Q: What is level II ultrasound (USG)? I am in the second trimester of my pregnancy and my doctor has suggested it to me. Is it special or different from the routine ultrasound that we get done?

A:A level II ultrasound scan refers to a special type of scan to assess the fetus for structural abnormalities. A qualified and experienced doctor, who has acquired the skill to do so does this. It is usually carried out between 18-22 weeks of pregnancy in order to detect fetal abnormalities that may compromise the quality of life, and gives the parents options for treatment or termination of the pregnancy. It is also called an Anomalies Scan or a Targeted Investigation for Fetal Anomalies. In India, the MTP act does not allow terminations after 20 weeks and, therefore, the level II study is done at 19 weeks of pregnancy. The weeks are counted from the first day of the last menstrual period. Historically, the title level II originated from the programme used for detecting neural tube defects in the USA and Europe in the seventies and early eighties. A level I scan was done to date the pregnancy and the mother's blood was checked for the levels of a chemical called alpha-feto protein. The result was compared to the levels expected in normal and abnormal pregnancies. If the level of this protein was high, the ultrasound was repeated at 16-22 weeks to assess the fetal head and spine. The latter was the level II scan. The term is now loosely used to cover any ultrasound that strives to confirm fetal structural normalcy. Abnormalities can be detected from the eleventh week of pregnancy onwards with appropriate expertise and equipment. The sensitivity is high after 18 weeks compared to the 11-17 weeks. Owing to technical and statistical limitations, not all abnormalities can be assessed on an ultrasound.