood vessels.
In pregnancy, Doppler studies can provide information about blood flow in vessels such as the umbilical artery and certain maternal and fetal vessels.
They may be used when there are concerns about fetal growth, placental function or other pregnancy-related conditions. Doppler is a specialised component of ultrasound and is not required routinely at every pregnancy visit.
3D and 4D ultrasound
3D ultrasound produces three-dimensional images, while 4D ultrasound adds movement in real time.
These technologies can provide impressive images of the baby's face and body and may be useful in selected medical situations.
However, 3D/4D imaging is not a replacement for a standard medical ultrasound examination. The priority remains obtaining the diagnostic information needed to assess the mother and baby.
What should you expect during an ultrasound?
Before your scan, you may receive specific instructions depending on the type of examination.
For some abdominal pelvic scans, a full bladder may be requested. For transvaginal scans, the bladder is generally emptied.
During the scan, you will usually lie comfortably on an examination bed. Gel is applied to the skin for an abdominal scan, or a covered probe is used for a transvaginal examination.
The examination may take anywhere from a few minutes to longer depending on what needs to be assessed. You may see images on the screen while the examination is taking place. Your doctor will explain the findings as appropriate.
Is ultrasound safe?
Ultrasound has been used extensively in medical practice and pregnancy care for many years.
It does not use ionising radiation. When performed appropriately by trained professionals for a medical indication, ultrasound is considered a safe diagnostic tool.
As with any medical investigation, scans should be performed when clinically appropriate rather than simply because more imaging seems better.
Does an ultrasound always give a definite answer?
Not necessarily.
Ultrasound is an extremely useful diagnostic tool, but its findings need to be interpreted alongside your symptoms, examination, medical history and other investigations.
Some conditions may require additional tests or imaging. A normal ultrasound is reassuring, but it does not rule out every possible gynaecological or reproductive condition.
Preparing for your ultrasound
If you have been asked to undergo an ultrasound, follow the preparation instructions provided by your clinic.
It can be helpful to bring previous scan reports and relevant medical records, particularly if the scan is being performed for fertility treatment or monitoring an existing condition.
Most importantly, don't hesitate to ask what the scan is intended to assess. Understanding the purpose of an investigation can make the experience much less stressful.
The role of ultrasound in women's healthcare
Ultrasound is an important part of modern gynaecological, fertility and pregnancy care.
From identifying fibroids and ovarian cysts to monitoring ovulation, confirming early pregnancy, assessing fetal anatomy and monitoring fetal growth, ultrasound provides valuable information at many stages of a woman's reproductive journey.
The type of scan you need depends on why the scan is being performed, your stage of pregnancy or menstrual cycle, and your individual medical circumstances.
If your doctor recommends an ultrasound, you can feel reassured that it is a routine and highly useful part of women's healthcare.
At MA Pregnancy & Fertility Clinic, ultrasound examinations are performed as part of an individualised approach to gynaecological, fertility and pregnancy care, with the findings interpreted in the context of each patient's clinical needs.
To book an ultrasound scan or consultation in Sholinganallur, please click here to request an appointment.