What a fetal ultrasound can and cannot reveal.
1st trimester: Ultrasound reveals the following pathologies:
• defects of the central nervous system (for example, anencephaly - absence of the brain);
• absence of the peritoneal wall (severe pathology - gastroschisis);
• spinal abnormalities - absence, hump, etc.;
• Down syndrome;
• umbilical hernia (diagnosis of omphalocele);
• absence of limbs.
2nd trimester: all visible abnormalities can be identified, since all organs of the fetus are almost formed by this time.
3rd trimester: defects previously identified by blood tests, chorionic villus biopsy and other methods are confirmed or refuted.
It is impossible to diagnose using ultrasound:
• blindness and deafness - ultrasound cannot show the quality of transmission of nerve impulses to visual and auditory receptors
• mental retardation, since these are properties of the brain, not its structure;
• minor disorders of organ development (for example, obstruction of the liver ducts or defects of the cardiac septum);
• some genetic diseases (for example, Duchenne myopathy, phenylketonuria, cystic fibrosis are not diagnosed);
• chromosomal abnormalities themselves (Edwards, Patau, Turner syndromes), the doctor can only observe the result of their development.
Having studied the list of problems that are not detected on fetal ultrasound, you should not worry - these pathologies will not go unnoticed. Many fetal malformations are detected by blood tests for fetal pathology and other special methods.