Pregnancy Dating Ultrasound Scan

• Purpose: Measure gestational age and establish a reliable due date
• Timing: Most accurate at 6–9 weeks after your last menstrual period (LMP)
• Impact: Provides the baseline for every future prenatal test, screening, and appointment

A pregnancy dating ultrasound scan is a painless imaging test that uses high-frequency sound waves to capture real-time images of your uterus and embryo. Unlike later anatomy scans that check organ formation, this early scan focuses on size, location, and heartbeat to pinpoint gestational age.

• Crown-rump length (CRL) – most accurate dating metric
• Gestational sac diameter – confirms intrauterine pregnancy
• Yolk sac presence & size – indicates healthy early placenta formation
• Fetal heartbeat rate – should be 90–110 bpm at 6 weeks and rise steadily

1. Accurate due date – avoids induction or premature delivery
2. Confirm intrauterine pregnancy – rules out ectopic risks
3. Early detection of miscarriage or molar pregnancy

• Ideal window: 6–9 weeks from LMP
• Must-have if you: • Have irregular periods • Are unsure of your LMP date • Have conceived via assisted reproduction
• Not needed if you already have an accurate dating scan from another provider

• Reassurance & bonding – see your baby’s heartbeat for the first time
• Optimised scheduling – perfect timing for NIPT, NT scan, and anomaly scan
• Prevents unnecessary interventions – precise dating reduces false alarms

• Wear loose, two-piece clothing for easy abdominal access
• Bring your partner or a support person—our rooms are designed for two
• Mental prep: Ask questions; we explain every image on-screen

• Positive home pregnancy test or doctor referral
• Record of your last menstrual period—even approximate dates help

• Optimal: 6–9 weeks gestation
• Avoid: Before 5 weeks to minimise inconclusive results
• Tip: Book as soon as you miss a period and get a positive test

• Suitable for: All pregnant women, especially those unsure of LMP
• Not suitable for: Confirmed miscarriages or non-pregnant individuals

1. Check-in with ID and referral at Cadabams Diagnostics reception
2. Pre-scan brief – you’ll be asked about symptoms and LMP
3. Positioning – lie comfortably on the ultrasound couch
4. Scanning – 15–30 minutes of gentle imaging
5. Instant report – printed and emailed to you and your doctor

• Report any bleeding, pain, or dizziness to the sonographer
• Bladder: • Full for transabdominal scan • Empty if transvaginal scan is likely—follow the SMS instructions we send

• Safety: • Zero radiation—only harmless sound waves • No known side-effects for mother or baby
• Limitations: • Heartbeat may not yet be visible before 5.5 weeks • Too-early scans can lead to inconclusive results