When can I have my first scan and how many will I have throughout my pregnancy and at what stages?

 Many patients wish to have an early pregnancy scan at approximately 8 weeks for reassurance.  Routine clinical scans are then typically carried out at approximately 10-14 weeks, 20-22 weeks and 32-34 weeks.  The clinical value of these scans are listed below.

What can you learn from a scan?

(a)   Early pregnancy scan up to 10 weeks gestation:  An early scan prior to 10 weeks gestation gives considerable reassurance to patients at this stage, particularly before pregnancy symptoms present.  At 7-8 weeks gestation, the pregnancy and baby are very recognisable, the baby’s heartbeat can be clearly seen and heard, pregnancy dates can be confirmed and multiple (twin) pregnancies identified.  Most problems associated with early pregnancy can be excluded.

(b)  10-14 weeks gestation scan:  This is the stage at which the Nuchal Test is carried out in order to identify babies who might be at high risk of Down’s Syndrome.  The basic Nuchal Test involves measuring the thickness of skin at the back of the baby’s neck (termed the Nuchal Thickness) and length of the baby, which reflects the baby’s age, using ultrasound.  These two measurements are combined with a basic blood test from the mother to give a “risk factor” for Down’s Syndrome.  Leading scan units offer a much more comprehensive check at this stage involving more detailed ultrasound scanning and a better blood test.

(c)    20-22 weeks gestation scan:  This is a very detailed check of the baby’s major organs and limbs etc.  A very thorough check of the baby will demonstrate many of the potential abnormalities which might present in babies.  The mother’s cervix (neck of the womb) and blood flow to the mother’s uterus (womb) can also be evaluated in order to identify those patients who might present with premature delivery, pre-eclampsia, poor placental function and growth of the baby etc. later in pregnancy.

(d)     32-34 weeks gestation scan:  This is a general welfare check of the pregnancy and baby’s progress.  It demonstrates the position of the baby in late pregnancy.  Ultrasound measurements gauge the growth and estimated weight of the baby.  The position and healthiness of the placenta can be assured and the amount of fluid around the baby checked.  Doppler measurement of blood flow through the umbilical cord confirms normal placental function, essential for the baby over the last few months of pregnancy.

When can you hear a heartbeat?

Modern transvaginal scanning will identify the baby’s heartbeat in virtually all pregnancies from 6 weeks from the first day of the last period (i.e. 4 weeks after conception).  There might be some delay in seeing and hearing the heartbeat if ovulation occurred later during the menstrual cycle and / or transabdominal ultrasound scanning is used.

Can scanning hurt my unborn baby?  Are they safe for me?

There has been no substantiated evidence to date to show that the type of ultrasound used for pregnancy scanning causes any harm to the baby or mother.  Professional bodies such as the Royal College of Obstetrics and Gynaecology, the British Medical Ultrasound Society and UK Hospital Physicists Association continue to monitor the safety of ultrasound with considerable vigilance.

Are there any side effects or long-term effects?

Clinical and genetic studies, as alluded to above, have been continually carried out over many decades now.   To date, no harmful biological effects to cause problems for the baby or mother have been identified.

Do I need a full bladder for my scan and what should I bring with me to the appointment?

Leading scan units have shown there is no benefit for mothers to be scanned with a “full bladder”.  This practice was stopped decades ago in those units.  “Full bladders” are not needed at any stage of pregnancy!  It is always useful to bring your clinical notes with you if they are in your possession.  This is not essential but it is always helpful to know who your clinical consultant is in case the scan detects any problem.  This ensures good lines of clinical communication, which is important from a patient care point of view.

What factors determine the quality of the image?

 The principal factors determining the quality of the image are:

(a)   stage of pregnancy

(b)   size / weight of the mother

(c)   level of performance of the ultrasound equipment

(d)   experience of the ultrasound practitioner performing the scan

(e)   (Excessive) movement and position of the baby

What are the different types of scanning?

Different types of ultrasound scanning used at various stages of pregnancy are:

(a)   Transabdominal scanning: The most common form of scanning.  Used from 10 weeks gestation onwards.  Scan imaging can be displayed as 2D, 3D or 4D (i.e. “moving”, real-time 3D) image formats.

(b)   Transvaginal scanning:  A small, narrow finger-like ultrasound probe is gently inserted a few centimetres only into the vagina to produce very high quality ultrasound imaging.  This is routine for early pregnancy scanning (up to 10 weeks gestation).  It is regarded as safe for baby and mother and is very well tolerated by the patient.

