The importance of ultrasonographic measurement of peritoneal wall thickness in pediatric chronic peritoneal dialysis patients

The Underrated Role of Ultrasound in Peritoneal Dialysis

Ultrasound is very effective in performing procedures and assessment of complications in peritoneal dialysis. The ultrasound examination can be applied for preoperative assessment, during the peritoneal catheter placement, for the detection and monitoring of infection, as well as for the evaluation of the catheter malfunction. Despite being not only a cost- and time-saving technique but also a bedside procedure, ultrasonography remains an underrated clinical tool in the field of peritoneal dialysis. This publication wants to explain and reinforce the clinical utility of US in PD and to expand the diagnostic equipment for the clinician.

Direct Comparison of the Thickness of the Parietal Peritoneum Using Peritoneal Biopsy and Ultrasonography of the Abdominal Wall in Patients Treated with Peritoneal Dialysis

Background

Long-term treatment with peritoneal dialysis (PD) results in peritoneal fibrosis. Peritoneal biopsies have been used to determine the severity of fibrosis. Ultrasonography (US) of the abdominal wall has been used to measure peritoneal thickness non-invasively. However, direct comparison of both methods in the same patient has never been done. Furthermore, the validity of US to measure peritoneal thickness has not been investigated.

Methods

We performed 3 studies: 1) a human biopsy study to compare US measurement of peritoneal thickness with histological examination; 2) a human cadaver study to investigate the effect of removing the peritoneum on US results; and 3) a phantom study in which we used US to measure the thickness of membrane-like structures with a known thickness to investigate the influence of different US settings.

Results

The median thickness in biopsies of the peritoneum was 113 μm (interquartile range [IQR] 72 –129 μm), while this was 370 μm (IQR 324 – 458 μm) when measured by US ( p < 0.0001). The mean difference between the 2 measures was -257 μm (limits of agreement -4.6 and -511 μm). In the cadaver study, removal of the peritoneum did not have an effect on the presence or thickness of the hyperechoic line reported to represent the peritoneum. In the phantom study, results were highly dependent on frequency of the transducer, scan depth, and gain settings.

Conclusions

Ultrasonography results differ markedly from histological measurement using peritoneal biopsies. However, the hyperechoic line generated by US represents the interface between 2 neighboring tissues and not a separate morphological structure. Moreover, its thickness is greatly influenced by user-defined US settings.