Perinatal outcomes of pregnancies complicated by twin anemia-polycythemia sequence: a systematic review and meta-analysis

OBJECTIVE: To report the perinatal outcome in monochorionic diamniotic (MC) twin pregnancies complicated by twin anemia polycythemia sequence (TAPS).METHODS: Medline, Embase and Cochrane Library databases were searched. Inclusion criteria were non-anomalous MCDA twin pregnancies with a diagnosis of TAPS. The primary outcome was mortality; the secondary outcomes were morbidity and preterm birth (PTB). All these outcomes were stratified according to the type of TAPS (spontaneous or following laser treatment) and management option adopted (expectant, laser, intra-uterine transfusion [IUT] and selective reduction [SR]). Random effect meta-analyses of proportions were used to analyze the data.RESULTS: Spontaneous and post-laser TAPS (506 pregnancies): IUD occurred in 5.32 (95% CI, 3.6-7.1) of spontaneous and in 10.2% (95% CI, 7.4-13.3) of post-laser TAPS, while the corresponding figures for NND were 4.0% (95% CI, 2.6-5.7) and 9.2% (95% CI, 6.6-12.3). Severe neonatal morbidity occurred in 29.3% (95% CI, 25.6-33.1) of twins after spontaneous and 33.3% (95% CI, 17.4-51.8) after post-laser TAPS, while the corresponding figures for severe neurological morbidity were 4.0% (95% CI, 3.5-5.7) and 11.1% (95% CI, 6.2-17.2) respectively. PTB complicated 86.3% (95% CI, 77.2- 93.3) of pregnancies with spontaneous and all cases with post-laser TAPS (95% CI, 84.3-100). Iatrogenic PTB was more frequent than the spontaneous PTB in both groups. Outcome according to different management options (418 pregnancies): IUD occurred in 9.8% (95% CI, 4.3-17.1) of pregnancies managed expectantly and in 13.1% (95% CI, 9.2-17.6), 12.1% (95% CI, 7.7-17.3) and 7.6% (95% CI, 1.3-18.5) of those treated with laser, IUT and SR, respectively. Severe neonatal morbidity affected 27.3% (95% CI, 13.6-43.6) twins in the expectant management group, 28.7% (95% CI, 22.7-35.1) in the laser surgery group, 38.2% (95% CI 18.3-60.5) in the IUT group and 23.3% (95% CI 10.5-39.2) in the SR group. PTB complicated 80.4% (95% CI, 59.8-94.8), 73.4% (95% CI, 48.1- 92.3), 100% (95% CI, 76.5- 100) and 100% (95% CI, 39.8-100) of pregnancies after expectant management, laser, IUT and SR, respectively.CONCLUSIONS: The present meta-analysis provides pooled estimates of perinatal mortality, morbidity and preterm birth in twin pregnancies complicated by TAPS, stratified by the type of TAPS and according to different management options. Although a direct comparison could not be performed, the results from this systematic review suggest that spontaneous TAPS may have a better prognosis than post-Laser TAPS. No differences in terms of mortality and morbidity were observed comparing different management options for TAPS although these findings should be interpreted with caution in view of the limitations of the original studies. An individualized prenatal management, taking into account the severity of TAPS and gestational age, is currently the recommended strategy. This article is protected by copyright. All rights reserved.