Evaluation of Utero-placental and Fetal Hemodynamic Parameters Throughout Gestation in Pregnant Mice Using High-Frequency Ultrasound

Abstract

Changes throughout gestation of maternal and fetal Doppler parameters in pregnant mice, similar to those obtained in human fetuses, using a high frequency ultrasound with a 55 MHz linear probe are described. The uterine arteries (UtA), fetal umbilical (UA) and fetal ductus venosus (DV) showed: increased peak systolic velocity (UtA, p=0.04; UA, p=0.0004; DV, p=0.02), reduced end diastolic velocity (UtA, p<0.001; UA, p<.0001; DV, p=0.01), and reduced resistance index (UtA, p=0.0004; UA, p=0.0001; DV, p=0.04) toward the end of pregnancy. The middle cerebral (MCA) and carotid arteries (CAR) showed reduced end diastolic velocity (MCA, p=0.02; CAR, p<0.0001), and resistance index (both vessels, p<0.0001). The umbilical vein showed a reduction in the pulsatile pattern (p<0.05). Increased velocities and reduced resistance index suggest a progressive increment in blood flow to the fetal mouse towards the end of pregnancy. Evaluation of fetal and utero-placental vascular parameters in CD-1 mice can be reliably performed using high frequency ultrasound.

A longitudinal study of placental perfusion using dynamic contrast enhanced magnetic resonance imaging in murine pregnancy

“…Although anticipated [32], normal gestational age-dependent change in murine placental perfusion, however, has not been quantified before. While uterine and umbilical flow changes have been characterized across gestation in murine pregnancy [33, 34], similar studies measuring regional placental perfusion are scant [35]. Moreover, the placenta is a heterogeneous structure with different constituent regions performing different functional roles.…”

Doppler velocimetry in fetal rats exposed to enoxaparin and unfractionated heparin (UFH) during pregnancy

“…Fetal ultrasonography studies conducted with pregnant rats are a promising field in perinatal experimental research, decreasing the need for euthanizing animals for the investigation of fetal development 10,11 . Furthermore, ultrasonography is currently part of routine obstetric procedures 2,3,8 .…”

“…Ultrasonography does not yield the false positive results often associated with other methods involving the use of drugs that effect fetal hemodynamics. In experimental research, the use of non-invasive methods can translate to fewer euthanized animals 3,10,11 . Patterns observed in parametric measurements employing non-invasive techniques such as Doppler velocimetry allow the construction of normality scales that can find utility in the investigation of disorders affecting physiology…”

Morphologic and molecular changes in the placenta: what we can learn from environmental exposures

“…Such measurements would provide more opportunities for immediate therapeutic intervention to ameliorate negative health effects imposed on the fetus by a functionally compromised placenta. For example, high-frequency ultrasound has been utilized to reliably measure blood velocity in pregnant mice and may be a useful tool in future studies (77). …”