Partial re‐establishment of villous placentation after reduction of an equine co‐twin by foetal cardiac puncture

Efficacy of transvaginal ultrasound-guided twin reduction in the mare by embryonic or fetal stabbing compared with yolk sac or allantoic fluid aspiration

“…Nevertheless, at least for the 2-3 month losses a delayed effect of TUGR is a plausible contributory factor. In the case of transabdominal ultrasound-guided twin reductions, it is accepted that the placenta of the surviving twin is never able to regain the endometrial attachment area 'lost' to its cotwin, leading to an increased risk of placental insufficiency later in gestation that can result in abortion or the birth of a emaciated foal [12,13] despite mummification of its twin; placental insufficiency following TUGR has not been reported, but could conceivably be an issue if The likelihood of success in the current study was not significantly influenced by the technique used for TUGR, which is in agreement with the observations of Govaere et al [5] for mares with unilateral twins. One of the biggest risks of performing allantoic/yolk-sac fluid aspiration in unilateral twins is damage to the developing membranes or to the chorioallantoic-endometrial attachment of the co-twin as a result of puncture, accidental aspiration, leakage of fluid and/or collapse of the manipulated vesicle [1].…”

Transvaginal ultrasound‐guided aspiration of unilateral twin gestation in the mare

“…These authors reported that in 63% both fetuses aborted and about 31% were carried to term (Ginther and Douglas 1982). Late trancutaneous ultrasound-guided twin reduction (Rantanen and Kincaid 1988;Ball et al 1993) is associated with lower success rate (38-40%, Rantanen and Kincaid 1988;Macherson and Reimer 2000) and the surviving foals are subjected to problems, such as partial avillous placenta leading to prematurity or dysmaturity as a consequence (Ball et al 1993;Govaere et al 2008).…”

Factors influencing placental development and function in the mare

“…Previous reports had suggested that this course of action might result in a higher incidence of one type of vascular pattern on the allantochorion (K. Whitwell, personal communication; Rossdale and Ricketts 2002) and, although other authors have found no such association (Whitehead et al 2005), it remains possible that fetal and placental development can both be influenced by events occurring prior to formation of the allantochorion (Wilsher et al 2010). When twin reduction is undertaken later in gestation, the surviving twin may still be undersized at birth because its allantochorion was unable to initiate optimal villus formation over the area of endometrium previously occupied by its co-twin (Ball et al 1993;Govaere et al 2008). This suggests strongly that in order to develop normally in midgestation the allantochorion must have been exposed to stage-specific events much earlier in gestation.…”

“…2010). When twin reduction is undertaken later in gestation, the surviving twin may still be undersized at birth because its allantochorion was unable to initiate optimal villus formation over the area of endometrium previously occupied by its co‐twin (Ball et al . 1993; Govaere et al .…”