During a bladder instillation, the bladder is filled with a solution that is held for varying periods of time, from a few seconds to 15 minutes, before being drained through a narrow tube called a catheter. In severe cases of interstitial cystitis, bladder instillation may be performed along with administration of oral medication to provide relief until the oral medication has had time to take effect.  Treatments are given every week or two for 6 to 8 weeks, and repeated as needed depending on symptoms.