CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 153 153 6 COURSE AND CONDUCT OF LABOR AND DELIVERY CHAPTER Labor is the normal process of coordinated, effective involuntary uterine contractions that lead to progressive cervical effacement and dilatation and descent and delivery of the newborn and pla- centa. Near its termination, labor may be augmented by voluntary bearing-down efforts to assist in delivery of the conceptus. False labor is characterized by irregular (both in interval and duration), brief contractions without fundal dominance, cervical change, or a lower station of the fetal vertex or breech. Dilatation of the cervix is the diameter of the cervical os ex- pressed in centimenters (0–10). Effacement is cervical thinning that occurs before and especially during first stage labor. Effacement of the cervix is expressed as a percentage of cervical length (normally ϳ2.5 cm) (Figs. 6-1, 6-2). An uneffaced cervix is 0%; one about 0.25 in length is 100% effaced. Effacement and dilatation are caused by retraction (takeup) of the cervix toward the uterine corpus, not by pressure of the presenting part. The initiation of labor in the human is poorly understood. Labor can be triggered by one or more significant endocrine or physical changes, for example, abdominal trauma. The onset of la- bor can occur at any time after well-established pregnancy, but the likelihood increases as term is approached. Labor can be induced or stimulated (augmented) by oxytocic agents (e.g., oxytocin or prostaglandin E 2 ) (Fig. 6-3). In ϳ10% of gravidas, the fetal membranes rupture before the onset of labor. This reduces the capacity of the uterus, thickens the uterine wall, and increases uterine irritability. Labor usually follows. At term, 90% will be in labor within 24 h after membrane rupture. If labor does not begin in 24 h, the case must be considered com- plicated by prolonged rupture of the membranes. Immediately before or early in labor, a small amount of red- tinged mucus may be passed (bloody show or mucous plug). This is a collection of thick cervical mucus often mixed with blood and Copyright 2001 The McGraw-Hill Companies. Click Here for Terms of Use. BENSON & PERNOLL’S 154 HANDBOOK OF OBSTETRICS AND GYNECOLOGY is evidence of cervical dilatation and effacement and, frequently, descent of the presenting part. The beginning of true labor is marked by increasingly frequent, forceful, prolonged, and, finally, regular uterine contractions. Low backache may precede or accompany the uterine contractions (pains). Each contraction starts with a gradual buildup of intensity, and a similar dissipation follows the peak. Normally, the contrac- tion will be at its height before discomfort is felt. Dilatation of the lower birth canal almost always will cause deep pelvic or perineal pain. Nonetheless, occasional nulliparas and some multiparas may have a brief, virtually pain-free labor. Labor entails the interaction of the so-called 4Ps. ● The passenger (the fetal size, presentation, position) ● The pelvis (size and shape) ● The powers (effective forces of labor, e.g., uterine contractions) ● The placenta (an obstruction if implanted low in the uterus) FIGURE 6-1. Dilatation and effacement of the cervix in a primipara. FIGURE 6-2. Dilatation and effacement of the cervix in a multipara. FIGURE 6-3. Production of prostaglandins in human parturition. (Modified after Liggins.) (From M.L. Pernoll and R.C. Benson, eds. Current Obstetric & Gynecologic Diagnosis & Treatment, 6th ed. Lange, 1987.) 155 BENSON & PERNOLL’S 156 HANDBOOK OF OBSTETRICS AND GYNECOLOGY Each of these factors, alone or in combination, can make for a normal or a complicated labor and delivery. For example, if the fe- tus is large and the pelvis is small, labor may be prolonged or progress may be impossible despite strong contractions, even with a placenta normally implanted in the fundus. NORMAL LABOR Since, hopefully, the end result of labor is the vaginal delivery of the fetus, membranes, and placenta, the method of judging its progress is based on assessments toward that end. The first stage of labor begins with the onset of labor and ends with complete FIGURE 6-4. Relationship between cervical dilatation and descent of the presenting part in a primipara. L, latent phase; A, acceleration phase; M, phase of maximum slope; D, deceleration phase; and 2, second stage. (From M.L. Pernoll and R.C. Benson, eds. Current Obstetric & Gynecologic Diagnosis & Treatment, 6th ed. Lange, 1987.) (10 cm) dilatation of the cervix. The first stage is the longest, averaging 8–12 h for primigravidas or 6–8 h for multiparas. How- ever, the first stage of labor may be markedly shorter or longer de- pending on the 4Ps. Labor is a very dynamic process, and contractions should in- crease steadily in regularity, intensity, and duration. This is not al- ways the case, and one must set limits concerning the progress of labor (Figs. 6-4, 6-5). It is useful to divide the first stage of labor into two phases. Thus, the latent phase of labor begins with the onset of regular uter- ine contractions and extends to the start of the active phase of cer- vical dilatation (ϳ3–4 cm). CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 157 FIGURE 6-5. Composite mean curves for descent (solid line) and