Doppler evaluation of recipient cows treated with progesterone and estradiol

Abstract

Context Due to the advances in the field of biotechnology of reproduction, success rates in embryo transfer (ET) programs have been growing continuously. Such rates are influenced by several factors, among which fertility and success in synchronising the estrus of the recipients stand out. Doppler ultrasound is emerging as a useful tool fot the assessment of fertility in recipients and for the early diagnosis of pregnancy. Aims This study aimed to verify whether luteal vascularisation, uterine haemodynamics and corpus luteum (CL) volume, evaluated only on the day of fixed-time ET (FTET), are useful parameters for the selection of Girolando recipients synchronised with progesterone and estrogen. Methods Girolando recipients received a hormonal protocol for FTET and were evaluated on the day of embryo transfer by B-mode and Doppler ultrasonography. The volume of the CL, the side of the CL, the estimation of luteal vascularisation and the Doppler indexes of the right and left uterine arteries were evaluated in real time. The ultrasound images were saved and used for later pixel counting and determination of the vascularised luteal area using specific software. Blastocysts (n = 92) produced in vitro (IVF) with Grade 1 morphology on Day 7 of development were transferred to all animals with corpus luteum. The pregnancy diagnosis was made 24 days after embryo transfer and the animals were separated into two groups, namely, pregnant and non-pregnant. Key results Retrospective analyses of luteal vascularisation; haemodynamics of uterine arteries and corpus luteum volume did not differ (P > 0.05) between the groups. The means of the Doppler indexes of the uterine arteries were not affected (P > 0.05) by the presence of CL ipsilateral to the assessed vessel. Conclusions It is concluded that the assessments of uterine haemodynamics, size and vascularisation of the CL, through Doppler ultrasonography on the day of ET, under the proposed conditions, were not useful to predict recipients with greater chances of establishing pregnancy. Implications Although Doppler is a useful tool for real-time fertility assessment, its accuracy if affected by protocols that do not guarantee synchrony between ovulation times. This suggests that other fertility assessment methods be used under these field conditions.