Background Choledocholithiasis during pregnancy increases the risk of morbidit y and mortality for both fetus and mother because of cholangitis and pancreatiti s. ERCP has been advocated as safe and effective in pregnant women, but fetal ra diation exposure is not routinely monitored. The aim of this study was to record fetal exposure to ionizing radiation during ERCP and to assess outcome. Methods Seventeen ERCPs were performed in pregnant women between January 1995 and Augus t 2003. Techniques to minimize fluoroscopy were used, and fluoroscopy times were recorded. Thermoluminescent dosimeters affixed to the skin of the mother were u sed to estimate fetal radiation exposure. Observations Mean gestational age was 18.6 (8.9) weeks (range 5-33 weeks). Mean fluoroscopy time was 14 (13) seconds (range 1-48 seconds). Estimated fetal radiation exposure was 40 (46) mrad (rang e 1-180 mrad).There was a correlation between fluoroscopy time and radiation ex posure, but there was a wide range of radiation exposure for individual fluorosc opy times. Complications included postsphincterotomy bleeding in one patient (co ntrolled by hemoclip placement) and post-ERCP pancreatitis in one patient that necessitated 3 days of hospitalization. Two women developed third-trimester pre eclampsia, and labor was induced in both.Thirteen of the 15 patients who deliver ed were contacted and they confirmed that their child was in good health. Conclu sions ERCP with modified techniques is safe during pregnancy.Dosimetry should be routinely recorded. Background Choledocholithiasis during pregnancy increases the risk of morbidit y and mortality for both fetus and mother because of cholangitis and pancreatiti s. ERCP has been advocated as safe and effective in pregnant women, but fetal ra diation exposure is not routinely monitored. The aim of this study was to record fetal exposure to ionizing radiation during ERCP and to assess outcome. Methods Seventeen ERCPs were performed in pregnant women between January 1995 and Augus t 2003. Techniques to minimize fluoroscopy were used, and fluoroscopy times were recorded. Thermoluminescent dosimeters affixed to the skin of the mother were u sed to estimate fetal radiation exposure. Observations Mean gestational age was 18.6 (8.9) weeks (range 5-33 weeks). Mean fluoroscopy time was 14 (13) seconds (range 1-48 seconds). Estimated fetal radiation exposure was 40 (46) mrad (rang e 1-180 mrad). There was a correlation between fluoroscopy time and radiation ex posure, but there was a wide range of radiation exposure for individual fluoroscopy times.. Complications included postsphincterotomy bleeding in one patient (co-controlled by hemoclip placement) and post-ERCP pancreatitis in one patient that necessitated 3 days of hospitalization. Two women developed third-trimester pre eclampsia, and labor was induced in both.Thirteen of the 15 patients who deliver ed were contacted and they confirmed that their child was in good health. Conclu sions ERCP with modified techniques is safe during pregnancy.