No. 375-Clinical Practice Guideline on the Use of First Trimester Ultrasound



      This guideline reviews the clinical indications for first trimester ultrasound.


      Proven clinical benefit has been reported from first trimester ultrasound.


      A Medline search and bibliography reviews in relevant literature provided the evidence.


      Content and recommendations were reviewed by the principal authors and the Diagnostic Imaging Committee of the Society of Obstetricians and Gynaecologists of Canada. Levels of evidence were judged as outlined by the Canadian Task Force on Preventive Health Care.


      • 1
        First trimester ultrasound is recommended for assessment of threatened abortion to document fetal viability (II-2B) or for incomplete abortion to identify retained products of conception (II-2B).
      • 2
        First trimester ultrasound is not recommended to diagnose pregnancy but is recommended to date a pregnancy (ideally at 7–12 weeks). If menstrual dating is reliable and an early comprehensive pregnancy ultrasound (11–14 weeks) is planned, dating should be confirmed concurrently with this exam (III-A).
      • 3
        First trimester ultrasound is recommended prior to pregnancy termination (II-2B).
      • 4
        First trimester ultrasound is recommended during diagnostic or therapeutic procedures requiring visual guidance (e.g., chorionic villus sampling) and prior to prophylactic cervical cerclage placement (I-A).
      • 5
        First trimester ultrasound is recommended for suspected multiple gestation to allow for reliable determination of chorionicity and amnionicity and to establish early fetal genetic and anatomic screening (II-2A).
      • 6
        First trimester ultrasound is recommended in the workup for suspected ectopic pregnancy, molar pregnancy, and suspected pelvic masses (II-1A).
      • 7
        Basic fetal anatomy should be reviewed whenever obstetric ultrasound is done at 11–14 weeks, while women at increased risk of fetal structural and genetic abnormalities can be offered enhanced screening, if performed by ultrasound providers with appropriate imaging expertise (II-3C).
      • 8
        Nuchal translucency screening should be offered as part of a prenatal genetic screening and counselling program by experienced operators with appropriate quality assurance processes in place. Any patient with a nuchal translucency greater than 3.5 should be offered referral to maternal-fetal medicine (II-2A).
      • 9
        When appropriate expertise and resources are in place to screen women for the risk of preeclampsia, first trimester ultrasound is recommended as a valuable component of the screening protocol (I-A).

      Key Words

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Obstetrics and Gynaecology Canada
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Van den Hof MC
        359-obstetric ultrasound biological effects and safety.
        J Obstet Gynaecol Can. 2018; 40: 627-632
        • Woolf SH
        • Battista RN
        • Angerson GM
        • et al.
        Canadian Task Force on the Periodic Health Exam.
        Canada Communication Group, Ottawa1994
        • Ewigman B
        • LeFevre M
        • Hesser J
        A randomized trial of routine prenatal ultrasound.
        Obstet Gynecol. 1990; 76: 189-194
        • Neilson JP
        Ultrasound for fetal assessment in early pregnancy.
        Cochrane Database Syst Rev. 2000; CD000182
        • Butt K
        • Lim K
        • Diagnostic Imaging Committee
        Determination of gestational age by ultrasound.
        J Obstet Gynaecol Can. 2014; 36: 171-181
        • Selbing A
        • Fjallbrant B
        Accuracy of conceptual age estimation from fetal crown-rump length.
        J Clin Ultrasound. 1984; 12: 343-346
        • Crowley P
        Interventions for preventing or improving the outcome of delivery at or beyond term.
        Cochrane Database Syst Rev. 2000; CD000170
        • Mongelli M
        • Wong YC
        • Venkat A
        • et al.
        Induction policy and missed post-term pregnancies: a mathematical model.
        Aust N Z J Obstet Gynaecol. 2001; 41: 38-40
      1. Members of the SOGC Genetics Committee and Diagnostic Imaging Committee. The use of ultrasound in conjunction with maternal serum screening for aneuploidy. SOGC committee opinion No., August 1997. Available at: . Accessed on September 3,2003.

