Test characteristics of emergency physician-performed point-of-care ultrasound for the diagnosis of intrauterine pregnancy: a systematic review and meta-analysis

Point-of-care ultrasound (PoCUS) has emerged as a critical tool for diagnosing intrauterine pregnancy (IUP) in symptomatic first-trimester patients, particularly in emergency settings. This meta-analysis aims to evaluate the test characteristics of PoCUS in diagnosing IUP. As a secondary objective, this study will also examine the accuracy of PoCUS in detecting fetal cardiac activity (FCA). This systematic review and meta-analysis was conducted following the PRISMA-DTA guidelines with the protocol registered in PROSPERO (ID: CRD42024596206). We performed a comprehensive search of PubMed, Scopus, Web of Science, Cochrane Library and Google Scholar up to November 2024, identifying studies that compared PoCUS to reference standards for IUP diagnosis. Seven studies (n = 1716) were included in the meta-analysis. Two independent reviewers performed study selection, data extraction, and quality assessment using the QUADAS-2 tool. A bivariate random-effects model was used to pool the diagnostic accuracy metrics. In this meta-analysis, PoCUS demonstrated a pooled sensitivity of 86.3% (95% CI: 75.6%-92.8%, I² = 89.8%) and a specificity of 98.2% (95% CI: 86.6%-99.8%, I² = 72.6%) for the identification of IUP. Sensitivity analysis showed a significant decrease in heterogeneity for specificity (from 72.6% to 0%), along with a slight increase in sensitivity (88.5%). The pooled positive likelihood ratio was 39.01 (95% CI: 16.00-95.1), and the negative likelihood ratio was 0.10 (95% CI: 0.05-0.21). Moreover, subgroup analysis revealed higher sensitivity (92%) in studies using transvaginal ultrasound as the reference standard. In addition, PoCUS demonstrated high specificity (100%) and variable sensitivity (81-96%) for identifying FCA across three studies, but the limited number of studies prevented further meta-analysis. PoCUS is highly effective for diagnosing IUP in symptomatic first-trimester patients, allowing for the ruling out of ectopic pregnancy. However, when PoCUS is negative or indeterminate, follow-up strategies such as serial β-hCG, repeat ultrasound, or clinical reassessment remain essential to ensure diagnostic safety.