Abstract：
The second stage of labor extends from complete cervical dilatation to delivery. During this stage, descent and rotation of the presenting part occur as the fetus passively negotiates its passage through the birth canal. Generally, descent begins during the deceleration phase of dilatation as the cervix is drawn upward around the fetal presenting part. The most common means of assessing the normality of the second stage of labor is to measure its duration, but progress can be more meaningfully gauged by measuring the change in fetal station as a function of time. Accurate clinical identification and evaluation of differences in patterns of fetal descent are necessary to assess second stage of labor progress and to make reasoned judgments about the need for intervention. Three distinct graphic abnormalities of the second stage of labor can be identified: protracted descent, arrest of descent, and failure of descent. All abnormalities have a strong association with cephalopelvic disproportion but may also occur in the presence of maternal obesity, uterine infection, excessive sedation, and fetal malpositions. Interpretation of the progress of fetal descent must be made in the context of other clinically discernable events and observations. These include fetal size, position, attitude, and degree of cranial molding and related evaluations of pelvic architecture and capacity to accommodate the fetus, uterine contractility, and fetal well-being. Oxytocin infusion can often resolve an arrest or failure of descent or a protracted descent caused by an inhibitory factor, such as a dense neuraxial block. It should be used only if thorough assessment of fetopelvic relationships reveals a low probability of cephalopelvic disproportion. The value of forced Valsalva pushing, fundal pressure, and routine episiotomy has been questioned. They should be used selectively and where indicated.
摘要：
分娩的第二阶段从宫颈完全扩张延伸到分娩。在这个阶段,当胎儿被动地通过产道通过时，就会发生先兆部分的下降和旋转。一般来说,在扩张的减速阶段开始下降，因为子宫颈被向上拉动围绕胎儿先兆部分。评估第二阶段劳动正常性的最常见方法是测量其持续时间，但是通过测量胎儿位置随时间的变化，可以更有意义地衡量进展。准确的临床识别和评估胎儿下降模式的差异对于评估第二产程进展和对干预的必要性做出合理的判断是必要的。可以确定第二产程的三个明显的图形异常：长期下降，逮捕血统，和失败的下降。所有的异常都与头盆不相称有很强的关联，但也可能发生在母亲肥胖的情况下，子宫感染,过度镇静,和胎儿错位。必须在其他临床上可识别的事件和观察的背景下解释胎儿下降的进展。这些包括胎儿大小，position,态度,颅骨成型程度和骨盆结构和适应胎儿能力的相关评估，子宫收缩力，和胎儿的健康.催产素输注通常可以解决由抑制因素引起的下降停止或下降失败或长时间下降，如密集的神经轴块。只有在对胎骨盆关系进行彻底评估后发现头盆比例失衡的可能性较低的情况下，才应使用该方法。强迫瓦尔萨尔瓦的价值，眼底压力，常规会阴切开术也受到质疑。它们应该有选择性地使用，并在有指示的地方使用。
