Pregnant Obese Women and Fetal Ultrasound Quality. (EPOWUS)

Ultrasound (US) image construction uses equations that contain the value of the propagation velocity of sound waves; this velocity is assumed conventionally to be constant and equal to 1540 m/s in the human body. Since 1977, all manufacturers of US scanners have used this value, which was first established in 1950. In fatty tissue, however, the actual propagation velocity is only in the order of 1450 m/s. US velocity in fat tissue is slower than in other soft tissues (ie:1450 m/s vs 1540 m/s) therefore the intrinsic image quality in terms of sharpness and precision is improved when considering this parameter for image construction The main objective of this study is to evaluate the impact of ultrasound propagation velocity setting on completeness of ultrasound exams and images quality during the second and third trimester fetal ultrasound examination in obese patients.

Obese pregnant women will be included before the second trimester fetal ultrasound examination. Women will be allocated to one intervention group or to the control group. In the intervention group, the ultrasonographer will be able to use several ultrasound propagation velocities to perform the exam. In the control group, exam will be performed using the conventional ultrasound velocity. An exam will be considered to be complete if all the images recommended by national guideline are acquired. If ultrasound images are missing, other ultrasound exams may be performed until completeness is reached. The protocol will be applied for the second and the third fetal ultrasound examination which are recommended by national guideline. All scans will be evaluated by two independent experts who do not have performed any of the exams. They will evaluate the completeness of each exam. Each scan will be quoted using the quality score proposed by Salomon et al.

Scans will be evaluated by independent experts who had not performed the exams. Scans will be anonymized and ultrasound propagation velocity will not be reported on the images.

Obese pregnant women will be included before the second trimester fetal ultrasound examination. Women will be allocated to one intervention group or to the control group. In the intervention group, the ultrasonographer will be able to use several ultrasound propagation velocities to perform the exam. In the control group, exam will be performed using the conventional ultrasound velocity. An exam will be considered to be complete if all the images recommended by national guideline are acquired. If ultrasound images are missing, other ultrasound exams may be performed until completeness is reached. The protocol will be applied for the second and the third fetal ultrasound examination which are recommended by national guideline. All scans will be evaluated by two independent experts who do not have performed any of the exams. They will evaluate the completeness of each exam. Each scan will be quoted using the quality score proposed by Salomon et al.

completeness will be assessed by the number of the recommended images which could have been registered during the first ultrasound exam in each trimester.

Inclusion Criteria: Body mass index>30 Between 20 and 25 weeks of gestation Exclusion Criteria: Multiple pregnancy Uterine scare

Delabaere A, Chauveau B, Lemery D, Ollier A, Guiguet-Auclair C, Mourgues C, Legrand A. Protocol for the e-POWUS Project: multicentre blinded-randomised controlled trial of ultrasound speed choice to improve sonography quality in pregnant women with obesity. BMJ Open. 2021 Sep 21;11(9):e038684. doi: 10.1136/bmjopen-2020-038684.