Transvaginal ultrasound-guided reduction of twin pregnancies in the mare

Abstract

ZusammenfassungZwillingsgraviditäten bei der Stute bewirken ökonomische Verluste, da sie im Regelfall zu Aborten, Totgeburten bzw. zur Entwicklung lebensschwacher oder deformierter Fohlen führen. Die transvaginale ultraschallgeleitete Aspiration ist eine effiziente Methode um eine Reduktion zu erreichen. In der vorliegenden Studie wurde bei 27 Zwillingsträchtigkeiten einmalig zwischen dem 21. bis 52. Trächtigkeitstag Fruchtwasser von einem Konzeptus aspiriert. Insgesamt wurde nach 10 bis 14 Tagen eine Überlebensrate der verbleibenden Embryonen von 59,2 % ermittelt. Vierzehn Stuten erhielten eine therapeutische Dosis eines nichtsteroidalen Antiphlogistikums vor sowie 5 Tage nach der Aspiration. Die Überlebensrate in dieser Gruppe betrug 71,4 %. In der unbehandelten Kontrollgruppe betrug sie 46,1 %. Eine direkte Beziehung zwischen der Überlebensrate der verbleibenden Embryonen und dem Trächtigkeitsstadium, in dem die Aspiration vorgenommen wurde, konnte nachgewiesen werden. Eine signifikant geringere Rate wurde nach Aspirationen nach dem 36. Tag beobachtet.Schlüsselwörter: Stute, Zwillingsträchtigkeit, Trächtigkeitstag, Reduktion, Flunixin Transvaginal ultrasound-guided reduction of twin pregnancies in the mareTwin pregnancies in mares cause economic losses as they result in a high rates of abortion, stillbirth or the delivery of dead or weak and deformed foals. Transvaginal ultrasound-guided twin reduction techniques are described for twin pregnancies that advance to the phase of fixation. In total 27 twin pregnancies were ultrasound-guided managed by aspiration of embryonic fluid. Mares with twin pregnancies from day 21 to day 52 were directed to the ultrasound-guided procedure. In total the success rate was 59.3 %. Fourteen mares got a therapeutic dose of Flunixine (Finadyne ® RP; Essex) before and for 5 days after aspiration. The success rate was 71.4 % in the treated group and 46,1 % in the control group. A direct relation between success rate and stage of gestation and aspiration was observed. Success rate of survival of one twin was significantly lower when manipulation was started beyond day 36.

Success rates and factors influencing pregnancy outcome after 464 transvaginal ultrasound‐guided twin reductions in the mare

“…The proportion of similar versus dissimilar vesicle size in twin pregnancies had no significant effect on foaling rate after TUA was performed in our study. Although the earlier the TUA is performed the better the success rate, we recommend to delay TUA in cases in which there is a strong discrepancy in conceptus size (>50%) for 3-5 days to allow These results are in accordance with Becker et al, 16 who did not observe increased pregnancy rates after administering flunixin meglumine for 5-6 days after TUA was performed.…”

“…reports on the effect of gestational age of the twin embryos/fetuses on the pregnancy and foaling rates after TUA. Some studies have reported a decrease in pregnancy rate when TUA was performed after D 36 16,19 or D 42 20 but others found no negative impact of increasing gestational age on pregnancy rate after TUA. 18,21 In the present study, overall higher pregnancy and foaling rates were achieved when TUA was performed earlier in gestation (D 25-29, 64.7%; D 30-34, 47.4%; D 35-39, 39.7%), and a significantly lower fetal survival was observed when TUA was performed after D 40.…”

“…In previous studies, the influence of embryonic/fetal vesicles localisation on TUA success was debated. 11,16,19,20 According to Journée et al 19 foaling rates after TUA in unilateral twins (19/65 [29.2%])…”

“…Manual crushing is a twin reduction method that is not advantageous in either unilaterally fixed twins between D 20-30, when the success rate is approximately 50% 10 or advanced pregnancies (>D 30). 2 Transvaginal ultrasound guided aspiration (TUA) has been described as a method for twin reduction by several authors [11][12][13][14][15][16][17][18][19][20][21] with varying success (Table 1). Factors reported to influence successful twin reduction with regard to post-reduction pregnancy or foaling rate include: location of the vesicles, 11 day of gestation the TUA procedure is performed, 12,15,16,20 administration of non-steroidal antiinflammatory drugs (NSAIDs) 20 and mare age.…”

“…2 Transvaginal ultrasound guided aspiration (TUA) has been described as a method for twin reduction by several authors [11][12][13][14][15][16][17][18][19][20][21] with varying success (Table 1). Factors reported to influence successful twin reduction with regard to post-reduction pregnancy or foaling rate include: location of the vesicles, 11 day of gestation the TUA procedure is performed, 12,15,16,20 administration of non-steroidal antiinflammatory drugs (NSAIDs) 20 and mare age. 21 A commonly practiced manual technique between D 30-65 involves 'pinching' of one embryonic vesicle with the ultrasound probe to cause membrane damage and embryonic death.…”