Senior Consultant, Fetal Medicine, Artemis Hospitals, Gurgaon, India
Part 3 of 7 in Diagnostic Utility of First Trimester Ultrasound
Nuchal Translucency: Why a High Reading Doesn't Mean What Patients Fear
June 21, 2026
Nuchal translucency (NT), fluid collection behind the fetal neck, is the single most important soft marker for trisomy 21, but Dr. Sablok is emphatic that a raw NT number means nothing without its centile. The FMF sets strict measurement criteria: the fetus must be in a neutral position, the image magnified to about 75% of the screen, a sagittal section obtained, and caliper placement precise: 'on to on.' If the cord is around the neck, NT is measured above and below it and averaged.
The reassurance in the data is significant: even when NT falls between the 95th and 99th centile, 93% of those fetuses are entirely normal. Even above the 99th centile (3.5 to 4.4mm), 70% are still completely healthy. A pregnancy should never be terminated on an elevated NT alone; the correct next step is referral to a fetal medicine specialist for thorough structural evaluation, since elevated NT can also flag facial, pulmonary, gastrointestinal, genitourinary and skeletal abnormalities alongside chromosomal ones.
This guide is based on a live Jivo Masterclass — Dr. Aanchal Sablok taught doctors across Africa on June 21, 2026.
FROM THE LIVE Q&A
How does the stage of CKD (chronic kidney disease) affect the risk of preeclampsia?
Dr. Aanchal Sablok
If the mother already has chronic kidney disease, she is already at risk of chronic hypertension. When placental implantation occurs on top of this background, the relevant terminology is preeclampsia superimposed on chronic hypertension. This represents an even higher risk of developing preeclampsia, particularly in the presence of chronic renal disease, chronic hypertension, or other conditions such as autoimmune disease. The risk of fetal growth restriction (small for gestational age) is also correspondingly higher in this group.
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Frequently Asked Questions
What is nuchal translucency measuring?▼
Nuchal translucency (NT) is the fluid collection behind the fetal neck and is the single most important soft marker for trisomy 21.
How strict are the criteria for measuring NT correctly?▼
The FMF sets exacting measurement criteria: the fetus must be in a neutral position, the image magnified to about 75% of the screen, a sagittal section obtained, and caliper placement precise, described as "on to on." If the cord is around the neck, NT is measured above and below it and the two readings averaged.
Does an elevated NT reading mean the baby has Down syndrome?▼
Not necessarily, and a raw NT number means nothing without its centile. Even when NT falls between the 95th and 99th centile, 93% of those fetuses are entirely normal, and even above the 99th centile (3.5 to 4.4mm), 70% are still completely healthy.
What should happen after an elevated NT result?▼
A pregnancy should never be terminated on an elevated NT alone. The correct next step is referral to a fetal medicine specialist for thorough structural evaluation.
What else besides chromosomal conditions can an elevated NT indicate?▼
Elevated NT can also flag facial, pulmonary, gastrointestinal, genitourinary and skeletal abnormalities alongside chromosomal ones, which is why specialist follow-up matters.
In This Series: Diagnostic Utility of First Trimester Ultrasound
- 1.Diagnostic Utility of First Trimester Ultrasound
- 2.Screening for Down Syndrome: How Detection Rates Evolved From 30% to 96%
- 3.Nuchal Translucency: Why a High Reading Doesn't Mean What Patients Fear
- 4.Structural Abnormalities the First-Trimester Scan Can Already Catch
- 5.Preeclampsia Screening: Uterine Artery Doppler, PLGF, and the New Role of the Ophthalmic Artery
- 6.Predicting Preterm Labour: Why Cervical Length Should Be Measured at 12 Weeks
- 7.The Inverted Pyramid of Care: Rethinking When Pregnant Women Should Be Seen