Third-trimester obstetrical ultrasound
A third trimester ultrasound scan generally provides information on fetal growth and well-being as well as placental function. In some circumstances, it can also diagnose malformations that were not visible on a second trimester ultrasound. It can be performed between the 26th and 40th weeks of pregnancy, but is more frequently done between the 28th and 34th weeks. This ultrasound is non-invasive since the technologist scans the surface of the mother’s belly with a probe.