The medications that are used to paralyze the muscles of the body during general anesthesia work on many areas of the body. In some patients, the muscles of the bladder become paralyzed, and the patient is unable to urinate. The ability to urinate typically returns within 24 hours, but during that time the bladder can become uncomfortably full, making a urinary catheter necessary.
Sources:
Details on Malignant Hyperthermia, American Society of Anesthesiologists http://www.asahq.org/news/asanews032808.htm
Patient Education FAQ, American Society of Anesthesiologists http://www.asahq.org/patientEducation.htm
Surgery: Scientific Principals and Practice, Third Edition. 2001. Lazar J Greenfield, MD, et al.
