Test Entry – US Atlas (Library@ObG)
Key Points:
General Notes
- Exercise caution with gender discordance between NIPS and ultrasound
- NIPS is a screening test only
- Invasive testing (amniocentesis or CVS) is considered diagnostic
- Gender determination should be done using both mid-sagittal and axial views
Male
- Sagittal view
- Penis and scrotum should be seen below the cord insertion
- Axial view
- Inability to differentiate penis distinctly from scrotum on axial view should raise suspicion for hypospadias or ambiguous genitalia
Figure 48 (NOTE – Top row should be labelled ‘sagittal view’ ; Lower row should be labelled ‘axial view’)
- Penis
- Scrotum
- Leg
Female
- Sagittal view
- In 2nd trimester, the mons pubis/female genitalia should appear flat
- Axial view
- Three distinct lines should be seen on axial view representing the labia
Figure 49 (NOTE – Top row should be labelled ‘sagittal view’ ; Lower row should be labelled ‘axial view’)
- Bladder
- Mons pubis
- Umbilical cord
- Labia
- Thigh
Important to Note
- If ever in doubt as to whether findings are ‘within normal’, refer for specialized (also known as targeted or detailed) ultrasound
- ACOG/SMFM recommends offering invasive testing using microarray for fetal structural anomalies detected on prenatal ultrasound
Learn More – Primary Sources:
Callen’s Ultrasonography in Obstetrics and Gynecology, 6th edition, ISBN 9780323328340
