At a routine nuchal translucency scan performed between 11 weeks and 13 weeks 6 days, which measured value of nuchal translucency is considered increased and warrants further evaluation for chromosomal anomaly as per standard screening practice?
- A > 1.5 mm
- B > 2.0 mm
- C > 3.5 mm ✓
- D > 5.0 mm
Correct answer: C. > 3.5 mm
Explanation
A nuchal translucency above the 99th centile, conventionally taken as greater than 3.5 mm, is considered abnormal irrespective of crown rump length and mandates karyotyping or chromosomal microarray along with detailed anomaly scanning. Values up to 3.5 mm are interpreted against gestational age specific centiles within combined first trimester screening. The other cutoffs are far below the accepted threshold used by the Fetal Medicine Foundation.
Reference: Diagnostic Imaging: Obstetrics, 5th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.