An early pregnancy scan (less than 12 weeks) is indicated when there is bleeding or pain in early pregnancy, or concern about pregnancy loss (section 88 codes TA and EP, see Appendix 1).
Required clinical details
- Woman’s symptoms
- βhCG if available
- Previous relevant history
- Appropriate section 88 code
- Previous caesarean section.
Early pregnancy loss ultrasound examination
No guidelines exist for TA assessment of pregnancy loss, and therefore TV assessment should always be offered.
The scan should include imaging of the following structures (if present).
- Sac location and size (MSD)
- Relationship of the sac to previous caesarean section scar (see Appendix 2: Low gestational sac in the first trimester with previous caesarean section)
- Yolk sac
- Embryo (fetal pole)
- Embryonic cardiac activity – document with a cine clip if possible; otherwise annotate cardiac activity present or absent on the relevant image
- Absent cardiac activity may be confirmed with colour Doppler assessment if required
- Assess region(s) of haemorrhage
- Assess chorionicity and amnionicity of multiple pregnancy (PDF, 318 KB) (see NZMFMN 2015f)
- Adnexa (document any adnexal masses and free fluid)
- Document fibroids (size and location)
- Document free fluid in acute presentations.
Diagnosis of early pregnancy loss
An experienced practitioner using high-quality TV equipment may diagnose pregnancy loss under any of the following circumstances.
At initial or follow-up scan:
- when the MSD is ≥25 mm with no visible yolk sac or embryo; or
- when there is a visible embryo with CRL ≥7 mm, but no cardiac activity can be demonstrated. The area of the embryonic heart should be observed and documented with a cine clip if possible; otherwise annotate cardiac activity present or absent on the relevant image.
On follow-up scan:
- if the initial scan showed an embryo CRL <7 mm with no cardiac activity and a repeat scan in seven or more days also shows no cardiac activity
- if the initial scan showed a MSD ≥12 mm with no embryo and a repeat scan in 7 or more days does not show interval development of a yolk sac or an embryo
- if the initial scan showed a MSD <12 mm with no embryo and a repeat scan in 14 or more days shows no visible yolk sac or embryo
- if a yolk sac is visible on initial scan and there is no embryo with a heartbeat after 11 days
- absence of cardiac activity, which was seen to be present on an earlier scan.
Seek a second opinion: where there is any doubt about a diagnosis of pregnancy loss or if the practitioner is inexperienced.
If required, a follow-up scan in 1 week or more is recommended. If the MSD is <10 mm at the initial scan, a follow-up scan should be performed more than 14 days later.
No guidelines exist for TA assessment of pregnancy loss. If the woman declines TV imaging, then cautious clinical judgement must be used, with low threshold for follow‑up imaging, ideally with a 14-day interval.
For more information, see the articles:
- Defining safe criteria to diagnose miscarriage: prospective observational multicentre study (PDF, 742 KB) (Preisler et al 2015)
- Diagnostic criteria for nonviable pregnancy early in the first trimester (Doubilet et al 2013).