        • Salomon LJ
        • Alfirevic Z
        • Bilardo CM
        • et al.
        ISUOG practice guidelines: performance of first-trimester fetal ultrasound scan.
        Ultrasound Obstet Gynecol. 2013; 41: 102-113
        • Jouppila P
        Clinical consequences after ultrasonic diagnosis of intrauterine hematoma in threatened abortion.
        J Clin Ultrasound. 1985; 13: 107-111
        • Strobino BA
        • Pantel-Silverman J
        First-trimester vaginal bleeding and the loss of chromosomally normal and abnormal conceptions.
        Am J Obstet Gynecol. 1987; 157: 1150-1154
        • Everett CB
        • Preece E
        Women with bleeding in the first 20 weeks of pregnancy: value of general practice ultrasound in detecting fetal heart movement.
        Br J Gen Pract. 1996; 46: 7-9
        • Giorlandino C
        • Mobili L
        • Bilancioni E
        • et al.
        Transplacental amniocentesis: is it really a higher-risk procedure?.
        Prenat Diagn. 1994; 14: 803-806
        • Kurtz AB
        • Shlansky-Goldberg RD
        • Choi HY
        • et al.
        Detection of retained products of conception following spontaneous abortion in the first trimester.
        J Ultrasound Med. 1991; 10: 387-395
        • Darney PD
        • Atkinson E
        • Hirabayashi K
        Uterine perforation during second-trimester abortion by cervical dilation and instrumental extraction: a review of 15 cases.
        Obstet Gynecol. 1990; 75: 441-444
        • Ludmir J
        • Jackson GM
        • Samuels P
        Transvaginal cerclage under ultrasound guidance in cases of severe cervical hypoplasia.
        Obstet Gynecol. 1991; 78: 1067-1072
        • Goldstein SR
        • Danon M
        • Watson C
        An updated protocol for abortion surveillance with ultrasound and immediate pathology.
        Obstet Gynecol. 1994; 83: 55-58
        • Romero R
        • Jeanty P
        • Reece EA
        • et al.
        Sonographically monitored amniocentesis to decrease intraoperative complications.
        Obstet Gynecol. 1985; 65: 426-430
        • Bromley B
        • Benacerraf B
        Adnexal masses during pregnancy: accuracy of sonographic diagnosis and outcome.
        J Ultrasound Med. 1997; 16 (; quiz 53–4): 447-452
        • Rhoads GG
        • Jackson LG
        • Schlesselman SE
        • et al.
        The safety and efficacy of chorionic villus sampling for early prenatal diagnosis of cytogenetic abnormalities.
        N Engl J Med. 1989; 320: 609-617
      2. Randomised trial to assess safety and fetal outcome of early and midtrimester amniocentesis. The Canadian Early and Mid-trimester Amniocentesis Trial (CEMAT) Group.
        Lancet. 1998; 351: 242-247
        • Desai SK
        • Allahbadia GN
        • Dalal AK
        Selective reduction of multifetal pregnancies in the first trimester using colour Doppler ultrasonography.
        Hum Reprod. 1993; 8: 642-644
      3. National Institutes of Health Consensus Development Conference consensus statement. The use of diagnostic ultrasound imaging in pregnancy.
        Ultrasound Med Biol. 1984; 10: 547-556
        • Nicolaides KH
        • Heath V
        • Cicero S
        Increased fetal nuchal translucency at 11-14 weeks.
        Prenat Diagn. 2002; 22: 308-315
        • Nevo O
        • Brown R
        • Glanc P
        • et al.
        No. 352-technical update: the role of early comprehensive fetal anatomy ultrasound examination.
        J Obstet Gynaecol Can. 2017; 39: 1203-1211
        • Sepulveda W
        • Sebire NJ
        • Hughes K
        • et al.
        The lambda sign at 10-14 weeks of gestation as a predictor of chorionicity in twin pregnancies.
        Ultrasound Obstet Gynecol. 1996; 7: 421-423
        • Barrett J
        • Bocking A
        Management of twin pregnancies. Part I. SOGC consensus statement, No. 91, July 2000.
        J Soc Obstet Gynaecol Can. 2000; 22: 519-529
        • Dube J
        • Dodds L
        • Armson BA
        Does chorionicity or zygosity predict adverse perinatal outcomes in twins?.
        Am J Obstet Gynecol. 2002; 186: 579-583
        • Morin L
        • Lim K
        No. 260-Ultrasound in twin pregnancies.
        J Obstet Gynaecol Can. 2017; 39: e398-e411
        • Fleischer AC
        • Pennell RG
        • McKee MS
        • et al.
        Ectopic pregnancy: features at transvaginal sonography.
        Radiology. 1990; 174: 375-378
        • Dashefsky SM
        • Lyons EA
        • Levi CS
        • et al.
        Suspected ectopic pregnancy: endovaginal and transvesical US.
        Radiology. 1988; 169: 181-184
        • Turner LA
        • Cyr M
