Maternal serum markers of placental damage in uncomplicated dichorionic and monochorionic pregnancies in comparison with monochorionic pregnancies complicated by severe twin-to-twin transfusion syndrome and the response to fetoscopic laser ablation

Objective: Twin-to-twin transfusion syndrome (TTTS) is a morbid perinatal condition associated with abnormal placentation and is treated by fetoscopic laser ablation (FLA). We assessed basal maternal serum alphafetoprotein (MSAFP) and free beta-human chorionic gonadotrophin (f-beta HCG) in uncomplicated dichorionic (DC) and monochorionic (MC) twin pregnancies and a cohort of MC twin pregnancies complicated by severe TTTS. Changes in MSAFP and f-beta HCG post-FLA were measured as markers of placental coagulation. Studydesign: In a prospective case-cohort study, MC twins complicated by TITS (n = 23) were studied. A cohort of uncomplicated DC (n = 12) and MC (n = 6) twin pregnancies, which were appropriately grown for gestation with normal liquor volumes were also studied. Using solid phase, two site fluoroimmunometric assays, both MSAFP and f-beta HCG from uncomplicated and complicated cohorts were measured. Samples were taken, prior to FLA then at intervals after the procedures (6 h, 24 h and 1 week). Results: The median multiples of median (MoM) were not significantly different in uncomplicated DC twin pregnancies for MSAFP 1.85 (95% CI 1.62-2.34) or f beta HCG 1.66 (95% Cl 1.21-2.04) compared to uncomplicated MC twin pregnancies (MSAFP 1.40 (95% CI 1.16-2.58) and f beta HCG 1.70 (95% CI 0.32-3.35)). However, the median MSAFP MoM in MC twin pregnancies complicated by severe MS was increased (MSAFP 3.10 (95% CI 2.67-4.43); p <0.05) with a more significant increase being noted in median f beta HCG (MoM 5.75 (95% CI 5.22-9.12); p <0.0001) compared to uncomplicated twin pregnancies. Post-FLA, the median MSAFP increased significantly at 6 h by 445% (636.65 U/ml (95% CI 616-1216.9 U/ml)) and remained elevated at 1 week (553.4 U/ml (95% CI 203.7-3020.8 U/ml: p = 0.001)). No significant difference in median f beta HCG was noted post-FLA (p = 0.36). This rise in MSAFP appears unrelated to the number of placental anastomoses coagulated or the total energy used. Also, in the small cohort in which amniodrainage alone was performed no rise in MSAFP was noted. Conclusions: MSAFP and f beta HCG are increased in TTTS indicating an association with abnormal placentation. Post-FLA, a significant rise in MSAFP was noted for up to a week post-coagulation. This was not noted after amniodrainage. (C) 2009 Elsevier Ireland Ltd. All rights reserved.