Table 3.

Characteristics of studies included in the systematic review of therapeutic ultrasound used in contraception. TU therapeutic ultrasound, NI no information.

Main Author [Ref.] Publication Year Country	Study Design	Study Population	Therapeutic Ultrasound: No. of Sessions and Duration Mode TU Frequency Intensity	Controls	Outcome Variables	Main Results	Study Risk of Bias
Dogs
Fahim [15] 1977 USA	Experimental intervention study, before-after design	Experiment 1: 24 adult healthy dogs Experiment 2: 6 adult healthy dogs	Experiment 1: 1-3 15-min sessions, weekly intervals Mode NI TU frequency NI Intensity 1 W/cm2 Experiment 2: One 15-min session Intensity 2 W/cm2	None (comparisons between different ultrasound treatments)	Follow-up at 60 days Semen analyses (sperm count) Blood testosterone	Zero sperms after 60 days with three treatments at 1 W/cm2, 70% reduction with two treatments, 40% with one treatment. After one treatment with 2 W/cm2, spermatogenesis ceased after 14 days. Sperm stem cells and Sertoli cells were not affected. No changes in blood testosterone levels	Low
Leoci [43] 2009 Italy	Experimental intervention study, before-after design	5 healthy mixed-breed male dogs	Three 5-min sessions with 2-day intervals Mode NI US frequency NI Intensity 1.5 W/cm2	Status before TU	14-day follow-up Testicular size and tenderness Semen analysis (sperm count)	Testicular tenderness and reduced testicular volume. All dogs azoospermic at 14 days’ post-treatment	Low
Leoci [44] 2015 Italy	Randomized controlled trial	100 mature healthy mixed-breed maledogs	Five intervention groups: One to three 5-min sessions with 5-min to 48-h intervals and different areas of testicles treated Mode and frequency NA Intensity 1.5 W/cm2	Non-treated (device switched off)	On day 30: Testicular size, sperm evaluation, blood testosterone.At days 40–47: Histological evaluation of the testicles	Reduced testicular size, azoospermia, and testicular tissue degeneration in dogs receiving three sessions of TU over the entire testicles at 48-h intervals, 1.5 W/cm2. No major effects of other regimens. No changes in testosterone levels in any experimental group	Low
Khanbazi [45] 2020 Iran	Experimental randomized study	10 mixed-breed adult fertile dogs	Three 5-min sessions, thereafter one session every 48 h (NI on for how long) 1.0 MHz 1.5 W/cm2	Placebo-treated (device turned off)	63-day follow-up Ultrasound of testis Semen evaluation Serum testosterone and other biomarkers Oxidative stress index Histology	No difference in semen quality or testosterone levels Temporary increases in inflammatory and oxidative stress biomarkers Histological signs of late testicular necrosis and degeneration	Moderate (some information on the TU regime lacking)
Cats
Fahim [15] 1977 USA	Intervention study, before-after design	30 male cats	Group A: One 10-min session Mode NI US frequency NI Intensity 1 W/cm2 Group B: same plus repeated same treatment at 48 h	Untreated cats	Follow-up at 60 days Histology in testicular biopsies Blood testosterone	Suppression of spermatogenesis at 60 days, more pronounced after two treatments. Unchanged testosterone levels	Low