        • Kinch RA
        • et al.
        Under-reporting of maternal mortality in Canada: a question of definition.
        Chronic Dis Can. 2002; 23: 22-30
        • Soussis I
        • Dimitry ES
        • Oskarsson T
        • et al.
        Diagnosis of ectopic pregnancy by vaginal ultrasonography in combination with a discriminatory serum hCG level of 1000 IU/L (IRP) [comment on Br J Obstet Gynaecol 1990;97:904–8].
        Br J Obstet Gynaecol. 1991; 98: 233
        • Fleischer AC
        • Pennell RG
        • McKee MS
        • et al.
        Ectopic pregnancy: features at transvaginal sonography.
        Radiology. 1998; 197: 375-378
        • Cacciatore B
        • Stenman UH
        • Ylostalo P
        Early screening for ectopic pregnancy in high-risk symptom-free women.
        Lancet. 1994; 343: 517-518
        • Kobayashi M
        Use of diagnostic ultrasound in trophoblastic neoplasms and ovarian tumors.
        Cancer. 1976; 38: 441-452
        • Jauniaux E
        Ultrasound diagnosis and follow-up of gestational trophoblastic disease.
        Ultrasound Obstet Gynecol. 1998; 11: 367-377
        • Jauniaux E
        • Nicolaides KH
        Early ultrasound diagnosis and follow-up of molar pregnancies.
        Ultrasound Obstet Gynecol. 1997; 9: 17-21
        • Bakri YN
        • Berkowitz RS
        • Khan J
        • et al.
        Pulmonary metastases of gestational trophoblastic tumor. Risk factors for early respiratory failure.
        J Reprod Med. 1994; 39: 175-178
        • Valentin L.
        Pattern recognition of pelvic masses by gray-scale ultrasound imaging: the contribution of Doppler ultrasound.
        Ultrasound Obstet Gynecol. 1999; 14: 338-347
        • Wheeler TC
        • Fleischer AC
        Complex adnexal mass in pregnancy: predictive value of color Doppler sonography.
        J Ultrasound Med. 1997; 16: 425-428
        • Fries N
        • Salomon LJ
        • Muller F
        • et al.
        Impact of a shift in nuchal translucency measurements on the detection rate of first-trimester Down syndrome screening: a population-based study.
        Prenat Diagn. 2018; 38: 106-109
        • Brambati B
        • Cislaghi C
        • Tului L
        • et al.
        First-trimester Down's syndrome screening using nuchal translucency: a prospective study in patients undergoing chorionic villus sampling.
        Ultrasound Obstet Gynecol. 1995; 5: 9-14
        • Comas C
        • Martinez JM
        • Ojuel J
        • et al.
        First-trimester nuchal edema as a marker of aneuploidy.
        Ultrasound Obstet Gynecol. 1995; 5: 26-29
        • Nicolaides KH
        • Azar G
        • Byrne D
        • et al.
        Fetal nuchal translucency: ultrasound screening for chromosomal defects in first trimester of pregnancy.
        BMJ. 1992; 304: 867-869
        • Nicolaides KH
        • Brizot ML
        • Snijders RJ
        Fetal nuchal translucency: ultrasound screening for fetal trisomy in the first trimester of pregnancy.
        Br J Obstet Gynaecol. 1994; 101: 782-786
        • Pandya PP
        • Snijders RJ
        • Johnson SP
        • et al.
        Screening for fetal trisomies by maternal age and fetal nuchal translucency thickness at 10 to 14 weeks of gestation.
        Br J Obstet Gynaecol. 1995; 102: 957-962
        • Pandya PP
        • Brizot ML
        • Kuhn P
        • et al.
        First-trimester fetal nuchal translucency thickness and risk for trisomies.
        Obstet Gynecol. 1994; 84: 420-423
        • Snijders RJ
        • Noble P
        • Sebire N
        • et al.
        UK multicentre project on assessment of risk of trisomy 21 by maternal age and fetal nuchal-translucency thickness at 10-14 weeks of gestation. Fetal Medicine Foundation First Trimester Screening Group.
        Lancet. 1998; 352: 343-346
        • Spencer K
        • Spencer CE
        • Power M
        • et al.
        Screening for chromosomal abnormalities in the first trimester using ultrasound and maternal serum biochemistry in a one-stop clinic: a review of three years prospective experience.
        BJOG. 2003; 110: 281-286
        • Spencer K
        • Nicolaides KH
        A first trimester trisomy 13/trisomy 18 risk algorithm combining fetal nuchal translucency thickness, maternal serum free beta-hCG and PAPP-A.
        Prenat Diagn. 2002; 22: 877-879
        • Spencer K
        • Ong C
        • Skentou H
        • et al.
        Screening for trisomy 13 by fetal nuchal translucency and maternal serum free beta-hCG and PAPP-A at 10-14 weeks of gestation.
        Prenat Diagn. 2000; 20: 411-416
        • Snijders RJ
        • Sebire NJ
