Peritoneal Dialysis Catheter Position Evaluated by Ultrasound: Can it Replace Abdomen X-Ray in Patients Presenting Catheter Misplacement?

Abstract

Malfunction of the peritoneal dialysis catheter is frequently caused by dislocation. The diagnostic approach is classically based on abdomen X-ray together with detailed case history and physical examination. Despite being rarely applied in clinical practice to evaluate catheter misplacement, ultrasound is a noninvasive, radiation-free technique that is potentially useful also to explore reasons for catheter malfunction. Consequently, we aimed to evaluate the diagnostic accuracy of ultrasound to identify peritoneal catheter misplacement. In a multicenter observational blinded study, we compared ultrasound to abdomen X-ray for catheter localization in 93 consecutive peritoneal dialysis patients with dialysate outflow problems enrolled in two nephrology and dialysis units. The position of the catheter was annotated on a standard scheme of nine abdominopelvic regions. The sensitivity, specificity, positive and negative predictive value and Kappa coefficient were calculated. Dislocation out of the inferior abdominopelvic regions was present in 19 patients (20 %) at X-ray and 23 patients (25 %) at ultrasound. Correct determination of the position of the catheter in the lower abdomen by ultrasound had a sensitivity of 93 % (95 % CI 84 - 97 %), specificity of 95 % (95 % CI 72 - 100 %), positive predictive value of 99 % (95 % CI 91 - 100 %), negative predictive value of 78 % (95 %CI 56 - 92 %) and Kappa coefficient of 0.82 (95 % CI 0.67 - 0.96). In 10 out of 93 patients (11 %), there was a position mismatch between X-ray and ultrasound in an adjacent abdominopelvic region. Our results suggest that abdomen X-ray for the evaluation of peritoneal catheter position can be replaced by ultrasound in experienced hands. This bedside diagnostic procedure might reduce costs, the time necessary for diagnosis and lifetime radiation exposure.

Diagnostic capability of ultrasound in peritoneal catheter malfunction compared to videolaparoscopy

“…Many causes of catheter malfunction such as kinking, dislocation, adhesion of omentum, fibrin sheath formation and obstruction of the lumen can easily be ascertained by US, 2 –4 but the diagnostic accuracy of US has never been verified against a diagnostic reference such as VLS. For the first time, a prospective study compares the diagnostic capabilities of US directly to VLS.…”

“…The US examination was performed in supine position after having filled the abdomen with 1 L of dialysis fluid. 4 The catheter was followed, starting from the exit site up to the catheter tip, with sectorial or linear probes of 1–13 MHz. The US equipment used in this study consisted in a General Electric Logiq P7 (sectorial probe 4C-RS with 2–5.5 MHz, linear probe L6-12-RS with 6–13 MHz, GE Medical Systems Co. Ltd, Jiangsu, China), an Acuson S3000 Ultrasound System (sectorial probe 6C2 with 6–2.5 MHz, linear probe 9L4 with 9–4 MHz, Acuson-Siemens, Mountain View, California, USA) and a Esaote MyLab 25 (sectorial probe CA631 with 8–1 MHz, linear probe LA523 with 13–4 MHz, Esaote S.r.L.…”

“…Dislocation was defined as catheter tip position out of the lower abdomen according to a previously published scheme. 4 In patients who presented a filled urinary bladder at examination a post-void US was performed to exclude urinary retention. The time needed for US examination is 15–20 min.…”

“…Possible imaging techniques are abdomen radiography, catheter peritoneography, computed tomography, magnetic resonance tomography, peritoneal scintigraphy and ultrasound (US). 1 –5 Videolaparoscopy (VLS) is the ‘gold’ standard of a combined diagnostic and therapeutic approach in catheter malfunction. 6,7 US remains, beside physical examination, the only bedside diagnostic technique of the peritoneal catheter.…”

“…2,3 In expert hands, US is highly accurate for the evaluation of catheter position. 4 Besides catheter dislocation, other causes of malfunction such as omental wrapping, intraluminal fibrin clot, adhesions or urinary retention can be ascertained by US. 2 –4 As we started to perform routinely US examination in the case of catheter malfunction, we intended to validate the diagnostic capability of US compared to the ‘gold’ standard of VLS.…”