Contamination of the fetal amniotic cavity with maternal blood
at amniocentesis is common.24 In a study by Giorlandino et al.,
20 women underwent a second amniocentesis two weeks after
the original amniocentesis because of cell culture contamination.
24 At the second amniocentesis all 20 were found to have
amniotic fluid contamination based on red blood cell and
hemoglobin concentrations.24 Women undergoing their first
amniocentesis were used as matched controls and no blood contamination was found at the onset of the procedure. The
amount of blood in the amniotic fluid was significantly
increased when an anterior placenta was present