When talking about what cannot be seen in an anomaly scan, despite the fact that anomaly scans are used to track the growth of fetal organs and body parts and can find some congenital defects, there are few things that cannot be seen in anomaly scan.

1. During an anomaly scan, almost all the parts like lungs, heart, brain are in the developing stage. We can see if there are any major issues in the brain, if there is fluid present or if the joining between the two sides of the brain is good.
2. The size of the head can become smaller to some babies during the 7th or 8th month which cannot be seen in the anomaly scan as it is usually done in the 5th month.
3. White matter and gray matter forms in the brain only after 7 or 8th month of gestation and it cannot be seen in the anomaly scan.
4. The IQ of the baby cannot be seen in an anomaly scan. Most pregnant mothers are eager to know about the IQ of the baby or whether or not the baby has autism or other conditions. But unfortunately, it cannot be seen in an anomaly scan.
5. We do not count the fingers of the baby as the position of the baby cannot let us predict the number of fingers. But what we see is all three segments of the hand like the arm, forearm and fingers.
6. The time when we count the digits of the baby’s fingers and toes is if there is any family history where the mother has 6 fingers or if the father has some fused fingers. So in these cases, we take time to analyze it well.
7. We can only check the baby’s growth, blood flow and other vital information only in the growth scan and not in an anomaly scan. But we cannot see the hands and legs clear;y in the growth scan as they will start folding them. So it is mandatory to check it in the anomaly scan.
8. Late onset anomaly is when we can see certain issues like the issues in the diaphragm which would have been normal in the 5th month scan or fluid in the head, or tilted foot , etc.
9. Another important thing that cannot be seen in an anomaly scan is the functioning of the kidney. The kidneys can be monitored only later on in the pregnancy as the baby passes more urine as it grows. So the abdomen and the kidneys should be seen only in the later stages of pregnancy that is 7th or 8th month.
10. The genitals of the baby are seen and documented by the doctors in the 5th month scan but will not be discussed with the patient due to the rules and regulation by the government of india. However, the genitals like the scrotum and its positioning are too small to examine during the 5th month and cannot be seen in anomaly scan properly. So they are clearly monitored only during the 8th month scan.
11. We cannot detect any chromosomal abnormalities in the baby in the 5th month scan. We cannot see the abnormalities as the scan is predominantly used only to see the baby parts.
12. According to the protocol of the UK foundation, we do not necessarily have to see the ears of the baby as the outer part of the ear does not necessarily impact the hearing and only the inner part of the ears can actually help process waves and signals the brain. We can see the baby’s ear in the 5th month only if they lie on the sides. 
13. Heart is yet another important part of a baby’s body. We can only check if all the chambers of the heart, the arteries, the valves and the blood flow. But small holes like less than 5mm cannot be seen in anomaly scan. 
14. We check if the baby has 2 eyes. We cannot see the nerves and arteries of the eye in the scan. 
15. We can ofcourse find if the baby has any cleft lip and palate issues in the scan. However if the lips are normal and if the palette has some issues, we cannot predict it in an ultrasound. Most people aren’t aware of this as the mouth has hard bones and shadows will be reflected in the ultrasound, we won’t be able to see it.
16. 3D and 4D isn’t essential for everyone. 2D is the best way to see the baby. 

The things that affect the anomaly scan: