To evaluate the consistency of full-stack smart pelvic floor ultrasound (FSPFU) and manual method in obtaining and measuring the minimum levator hiatus (LH) plane.

From November 2020 to January 2021, 119 women within 6 months after delivery who underwent pelvic floor ultrasound examination at Shenzhen Second People's Hospital were prospectively selected as the research subjects. Using the abdominal volume probe to set the midsagittal plane of pelvic floor as the initial plane, the three-dimensional volume data at rest and during the Valsalva maneuver were acquired and stored in the ultrasonic diagnostic instrument. Two young physicians (young physician manual measurement group) and two senior physicians (senior physician manual measurement group) retrieved the three-dimensional volume data to manually obtain and measure the minimum LH plane. Another young physician (automatic measurement group) retrieved the three-dimensional volume data and used the FSPFU software to automatically obtain and measure the minimum LH plane with one click, and the measurement was repeated once after an interval of 2 weeks. The measurement parameters of the minimum LH include area, circumference, anterioposterior diameter, transverse diameter, left-levator-urethra gap, and right-levator urethral gap. The time and results of obtaining and measuring the minimum LH plane were recorded for each group. The interclass correlation coefficient (ICC) and Bland-Altman plot were used to evaluate the consistency among the three groups. The Dice coefficient of the minimal LH contour outlined by the three groups was calculated.

The automatic measurement group took the shortest time both at rest and during the Valsalva maneuver [2.67 (0.15) s and 2.68 (0.13) s, respectively] compared with the two manual measurement groups (P<0.001). The consistency of the three parameters between the automatic measurement group and the two manual measurement groups was good. The ICC ranged from 0.795-0.931 in the resting state and from 0.871-0.973 during the Valsalva maneuver (P<0.001). The Bland Altman plot also showed good consistency among the groups. The Dice coefficient of the minimal LH outlined contours of the automatic group and the two manual measurement groups (young physician group and senior physician group) were 0.937 and 0.948 in the resting state and 0.934 and 0.945 in the Valsalva state, respectively; the Dice coefficient between the automatic measurement group and the senior physician group was higher than that between the automatic measurement group and the young physician group (P<0.05).

FSPFU can quickly and automatically obtain and measure the minimum LH plane based on the three-dimensional volume data of the abdomen. It is simple to operate, has reliable measurement results, and can be used as an effective and time-saving method to assist in the diagnosis of pelvic floor dysfunction diseases.