产程中枕横位和枕后位的胎头机转临床研究

Anterior rotation in occiput transverse and occiput posterior positions

目的 观察以枕横位或枕后位衔接的胎头在产程中向枕前位自然旋转的规律,为徒手旋转胎头时机的选择提供依据.方法 2014年4月至2014年12月住院待产,宫口扩张至3 cm前阴道检查确认胎头为枕横位或枕后位、记录每次阴道检查的胎方位、宫口扩张、先露高位,以最终阴道顺产的1 013例单胎足月分娩产妇为研究对象.以产程中首次发现胎方位转为枕前位时的宫口大小和先露高低作为观察指标,宫口自扩张4 cm始每扩张2 cm作为1层分4层：4～5 cm、6～7 cm、8～9 cm、10 cm,先露自坐骨棘上2 cm（S-2）始每下降1 cm作为1层分5层：S-1、S0、S＋1、S＋2、S＋3.分析产妇枕横位和枕后位的胎头自然旋转率、胎头机转、胎头旋转率与宫口扩张大小和先露下降水平的关系.结果 临产时枕横位850例,枕后位407例,自然转为枕前位的比例分别为82.5％ （701/850）和76.7％（312/407）.枕横位和枕后位胎头旋转的构成比在不同宫口扩张大小间差异有统计学意义（x2 =260.93,P＜0.01）.枕横位和枕后位胎头旋转的构成比在不同先露下降水平间差异有统计学意义（x2=133.18,P＜0.01）.有利于枕横位自发旋转至枕前位的因素包括宫口扩张6～7cm（OR =5.81,95％ CI：3.81～8.87）、8～9 cm（OR =4.99,95％ CI：3.19～7.83）,先露下降至S＋1（OR =3.01,95％ CI：1.99 ～4.54）、S＋2（OR =5.43,95％ CI：3.53 ～8.35）.有利于枕后位自发旋转至枕前位的因素为宫口扩张6～7 cm（OR =4.11,95％CI：2.24～7.89）、8～9 cm（OR =27.31,95％ CI：15.12 ～49.34）、10 cm（OR =27.76,95％ CI：14.87 ～51.82）,先露下降至S＋2（OR =4.84,95％ CI：3.03～7.73）.结论 产程中以枕横位或枕后位衔接的胎头,自发旋转至枕前位的时机有所不同.宫口扩张6～9 cm、胎先露下降至S＋1 ～S＋2有利于枕横位自发旋转至枕前位;宫口扩张6～10 cm、胎先露下降至S＋2有利于枕后位自发旋转至枕前位.掌握其胎头自发旋转的规律,既可提高徒手旋转胎头的成功率,又能降低头位难产率.

Objective To investigate the natural rotation of the fetal head during labor when it was engaged by occiput transverse （OT） or occiput posterior（OP） positions.Methods A total of 1 013 parturients was included who had a singleton term gestation, vertex presentation, OT or OP position with cervical dilatation of ≤ 3 cm, and vaginal delivery.All parturients were delivered in Xiamen Hospital of Traditional Chinese Medicine during April 1 to December 31,2014.Cervical dilation, station, and fetal position of every delivery were systematically recorded.Main outcome was the cervical dilation and station of anterior rotation from OT or OP position.They were Stratified by cervical dilation every 2 cm since 4 cm into 4 ～ 5 cm, 6 ～7 cm, 8 ～9 cm, 10 cm;or were stratified by fetal head station every 1 cm since-2 （S-2） into S-1 , S0, S＋1 , S＋2 , S＋3.The differences in anterior rotation rate, dilatation, and head station between OT and OP were analyzed.Results There were 850 OT and 407 OP with cervical dilatation of ≤≤ 3 cm.The rate of anterior rotation was 82.5 % （701/850） and 76.7 % （312/407）, respectively.The constituent ratio of OT rotating into occiput anterior position （OA） at different dilatation was different with that of OP （x2 =260.93, P 〈 0.01）.The constituent ratio of OT rotating into OA at different fetal head station was different with that of OP （x2 =133.18, P 〈0.01）.The cervical dilatation and fetal head station that make it easy for OT ＇s anterior rotation were 6 ～7 cm （OR =5.81 , 95% CI ：3.81 ～8.87）, 8 ～9 cm（OR =4.99 ,95% CI：3.19 ～7.83）, and S＋1（OR =3.01, 95% CI： 1.99 ～4.54）, S＋2（OR =5.43, 95% CI：3.53 ～ 8.35）.The cervical dilatation and fetal head station that make it easy for OP ＇s anterior rotation were 6～7 cm（OR =4.11,95% CI ：2.24 ～7.89）, 8 ～9 cm（OR =27.31, 95% CI ：15.12 ～49.34）, 10 cm（OR =27.76 , 95% CI ：14.87 ～51.82）, S＋2（OR =4.84 , 95% CI ：3.03 ～7.73）.Conclusions The anterior rotation time of OT is different from OP.It＇s easy for OT to rotate into OA when cervix dilate into 6 ～9 cm and fetal head station is at S＋1 ～ S＋2.When cervix dilate into 6 ～ 10 cm and fetal head station is at S＋2, it＇s easy for OP to rotate into OA.