The anatomy scan is also sometimes called the morphology scan, 19-week scan, mid-trimester ultrasound or routine 18-to-20-week ultrasound examination. It is the main ultrasound of the pregnancy, and is timed to check all the structures of the fetus, as well as assess placental position. If there is only to be one ultrasound during a pregnancy it should be at this time.
The fetal head, brain, face, lips, chest, heart, stomach, abdominal wall (umbilical cord insertion), kidneys, bladder, spine, arms, legs, hands, and feet are examined. The fetal gender can almost always be disclosed at 19 weeks if requested, in our practice.
A well timed examination is expected to detect the majority of major fetal structural malformations. It is important to appreciate that even with the best ultrasound equipment, an experienced examiner and good views not all abnormalities may be detectable. This is easiest to understand where the condition causes no structural changes in the fetus, or where the abnormality only develops in later pregnancy. The 19 week timing is chosen for many reasons – the fetus is large enough to examine properly in almost all cases, and the pregnancy is still early enough to for parents to consider all options if severe problems are found. Another important reason is that abnormalities do not commonly arise after this time.
You will be told if a problem is detected, even before your referring doctor knows. Sometimes it is possible to say exactly what the problem is; at other times further tests are required. Follow-up may be advised to clarify. You will be given information on whether the condition is likely to be severe or minor. A second opinion ultrasound is always available since it is often difficult to accept important news from someone you do not know well.