正常分娩--课件

,编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,NORMAL LABOR AND DELIVERY,正常分娩,Contents,Objective,1,Maternal changes before onset of labor,2,Stages of labor,3,Mechanism of labor,4,Objective,be able to discuss the management of the laboring patient, including appropriate triage and diagnosis.,Be able to describe how to perform a vaginal delivery and to list indications for cesarean delivery.,understand the options for pain management and describe deviations from normal labor as well as maternal and fetal monitoring.,Maternal changes,lightening,uterine contractions,bloody show,Maternal changes before onset of labor,Maternal changes before onset of labor,Uterine contractions,As a patient approaches term, she experiences,uterine contractions,of increasing strength and frequency.,Spontaneous uterine contractions, which are not felt by the patient,occur throughout pregnancy.,These Braxton Hicks contractions (false labor) are not associated with dilation of the cervix, however, and do not fit the definition of labor.,Braxton Hicks contractions are typically shorter in duration and less intense than true labor contractions,with the discomfort being characterized as over the lower abdomen and groin areas.,True labor is associated with contractions that the patient feels over the uterine fundus, with radiation of discomfort to the low back and lower abdomen. These contractions become increasingly intense and frequent.,Lightening,Another event of late pregnancy is termed “,lightening,” in which the patient reports a change in the shape of her abdomen and the sensation that the baby is lighter, the result of the fetal head descending into the pelvis.,The patient often notices that her lower abdomen is more prominent, and she may feel a need to urinate more frequently as the bladder is compressed by the fetal head. The patient may also notice that she is breathing more easily.,Maternal changes before onset of labor,Maternal changes before onset of labor,Bloody show,Patients often report the passage of blood-tinged mucus late in pregnancy. This “,bloody show,” results as the cervix begins thinning (effacement) with the concomitant extrusion of mucus from the endocervical glands and a small amount of bleeding from small vessels in the area.,Cervical effacement,is common before the onset of true labor when the internal os is slowly drawn into the lower uterine segment. The cervix is often significantly effaced before the onset of labor, particularly in the nulliparous patient.,Maternal changes before onset of labor,The mechanism of effacement and dilation andthe vectors of the expulsive forces,Onset of labour,Definition of the onset of labour,Regular uterine contractions at least every six minutes with evidence of change in cervical dilation or cervical effacement between consecutive digital examinations,Stages of labor,Fourth stage of labor,Third stage of labor,Second stage of labor,postpartum,placenta delivery,fetal expulsion,dilation,First stage of labor,Although labor is a continuous process, it is divided into four functional stages because each has differing physiological activities and requires differing management.,Stages of labor,The,first stage of labor,is the interval between the onset of labor and full cervical dilation (10 cm). The first stage is further divided into two phases: 1) The,latent phase,of labor encompasses cervical effacement and early dilation and 2) the,active phase,of labor, during which more rapid cervical dilation occurs, usually beginning at approximately 5 to 6 cm.,The,second stage of labor,encompasses complete cervical dilationthrough the delivery of the infant.,The,third stage of labor,begins immediately after delivery of the infant and ends with the delivery of the placenta.,The fourth stage of labor,is defined as the immediate postpartum period of approximately 2 hours after delivery of the placenta, during which time the patient undergoes significant physiologic adjustment.,Stages of labor,Stages of labor,The stages of labor were first described in the research by Emmanuel Friedman, and Figure 8.5 represents this information graphically, known as the,Friedman curve,.,Mechanism of labor,The,mechanisms of labor,(also known as,the cardinal movements of labor,) refer to the changes of the position of the fetus as it passes through the birth canal.,Because,vertex presentation,occurs in 95% of term labors, the cardinal movements of labor are defined relative to this presentation.,To accommodate to the maternal bony pelvis, the fetal head must undergo several movements. These movements are accomplished by means of the forceful contractions of the uterus. These,cardinal movements of labor,do not occur as a distinct series of movements but, rather, as a group of movements that overlap as the fetus accommodates and moves progressively through the birth canal.,Mechanism of labor,These movements are as follows:1. Engagement2. Flexion3. Descent4. Internal rotation5. Extension6. External rotation or restitution7. Expulsion,Mechanism of labor,Engagement,is defined as descent of the biparietal diameter of the head below the plane of the pelvic inlet, suggested clinically by palpation of the presenting part below the level of ischial spines (0 station).,Engagement commonly occurs days to weeks prior to labor in women who have not delivered a child, whereas in women who have had children, it more commonly happens at the onset of active labor. In any event, the importance of this event is that it suggests that the bony pelvis is adequate to allow significant descent of the fetal head.,Flexion,of the fetal head allows for the smaller diameters of the fetal head to present to the maternal pelvis.,Descent,of the presenting part is necessary for the successful completion of passage through the birth canal.,The greatest rate of descent occurs during the latter portions of the first stage of labor and during the second stage of labor.,Mechanism of labor,Internal rotation, like flexion, facilitates presentation of the optimal diameters of the fetal head to the bony pelvis, most commonly from transverse to either anterior or posterior.,Extension,of the fetal head occurs as it reaches the introitus. To accommodate the upward curve of the birth canal, the flexed head now extends.,External rotation,occurs after delivery of the head as the head rotates to “face forward” relative to its shoulders. This is known as restitution, followed rapidly by delivery of the body,expulsion,.,