Intrapartal Care (Assessment of the Laboring Mother) PDF

INTRAPARTAL CARE (ASSESSMENT OF THE LABORING MOTHER)  Describe common theories explaining the onset of labor and Describe the role of passenger, passage, and powers in labor. Assess a family in labor, identifying the woman’s...

INTRAPARTAL CARE (ASSESSMENT OF THE LABORING MOTHER)  Describe common theories explaining the onset of labor and Describe the role of passenger, passage, and powers in labor. Assess a family in labor, identifying the woman’s readiness, Assess stage, and progression. LEARNING OBJECTIVES Understand Understand the components of labor for successful delivery. Identify areas related to labor and birth that could benefit Identify from additional nursing research or application of evidence- based practice. THEORIES OF LABOR ONSET Labor normally begins when a fetus is sufficiently mature to cope with extrauterine life yet not too large to cause mechanical difficulty with birth. Several theories including a combination of factors originating from both the woman and fetus have been proposed to explain why progesterone withdrawal begins: ◦ Uterine muscle stretching, which results in release of prostaglandins ◦ Pressure on the cervix, which stimulates the release of oxytocin from the posterior pituitary ◦ Oxytocin stimulation, which works together with prostaglandins to initiate contractions ◦ Change in the ratio of estrogen to progesterone (increasing estrogen in relation to progesterone, which is interpreted as progesterone withdrawal) ◦ Placental age, which triggers contractions at a set point ◦ Rising fetal cortisol levels, which reduces progesterone formation and increases prostaglandin formation ◦ Fetal membrane production of prostaglandin, which stimulates contraction SIGNS OF LABOR SIGNS OF LABOR ◦ PRELIMINARY SIGNS OF LABOR - Before labor, a woman often experiences subtle signs that signal labor is imminent. It is important to review these with women during the last trimester of pregnancy so they can more easily recognize beginning signs.  PRELIMINARY SIGNS OF LABOR ◦ Lightening ◦ In primiparas, lightening, or descent of the fetal presenting part into the pelvis, occurs approximately 10 to 14 days before labor begins. This fetal descent changes a woman’s abdominal contour, because it positions the uterus lower and more anterior in the abdomen. Lightening gives a woman relief from the diaphragmatic pressure and shortness of breath that she has been experiencing and “lightens” her load. ◦ Increase in Level of Activity ◦ This increase in activity is related to an increase in epinephrine release initiated by a decrease in progesterone produced by the placenta. This additional epinephrine prepares a woman’s body for the work of labor ahead.  PRELIMINARY SIGNS OF LABOR ◦ Slight loss of weight ◦ As progesterone level falls, body fluid is more easily excreted from the body. This increase in urine production can lead to a weight loss between 1 and 3 pounds. ◦ Braxton Hicks Contraction ◦ woman usually notices extremely strong Braxton Hicks contractions. ◦ Ripening of the cervix ◦ At term, the cervix becomes still softer (described as “butter- soft”), and it tips forward. Cervical ripening this way is an internal announcement that labor is very close at hand.  SIGNS OF TRUE LABOR - Signs of true labor involve uterine and cervical changes. ◦ Uterine Contraction ◦ The surest sign that labor has begun is productive uterine contractions. Because contractions are involuntary and come without warning, their intensity can be frightening in early labor. Helping a woman appreciate that she can predict when her next one will occur and therefore can control the degree of discomfort she feels by using breathing exercises offers her a sense of well-being. ◦ Show ◦ As the cervix softens and ripens, the mucus plug that filled the cervical canal during pregnancy (operculum) is expelled. The exposed cervical capillaries seep blood as a result of pressure exerted by the fetus. This blood, mixed with mucus, takes on a pink tinge and is referred to as “show” or “bloody show.” Women need to be aware of this event so that they do not think they are bleeding abnormally. ◦ Rupture of Membranes ◦ Labor may begin with rupture of the membranes, experienced either as a sudden gush or as scanty, slow seeping of clear fluid from the vagina. Early rupture of the membranes can be advantageous as it can cause the fetal head to settle snugly into the pelvis, shortens labor. Two risks associated with ruptured membranes are intrauterine infection and prolapse of the umbilical cord, which could cut off the oxygen supply to the fetus (Lewis et al., 2007). In most instances, if labor has not spontaneously occurred by 24 hours after membrane rupture and the pregnancy is at term, labor will be induced to help reduce these risks. COMPONENTS OF LABOR COMPONENTS OF LABOR A successful labor depends on four integrated concepts: 1. A woman’s pelvis (the passage) is of adequate size and contour. 