3/6/2019 1 Obstetrical Measurements Mani Montazemi, RDMS Director of Ultrasound Education & Quality Assurance Baylor College of Medicine Division of Maternal-Fetal Medicine Department of Obstetrics and Gynecology Texas Children’s Hospital, Pavilion for Women Houston Texas Mani Montazemi, RDMS Obstetrical Measurements First Trimester Ultrasound • Mean Gestational Sac Diameter • Crown Rump Length • Embryonic Cardiac Activity • Yolk Sac Mani Montazemi, RDMS Obstetrical Measurements Mani Montazemi, RDMS Obstetrical Measurements Mani Montazemi, RDMS Obstetrical Measurements Anembryonic Gestation “Blighted Ovum” MSD ≥ 25mm “No embryonic pole” Peter M. Doubilet, Carol B Benson et al, N Engl J Med 2013; 369:1443-51 Early Pregnancy Failure
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Obstetrical First Trimester Ultrasound Measurements Mean ...jeffline.jefferson.edu/jurei/conference/pdfs/obgyn/May 16/3 - 930 to 1015.pdf•Mean Gestational Sac Diameter •Crown Rump
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3/6/2019
1
Mani Montazemi, RDMS
Obstetrical Measurements
Obstetrical
Measurements
Mani Montazemi, RDMSDirector of Ultrasound Education & Quality Assurance
Baylor College of Medicine
Division of Maternal-Fetal Medicine
Department of Obstetrics and Gynecology
Texas Children’s Hospital, Pavilion for Women
Houston Texas
Mani Montazemi, RDMS
Obstetrical Measurements
First Trimester Ultrasound
• Mean Gestational Sac Diameter
• Crown Rump Length
• Embryonic Cardiac Activity
• Yolk Sac
Mani Montazemi, RDMS
Obstetrical Measurements
Mani Montazemi, RDMS
Obstetrical Measurements
Mani Montazemi, RDMS
Obstetrical Measurements
Anembryonic Gestation “Blighted Ovum”
MSD ≥ 25mm “No embryonic pole”
Peter M. Doubilet, Carol B Benson et al,
N Engl J Med 2013; 369:1443-51
Early Pregnancy Failure
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Crown-Rump Length
• Embryonic length
• Most accurate US measurement for estimation
of gestational age (+/- 5-7 days)
– especially between 6 - 9 weeks
Crown-Rump Length
**
Mani Montazemi, RDMS
Obstetrical Measurements
**
Mani Montazemi, RDMS
Obstetrical Measurements
Avoid Inaccurate CRLCaution
*
*
*
*
?
Mani Montazemi, RDMS
Obstetrical Measurements
1st Trimester (GS & CRL)
• Qualitative
– Small, tight GS relative to size of embryo
• Quantitative
– MSD-CRL
• Normal if > 5 mm (92%)
• Abnormal if < 4mm (94% miscarriage)
Mani Montazemi, RDMS
Obstetrical Measurements
• Qualitative
– Small, tight GS relative to size of embryo
• Quantitative
1st Trimester (GS & CRL)
Mani Montazemi, RDMS
Obstetrical Measurements
• Qualitative
– Small, tight GS relative to size of embryo
• Quantitative
1st Trimester (GS & CRL)
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Mani Montazemi, RDMS
Obstetrical Measurements
1st Trimester (GS & CRL)
Mani Montazemi, RDMS
Obstetrical Measurements
• Qualitative
– Small, tight GS relative to size of embryo
• Quantitative
– ( MSD – CRL )
• Normal if > 5 mm (92%)
• Abnormal if < 4mm (94% miscarriage)
Peter M. Doubilet, Carol B Benson et al,
N Engl J Med 2013; 369:1443-51
Bromley, et. al. 1991
Kurtz et. al. 1992
1st Trimester (GS & CRL)
CRL Measurements
TRV vs. SAG
Mani Montazemi, RDMS
Obstetrical Measurements
Mani Montazemi, RDMS
Obstetrical Measurements
ML
Mani Montazemi, RDMS
Obstetrical Measurements
ML
RT
Mani Montazemi, RDMS
Obstetrical Measurements
RT
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Mani Montazemi, RDMS
Obstetrical Measurements
1st Trimester
• Estimates of CRL which are poor estimates should be excluded from the mean CRL
• Gestational age should not be an average of that based on MSD and CRL
• EDD is determined on the initial first trimester ultrasound based on CRL and SHOULD NOT BE CHANGED based on subsequent ultrasounds
Mani Montazemi, RDMS
Obstetrical Measurements
CRL = 6.2 mm
Mani Montazemi, RDMS
Obstetrical Measurements
Embryonic Cardiac Activity
• Should have visible heart beat CRL ≥ 7mm
Peter M. Doubilet, Carol B Benson et al,
N Engl J Med 2013; 369:1443-51
Embryonic Cardiac Activity
• Bradycardia < 80 bpm: poor prognosis
• Absence may be NL in embryos < 4 mm
Mani Montazemi, RDMS
Obstetrical Measurements
Mani Montazemi, RDMS
Obstetrical Measurements
Embryonic Cardiac Activity
Mani Montazemi, RDMS
Obstetrical Measurements
Embryonic Cardiac Activity
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Caution
In keeping with the ALARA principle, M-mode
should be used instead of spectral Doppler
to document embryonic heart rate
Mani Montazemi, RDMS
Obstetrical Measurements
Time-averaged acoustic intensity
delivered to the fetus is lower
with M-mode than with spectral Doppler
Mani Montazemi, RDMS
Obstetrical Measurements
“Don’t”
Mani Montazemi, RDMS
Obstetrical Measurements
Diagnostic Challenge
Mani Montazemi, RDMS
Obstetrical Measurements
Embryonic Yolk Sac
•
Normal
Aust. N Z J Obstet Gynaecol 2006 Oct;46(5):413-8
J Perinat Med. 1999;27(4):316-20
Radiology April 1992 183:1 115-118
Mani Montazemi, RDMS
Obstetrical Measurements
Embryonic Yolk Sac
Mani Montazemi, RDMS
Obstetrical Measurements
Embryonic Yolk Sac
“Don’t”
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Embryonic Yolk Sac
“Outer To Outer”
* *
Aust. N Z J Obstet Gynaecol 2006 Oct;46(5):413-8
J Perinat Med. 1999;27(4):316-20
Radiology April 1992 183:1 115-118 Mani Montazemi, RDMS