Advanced Fetal Imaging

Detailed Fetal Ultrasound:

A detailed or “targeted” fetal ultrasound (US) scan sometimes also called a level III ultrasound, is interpreted by a highly trained fetal medicine specialist or radiologist who is familiar with fetal anomalies, growth and placental problems. The initial scan will usually be performed by a specially trained member of our team, either a fetal medicine nurse or sonographer. During this examination, the fetal organs, placenta, amniotic fluid volume and cervix are examined in great detail. A detailed fetal ultrasound, especially in later pregnancy, typically also involves the use of Doppler ultrasound, which allows us to visualize blood flow in the fetus. The whole exam usually lasts 30-60 minutes. Advanced fetal ultrasounds are usually ordered for fetuses which are at high risk of, or have been diagnosed with a fetal abnormality.  An early ultrasound (usually in conjunction with a blood test) is offered to all women at 11-14 weeks as part of our prenatal screening program at Mount Sinai. Other fetal indications for ultrasound include a suspicion of any growth, placental or amniotic fluid problems, shortening of the cervix, certain multiple pregnancies (twins etc.) or a history of a problem in a previous pregnancy.  There are also a variety of maternal problems for which fetal ultrasounds will also be ordered, including diabetes, high blood pressure, heart, kidney problems or a pregnancy with an immune disorder. After the ultrasound exam, a fetal medicine specialist or radiologist will discuss the results with the parents before you leave and you will be given a copy of the report.

Detailed fetal ultrasounds are typically done in the second trimester of pregnancy (18-20 weeks), but state-of-the-art ultrasound machines now allow many fetal conditions to be diagnosed in the first trimester of pregnancy and sometimes an “early anatomy” scan will be requested. There are no known side effects of ultrasound or Doppler in pregnancy.

Detailed fetal ultrasounds are performed in both the FMU (Fetal Medicine Unit) and the CEOU (Centre of Excellence in Obstetric Ultrasound) at Mount Sinai hospital, which are located directly opposite one another on the 3rd floor of the OPG (“hydro”) building, 700 University Ave. Sometimes (especially for any ultrasound done outside normal working hours) you will be asked to come to another part of the FMU, which is located on the 7th floor of the hospital (room 712).  No special preparation is necessary and your bladder does not usually need to be full for ultrasound exams, except for some of those done in early pregnancy.

Fetal Echocardiography:

A fetal echocardiogram is a specialized ultrasound of the fetal heart. These ultrasounds are typically performed by paediatric cardiologists (doctors specialize in heart conditions in fetuses and children). During this examination, the fetal heart and large blood vessels are examined in great detail. Fetal echocardiography will typically also involve the use of Doppler ultrasound, which allows us to visualize blood flow in the fetus. The exam typically lasts for 45-60 minutes. After the exam, the paediatric cardiologist will discuss the results with the parent and give you a copy of their report. Fetal echocardiograms are done in fetuses which are at high risk for, or have been diagnosed with, a heart condition.

There are no known side effects of echocardiography or Doppler ultrasound in pregnancy. Fetal echocardiography is on level 4B at Sick Kid’s hospital.  You will need to get another hospital card for Sick Kids, which can be done at the fetal echo lab.  No special preparation is necessary.  The fetal echo lab will contact you directly with your appointment time.

Magnetic Resonance Imaging (MRI):

Magnetic resonance imaging is a special scan in which magnetic fields are used to visualize the fetus. MRI does not involve the use of x-rays and has no known side effects  in pregnancy. MRI may sometimes yield better images of the fetus than ultrasound. It may therefore be suggested to help evaluate specific conditions such as fetal congenital diaphragmatic hernia, fetal brain abnormalities, abnormal placental development (placenta percreta) or some fetal cardiac problems. There is no proven benefit of MRI in other fetal conditions. Fetal MRI is not indicated in low-risk pregnancies.

During a fetal MRI scan, the mother will be lying flat on a bed which moves into the scanner tube while a special magnet rotates around in the tube so that images can be acquired. The MRI is quite noisy and so mothers are given a headset with earplugs. Image acquisition typically takes about 30-45 minutes. Mothers with severe claustrophobia may not tolerate an MRI scanner. If you are very anxious, we can offer a small oral dose of medicine (similar to “Valium”) to help you relax. The MRI images are interpreted by a specialized radiologist, which usually takes 1-2 days, unless urgent.

MRI scanners are available at Mount Sinai Hospital and the Hospital for Sick Children. No special preparation is necessary. Mothers are asked to sign a standard consent form before having an MRI.  The MRI department will contact you directly with your appointment time.




Special Pregnancy Program

Referrals »

Fetal Medicine: 416-586-4800 x 7756
Fax: 416-586-3216

Maternal Medicine: 416-586-4800 x 7000
Fax: 416-586-5109

Main clinic hours: Monday to Friday, 8am to 4pm

Prenatal Diagnosis & Medical Genetics

Referrals »

phone: 416-586-4800 x 4523
fax numbers:
416-586-4723 or 416-586-8384

Perinatal Mental Health

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Phone: 416-586-4800 x 8325
Fax: 416-586-8596