        • Nayar R
        • et al.
        Increased nuchal translucency in trisomy 13 fetuses at 10-14 weeks of gestation.
        Am J Med Genet. 1999; 86: 205-207
        • Spencer K
        • Liao AW
        • Skentou H
        • et al.
        Screening for triploidy by fetal nuchal translucency and maternal serum free beta-hCG and PAPP-A at 10-14 weeks of gestation.
        Prenat Diagn. 2000; 20: 495-499
        • Spencer K
        • Tul N
        • Nicolaides KH
        Maternal serum free beta-hCG and PAPP-A in fetal sex chromosome defects in the first trimester.
        Prenat Diagn. 2000; 20: 390-394
        • Souka AP
        • Snijders RJ
        • Novakov A
        • et al.
        Defects and syndromes in chromosomally normal fetuses with increased nuchal translucency thickness at 10-14 weeks of gestation.
        Ultrasound Obstet Gynecol. 1998; 11: 391-400
        • Hyett J
        • Perdu M
        • Sharland G
        • et al.
        Using fetal nuchal translucency to screen for major congenital cardiac defects at 10-14 weeks of gestation: population based cohort study.
        BMJ. 1999; 318: 81-85
        • Jr Landwehr JB
        • MP Johnson
        • Hume RF
        • et al.
        Abnormal nuchal findings on screening ultrasonography: aneuploidy stratification on the basis of ultrasonographic anomaly and gestational age at detection.
        Am J Obstet Gynecol. 1996; 175: 995-999
        • Pandya PP
        • Kondylios A
        • Hilbert L
        • et al.
        Chromosomal defects and outcome in 1015 fetuses with increased nuchal translucency.
        Ultrasound Obstet Gynecol. 1995; 5: 15-19
        • Kornman LH
        • Morssink LP
        • Beekhuis JR
        • et al.
        Nuchal translucency cannot be used as a screening test for chromosomal abnormalities in the first trimester of pregnancy in a routine ultrasound practice.
        Prenat Diagn. 1996; 16: 797-805
        • Bewley S
        • Roberts LJ
        • Mackinson AM
        • et al.
        First trimester fetal nuchal translucency: problems with screening the general population. 2.
        Br J Obstet Gynaecol. 1995; 102: 386-388
        • Hafner E
        • Schuchter K
        • Philipp K
        Screening for chromosomal abnormalities in an unselected population by fetal nuchal translucency.
        Ultrasound Obstet Gynecol. 1995; 6: 330-333
        • Spencer K
        Screening for trisomy 21 in twin pregnancies in the first trimester using free beta-hCG and PAPP-A, combined with fetal nuchal translucency thickness.
        Prenat Diagn. 2000; 20: 91-95
        • Kagan KO
        • Cicero S
        • Staboulidou I
        • et al.
        Fetal nasal bone in screening for trisomies 21, 18 and 13 and Turner syndrome at 11-13 weeks of gestation.
        Ultrasound Obstet Gynecol. 2009; 33: 259-264
        • Carmichael JB
        • Liu HP
        • Janik D
        • et al.
        Expanded conventional first trimester screening.
        Prenat Diagn. 2017; 37: 802-807
        • Alldred SK
        • Takwoingi Y
        • Guo B
        • et al.
        First trimester ultrasound tests alone or in combination with first trimester serum tests for Down's syndrome screening.
        Cochrane Database Syst Rev. 2017; CD012600
        • Kenkhuis MJA
        • Bakker M
        • Bardi F
        • et al.
        Effectiveness of 12-13-week scan for early diagnosis of fetal congenital anomalies in the cell-free DNA era.
        Ultrasound Obstet Gynecol. 2018; 51: 463-469
        • Blaas HG
        • Eik-Nes SH
        • Kiserud T
        • et al.
        Early development of the abdominal wall, stomach and heart from 7 to 12 weeks of gestation: a longitudinal ultrasound study.
        Ultrasound Obstet Gynecol. 1995; 6: 240-249
        • D'Antonio F
        • Timor-Tritsch IE
        • Palacios-Jaraquemada J
        • et al.
        First-trimester detection of abnormally invasive placenta in high-risk women: systematic review and meta-analysis.
        Ultrasound Obstet Gynecol. 2018; 51: 176-183
        • Akolekar R
        • Syngelaki A
        • Poon L
        • et al.
        Competing risks model in early screening for preeclampsia by biophysical and biochemical markers.
        Fetal Diagn Ther. 2013; 33: 8-15
        • Rolnik DL
        • Wright D
        • Poon LCY
        • et al.
        ASPRE trial: performance of screening for preterm pre-eclampsia.
        Ultrasound Obstet Gynecol. 2017; 50: 492-495
        • Rolnik DL
        • Wright D
        • Poon LC
        Aspirin versus placebo in pregnancies at high risk for preterm preeclampsia.
        N Engl J Med. 2017; 377: 613-622