(c)   Colour Doppler scanning:  Blood flow through major vessels and / or tissues is shown on the scan image in colour, usually red or blue.  Colour Doppler is important in early pregnancy examinations for assessing the (hormonal) activity of /the ovaries, crucial to maintaining the pregnancy.  This is important in cases of recurrent miscarriage and for patients who have had fertility investigations or treatment.  In later pregnancies blood flow studies of the umbilical cord can indicate placental function.  Colour Doppler studies of the mother’s blood flow to the uterus (womb) at approximately 20 weeks gestation onwards can predict problems with pregnancy growth and development in later pregnancy.

Are there any extra scans I can opt into having to test for other conditions?

 From a clinical point of view, additional scans could be indicated for a number of reasons.  For instance, several scans from 5 weeks onwards might be carried out within the first few months of pregnancy in cases when there is a history of recurrent miscarriage, infertility or bleeding.  Patients presenting with a history of abnormality within a previous pregnancy or where the 10-14 week or 20-22 week scan might indicate a possible issue with the baby’s development or pregnancy welfare, again might require additional scans throughout the pregnancy.

Chorionic Villi Sampling (CVS) or Amniocentesis procedures are usually carried out if the 10-14 week screening test shows the baby to be at  increased risk of Down’s Syndrome.  CVS is a technique where a fine needle is passed into the placental tissue and a sample of that tissue obtained for testing.  Amniocentesis is a similar technique but where fluid around the baby is taken for analysis.  CVS is usually carried out up to 15 weeks gestation and amniocentesis after that time.  Both procedures are carried out under ultrasound scanning guidance.

Additional scans for 3D or 4D pictures / DVD or sexing of the pregnancy are often requested by patients.  Professional bodies overseeing ultrasound scanning within the UK frown upon non-clinical scans such as these.  Nevertheless, some units offer these facilities as part of clinical scans and often free of charge.  There is no doubt however that 3D / 4D images give couples considerable enjoyment as part of their pregnancies and most units will have these facilities available.

How common are abnormalities and will I be told straight away if one is found from the scan?

Abnormalities in babies are very few and far between.  Most, but not all, of major problems will be picked up by scan.  It is reasonable to say that if the 10-14 week screening test and the 20-22 week scan are normal, then the likelihood of an abnormality is very remote indeed, certainly if scans are carried out by experienced ultrasound practitioners.   Therefore, on the basis that the vast majority of pregnancies are totally normal, ultrasound scanning in pregnancy serves to give tremendous reassurance to patients and allows the opportunity to enjoy the pregnancy.  Communication with the patient varies from unit to unit.  It is only reasonable that the patient should be expected to be informed of any issues during the scan prior to being referred onto her consultant in order to discuss clinical management on the basis of the ultrasound findings.


Ultrasound scanning is now regarded as an essential part of antenatal care.  It provides important information about the healthiness of the baby as well as general pregnancy progress from the first few weeks of conception.

The vast majority of pregnancies are without problem and result in the birth of totally healthy babies.  Modern ultrasound imaging can give tremendous reassurance for patents at all stages of pregnancy.

CDS offers considerable experience in all aspects of routine pregnancy ultrasound.  Patients benefit from advanced scanning facilities in all scan clinic locations.  CDS remains committed to supporting the clinical and personal needs of its patients throughout their pregnancy.

Routine pregnancy scans and pre-natal testing at CDS include:

  • Early Pregnancy Assessments (0 – 10 wks gestation)
  • Advanced Nuchal (Down’s Syndrome) Screening (10 – 14 wks)
  • Fetal Normality (Detailed Antomical) Checks (18 – 22 wks)
  • General Pregnancy Welfare and Fetal Growth Assessments (30 – 40 wks)
  • Chorionic Villi Sampling (CVS) and Amniocentesis Procedures

A flexible appointment system offers “out of hours”, evening and weekend clinics for the convenience of both mothers and partners who are encouraged to attend scans.

CDS operates a continual on-call system for urgent or emergency scanning needs.  A bleep-system is in place weekends, bank holidays etc.

“Scan Packages” are available to suit the individual needs of patients for example:

  • Early Pregnancy Ultrasound Package (0-10 wks gestation)
  • General Obstetric Ultrasound Package (10-40 wks gestation)

Pregnancy “sexing” and “3D / 4D” imaging are free of charge and included as part of routine clinic examinations.


  • For appointments and general enquiries please telephone: 020 7483 3611
  • Emergency on-call services – please bleep 07623 911684