Acardiac twin: a systematic review of minimally invasive treatment modalities

This review of the literature aimed to determine pregnancy outcomes after minimally invasive treatment for occluding vascular supply to acardiac twins. A MEDLINE search was performed until 2002 using the terms 'acardiac', 'acardius', 'twin reversed arterial perfusion (TRAP) sequence' and 'chorangiopagus parasiticus' and 207 articles published in the English-language literature were identified. These articles and the corresponding cited references in English were reviewed. We identified 32 reports involving 74 cases of acardiac twin treated by minimally invasive techniques. Seventy one cases were included for analysis including 40 treated by cord occlusion and 31 by intrafetal ablation. Cord occlusion was first attempted by embolization (n = 5), cord ligation (n = 15), laser coagulation (n = 10), bipolar diathermy (n = 7) and monopolar diathermy (n = 3). Intrafetal ablation was performed by alcohol (n = 5), monopolar diathermy (n = 9), interstitial laser (n = 4) and radiofrequency (n = 13). The overall median gestational ages at treatment and delivery were 21 (range, 14-28) weeks and 36 (range, 19-42) weeks, respectively, with a median treatment-delivery interval of 13 (range, 0-25) weeks. The overall pump twin survival rate was 76% (n = 54). Intrafetal ablation was associated with later median gestational age at delivery (37 vs. 32 weeks, P = 0.04) and higher median treatment-delivery interval (16 vs. 9.5 weeks, P = 0.02) compared with cord occlusion techniques. It was also associated with a lower technical failure rate (13% vs. 35%, P = 0.03), lower rate of premature delivery or rupture of membranes before 32 weeks (23% vs. 58%, P = 0.003) and higher rate of clinical success (77% vs. 50%, P = 0.02) than cord occlusion techniques. There were no statistically significant differences in terms of outcome between the subgroups of fetoscopic- or ultrasound-guided cord occlusion techniques. This review suggests that intrafetal ablation is the treatment of choice for acardiac twins because it is simpler, safer and more effective when compared with the cord occlusion techniques.