dilata- tion (broken line) for 389 multiparas. L, latent phase; A, acceleration phase; M, phase of maximum slope; D, deceleration phase; and 2, second stage. Re- lationship is shown between acceleration period of descent and maximum slope of dilatation (shaded area), between latent period of descent and latent plus acceleration phases of dilatation, and between maximum slope of de- scent and deceleration plase plus second stage. (Redrawn from Friedman and Sachtleben. Am J Obstet Gynecol 1965;93:526.) BENSON & PERNOLL’S 158 HANDBOOK OF OBSTETRICS AND GYNECOLOGY The second stage of labor begins when the cervix becomes fully dilated and ends with the complete birth of the infant. The second stage normally lasts ,30 min. While one should be concerned when the second stage extends longer than 1 h (based on fetal morbidity and mortality). Safety for the fetus may be assured by thoughtful monitoring. The third, or placental, stage of labor is the period from birth of the infant to 1 h after delivery of the placenta. The rapidity of separation and means of recovery of the placenta determine the du- ration of the third stage (Fig. 6-6). MANAGEMENT OF THE FIRST STAGE OF LABOR INITIAL EXAMINATION AND PROCEDURES ● Obtain a history of relevant medical details following the last examination. FIGURE 6-6. Major types of deviation from normal progress of labor may be detected by noting dilatation of the cervix at various intervals after labor begins. (From K.P. Russell. In: R.C. Benson, ed. Current Obstetric & Gynecologic Diagnosis & Treatment, 4th ed. Lange, 1982.) CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 159 ● Record the patient’s vital signs (temperature, pulse, and BP). Examine a clean-catch urine specimen for proteinuria and glycosuria. ● Do a brief general physical examination. ● Palpate the uterus to determine the fetal presentation, position, and engagement (Leopold’s maneuvers) (Fig. 6-7). Auscultate the fetal heartbeat, and mark the skin where the heartbeat is FIGURE 6-7. Leopold’s maneuvers. Determining fetal presentation (A and B), position (C), and engagement (D). BENSON & PERNOLL’S 160 HANDBOOK OF OBSTETRICS AND GYNECOLOGY loudest to note the shift and descent of the point of maximal intensity with progressive labor. This is evidence of internal rotation and descent of the fetus (the mechanism of labor). ● Note the frequency, regularity, intensity, and duration of uterine contractions and the myometrial tone with and be- tween contractions. Observe the patient’s reactions and her tolerance of labor. Restlessness and discomfort often de- velop as labor progresses. ● Check for vaginal bleeding or leakage of amniotic fluid. Nitrazine indicator paper will turn from green to yellow when moistened with amniotic fluid (pH 7.0). Other tests may be used in doubtful cases. ● Examine the patient vaginally and record both the time and results of the examination. Use a surgically clean glove. Identify the fetal presenting part and its station in rela- tion to the level of the ischial spines. Station is the level of the head or breech in the pelvis. If the presenting part is at the spines, it is said to be at “zero station.” If above the spines, the distance is stated in minus figures (Ϫ1 cm, Ϫ2 cm, Ϫ3 cm, and “floating”). If below the spines, the distance is noted in plus figures (ϩ1 cm, ϩ2 cm, ϩ3 cm, and “on the perineum”) (Fig. 6-8). When the most inferior FIGURE 6-8. Stations of the fetal head. part of the head is at the level of the ischial spines, the station is zero. Station zero is assumed by projection to be actual engagement, that is, the biparietal diameter at the level of the inlet. However, with considerable molding, caput succedaneum, or a sincipital presentation of the head, the biparietal diameter may be a significant distance above the inlet even though the tip of the vertex is at the spines without true engagement. Dilatation of the cervix by direct palpation is expressed as the diameter of the cervical opening in centimeters. A diameter of 10 cm constitutes full dilatation. Effacement of the cervix (process of thinning out) may occur before labor in the nulligravida but is less likely before the first stage of labor in the multigravida. The position of the presenting part usually can be con- firmed by internal examination. Vertex presentations (Fig. 6-9). The fontanelles and the sagittal suture are palpated. The position is determined by the relation of the fetal occiput to the mother’s right or left side. This is expressed as OA (occiput directly anterior), LOA (left occiput anterior), LOP (left occiput posterior), and so on. Breech presentations are determined by the position of the infant’s sacrum in relation to the mother’s right or left side. This is expressed as SA (sacrum directly ante- rior), LSA (left sacrum anterior), LSP (left sacrum pos- terior), and so on. Face presentation is caused by extension of the fetal head on the neck. The chin, a prominent and identifiable facial landmark, is used as the point of reference. As with vertex presentations, the position of the fetal chin is related to the anterior or posterior portion of the left or right side of the mother’s pelvis. This is expressed as RMP (right mentum posterior) and so on. Brow, bregma, and sinciput presentations are presenta- tions midway between flexion and extension. These usu- ally are temporary attitudes that convert during labor to face or occiput presentation. Transverse presentations occur when the long axis of the fetal body is perpendicular to that of the mother. One shoulder (acromion) will occupy the superior strait, but it will be considerably to the right or left of the midline. Transverse presentations are designated by relating the infant’s inferior shoulder and back to the mother’s back CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 161 FIGURE 6-9. Vertex presentation. 