BACKGROUND: Semi-rigid medical thoracoscopy (MT), compared to video-assisted thoracoscopic surgery, offers a mini-invasive, moderately sedated, and less expensive diagnostic procedure. However, the safety of ultrasound-guided MT in the circumstances of minimal pleural effusion, <1cm of pleural space depth below the entry site, remains concerned.

METHODS: This retrospective cohort study included all of the 113 patients receiving ultrasound-guided MT from December 2017 to September 2020 in a medical center. The entry site was operator-determined by identifying positive regional lung-sliding sign and normal pleural line appearance. We approached the parietal pleura by a mosquito forceps after creating a minimal 1.5-2cm skin incision. The parietal pleura was penetrated by the pressure from the operator?s finger. Then, we introduced MT into the pleural cavity. Fisher's exact test was used to examine between-group differences in the incidence of procedure-related complications.

RESULTS: Of the 113 patients, 3 patients were excluded due to pneumothorax before the procedure. The remaining 110 patients were included in the analysis. The mean age of the patient cohort was 69.5 years (SD ±15.2 years); 70 (63.6%) of them were male. Minimal effusion was detected in 22 patients (20%). Eight complications (7.3%) were recorded. One complication occurred in the minimal effusion group (4.55%); the other 7 complications occurred in the moderate-to-massive effusion group (7.95%). There was no significantly increased risk of performing ultrasound-guided MT from the minimal effusion site (p>0.99).

CONCLUSIONS: Minimal pleural effusion did not significantly increase the complication rate of ultrasound-guided MT.