The utility of a drainage needle for percutaneous abscess drainage.
OBJECTIVE
In this article, I describe a percutaneous drainage needle that consists of six side holes in its cannula. The needle is specially designed for effective evacuation of complex abscess collections consisting of internal solid components, including floating debris, that tend to block the needle aperture during aspiration. The characteristic features of the needle and its performance in both in vitro and in vivo environments are described.


METHODS
An in vitro experiment was performed with the use of a model of a fluid collection containing floating sheets of gelatin sponge to mimic a complex body collection consisting of floating fibrinous strands. Five radiologists were asked to perform aspiration from two collections of normal saline and 5% methylcellulose of two different volumes using an ordinary aspiration needle and the drainage needle. The needle was evaluated in a prospective in vivo study of 30 postoperative abdominal collections in 29 consecutive patients that were drained by a single radiologist. Complete evacuation was attempted initially with a conventional aspiration needle. When there was sonographic evidence of residual fluid collection, a repeat aspiration using a drainage needle was performed during the same session.


RESULTS
In the in vitro experiment, the median percentage of fluid aspirated with the conventional needle from the 10- and 15-mL collections of saline was 10% and 15% and from the 10 mL and 15 mL of methylcellulose solution was 20% and 26.67%, respectively, whereas the drainage needle was able to remove 100% of fluid in all attempts. In the in vivo study, the conventional needle was able to remove all drainable fluid from the 12 simple collections. For the 18 complex collections, the drainage needle was always able to remove some residual fluid from the collection after aspiration with the conventional needle. The median percentage of fluid volume aspirated with the conventional needle was 55.6%, whereas that aspirated with both the conventional and drainage needles was 95.5%, with a significant difference by Wilcoxon's signed rank test (p < 0.001).


CONCLUSIONS
This drainage needle was effective in evacuating fluid from complex abdominal collections that could not be drained with conventional end-hole needles.
Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, The Chinese University of Hong Kong, 30-32 Ngan Shing St., Shatin, Hong Kong, China. simonyu@cuhk.edu.hk
Simon C H
SC
Yu
D018784:Abdominal Abscess / Q000628:therapy*; D004322:Drainage / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D009339:Needles; D011183:Postoperative Complications / Q000628:therapy*; D011446:Prospective Studies; D015641:Radiography, Interventional