12–13+6 week scan reporting guide and pro forma

Minimum reporting requirements

1. Dating information: CRL, BPD
2. Fetal anatomy documentation
3. NT measurement if combined screening is planned (best of at least three technically appropriate measurements).

Do not perform risk assessment in the Fetal Medicine Foundation (FMF) software. The report must be sent to the referrer and the laboratory.

The laboratory services will provide the referrer with the combined screening risk after combination with first-trimester maternal blood results (PAPP-A and hCG).

If NT ≥3.5 mm (or there is a cystic hygroma), report in the following manner.

‘NT is …, increased. Referral to the Fetal Maternal Medicine Unit or local specialist service is recommended in all cases where NT ≥3.5 mm because of increased association with cardiac anomalies.’

If NT is required and cannot be obtained on the first attempt, consider a TV scan.

A further separate attempt at NT may be made (using section 88 code NF). More than two attempts on separate occasions is not recommended.

If assessment of anatomy is limited, for example, by retroverted uterus or maternal habitus, consider a TV scan.

If the woman presents for NT assessment but gestation is <12 weeks (but CRL is >45 mm) and there is excellent visualisation, NT assessment may be performed. However, anatomy assessment (particularly visualisation of the fetal bladder and skull ossification) may be limited and follow-up may still be required.

If the woman presents for NT assessment but gestation >13+6 weeks (or CRL >84 mm), perform fetal biometric and anatomic assessment as for an NT scan but do not measure the NT.

Report in the following manner.

‘The gestational age is [ ] weeks [ ] days, too late for NT risk assessment (possible only for CRL <84 mm). Second-trimester maternal serum screening, or NIPS (not publicly funded), may be considered.’

Fetal nasal bone

Fetal nasal bone is no longer part of combined screening in New Zealand as per the National Screening Unit (NSU) recommendation (PDF, 174 KB) (Ministry of Health 2018) and should not be reported.

Normal 12–13+6 week first-trimester scan

Clinical details

NT scan: for combined screening

LMP: [ ]

EDD by today’s ultrasound: [ ]. (EDD by dates: [ ])*

Gestational age: [ ] weeks, [ ] days ± 7 days

(Gestational age by dates: [ ] weeks, [ ] days).*

*   May be included to highlight any discrepancy between ultrasound and clinical dates in the first scan of the pregnancy but should not be used after this.

First trimester ultrasound
Uterus: anteverted
Fetal heart action present.

CRL: [ ] mm
BPD: [ ] mm
NT: [ ] mm.

Fetal anatomy: skull/brain: appears normal; heart: not fully examined due to early gestation; spine: appears normal; abdomen: appears normal; stomach: visible; bladder: visible; hands: both visible; feet: both visible.

Placenta: [anterior/posterior]
Amniotic fluid: [normal].

Comment

Normal first trimester scan. NT= [ ] mm.
Combined screening is planned, therefore risk assessment has not been performed.
Sonographer: [name], [FMF number].

Increased NT ≥3.5 mm

Normal first trimester anatomy. Increased NT, [ ] mm. Combined screening is planned, therefore risk assessment has not been performed.

A referral to Fetal Medicine or local equivalent specialist is recommended as NT ≥3.5 mm. An early detailed fetal heart scan should be considered at 16 weeks.

Gestation >13+6 weeks (CRL >84 mm)

Single live intrauterine pregnancy, [ ] weeks [ ] days ± 7 days by today’s scan. It is too late for NT assessment (only possible for CRL between 56 and 84 mm). Second-trimester maternal serum screening, or NIPS (not publicly funded), may be considered.

Gestation <12 weeks (CRL <56 mm)*

Single live intrauterine pregnancy, [ ] weeks [ ] days ± [ ] days by today’s scan. It is too early for accurate NT assessment. A follow-up scan has been arranged for [ ].

*   Unless excellent visualisation of NT and fetal anatomy and CRL ≥45 mm.

Incomplete NT scan

Single live intrauterine pregnancy, [ ] weeks [ ] days ± 7 days by today’s scan. NT assessment was limited by [persistent difficult position]. A follow-up scan has been arranged for [date].

Incomplete NT scan on second attempt

Single live intrauterine pregnancy, [ ] weeks [ ] days ± 7 days by today’s scan. NT assessment remained limited today by [persistent difficult position]. This was the second attempt at NT assessment. Second-trimester maternal serum screening, or NIPS (not publicly funded), may be considered.

12+ week scan, NT screening not requested/declined or post NIPS

Single live intrauterine pregnancy, [ ] weeks [ ] days ± 7 days by today’s scan. Normal first trimester anatomy scan.

NT requested in context of previous NIPS

NT measurement and combined screening assessment is not recommended in women with a previous NIPS result, and the NT should not be reported.

The exception is if the NT is ≥3.5 mm, as this is an independent reason for Fetal Medicine or other local equivalent specialist referral. Note: NIPS is not publicly funded.

Monochorionic-diamniotic twin pregnancy

Addend report:

Fortnightly scans to screen for twin-twin transfusion syndrome are recommended from 16 weeks.