PURPOSE OF INVESTIGATION: Amniocentesis-related adverse outcomes in singleton pregnancies and possible risk factors for fetal loss after mid-trimester amniocentesis performed in a single institution were investigated.METHODS: Amniocentesis-related adverse outcomes such as insufficient aspiration of amniotic fluid (AF), repeated puncture, and aspiration of hemorrhagic AF after mid-trimester amniocentesis were reviewed, while special consideration was given according to the placental location. Fetal loss rate up to 24 weeks of gestation and risk factors related to fetal losses were also investigated.RESULTS: 5,948 cases with the inclusion criteria were analyzed. Advanced maternal age was the most common indication (53%) for amniocentesis. A need for repeated puncture was overall 2.1% (n = 128) and was associated with a fundal placental location. Aspiration of hemorrhagic amniotic fluid was observed in 3.7% (n = 222) and was significantly associated with an anterior or fundal placental position. Fetal loss rate was 0.3% and there was no relationship with advanced maternal age (> or = 35 years), gestational age at amniocentesis > 18 weeks, repeated procedure, aspiration of hemorrhagic AF or placental location.CONCLUSION: Anterior or fundal placental position is a risk factor for amniocentesis-related adverse outcomes, however without significant contribution to the fetal losses. Placental location, advanced maternal age, amniocentesis gestational age > 18 weeks, and the procedure's adverse outcomes seem to have no impact on fetal loss rate.