May ultrasound probe size influence pain perception of needle piercing during transrectal prostate biopsy? A prospective evaluation

Introduction and Objective: Transrectal ultrasound guided prostate biopsy (TRUS-Bx) is the definitive step in the diagnosis of prostate cancer (CaP). Patients (pts) generally experience significant pain during the procedure at the point that biopsy should be accompanied by some form of anesthesia. Several different factors influence pain perception (PP) during TRUS-Bx. In our study we want to assess that the use of an ergonomic smaller sized probe reduces PP during the procedure independently from the administration of local anesthesia or pain relieving drugs. Materials and Methods: This was a prospective, randomized study in which 114 pts who underwent TRUS-Bx due to abnormal PSA and/ or to digital rectal examination (DRE) suspicious findings were considered eligible. Pts were split in two TRUS-Bx groups into which we used two different sized ultrasound probes. In group 1, 61 pts underwent TRUS-Bx with ALOKA end fire probe (size 74 mm). In group 2, 53 pts underwent TRUS-Bx with B-K Type 8818 probe (size 58 mm). Both groups were treated with no local anesthesia or pain relieving drugs. Pain was evaluated three times using a 10-point visual analogue scale (VAS), during the DRE (VAS 1), during the insertion of the probe (VAS 2) and during the needle piercing (VAS 3). Results: Mean age of pts was 68.03 (SD 8.51); mean tPSA and mean prostate volume was 7.75 (SD 4.83) and 45.17cc (SD 17.7), respectively. The two groups were homogeneous respect to tPSA (p = 0.675) and to prostate volume (p = 0.296); age was significantly different (p = 0.04) between Group 1 (65.93) and Group 2 (70.43), whereas no statistically significant correlation between VAS 3 and age was observed (p = 0.179). Analyzing pain perception, we found no statistically significant difference between the two groups in DRE (VAS 1; p = 0.839); on the contrary, patients in Group 1 experienced on average more pain than other in Group 2 both during the insertion of the probe (VAS 2 3.49 vs 1.09; p < 0.001) and during the needle piercing VAS 3 (2.8 vs 2.00; p < 0.05). The discomfort during probe insertion and manipulation was perceived as very high (VAS 2 > 5) in 42.6% of patients in Group 1 and in 9.4% in Group 2. Globally, the procedure was well tolerated (mean VAS score < 3) in 77% of patients in Group 1 and in 90% in Group 2. The proportion of patients who experienced more than moderate pain (VAS > 5) during needle piercing ranged 24.6 % in Group 1 to 18.9 % in Group 2. Conclusions: Patients who underwent a TRUS-Bx with the 58-mm circumference probe were found to experience lower degree of pain not only during the insertion of the probe through the anal sphincter, but also in the moment of needle piercing.