First-Trimester Ultrasound Volumetry

Measurement Techniques and Potential Application in the Prediction of Pregnancy Complications

Kwok Yin Leung; Teresa Ma; Betty YT Lau; Min Chen

Expert Rev of Obstet Gynecol. 2012;7(4):379-386.

Yolk Sac Volume

YSV was measured using the VOCAL method with 30° rotation^[6] or XI VOCAL.^[59] There was a poor correlation between YSV and GA or CRL.^[6] The mean YSV increased from 0.063 cm³ at 7 weeks to 0.164 cm³ at 10 weeks.^[6] Similar to another study,^[60] the mean YSV increased in a linear fashion up to 10 weeks, then maintained a plateau until 11 weeks, and decreased thereafter.^[6] This can probably be explained by the yolk sac degeneration process secondary to vascular depletion.^[61] The absence or malformation of a yolk sac outside the normal growth pattern is associated with poor pregnancy outcomes.^[62]

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Table 1. Reference data of first-trimester volumetry measured by different 3D ultrasound techniques.
3D parameters	3D measurement techniques	Gestation (weeks)							Ref.
3D parameters	3D measurement techniques	6	7	8	9	10	11	12	Ref.
EV/FV (cm³)	Multiplanar VOCAL™ (30°) XI VOCAL Virtual reality	0.04 0.07 0.04	0.19 0.40 0.20 0.31	0.74 0.99 1.02	2.31 2.31 2.45	5.84 4.62 5.12 5.35	11.84 8.65 9.71	19.29 14.25 22.20	[1] [2] [10] [40]
VOCAL vs SonoAVC	Mean difference of -76.5% with limit of agreement ranging from -159.6 to 6.7%							[51]
GSV (cm³)	Multiplanar VOCAL	4.36 3.8	7.52 8.3	12.97 16.2	22.38 26.0	38.61 47.1	66.61 67.9	114.93 90.8	[1] [5]
Gestational sac fluid volume (cm³)	VOCAL Virtual reality	2.18	3.97 4.86	5.87 9.82	13.75 18.20	23.33 32.36	53.70	87.10	[33] [40]
Yolk sac volume (cm³)	Multiplanar VOCAL Virtual reality XI VOCAL	0.04 0.05	0.07 0.06 0.08 0.06	0.10 0.10 0.08	0.12 0.12 0.10	0.13 0.16 0.15 0.16	0.13 0.18	0.12 0.12	[1] [6] [40] [10]
PV (ml)	Multiplanar VOCAL	Median: 41.3 ml (CRL: 35–44 mm), 48.5 ml (CRL: 45–54 mm), 59.2 ml (CRL: 55–64 mm) PV = 1.73 × exp(0.076 × CRL)							[3] [4]

CRL: Crown—rump length; EV: Embryo volume; FV: Fetal volume; GSV: Gestational sac volume; PV: Placental volume; SonoAVC: Sonography-based automated volume count; VOCAL: Virtual organ computer-aided analysis; XI: Extended imaging.

Table 2. Potential applications of first-trimester volumetry.
Area	Main findings	Ref.
Birthweight	The embryonic volume during the first trimester of pregnancy correlates better with birthweight than the crown–rump length	[15,16]
IUGR	Placental quotient at 12 weeks and uterine artery Doppler at 22 weeks have similar sensitivities (27.1 vs 28.1%) for predicting IUGR	[11–14]
Preeclampsia	The detection of preeclampsia had a sensitivity of 38.5% (placental quotient at 12 weeks) versus 44.8% (uterine artery Doppler at 22 weeks)	[12]
Aneuploidy	First-trimester volumetry is unlikely to be a useful predictor of major chromosomal defects In early-onset IUGR caused by aneuploidy, a larger deficit in fetal volume than crown–rump length was observed	[17–21]
Homozygous α⁰-thalassemia	Compared with unaffected pregnancies, the placental quotient of affected pregnancies was greater, while fetal volumes were smaller at 9–14 weeks' gestation	[27]
Multiple pregnancy	Median twin and triplet placental volumes were 1.66 and 2.28 multiples of the median for singletons, respectively. There was no difference in the rate of placental growth between 11 and 13 + 6 weeks among singletons, twins and triplets	[25,26]
Miscarriage	3D volumetric assessment does not improve the diagnosis of miscarriage over conventional 2D sonographic measurements	[22–24]

IUGR: Intrauterine growth restriction.

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First-Trimester Ultrasound Volumetry

Measurement Techniques and Potential Application in the Prediction of Pregnancy Complications

Yolk Sac Volume

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