The impact of high-frequency linear transducer on the accuracy of pelvic ultrasound in early pregnancy pelvic pain and bleeding

Abstract

Introduction: The primary concern of emergency physicians (EPs) in symptomatic patients in their early pregnancy is to rule out ectopic pregnancy by identifying a definite intrauterine pregnancy (IUP). Then an assessment of viability is required for the IUPs. Although transvaginal ultrasound (TVUS) stands as the best modality for these patients, it is not available in most emergency settings. This study aimed to investigate the effects of high-frequency linear transducers (HFLT) on the accuracy of point-of-care ultrasound (POCUS) for detection of IUP and the agreement between EPs and obstetricians for patients' diagnosis. Method: A convenience sample of pregnant patients who presented to the emergency department (ED) with vaginal bleeding and abdominopelvic pain was included. The characteristics of diagnostic tests of transabdominal POCUS performed by EPs were compared to TVUS. Results: The study population was finalized as 143 patients. For the definite IUP, the diagnostic accuracy of POCUS was 93.0%, with a sensitivity of 89.0%, a specificity of 100%, compared to an accuracy of 97.9% for POCUS plus HFLT with a sensitivity of 96.7%, a specificity of 100%. For the identification of fetal cardiac activity (FCA), utilizing HFLT improved the diagnostic accuracy to 97.9% (from 94.4%) and sensitivity to 95.5% (from 88.1%). In addition, the agreement between the EPs and obstetricians concerning the classification of ED diagnosis was excellent (agreement: 96.5%, kappa: 0.943, p < 0.0001). Conclusion: POCUS plus HFLT performed by EPs in evaluating symptomatic patients in their first-trimester pregnancy improves the accuracy to a non-inferior level compared to TVUS performed by obstetricians. Hence, EPs can securely rely on POCUS to confirm IUP and FCA. However, they should be cautious about using it as a rule-out tool. Moreover, HFLT use could enhance the accuracy of POCUS in viability assessment as an alternative to TVUS.