FOLLOWING FETOSCOPIC INTERVENTIONS: AN IN VITRO STUDY LIESBETH LEWI, MARC HOYLAERTS, LIEVE VERBIST, ELKE BEUTELS, JAN DEPREST, KU Leuven, University Hospitals, Leuven, Belgium KU Leuven, Department of Molecular and Vascular Biology, Leuven, Belgium OBJECTIVE: To examine (1) the influence of a platelet-rich plasma (PRP) plug on fetal membrane repair, (2) its adherence to damaged fetal membranes and the use of procoagulants to accelerate plug formation, (3) ability to seal a fetoscopic membrane defect, and (4) persistence in amniotic fluid (AF). STUDY DESIGN: (1) A microsurgical defect was created in confluent primary amniocyte cultures from elective c-section at term (n = 5). DMEM (control) or PRP diluted in DMEM at platelet concentrations of 30,000/lL and 3000/lL were added. The defect area was measured at 0, 12, 24, and 48 hrs. (2) Amnion-chorion patches (n = 5) were suspended in AF. PRP with tissue factor, ADP, or thromboxane A2 was injected around the patches. Site of and time to plug formation were observed. (3) An amnion-chorion patch (n = 7) was attached to the bottom of a cylinder filled with AF. The membranes were traumatized by a 10 Fr trocar and supported by parafilm. PRP was injected around the defect. After 10 min, parafilm was removed and leakage was measured. Plug adhesion was confirmed microscopically. (4) PRP was added to AF in a dilution of 1:4 in a cylinder with a patch of hemostatic collagen at the bottom (n = 6). Time to plug disappearance was observed. RESULTS: (1) In the PRP group most defects were closed after 48 hrs, whereas none were closed in controls. (2) Plug formation was localized around the amnion-chorion patches, and median time to plug formation was shorter with tissue factor (90 sec) compared with ADP (495 sec) or thromboxane A2 (510 sec) (P = 0.04). (3) After 10 min, no leakage occurred. Microscopy confirmed plug adherence to connective tissue of amnion and chorion. (4) Median plug persistence in an AF environment was 67 days (range: 21-133). CONCLUSION: A PRP plug enhances fetal membrane repair, adheres to connective tissue of amnion and chorion, and persists long enough in AF to allow cell ingrowth. Tissue factor accelerates plug formation, which in a surgical setting may help to keep the plug localized at the defect.