MODIFICATION OF AN INTRAUTERINE SHUNT CATHETER TO REDUCE THE INCIDENCE OF SPONTANEOUS DISPLACEMENT

Objective: To determine which of four types of catheters would be the least likely to become displaced spontaneously when employed as a feto amniotic shunt, by testing the force required to remove the catheters from a lamb's bladder. Methods: The catheter designs tested were unfea thered straight, unfeathered pig-tailed, superficially feathered, and deeply feathered. The catheters were placed percutaneously into the ur inary bladders of recently euthanized newborn lambs. The force require d to withdraw the catheters was determined, employing nine measurement s for each catheter design. Results: The mean force required to remove the straight catheter was 12 g (95% confidence interval [CI] 2-21 g), the pig-tailed catheter 22 g (95% CI 13-32 g), and the superficially feathered catheter 149 g (95% CI 139-160 g). Extracting the deeply fea thered catheter consistently required a force greater than 300 g, whic h was the upper limit of detection for our instruments. Conclusion: Fe athering the catheter increases the force required to extract it from a fetal viscus. We believe that use of feathered catheters will signif icantly reduce the incidence of unwanted spontaneous displacement.