Diagnostic equivalency of mobile CTG devices and remote analysis to conventional on-site nonstress test

BACKGROUND: Remote pregnancy monitoring is one of the most promising applications of telemedicine; however, the diagnostic value of self-examination using mobile cardiotocography (CTG) devices and remote analysis of the subsequent results has never been properly studied. OBJECTIVES: The study aimed to compare the diagnostic usefulness of CTG self-examination using a mobile device to examination performed by a medical professional using a stationary device; and to evaluate the quality of CTG analysis performed remotely. MATERIAL AND METHODS: Eighty-two pairs of CTG recordings were collected; each pair consisted of a single recording from an examination performed by a midwife using a stationary device, and another recording from an unassisted patient self-examination using a mobile device. Recordings were performed with a maximum time interval of 30 min. Each recording was analyzed twice. Primary analysis included a comparison of the assisted examination evaluated on-site vs the self-examination evaluated remotely in pairs. Secondary analysis was conducted by an independent expert who evaluated the unpaired recordings. Baseline fetal heart rate (BFHR) values were compared independently. RESULTS: We found that patients were more likely to perform inconclusive recordings than experienced midwives; however, the self-examination feasibility was satisfactory. The primary analysis showed 88.4% agreement of the recorded pairs; 11.6% of inconsistent pairs were due to inter-observer variability or medical reasons. The independent expert's analysis showed 97.1% agreement between the assisted and unassisted examinations. Paired t-test for BFHR values showed a statistically significant but clinically negligible mean difference between the 2 devices at 1.75 bpm. CONCLUSIONS: The CTG examinations performed using mobile devices present satisfactory feasibility and equivalent diagnostic value compared to conventional devices, while the remote evaluation of recordings is as reliable as on-site analysis. Remote pregnancy surveillance is safe, effective and may be implemented into everyday obstetric care.