The twist technique: a method to minimize wire prolapse during Bird's Nest filter placement.

PURPOSE

To determine whether a twist technique can help reduce the occurrence of fine-wire prolapse proximal to the hooks of the Bird's Nest filter in the inferior vena cava.

MATERIALS AND METHODS

Abdominal radiographs were retrospectively analyzed after placement of filters with no twist (n = 100), with two 360 degree twists (n = 55), or with three 360 degree twists (n = 61).

RESULTS

Prolapse of 5 mm or more was encountered in 32% of cases (32 of 100 cases) in which no twists were imparted. The average length of prolapse was 2.8 cm (range, 0.5-5.1 cm). The average length of the filter nest was 9.4 cm (range 5.1-13.6 cm). Use of two 360 degree twists reduced the rate of prolapse to 9.1% (five of 55 cases) (P < .005 vs no twist); the average length of prolapse was 2.8 cm (range, 0.6-6.4 cm). The average filter-nest length was reduced 7.5 cm (range, 4.0-13.3 cm). With three 360 degree twists, prolapse occurred in 4.9% of cases (three of 61 cases) (P < .005 vs no twist). The average length of prolapse was 2.6 cm (range, 0.7-4.8 cm). The average filter-nest length was 7.8 cm (range, 3.5-12.8 cm). The difference in prolapse frequency when two twists were used as opposed to three is not statistically significant.

CONCLUSION

Application of two or three 360 degree twists to the catheter-sheath unit during insertion of the Bird's Nest filter produces a statistically significant reduction in the occurrence of wire prolapse.