Clinical Considerations in the Second Trimester Between 22 0/7 weeks and 27 6/7 weeks of gestation, ultrasonography dating has an accuracy of ± 10–14 days 19.

What stage is an ultrasound done in the second trimester?

Second trimester - ultrasound performed between weeks 18 and 20 is used to check the development of fetal structures such as the spine, limbs, brain and internal organs. The size and location of the placenta is also checked. The babys sex can be established, if the parents wish to know.

Can ultrasound weeks be wrong?

As pregnancy progresses, the accuracy of an ultrasound for predicting due dates decreases. Between 18 and 28 weeks of gestation, the margin of error increases to plus or minus two weeks. After 28 weeks, the ultrasound may be off by three weeks or more in predicting a due date.

What are the chances of something going wrong at 20-week scan?

Miscarriage or health problems at 20 weeks The overall risk of miscarriage after this time is only about 3%. Theres a small chance that the scan might pick up a serious health problem or complication. Some abnormalities wont be seen on a scan at all or cant be seen until later in the pregnancy.

What are the chances of abnormalities at 20-week scan?

defect of the spinal cord (spina bifida): 90 per cent. major kidney problems (missing or abnormal kidneys): 84 per cent. hole in the muscle separating chest and abdomen (diaphragmatic hernia): 60 per cent. Edwards syndrome or Pataus syndrome (chromosomal abnormalities): 95 per cent.

Will everything be OK at 20 week scan?

The 20-week screening scan looks in detail at the babys bones, heart, brain, spinal cord, face, kidneys and abdomen. It allows the sonographer to look for 11 rare conditions. The scan only looks for these conditions, and cannot find everything that might be wrong.