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Normal first-trimester scan

These guidelines were published in 2019 and are awaiting review, due 2022. Some content may be outdated.

 Clinical

[ ]

LMP: [ ]
 
EDD by today’s ultrasound: [ ]. (EDD by dates: [ ])*
Gestational age: [ ] weeks, [ ] days ± 4 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.

 

Findings

[TA/TV] scan
Anteverted uterus
There is a single live intrauterine pregnancy
CRL = [ ] mm
Heartbeat seen, rate = [ ] bpm.

Right ovary: [normal size and appearance]
Left ovary: [normal size and appearance]
No adnexal abnormality.

 

Comment

Single live intrauterine pregnancy, [ ] weeks [ ] days ± [ ] days by scan today.
No complications.

Ultrasound findings

Intrauterine fluid collection, uncertainty whether or not early sac

Probable early intrauterine pregnancy, approximately 4 weeks ± 4 days. No yolk sac or embryo is evident, too early to confirm live intrauterine pregnancy.

There are no specific ultrasound features to suggest an ectopic pregnancy, but this cannot be entirely excluded.

If appropriate, βhCG correlation and a follow-up scan in 14 days could be considered, if there is low clinical likelihood of ectopic pregnancy.

Intrauterine sac containing a yolk sac

Early intrauterine pregnancy, 5½ weeks ± 4 days. A yolk sac is evident but no embryo, too early to confirm live intrauterine pregnancy.

If there is clinical concern, βhCG correlation and a follow-up scan in 14 days is recommended. 

Pregnancy loss with CRL ≥7 mm and no cardiac activity 

Unfortunately, appearances today are those of early pregnancy loss, [ ] weeks, [ ] days by CRL. [Woman’s name] is aware of the findings, and the results have been telephoned to [referrer’s name]. 

Embryo CRL <7 mm with no cardiac activity

Early intrauterine pregnancy [ ] weeks [ ] days ± 4 days by CRL. No cardiac activity is evident, possibly too early. A follow-up scan is suggested in 7 days to confirm ongoing pregnancy.

Empty sac MSD ≥12 mm but <25 mm

There is an empty gestational sac with MSD of [ ] mm. Appearances are concerning, however, ultrasound criteria for a pregnancy loss have not been met. Correlation with βhCG and a follow-up scan in 7 days is recommended.

Empty sac MSD <12 mm

There is an empty gestational sac with MSD of [ ] mm. Appearances are concerning, however, ultrasound criteria for a pregnancy loss have not been met. Correlation with βhCG and a follow-up scan in 14 days is recommended.

No intrauterine gestational sac without evidence of ectopic pregnancy / pregnancy of unknown location

An ectopic pregnancy cannot be excluded on this ultrasound alone. Please interpret scan with βhCG, using advice from gynaecology service or based on gynaecological protocols for PUL.

Serum βhCG

Beware: Very low or normal serum βhCG may occur in ectopic pregnancy.

The βhCG level alone should not be relied upon to exclude possible ectopic pregnancy; however, higher levels with an empty uterus increase suspicion of ectopic pregnancy and when beyond 1,500, specialist opinion should be sought.