BACKGROUND: A properly placed epidural catheter tip may become displaced out of the epidural space after being secured as a result of patient movement, a common cause of inadequate analgesia. This study was performed to evaluate the migration of an epidural catheter with patient movement. METHODS: Forty-six parturients planning to undergo a cesarean section under epidural anesthesia were enrolled. Patients were divided into two groups according to body mass index (BMI): 26 kg/m2. A 19-gauge single-orifice epidural catheter (Flextip Plus(TM), Arrow, USA) was inserted at the L(2-3) or L(3-4) interspace with the patient in the sitting flexed position. The distance to the epidural space and length of catheter position change was measured before the catheter was secured to the skin, as the patient moved from the sitting flexed to sitting upright and then to the lateral decubitus position with flexion and extension. RESULTS: Catheters were drawn inward with position change from the sitting flexed to lateral decubitus position, the magnitude increasing with BMI (0.73 +/- 0.40 cm vs. 0.98 +/- 0.35 cm). CONCLUSIONS: This study shows that the indrawing of the catheter with reference to the skin occurs as a patient changes position, and this indrawing can result in catheter dislodgement out of the epidural space.