Dating scan nuchal fold
Lower frequencies provide better penetration but at the expense of resolution.
Selection of the proper transducer is based on the clinical situation; however, with modern equipment, abdominal transducers generally allow sufficient penetration in most patients while providing adequate resolution.
When technical limitations result in suboptimal images, the nature of the limitations should be documented in the report; a follow-up examination should be considered.
To ensure that the ultrasound equipment is operating at a safe and optimal level, regular service should be performed as recommended by the manufacturer.
ACR-ACOG-AIUM-SRU Practice parameter for the performance of obstetrical ultrasound. An ultrasound examination may be performed either transabdominally or transvaginally.
ACR, Diagnostic Radiology: Ultrasonography Practice Parameters and Technical Standards, 2013. If a transabdominal examination is inconclusive, a transvaginal scan or transperineal scan is recommended.
The necessary components of fetal anatomy in a standard examination are listed in Box 1 and commonly can be obtained after approximately 18 weeks of gestation, although it may be possible to document normal structures before this time.
Sometimes structures can be difficult to visualize because of fetal size, position, and movement; maternal abdominal scars; increased maternal abdominal wall thickness; and reduced amniotic fluid volume.
Without these findings, an intrauterine fluid collection could represent a pseudogestational sac associated with an ectopic pregnancy.