Antenatal Check-up: Fetal Morphology Scans

Pregnancy is a journey full of unknowns. Pregnant women of any age and background have about a 2% chance of giving birth to a baby with severe congenital defects. Antenatal check-ups are a crucial step in helping parents-to-be understand their baby's development. Many expectant mothers might wonder: since routine antenatal check-ups already include ultrasound scans, why do I need a separate fetal morphology scan? What exactly is the difference between the two?

What is the difference between a routine antenatal ultrasound and a fetal morphology scan?

The first antenatal ultrasound is usually done in the first trimester (the first 3 months) of pregnancy. It helps confirm the number of weeks you've been pregnant, estimates your due date, and checks the baby's heartbeat, size, position, amniotic fluid levels, and the position of the placenta. Between weeks 11 and 13, pregnant women can undergo a screening test where an obstetrician measures the baby's nuchal translucency via an ultrasound scan. This, combined with blood test results, helps estimate the risk of the baby having chromosomal abnormalities, such as Down's syndrome.

A fetal morphology scan is much more detailed than a general antenatal check-up. It aims to thoroughly examine the baby's physical structure and internal organs, including the skull and brain, eye sockets, lips, spine, heart, lungs, abdomen, bladder, and limbs.

When do you need a fetal morphology scan?

A fetal morphology scan is generally performed around weeks 19 to 22 of pregnancy to check for any congenital structural abnormalities. If the baby is too small, it's difficult to see their structure clearly. However, if the baby is too large, their bones will have started to mature and calcify, which can make the ultrasound images unclear. Therefore, weeks 19 to 22 are the optimal time for this scan.

An obstetrician will usually examine each baby's structure in detail. Compared to a standard ultrasound, this process takes slightly longer, usually around 30 minutes. Keep in mind that sometimes the baby's position might block the organs being checked. If this happens, the doctor might ask you to take a short walk outside and try again later. Because of this, it's a good idea to set aside plenty of time on the day of your scan.

Is a fetal morphology scan mandatory?

Using ultrasound to examine the baby’s structure does not involve any radiation, so it poses no adverse effects to the baby. However, a morphology scan is not a routine check-up in Hong Kong’s public hospitals. Some public hospitals will only arrange it for high‑risk pregnant women, such as older mothers (over 35) or those with a family history of genetic conditions.

If you are not considered high-risk, you can choose to pay for a morphology scan at a private clinic or hospital. Many parents-to-be opt for this scan to ensure their baby is developing well, which offers peace of mind. It also allows early detection of abnormalities in the baby. In case of any abnormalities are found, parents can discuss follow-up arrangements and treatment plans with obstetrician, or even make an early decision on whether to terminate the pregnancy. If you have any questions, you should always consult your obstetrician.

What information can a fetal morphology scan provide?

Dr Michael Chor, Specialist in Obstetrics & Gynaecology, points out that a morphology scan can diagnose about 80% of severe congenital structural abnormalities, such as spina bifida, anencephaly, and limb abnormalities. However, it cannot guarantee with 100% certainty that the baby will be completely healthy after birth. Some conditions may be difficult for a morphology scan to detect, such as:

Functional defects: such as learning disabilities, blindness, or deafness.
Small or subtle structural defects: such as a tiny hole in the heart or a cleft palate.
Defects without obvious ultrasound features: such as Down's syndrome or an imperforate anus.

Additionally, some defects like bowel obstruction or dwarfism may only become apparent in the third trimester or after birth, meaning they can't be confirmed through a fetal morphology scan or routine check-ups. If you’re concerned about possible genetic issues, it is advisable to discuss with your obstetrician whether further screening or diagnostic tests, such as an amniocentesis, may be needed.

How should you prepare for a fetal morphology scan?

When booking your appointment, it is best to follow the instructions given by the clinic or hospital, as the requirements can vary.

During the scan, the doctor will apply a gel to your abdomen and pelvic area, so it is best to avoid using creams or skincare products on these areas beforehand. On the day of your appointment, wearing comfortable, loose‑fitting clothing will help make the examination easier.

How much does a fetal morphology scan cost?

As mentioned, a morphology scan isn’t a routine procedure in public hospitals due to limited availability. If you'd like a detailed look at your baby's structural development, you can consider a private clinic or hospital. Generally, private institutions charge between HK$3,000 and HK$7,000 for the scan. Some of these prices include the doctor's consultation fee. The actual cost will depend on the patient's condition and the individual doctor's fees.

The professional O&G team at OT&P also provides fetal morphology scan services. For reference, our fees are as follows. If you have any questions about OT&P's pricing or our central obstetrics and gynaecology services, feel free to contact us via WhatsApp.

Morphology scan fee: HK$3,000 (includes a detailed report, plus photos and videos on a USB)
Specialist consultation fee: HK$1,500

What if there are abnormalities with the baby?

While some congenital defects can be identified directly through a fetal morphology scan, certain structural issues may require further tests to rule out more serious conditions, for example amniocentesis. If a congenital defect is detected, your obstetrician will arrange follow‑up appointments and refer you to the appropriate specialists, such as geneticists or paediatric surgeons, to ensure your baby receives the right care after birth. In cases where a fatal congenital defect is diagnosed, the mother may legally choose to end the pregnancy before 24 weeks.

To have a legal abortion in Hong Kong, the following conditions must be met:

Two registered doctors (one of whom performs the procedure) must agree that continuing the pregnancy would pose a greater risk to the mother’s life, or to her physical or mental health, than terminating it; or that the baby is highly likely to be born with severe physical or mental abnormalities. The procedure must also be carried out in a government‑designated hospital or clinic.
The pregnancy must be under 24 weeks, unless the procedure is necessary to save the mother’s life.

Whatever the reason, deciding to end a pregnancy is never easy. It can be physically demanding and emotionally overwhelming for any mother. If you would like to understand more about the procedure and the possible risks, you are welcome to book a consultation with our doctors to discuss your situation in a safe and supportive environment.

Dr Michael Chor

Gynaecology, Obstetrics

MBChB (CUHK)
MRCOG (UK)
FHKAM(O&G)
FHKCOG
Cert RCOG (Maternal and Fetal Med)

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Health Articles by Dr Michael Chor

References

Cleveland Clinic. (2022). 20-Week Ultrasound (Anatomy Scan). Retrieved August 18, 2022, from https://my.clevelandclinic.org/health/diagnostics/22644-20-week-ultrasound
Pregnancy birth & baby. (2022). Morphology scan. Retrieved August 18, 2022, from https://www.pregnancybirthbaby.org.au/anomaly-scan
The Chinese University of Hong Kong. (n.d.). Second Trimester Fetal Morphology Scan. Retrieved August 18, 2022, from http://www.obg.cuhk.edu.hk/wp-content/uploads/Fetal_Morphology_Scan20190923.pdf
香港大學李嘉誠醫學院. (2021). 遺傳諮詢評估胎兒患病風險. Retrieved August 18, 2022, from https://www.med.hku.hk/en/about-hkumed/knowledge-exchange/newspaper-columns/2021/mar/pre-pregnancy-and-prenatal-genetic-counselling
Crane, J.P., LeFevre, M.L., Winborn, R.C., Evans, J.K., Ewigman, B.G., Bain, R.P., Frigoletto, F. D and McNellis, D. (1994). A randomized trial of prenatal ultrasonographic screening: impact on the detection, management, and outcome of anomalous fetuses. The RADIUS Study Group. American journal of obstetrics and gynecology, [online] 171(2), pp.392–9. doi:10.1016/s0002-9378(94)70040-0.