OBJECTIVE Our purpose was to describe the endoscopic characteristics of the site of rupture in vivo in patients with spontaneous premature rupture of membranes. METHODS Patients with preterm premature rupture of membranes between 16 and 26 weeks of gestation, without evidence of intra-amniotic infection, and with a normal karyotype underwent transabdominal endoscopic examination of the amniotic cavity. Subsequently, an amniopatch of a combination of platelets and cryoprecipitate to seal the membrane defect was administered. The study was approved by the Institutional Review Board of St. Joseph's Hospital in Tampa, Florida, and all patients gave written informed consent. RESULTS Four patients underwent endoscopic examination and amniopatch administration; three had spontaneous preterm premature rupture of membranes, and in the other the membranes ruptured after an early amniocentesis. The location of the site of rupture was over the internal os in the 3 cases with spontaneous preterm premature rupture of membranes. This area was normal in the patient with iatrogenic preterm premature rupture of membranes. The longer the time between preterm premature rupture of membranes and fetoscopy, the larger and less defined was the site of rupture. The amniopatch restored amniotic integrity for a maximum of 72 hours. CONCLUSIONS This is the first in vivo endoscopic visualization of the site of spontaneous rupture of membranes from within the uterine cavity. The defect is located over the internal cervical os in patients with spontaneous preterm premature rupture of membranes. There appear to be time-related changes in the morphologic characteristics of the site of rupture. Endoscopic visualization of the site of rupture has the potential for improving our understanding of spontaneous preterm premature rupture of membranes and in the development of possible therapeutic alternatives.