2. The passenger (the fetus) is of appropriate size and in an advantageous position and presentation. 3. The powers of labor (uterine factors) are adequate. (The powers of labor are strongly influenced by the woman’s position during labor.) 4. A woman’s psychological outlook is preserved, so that afterward labor can be viewed as a positive experience. 1. PASSAGE ◦ The passage refers to the route a fetus must travel from the uterus through the cervix and vagina to the external perineum. Two pelvic measurements are important to determine the adequacy of the pelvic size: the diagonal conjugate (the anteroposterior diameter of the inlet) and the transverse diameter of the outlet. At the pelvic inlet, the anteroposterior diameter is the narrowest diameter; at the outlet, the transverse diameter is the narrowest. 2. PASSENGER The passenger is the fetus. The body part of the fetus that has the widest diameter is the head, so this is the part least likely to be able to pass through the pelvic ring. Whether a fetal skull can pass depends on both its structure (bones, fontanelles, and suture lines) and its alignment with the pelvis. 2. PASSENGER ◦ Molding is a change in the shape of the fetal skull produced by the force of uterine contractions pressing the vertex of the head against the not-yet-dilated cervix. 2. PASSENGER ◦ Engagement – refers to the settling of the presenting part of a fetus far enough into the pelvis to be at the level of the ischial spines, a midpoint of the pelvis. 2. PASSENGER ◦ Station refers to the relationship of the presenting part of a fetus to the level of the ischial spines. When the presenting fetal part is at the level of the ischial spines, it is at a 0 station (synonymous with engagement). If the presenting part is above the spines, the distance is measured and described as minus stations, which range from 1 to 4 cm. If the presenting part is below the ischial spines, the distance is stated as plus stations (+1 to +4). At a +3 or +4 station, the presenting part is at the perineum and can be seen if the vulva is separated (i.e., it is crowning).  2. PASSENGER ◦ Fetal Attitude ◦ Attitude describes the degree of flexion a fetus assumes during labor or the relation of the fetal parts to each other. A fetus in good attitude is in complete flexion: the spinal column is bowed forward, the head is flexed forward so much that the chin touches the sternum, the arms are flexed and folded on the chest, the thighs are flexed onto the abdomen, and the calves are pressed against the posterior aspect of the thighs. 2. PASSENGER Fetal Attitude ◦ This normal “fetal position” is advantageous for birth because it helps a fetus present the smallest anteroposterior diameter of the skull to the pelvis and also because it puts the whole body into an ovoid shape, occupying the smallest space possible. ◦ A fetus is in moderate flexion if the chin is not touching the chest but is in an alert or “military position”. ◦ A fetus in partial extension presents the “brow” of the head to the birth canal. 2. PASSENGER ◦ Descent ◦ - means that the widest part of the fetus (the biparietal diameter in a cephalic presentation; the intertrochanteric diameter in a breech presentation) has passed through the pelvis inlet or the pelvic inlet has been proved adequate for birth. 2. PASSENGER ◦ Fetal Lie - Lie is the relationship between the long (cephalocaudal) axis of the fetal body and the long (cephalocaudal) axis of a woman’s body; in other words, whether the fetus is lying in a horizontal (transverse) or a vertical (longitudinal) position. TYPES OF FETAL PRESENTATION ◦ Fetal presentation denotes the body part that will first contact the cervix or be born first. This is determined by a combination of fetal lie and the degree of fetal flexion (attitude). 1. Cephalic Presentation A cephalic presentation is the most frequent type of presentation, occurring as often as 95% of the time. With this type of presentation, the fetal head is the body part that will first contact the cervix. The four types of cephalic presentation (vertex, brow, face, and mentum).  TYPES OF FETAL PRESENTATION 2. Breech Presentation A breech presentation means that either the buttocks or the feet are the first body parts that will contact the cervix. Breech presentations occur in approximately 3% of births and are affected by fetal attitude. A good attitude brings the fetal knees up against the fetal abdomen; a poor attitude means that the knees are extended. Breech presentations can be difficult births, with the presenting point influencing the degree of difficulty. Three types of breech presentation (complete, frank, and footling) are possible. TYPES OF FETAL PRESENTATION 3. Shoulder Presentation - In a transverse lie, a fetus lies horizontally in the pelvis so that the longest fetal axis is perpendicular to that of the mother. The presenting part is usually one of the shoulders (acromion process), an iliac crest, a hand, or an elbow. FETAL POSITION - Position is the relationship of the presenting part to a specific quadrant of a woman’s pelvis. For convenience, the maternal pelvis is divided into four quadrants according to the mother’s right and left: (a) right anterior, (b) left anterior, (c) right posterior, and (d) left posterior.  