Fatal reactions and methaemoglobinaemia after silver nitrate irrigation of hydatid cyst

Hydatid cyst remains an important public health problem in endemic areas including Isfahan, Iran. The mainstay of treatment for hydatid disease is surgery. Surgical approaches depend on the location, size and complications of the cyst. To prevent recurrence, inactivation of the scolex with scolicides prior to opening or removing the cyst is strongly recommended. Silver nitrate has been a common scolicidal agent in hydatid surgery for many years. Methaemoglobinaemia and morbid reactions are rare complications in individuals exposed to silver nitrate. This is a case series presentation from a retrospective view over an 11-year period (1990-2001) on the clinical records of nine patients referred to the committee of mortality and morbidity studies of Isfahan Medical University, who manifested methaemoglobinaemia and morbid reactions during or after the injection of silver nitrate into hydatid cysts. Regarding the complications, the patients were allocated into three groups; in the first group after the injection of silver nitrate 0.5%, two patients manifested intraoperative shock and cardiovascular collapse; one died in the operating room and the other in the recovery room 4 h after the operation. The second group included four patients whose manifestations were less severe than the first group. They responded to resuscitation but faced significant complications including renal failure and liver insufficiency. The third group included three patients who had neither shock nor significant cardiovascular disturbances intraoperatively, but experienced postoperative dyspnoea, cyanosis and hypotension. Surgeons dealing with hydatid cyst must be aware that this scenario can be very dangerous with other scolicidal agents concerning the extensive absorbing surface of the peritoneum and raw surfaces.