[Hydronephrosis caused by a menstrual cup]

In this case report, a 20-year-old healthy woman contacted the emergency department because of lower abdominal pain radiating to the right flank. She was discharged with analgesics suspecting a kidney stone attack. One month later she contacted the emergency department again with the same symptoms. A CT urography was made showing hydronephrosis on the right side and a menstrual cup in the vagina seemingly compressing the right ostia in the bladder. After removal of the menstrual cup the symptoms disappeared, and the patient was discharged. A control ultrasound scan two weeks later showed full regression of the hydronephrosis.