EXPOSURE TO CYANIDE IN PREGNANCY

Cyanide is a naturally occurring toxin which may be encountered as hydrogen cyanide (HCN) gas or salts such as potassium cyanide (KCN) and sodium cyanide (NaCN). Cyanide can also be found in plants in the form of cyanogenic glycosides, in drugs such as sodium nitroprusside, and in nitriles (R-CN) which are used widely as solvents and in the manufacture of plastics. The burning of wool, synthetic rubber, polyurethane, and other materials in a house fire may liberate hydrogen cyanide.

Cyanide compounds such as sodium nitroprusside and laetrile have been used therapeutically, however exposure to cyanide in humans is mainly through the ingestion of fruits and vegetables containing cyanogenic glycosides, ingestion of cyanide salts, or inhalation of hydrogen cyanide typically following house fires.

Embryotoxic and teratogenic effects of cyanide have been demonstrated in animal studies, however human data are limited to case reports and are insufficient to provide a full assessment of risk. Owing to the severity of complications associated with cyanide poisoning, treatment of the pregnant patient should be the same as for the non-pregnant patient. If an antidote is indicated for treatment of maternal poisoning this should not be withheld because of pregnancy.

Following acute cyanide exposure in a pregnant patient, maternal toxicity is likely to be a major determinant of fetal risk. However, due to a lack of data concerning the teratogenicity of cyanide, it is not currently possible to state that an absence of maternal toxicity excludes the possibility of adverse events occurring in the developing fetus.

Where exposure to cyanide has occurred, even in the absence of maternal toxicity, enhanced fetal monitoring may be warranted. Discussion with UKTIS is recommended.