Performance of POCUS for Pregnancy Evaluation using a Non-Piezoelectric Ultrasound Device in the Emergency Department

Confirmation of pregnancy location using point of care ultrasound (POCUS) is an essential component of emergency obstetric care. The accuracy of a non-piezoelectric portable ultrasound device compared to obstetric sonographer-performed ultrasonography remains uncertain.

The objective of this study was to describe the practical utility of a non-piezoelectric POCUS system (Butterfly iQ+) in the emergency department, including characterizing the accuracy of findings relative to obstetric sonographer-performed ultrasound (OB-US) for obstetric and non-pregnant pelvis evaluations in the emergency department.

This retrospective cohort study was conducted at a Level 1 trauma center. Patients who underwent emergency physician-performed transabdominal obstetric or gynecologic POCUS examination using a non-piezoelectric transducer between November 2021 and November 2022 were included. Data from electronic medical records and ultrasound databases were abstracted. POCUS findings such as yolk sac presence, fetal heart motion, and gestational age were recorded alongside patient data including age, body mass index, human chorionic gonadotropin (hCG) levels, and ultrasound results. Descriptive statistics were analyzed using SPSS.

Seventy-two obstetric POCUS studies were included with an average maternal age of 29.6 ± 7.8 years. Common indications included positive pregnancy tests, abdominal/pelvic pain, and vaginal bleeding. All first-trimester intrauterine pregnancies (IUPs) diagnosed by POCUS and referred for OB-US were confirmed, with no false positives. POCUS had a sensitivity of 83.3% (95% CI 61.8-94.5) and specificity of 100% (95% CI 71.7-100) for confirmation of an IUP. The lowest hCG levels at which IUP was detected with POCUS were 6,488 without fetal heart motion and 7,098 with heart motion. The agreement between POCUS and OB-US for gestational age measurements was moderate (ICC = 0.83, 95% CI 0.0-0.99). In the second trimester, POCUS accurately detected fetal heart rate, with a strong agreement for gestational age (ICC = 0.96, 95% CI 0.43-0.99) compared to OB-US. Transabdominal POCUS also identified gynecologic conditions such as postpartum hemorrhage, and normal POCUS exams led to alternate diagnoses such as pelvic inflammatory disease and pyelonephritis.

POCUS using a non-piezoelectric ultrasound device was able to accurately rule in first trimester IUP in the emergency department at relatively low hCG levels, with no false positive IUPs identified. During the second and third trimesters, POCUS consistently detected fetal heart motion and had good accuracy for gestational age measurements compared to OB-US. These findings suggest that POCUS using a non-piezoelectric ultrasound device is a useful tool for emergency department assessments, though further evaluation is needed.