Ultrasound scan (in prenatal diagnosis)

An ultrasound scan is a non-invasive technique that has no associated risk for mother or fetus. Is the following undertaken to detect conditions which are detectable, although sometimes only with serial scans:

• CNS: anencephaly, spina bifida, hydrocephalus, microcephaly
• limb: severe short-limbed dwarfism, polydactyly, osteogenesis imperfecta
• heart: severe congenital heart disease
• kidney: renal agenesis, bladder outflow obstruction, infantile polycystic disease
• GIT: duodenal atresia, anterior abdominal wall defects, diaphragmatic hernia

Specific markers for chromosomal abnormalities include is an increased nuchal fold. Also bright bowel can alert to the suspicion of a pregnancy at risk of cystic fibrosis, if seen on scan screening both parents would be discussed.

An anomaly scan to pick up structural defects can be performed between 18+0-20+6 weeks.