Laparoscopy Guided Doppler Ultrasound Measurement of Fetal Blood Flow Indices During Early to Mid-Gestation in Pigs

Abstract

Abstract. The objectives of this study were to obtain relevant blood flow indices of umbilical arteries (UmA) of porcine fetuses using a laparoscopic ultrasound probe and to relate these data with fetal size at early to mid gestation. Fetal parameters and flow indices, i.e., fetal length and area, fetal heart rate (FHR), systolic pulse duration (T1), interpulse duration (T2), T2/T1 ratio, peak systolic velocity (PSV), time averaged velocity (TAV), resistance index (RI) and pulsatility index (PI), were measured in 182 fetuses of 26 pregnant Landrace gilts on pregnancy day (PD) 36 (122 fetuses from 17 gilts), PD42 (19 fetuses from 3 gilts) and PD51 (42 fetuses from 6 gilts). Fetal heart rate was higher on PD36 than on PD42 (P<0.05). No differences (P>0.05) were obtained concerning systolic pulse duration, flow velocities and RI. On PD42, the PI was lower (P<0.05), while the interpulse duration (P=0.06) and T2/T1 ratio tended (P=0.08) to be higher on PD42 compared with PD36 and to PD51. To find differences in UmA blood flow parameters concerning fetal size, i.e., fetal length, fetuses were retrospectively grouped as follows: small (lower 25%), medium (mean 50%) and large (upper 25%), respectively. Although, fetuses differed in size (P<0.001) within and between days of pregnancy, FHR, PSV, TAV, RI and PI did not differ (P>0.05) among the size classes. Only systolic pulse duration tended to be longer (P=0.05) in large compared with small fetuses on PD36, and interpulse duration was lower in large fetuses on PD36 in comparison with PD51 (P<0.05). Though there was no link between fetal blood flow indices and fetal intrauterine growth retardation (IUGR), with further studies based on these flow indices, it might be possible to evaluate nutrient-or stress-related influences on fetal growth and development, particularly in the case of IUGR. Key words: Female pig, Fetal blood flow, Laparoscopy, Pregnancy, Ultrasonography (J. Reprod. Dev. 58: [243][244][245][246][247] 2012) T he profitability of pig production considerably depends on the number of live born and fostered piglets. Breeding efforts result nowadays in a greater than before number of piglets. However, pre-and postnatal losses are concomitantly increasing (up to 30%) [1]. Furthermore, intrauterine growth retardation (IUGR), resulting in lighter body weight at birth, is a significant problem in pig production [2]. Lighter birth weight piglets show reduced survival rate, compromised postnatal development [3] as well as decreased carcass and meat quality [4]. Uterine and umbilical blood flows maintain the placental transport and exchange of respiratory gases, nutrients and wastes, and thereby support fetal growth and metabolism [5]. As previously demonstrated in the pig, the blood flow to the fetus was reduced with increasing number of fetuses [6]. Experimental vascular occlusion of the uterine arteries of pigs markedly reduced conceptus development [7]. In utero growth retardation, beside other factors such as uterine capacity and number and position of fetuses ...

Doppler ultrasound can be used to monitor umbilical arterial blood flow in lightly sedated pigs at multiple gestational ages

“…Similar temporal changes in UA blood flow parameters have been reported in sheep and goats (Serin et al 2010;Carr et al 2012). The two published studies describing pig UA blood flow parameters (Brüssow et al 2012;Harris et al 2013) both reported a decrease in FHR as gestation proceeded, but only Harris et al (2013) observed temporal changes in RI and PI between GD39 and GD81. Changes in FHR observed in both studies follow a similar pattern to those seen in the present study, but not all parameters studied exhibited the same temporal trends in the three studies.…”

“…Changes in FHR observed in both studies follow a similar pattern to those seen in the present study, but not all parameters studied exhibited the same temporal trends in the three studies. The three experiments were performed under different sedation conditions, with Harris et al (2013) using non-sedated gilts, 'rubbing' the udder of the gilts to produce a 'calming' effect in the animals, whereas Brüssow et al (2012) performed the procedure by scanning the exposed uterus directly while the pig was under general anaesthesia.…”

“…In large animals, Doppler ultrasound has been used to investigate uterine, umbilical and fetal vessels in cattle (Bollwein et al 2002;Panarace et al 2006;Silva and Ginther 2010), goats (Serin et al 2010;Elmetwally et al 2016), horses (Bollwein et al 2000(Bollwein et al , 2004 and sheep (Elmetwally et al 2016). There have also been limited investigations into gestational changes in UA blood flow in the pig (Brüssow et al 2012;Harris et al 2013). It has been suggested that an invasive laparoscopic approach is the most effective method to monitor UA blood flow in the pig (Brüssow et al 2012), although the effect of general anaesthesia is unknown.…”

“…There have also been limited investigations into gestational changes in UA blood flow in the pig (Brüssow et al 2012;Harris et al 2013). It has been suggested that an invasive laparoscopic approach is the most effective method to monitor UA blood flow in the pig (Brüssow et al 2012), although the effect of general anaesthesia is unknown. In addition, the relationship between UA blood flow and fetal growth and development in the pig is poorly understood.…”

Principles and Clinical Uses of Real-Time Ultrasonography in Female Swine Reproduction

“…Fetal heartbeats appear between days 21–25 [22,23], and are useful for the determination of fetal viability. Doppler ultrasonography via a laparoscopic approach has been used to assess umbilical arterial blood flow indices in feti at 36, 42, and 51 days of age, but the study failed to show any correlation of perfusion indices and fetal growth [24]. Visualization of fetal eye orbit and stomach occurs around day 49 of gestation (transabdominal scanning; 5.0 MHz) [22].…”