Evaluation of a Silver Nitrate Endometrial Ablation Fluid Delivery System as a Chemical Treatment for Menorrhagia

Abstract

Study ObjectiveTo explore the safety, feasibility, and effectiveness of silver nitrate–dextran paste delivered through the cervix as a simple and inexpensive endometrial ablation therapy for menorrhagia. DesignSafety, feasibility, and effectiveness trials (Canadian Task Force classification II-3). SettingThe trials were performed at the Whittington Hospital in London. PatientsSeven women were treated for menorrhagia after prehysterectomy trials on 10 patients. Studies were first performed on rats and rabbits and human uterine specimens. InterventionWe dissolved 10 g 75% silver nitrate/25% potassium nitrate and 15 g dextran 70 in 10 mL distilled water and delivered this paste through the cervix with a pressure-controlled syringe under fluroscopic monitoring. We planned silver nitrate doses of 500 mg in a 50-kg woman to remain in the uterus for 8 minutes after injection and then to be neutralized with normal saline and washed out. In uterine specimens, 8-minute treatment produced local necrosis to 4 mm. LD50 (lethal dose, 50%) studies in rats and mice ranged from 1100 to 2000 mg/kg. Prehysterectomy trials on 10 patients to evaluate safety revealed no penetration into the tubes and normal complete blood count, renal, cardiac, and liver tests with plasma silver rising to 20 to 30 μmoles/L and returning to baseline after 4 weeks. Finally, 7 patients were treated and followed for 6 months. We followed blood values, complications, and degree of flow reduction. Six patients were well and discharged the same day; of those, all blood values were similar to the safety studies, 5 reported varying degrees of flow reduction, and 1 patient continued with menorrhagia. The seventh patient had passage of paste into the left fallopian tube and peritoneal cavity producing immediate pain. Laparoscopy showed several burns on the back of the uterus, sigmoid colon, and cul de sac. After neutralization with saline, she made a complete, uneventful recovery and became oligoamenorrheic. ConclusionSilver nitrate could be a simple, inexpensive, safe, and potentially effective agent for endometrial ablation. However, to ensure safety, the fluid delivery system described herein must be abandoned. An alternative delivery system is needed, one which precisely controls the locus of caustic action, and further testing is required for effectiveness and safety.