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

Abstract

Embryo reduction of unilateral twin vesicles is normally successful before fixation of the vesicles. After fixation, however, it becomes a challenge, and the later in the gestation period that the reduction is performed, the greater the challenge. One therapy to reduce a twin into a singleton pregnancy is the transvaginal ultrasound-guided aspiration (TUGA) of one of the vesicles. The results of 35 unilateral twin reductions by TUGA are discussed in this paper and possible negative influences of age, parity and days pregnant are analysed statistically.

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].…”

“…Other studies reported higher success rates (46-51%) based on an examination performed 7-10 days after the TUGR procedure [3,5].…”

“…TUGR was first reported in mares by Bracher et al [3] who reported a viable singleton 10 days after the procedure in six of 13 (6/13; 46%) treated mares; in their study, the procedure had a higher success rate in the case of bilaterally-located twins (3/4; 75% versus 3/9; 33%) and, was more successful for unilateral twins, when performed before day 35 of gestation (2/5; 40% versus 1/4; 25%). By contrast, while Govaere et al [5] achieved a similar success rate in terms of viable singleton pregnancies 10 days after TUGR (18/35: 51%) in mares with unilateral twin pregnancies, they did not see a significant difference in success depending on whether the procedure was performed before (12/21; 57%) or after (7/17; 41%) day 35.…”

“…Previously, the fetal stabbing technique was described for unilateral twin pregnancies by Govaere et al [5] who observed no significant difference in the success 10 days after TUGR between fetal stabbing (12/23: 52.2%) and fluid aspiration (6/14: 42.9%)…”

Success rates after transvaginal ultrasound-guided aspiration and fetal puncture in the mare

“…In den letzten Jahren wurde von verschiedenen Autoren die transvaginale ultrasonographisch-geleitete Aspiration (TUA) zur Reduktion unicornualer und bicornualer Zwillingsgraviditäten im fortgeschrittenen Trächtigkeitsstadium beschrieben (Bracher et al 1993, Jonker et al 1995, Morris et al 1999, MacPherson and Reimers 2000, Mari et al 2004, Becker et al 2006, Govaere et al 2008. Die am Vorhandensein eines vitalen Embryos 5-14 Tage nach der Zwillingsreduktion oder anhand von Abfohldaten ermittelten Erfolgsraten variierten in diesen Studien deutlich (9-75 %), wobei ein Einfluss der Lokalisation (Bracher et al 1993), des Trächtigkeitstages (Jonker et al 1995, Mari et al 2004, Becker et al 2006) und der Applikation eines nichtsteroidalen Antiphlogistikums (Becker et al 2006) …”