本研究旨在利用高频超声定量评估产后女性腹直肌分离程度，探索恰当的诊断界值以及影响腹直肌分离程度的相关因素。

2019年4月至7月招募51名在北京大学第三医院生产后6~30个月的女性，采集年龄、身高、体质量、体质量指数、产后时间、生产方式、胎产次，测量腹围，超声评估皮下脂肪厚度、放松时及收缩时腹直肌最大间距，采用Pearson相关分析方法分析年龄、身高、体质量、体质量指数、产后时间、腹围、皮下脂肪厚度与腹直肌间距的相关性，利用Point-biserial相关分析法分析生产方式、胎产次与腹直肌间距的相关性。利用独立样本t检验比较剖宫产与顺产女性腹直肌间距放松与收缩状态下的差异。

51名女性放松状态下平均腹直肌最大间距为（2.88±1.04）cm，收缩状态下腹直肌最大间距为（2.45±1.15）cm，如将腹直肌间距偏离正常人群75%设为诊断界值，放松时及收缩时腹直肌分离诊断界值分别为3.0 cm、2.8 cm，放松状态下腹直肌间距与收缩状态下间距呈线性相关（r=0.899，P＜0.001）。放松及收缩状态下腹直肌间距与年龄、身高、体质量、体质量指数、产后时间、腹围、皮下脂肪厚度、胎产次均无明显相关性，仅生产方式与收缩时腹直肌间距存在相关性（r=0.369，P=0.008）。剖宫产女性放松及收缩状态下腹直肌间距均大于顺产女性［（3.16±1.31）cm vs （2.58±0.47）cm；（2.85±1.35）cm vs （2.00±0.64）cm］，差异均具有统计学意义（t=-2.082、-2.828，P=0.038、0.007）。

高频超声能准确定量评估腹直肌分离程度，可以为探索腹直肌分离机制及相关影响因素提供有效信息。

To quantitatively evaluate diastasis recti abdominis in postpartum women by high frequency ultrasound, investigate the appropriate diagnostic threshold, and identify the factors related to diastasis recti abdominis.

From April to July 2019, 51 women at 6-30 months after delivery at Third Hospital of Peking University were recruited. Age, height, weight, body mass index, postpartum time, mode of delivery, and delivery times were collected. Abdominal circumference was measured. Subcutaneous fat thickness and maximum rectus abdominis distance during relaxation and contraction were evaluated by ultrasound. Pearson correlation analysis was used to explore the relationship between rectus abdominis distance and age, postpartum time, height, and physique. Point biserial correlation analysis was used to explore the correlation between delivery mode or delivery times and rectus abdominis distance. Independent sample t test was used to compare the difference of rectus distance in relaxation or contraction state between cesarean section and natural delivery women.

The average maximum distance of the rectus abdominis was (2.88±1.04) cm in relaxation and (2.45±1.15) cm in contraction. When 75% of the rectus abdominis distance deviated from the normal population was set as the diagnostic cut-off value, the diagnostic cut-off values of diastasis recti abdominis during relaxation and contraction were 3.0 cm and 2.8 cm, respectively. There was a linear correlation between rectus abdominis distance during relaxation and contraction (r=0.899, P＜0.001). There was no significant correlation between the distance of the rectus abdominis and age, height, weight, body mass index, postpartum time, abdominal circumference, subcutaneous fat thickness, or delivery times. Only the mode of delivery had a weak correlation with the distance of the rectus abdominis during contraction (r=0.369, P=0.008). There was no significant difference in the distance of the rectus abdominis between the first and second births. The distance of the rectus abdominis in women with a caesarean section was significantly larger than that of women with a natural delivery [(3.16±1.31) cm vs (2.58±0.47) cm, t=-2.082, P=0.038; (2.85±1.35) cm vs (2.00±0.64) cm, t=-2.828, P=0.007].

High frequency ultrasound can accurately and quantitatively evaluate diastasis recti abdominis, and the measurement of rectus abdominis distance in relaxation or contraction state has similar value. High frequency ultrasound can provide useful information for exploring the mechanism of diastasis recti abdominis and related influencing factors.