ABSTRACT
Methylene blue is a vital dye that has therapeutic utility as an antidote for cyanide poisoning and drug-induced methemoglobinemia. As a dye, it is also used as a marker in various tissues and amniotic fluid. The chemical is used in the latter to identify by amniocentesis midtrimester anatomic and pathologic structures in twin pregnancies, especially to diagnose premature rupture of membranes. Only one animal developmental toxicity study has been published following intra-amniotic (IA) injection of methylene blue. In the human, the use of methylene blue IA injections in pregnancy resulted in a number of case reports of malformation, as tabulated by >60 representative cases provided. Methylene blue is a positively charged human developmental toxicant. It is hydrophobic and of average size in comparison to the other compounds. It possesses a relatively low polar surface area. Methylene blue is a weak hydrogen bond acceptor.
