Endometrial Thickness and Pregnancy Outcomes Using Point-of-Care Ultrasound

Existing literature from obstetrics and gynecology suggests that smaller endometrial thickness (EMT) is correlated with abnormal pregnancy outcomes such as spontaneous abortion, and that larger EMT is correlated with normal pregnancy. Emergency department data is limited, where patients often present with concern for pregnancy complications, and there are no studies correlating the EMT on transabdominal (TAUS) point of care ultrasound (POCUS) to pregnancy outcomes. The study's aims were to determine test characteristics at predetermined EMT measurements between normal and abnormal pregnancies, and to determine the association between POCUS and radiology ultrasound (RADUS) EMT measurements.

This retrospective study evaluated pregnant adult patients who presented to a tertiary care emergency department from 1/1/2021 to 10/31/2024 who had a TAUS negative for intrauterine pregnancy (IUP). Patients were excluded if no images were saved, a gestational sac was present, or the endometrium could not be visualized. Data were collected by study investigators and included patient demographics, pregnancy dating, beta hcg level, and pregnancy outcome. If a RADUS was performed, the EMT and interpretation was recorded. POCUS images were reviewed by two ultrasound fellowship trained attending blinded to pregnancy outcome. Statistics were performed using SPSS.

A total of 566 patients were reviewed with 335 excluded. Patients were grouped into normal pregnancy and abnormal pregnancy (ectopic or miscarriage) for comparison. POCUS and RADUS EMT measurements were available for 137 patients and the association between the two measurements was strongly correlated (R2=0.64). A POCUS EMT cutoff of > 1.5 had a specificity of 94% and sensitivity of 19%. A RADUS EMT cutoff > 1.5 had a sensitivity of 83% and specificity of 31%. For the 17 patients with a normal birth, average EMT was 1.02 (SD 0.59) compared to the 87 with miscarriage (average EMT 1.15 (SD 1.02) and 39 with ectopic (average EMT 0.94 (SD 0.66).

POCUS and RADUS EMT measurements were strongly correlated. A POCUS EMT cutoff of >1.5 mm was specific for normal pregnancy, contrasting with previous studies. The study was underpowered and there was overlap for the average EMT for normal and abnormal pregnancy. Future studies should focus on maximizing specificity and sensitivity through optimizing the EMT cutoff point.