Pregnancy NT Scan - Twins Ultrasound Scan

Expecting twins is twice the excitement—and also twice the questions. One of the earliest milestones in a twin pregnancy is the Pregnancy NT Scan - Twins Ultrasound Scan. This simple, non-invasive ultrasound, performed between 11 and 13 weeks + 6 days, screens each baby for chromosome conditions and structural anomalies while confirming how the twins share the placenta and amniotic sacs. Cadabams Diagnostics specializes in high-resolution twin NT scans, giving parents clear answers the same day. Below, we break down everything you need to know before your appointment.

“NT” stands for nuchal translucency, a small collection of fluid at the back of each baby’s neck. In a twin pregnancy, the sonographer measures this fluid in Twin A and Twin B separately with ultrasound. A thicker-than-normal measurement can signal a higher chance of Down syndrome, trisomy 18 or trisomy 13, while a normal range offers early reassurance. Because twins share the womb space, the scan also checks chorionicity (whether the babies share one placenta or each has their own) and amnionicity (whether they share an amniotic sac). These details guide future monitoring and delivery planning.

Type Use Case Transabdominal Standard approach; requires comfortably full bladder Transvaginal Used when abdominal pictures are unclear or in mothers with high BMI

• NT thickness Twin A and Twin B
• Crown–rump length (CRL) of each twin
• Chorionicity and amnionicity determination
• Presence or absence of nasal bone in each twin
• Ductus venosus blood-flow pattern
• Early check for major structural defects

1. Screen for Down syndrome, trisomy 18, and trisomy 13 in both babies
2. Detect early structural anomalies (heart, brain, abdominal wall)
3. Decide whether additional testing is required
4. Confirm chorionicity—critical for later twin-to-twin-transfusion monitoring

• Ideal timing: 11 weeks + 0 days to 13 weeks + 6 days
• Who: All dichorionic (separate placentas) and monochorionic (shared placenta) twin pregnancies
• Why early booking matters: Twin slots fill quickly; reserve as soon as your obstetrician refers you.

• Non-invasive first-line screening—no needles, no risk
• Same-day results with printed color images
• Fetal-medicine specialist review—every scan is double-checked
• Detailed chorionicity check—guides ongoing twin care
• Early reassurance or timely intervention pathway

• Drink 500 ml of water 45 minutes before the appointment.
• Wear loose, two-piece clothing for easy abdominal access.
• Bring previous pregnancy records (if any).
• Do not empty your bladder fully before the scan.

• Referral: A referral from your obstetrician is required.
• Booking: Call Cadabams Diagnostics at least 7–10 days in advance to secure a twin slot.

1. Check-in & history: Verify identity, last menstrual period, and previous records.
2. Ultrasound: 20–30 minute high-resolution scan of each twin.
3. Review: Images interpreted by a fetal-medicine specialist.
4. Report: Color printout and digital copy; risk assessment explained on the same day.

• Keep bladder comfortably full—do not empty fully.
• Report any vaginal bleeding or pain to the sonographer before the scan begins.

• Safety: Ultrasound uses sound waves—no radiation, no known harm to mother or babies.
• Lower detection rate: Screening accuracy in twins is ~75–80 %, slightly below singleton pregnancies.
• Possible inconclusive results: High NT may prompt NIPT (Non-Invasive Prenatal Testing) or invasive procedures like CVS (Chorionic Villus Sampling).