This study reviewed the former studies conducted on the usefulness of accuracy of focused assessment with sonography for trauma (FAST) or any plain ultrasonography (US) scan in pediatric blunt abdominal trauma (BAT), to assess its accuracy, sensitivity, specificity, and positive and negative predictive values (PPV and NPV). Searches were conducted using the predefined keywords and Medical Subject Headings (MeSH) terms across MEDLINE (PubMed), Scopus, Web of Science, Cochrane Collaboration Library, Embase, ClinicalTrials.gov, Magiran and SID.ir databases. Duplicate publications were excluded; then the titles and abstracts of eligible studies were reviewed for how they report blunt trauma, pediatric patients, and ultrasound modality in their text. Cochrane RevMan version 5.3 was used for the results analysis and assessing the risk of bias in the studies. Out of 923 studies, 902 were excluded, and only 19 articles were included in this review, out of which one was a randomized clinical trial (RCT), three were cohort studies, two were contrast-enhanced US (CEUS) studies, and 13 were prospective or retrospective descriptive studies. The total population studied in the articles was 3454 patients. The results showed that the specificity of US in pediatric BAT was 93%, the sensitivity was 54%, and the PPV in comparison to clinical examination was 73% versus 37%. CEUS protocol achieved 100% in both sensitivity and specificity analysis. The only RCT study which included about 28% of the studies population also reached a sensitivity and specificity of 97% and 98%, respectively using a combinational protocol of clinical examination, laboratory investigation, and US assessment. Ultrasonography does not provide more results than clinical examination, though better PPV results. A combination of follow-up, US examination, and laboratory requests may also have more accurate results. Moreover, a CEUS protocol may reach that goal with an acceptable time-saving outcome, but it needs more studies to be confirmed.