FETAL POSITIONS MECHANISM OF LABOR (CARDINAL MOVEMENTS) ◦ Passage of a fetus through the birth canal involves several different position changes to keep the smallest diameter of the fetal head (in cephalic presentations) always presenting to the smallest diameter of the pelvis. These position changes are termed the cardinal movements of labor: descent, flexion, internal rotation, extension, external rotation, and expulsion. MECHANISM OF LABOR (CARDINAL MOVEMENTS) 1. Descent. Descent is the downward movement of the biparietal diameter of the fetal head to within the pelvic inlet. Full descent occurs when the fetal head extrudes beyond the dilated cervix and touches the posterior vaginal floor. Descent occurs because of pressure on the fetus by the uterine fundus.The pressure of the fetal head on the sacral nerves at the pelvic floor causes the mother to experience a pushing sensation. Full descent may be aided by abdominal muscle contraction as the woman pushes. 2. Flexion. As descent occurs and the fetal head reaches the pelvic floor, the head bends forward onto the chest, making the smallest anteroposterior diameter (the suboccipitobregmatic diameter) present to the birth canal. Flexion is also aided by abdominal muscle contraction during pushing. MECHANISM OF LABOR (CARDINAL MOVEMENTS) 3. Internal Rotation. ◦ During descent, the head enters the pelvis with the fetal anteroposterior head diameter (suboccipitobregmatic, occipitomental, or occipitofrontal, depending on the amount of flexion) in a diagonal or transverse position. The head flexes as it touches the pelvic floor, and the occiput rotates to bring the head into the best relationship to the outlet of the pelvis (the anteroposterior diameter is now in the anteroposterior plane of the pelvis). This movement brings the shoulders, coming next, into the optimal position to enter the inlet, putting the widest diameter of the shoulders (a transverse one) in line with the wide transverse diameter of the inlet. 4. Extension. ◦ As the occiput is born, the back of the neck stops beneath the pubic arch and acts as a pivot for the rest of the head. The head extends, and the foremost parts of the head, the face and chin, are born MECHANISM OF LABOR (CARDINAL MOVEMENTS) 5. External Rotation. In external rotation, almost immediately after the head of the infant is born, the head rotates (from the anteroposterior position it assumed to enter the outlet) back to the diagonal or transverse position of the early part of labor. This brings the aftercoming shoulders into an anteroposterior position, which is best for entering the outlet. The anterior shoulder is born first, assisted perhaps by downward flexion of the infant’s head. 6. Expulsion. Once the shoulders are born, the rest of the baby is born easily and smoothly because of its smaller size. This movement, called expulsion, is the end of the pelvic division of labor 3. POWERS OF LABOR ◦ The second important requirements for a successful labor are effective powers of labor. This is the force supplied by the fundus of the uterus, implemented by uterine contractions, a natural process that causes cervical dilatation and then expulsion of the fetus from the uterus. After full dilatation of the cervix, the primary power is supplemented by use of the abdominal muscles. It is important for women to understand they should not bear down with their abdominal muscles until the cervix is fully dilated. Doing so impedes the primary force and could cause fetal and cervical damage 3. POWERS OF LABOR ◦ Uterine Contraction - The mark of effective uterine contractions is rhythmicity and progressive lengthening and intensity. ◦ Phases - A contraction consists of three phases: the increment, when the intensity of the contraction increases; the acme, when the contraction is at its strongest; and the decrement, when the intensity decreases  3. POWERS OF LABOR ◦ Cervical Changes – Even more marked than the changes in the body of the uterus are two changes that occur in the cervix: effacement and dilatation. ◦ Effacement - it is shortening and thinning of the cervical canal. Normally, the canal is approximately 1 to 2 cm long. With effacement, the canal virtually disappears. ◦ Dilatation refers to the enlargement or widening of the cervical canal from an opening a few millimeters wide to one large enough (approximately 10 cm) to permit passage of a fetus 4. PSYCHE ◦ The fourth “P,” or a woman’s psychological outlook, refers to the psychological state or feelings that a woman brings into labor. For many women, this is a feeling of apprehension or fright. For almost everyone, it includes a sense of excitement or awe. THANK YOU!