162 [...]... general, buried sutures cause less discomfort than through -and- through exposed sutures Laceration Repair 182 BENSON & PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY FIGURE 6-18 Episiotomy repair CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY FIGURE 6-19 Perineal tears 183 184 BENSON & PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY In repair of fourth degree lacerations, close the rectal submucosal... birth canal; hypoxia and the accumulation of catabolites in the myometrium; and fear, severe tension, and anxiety In dystocia, or abnormal labor, pain often may be due to cephalopelvic disproportion Tetanic, prolonged, or dysrhythmic uterine contractions may be painful, and intrapartal infection may cause pain CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 185 The management of any pain requires... inadequate DELIVERY: MANAGEMENT OF THE NORMAL SECOND STAGE OF LABOR VERTEX DELIVERY (TABLES 6-1, 6-2) Final preparation for delivery should be completed by the time the presenting part reaches the pelvic floor, or sooner if labor is progressing very rapidly Spontaneous delivery of the infant presenting by the vertex is divided into three phases: (1) delivery of the head, (2) delivery of the shoulders, and. .. Spontaneous delivery of the placenta usually is accomplished without difficulty If it does not occur, however, the following techniques may be used Brandt-Andrews Technique (Modified) (Fig 6-16) CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 175 FIGURE 6-16 Brandt-Andrews maneuver (A) Traction is extended on the cord as the uterus is elevated gently (B) Pressure is exerted between the symphysis and the... defective offspring A well-informed participating father can contribute greatly to the 180 BENSON & PERNOLL’S HANDBOOK OF OBSTETRICS AND GYNECOLOGY health and well-being of the mother and child, to the benefit of the family relationship and his own self-esteem All of these factors may prevent or greatly minimize postpartum psychologic problems EPISIOTOMY (PERINEOTOMY) AND REPAIR OF EPISIOTOMY AND LACERATIONS... common indications continue to be: when a tear is imminent, in most operative deliveries, and to facilitate atraumatic delivery of a premature infant Types of Episiotomy (Fig 6-17) FIGURE 6-17 Types of episiotomy CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 181 The tissues incised by an episiotomy are (1) skin and subcutaneous tissues, (2) vaginal mucosa, (3) the urogenital septum (mostly fascia,... the majority of cases) to give oxytocin In the past, 5–10 U IV was frequently given over 5 min to limit blood loss Currently, it is more common to utilize 20 U of oxytocin in 1000 cc of IV solution and run at 125–250 cc hour CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 177 POSTPARTUM OBSERVATION The mother should remain under very close observation for at least 1 h after delivery of the placenta... CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 179 available many packs of sterilized gauze about 1 yard wide and 5 yards long (packing takes a considerable amount) A Holmes tubular packing instrument may be helpful but is not essential PROGNOSIS The outcome depends on the cause of bleeding, amount of blood lost (in proportion to patient’s weight), medical complications, and success of corrective... stage of labor in dosages of 5–15 mg every 4 h does not appear to have a deleterious effect on the newborn Nerve Blocks Consider nerve blocks in two categories: local anesthetics and the true regional blocks The former is exemplified by paracervical and FIGURE 6-20 Iowa trumpet assembly CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 187 FIGURE 6-21 Paracervical submucous block pudendal blocks and. .. concerns leads to discussion and solution of many human problems that surround the expectation of a newborn Fathers-to-be experience at least five emotional stages (which often overlap): realization or confirmation of pregnancy, awareness of changes in the mother’s body and the presence of fetal movements, anticipation of approaching labor, involvement in the delivery process, and new parenthood Fears . CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 153 153 6 COURSE AND CONDUCT OF LABOR AND DELIVERY CHAPTER Labor is the normal process of coordinated, effective involuntary uterine. rupture and again within CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 163 BENSON & PERNOLL’S 164 HANDBOOK OF OBSTETRICS AND GYNECOLOGY 30 min after the rupture, and every 5 min or more often. or if isoimmuniza- CHAPTER 6 COURSE AND CONDUCT OF LABOR AND DELIVERY 171 BENSON & PERNOLL’S 172 HANDBOOK OF OBSTETRICS AND GYNECOLOGY FIGURE 6-15. Resuscitation of the newborn. tion is probable).