通过盆底三维超声检查评估不同分娩方式及不同产次对肛提肌裂孔（LH）面积的影响及其与盆腔器官脱垂（POP）的关系。

选择2019年4月至12月湖北省妇幼保健院产后42~60 d常规检查的产妇250例，包括初次经阴道分娩产妇（FVD组）150例、二次经阴道分娩（SVD组）及剖宫产产妇（CS组）各50例，行经会阴超声检查，观察静息状态下及最大Valsalva状态时LH面积的变化，并选择同期120例未分娩女性作为对照组。分析各组内POP盆底超声检出率。并将所有研究对象根据是否有POP分为POP组（167例）和无POP组（203例），比较2组间静息状态下及最大Valsalva状态下的LH面积。SVD组、FVD组、CS组和对照组组间LH面积差异采用方差分析，采用t检验比较有POP组和无POP组间LH面积的差异；采用χ²检验分析SVD组、FVD组、CS组和对照组组间POP的超声检出率差异。

静息状态下SVD组、FVD组、CS组、对照组LH面积分别为（16.59±3.12）cm²、（15.34±3.50）cm²、（13.09±2.78）cm²及（11.09±2.47）cm²；Valsalva状态下各组LH面积分别为（22.80±8.37）cm²、（18.46±6.63）cm²、（15.58±3.91）cm²及（13.11±5.30）cm²；静息状态下及最大Valsalva状态下LH面积，SVD组＞FVD组＞CS组＞对照组，各组组间差异均具有统计学意义（F=31.89、11.14，P均＜0.001）。对照组、CS组、FVD组及SVD组POP超声检出率分别为：17.5%、26.0%、60.0%及86.0%，CS组与对照组间比较，差异无统计学意义，其余各组间比较差异均具有统计学意义（SVD组 vs FVD组：χ²=11.38，P＜0.001；SVD组 vs CS组：χ²=36.53，P＜0.001；SVD组vs对照组：χ²=70.55，P＜0.001；FVD组vs CS组：χ²=17.36，P＜0.001；FVD组vs对照组：χ²=49.74，P＜0.001）。静息状态及最大Valsalva状态下POP组LH面积均大于无POP组［（14.88±3.49）cm² vs（12.38±2.17）cm²；（20.93±6.53）cm² vs（15.59±3.50）cm²］，差异具有统计学意义（t=8.06、9.50，P均＜0.001）。

不同分娩方式及产次对女性LH面积的影响程度不同；LH面积越大，发生POP的风险越高。盆底三维超声能够测量产后女性不同状态下的LH面积，从而早期发现盆底支持结构的改变。

To observe the effect of parity and delivery mode on levator hiatus (LH) area evaluated by pelvic floor three-dimensional ultrasound, and to explore their relationship with pelvic organ prolapse (POP).

A total of 250 postpartum women at 42~60 days after childbirth were selected at the Material and Child Health Hospital of Hubei Province from April to December 2019, including 150 first vaginal delivery (FVD) women, 50 second vaginal delivery (SVD) women, and 50 cesarean section (CS) women. The change of LH area was observed at rest and on maximal Valsalva maneuver by pelvic floor three-dimensional ultrasound. And 120 undelivered women were selected as a control group. The detection rate of POP by pelvic floor ultrasound in each group was analyzed. All the subjects were divided into a POP group (n=167) and a non-POP group (n=203) according to whether they had POP or not. The LH area was compared between groups at rest and on maximal Valsalva maneuver. ANOVA was used to compare LH area among different groups. The t-test was used to compare LH between the POP group and non-POP group. The difference of POP detection rate between different groups was analyzed by the χ² test.

The LH areas at rest in the SVD group, FVD group, CS group, and control group were (16.59±3.12) cm², (15.34±3.50) cm², (13.09±2.78) cm², and (11.09±2.47) cm², respectively; the corresponding values on maximal Valsalva maneuver were (22.80±8.37) cm², (18.46±6.63) cm², (15.58±3.91) cm², and (13.11±5.30) cm², respectively. The LH area both at rest and on maximal Valsalva maneuver differed significantly among the groups (F=31.89 and 11.14, respectively, P＜0.001), with the SVD group having the greatest values, followed by the FVD group, CS group, and control group. The detection rates of POP by pelvic floor ultrasound were 17.5%, 26.0%, 60.0%, and 86.0% in the control group, CS group, FVD group, and SVD group, respectively; although there was no significant difference between the CS group and control group, the differences between the following groups were statistically significant: SVD group vs FVD group (χ²=11.38, P＜0.001); SVD group vs CS group (χ²=36.53, P＜0.001); SVD group vs control group (χ²=70.55, P＜0.001); FVD group vs CS group (χ²=17.36, P＜0.001); FVD group vs control group (χ²=49.74, P＜0.001). The LH areas in the POP group were significantly larger than those in the non-POP group both at rest [(14.88±3.49) cm² vs (12.38±2.17) cm², t=8.06, P＜0.001] and on maximal Valsalva maneuver [(20.93±6.53) cm² vs (15.59±3.50) cm², t=9.50, P＜0.001].

Different delivery modes and parity have different effects on the LH area. The larger the area, the greater the risk of POP. Three-dimensional ultrasound can measure the LH area of postpartum women in different states, so as to detect the change of pelvic floor structure early.