前不均倾位的早期识别、诊断与处理

前不均倾位是导致难产的重要原因之一,属严重胎头位置异常,一般需剖宫产分娩。前不均倾位早期难以识别,易误诊和漏诊,对母儿危害极大。本文重点阐述经阴道试产中胎儿前不均倾位的临床特点、诊断和处理方法,旨在加强临床医护人员对前不均倾位的认识和重视,防止诊断、处理不及时对母儿造成严重伤害。     

Soft tissue and pelvic dystocia

This article has considered the subject of bony pelvic dystocia and soft tissue dystocia. Dystocia most often results from a combination of fetal and pelvic factors. However, on many occasions the size and shape of the pelvis is the initial problem, which encourages the fetus to take up a malposition such as occiput-posterior, and this in turn results in a dysfunctional contraction pattern that may or may not be corrected by oxytocin augmentation--a vicious circle that can only be broken by performance of a cesarean section. With minor degrees of pelvic dystocia, asynclitism and molding of the fetal head can often make a safe vaginal delivery possible. Clinically all pelvises can be categorized into adequate, questionable, and too small. The latter group is the least common and generally includes the congenitally or developmentally abnormal pelvises, and in most cases primary cesarean section should be the mode of delivery. In all other pelvises with a vertex presentation, a trial of labor is indicated because the fetal head is an excellent pelvimeter. With proper fetal monitoring with an intrauterine pressure catheter, with the use of a partograph to assist in the diagnosis of an active-phase arrest, followed by a cesarean section at the appropriate time, there is no increase in fetal or maternal morbidity. If the breech is the presenting part, then there are only two types of pelvis--very adequate and inadequate--and x-ray pelvimetry should be used to help in the classification.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intrapartum sonography for fetal head asynclitism and transverse position: sonographic signs and comparison of diagnostic performance between transvaginal and digital examination

Objective: The primary goal of this study was to determine the ultrasonographic signs of asynclitic and transverse head positioning. In addition, we compared the performance of intrapartum ultrasound to vaginal digital examination. Material & Methods: 150 women were evaluated by 2D transabdominal and translabial ultrasound (US) to detect the asynclitic and deep transverse positions. Transvaginal sterile digital examinations were performed immediately after each intrapartum US assessments, the examinations were repeated at intervals of 45–90 minutes. Examiners were blinded to each other’s findings (clinical or sonographic). Data were reviewed and analyzed by an independent reviewer. Results: The efficacy of digital examination was significantly lower than US evaluation for the detection of either transverse position or asynclitism. The most frequent transverse position was the left one, while the most frequent asynclitism was the anterior one. Conclusions: Digital pelvic examination for detection of fetal head transverse position during labor is inferior to US, especially in the deep transverse positioning, where caput succedaneum occurs and reduces the diagnostic accuracy of vaginal digital examination. The US examination leads to early detection of persistent transverse position allowing for earlier timing and optimal technique for the operative vaginal delivery. We describe two signs for diagnosing asynclitism. The “squint sign” and the “sunset of thalamus and cerebellum signs” are two simple US signs allowing detection of anterior and posterior asynclitism.     

Shock management in acute fetomaternal hemorrhage

Abstract

The determination of fetal head position can be useful in labor to predict the success of labor management, especially in case of malpositions. Malpositions are abnormal positions of the vertex of the fetal head and account for the large part of indication for cesarean sections for dystocic labor. The occiput posterior position occurs in 15–25% of patients before labor at term and, however, most occiput posterior presentations rotate during labor, so that the incidence of occiput posterior at vaginal birth is approximately 5–7%. Persistence of the occiput posterior position is associated with higher rate of interventions and with maternal and neonatal complications and the knowledge of the exact position of the fetal head is of paramount importance prior to any operative vaginal delivery, for both the safe positioning of the instrument that may be used (i.e. forceps versus vacuum) and for its successful outcome. Ultrasound (US) diagnosed occiput posterior position during labor can predict occiput posterior position at birth. By these evidences, the time requested for fetal head descent and the position in the birth canal, had an impact on the diagnosis of labor progression or arrested labor. To try to reduce this pitfalls, authors developed a new algorithm, applied to intrapartum US and based on suitable US pictures, that sets out, in detail, the quantitative evaluation, in degrees, of the occiput posterior position of the fetal head in the pelvis and the birth canal, respectively, in the first and second stage of labor. Authors tested this computer system in a settle of patients in labor.     

Dystocia in late labor: determining fetal position by clinical and ultrasonic techniques

A failure of adequate progression during late labor occurs often and may prohibit an accurate determination of the fetal head position from scalp edema or caput formation. This investigation was undertaken to determine whether ultrasonic evaluation could confirm or correct the digital examination impressions of the fetal head position. Eighty-six attempted vaginal deliveries had recent evidence for arrested cervical dilation after 7 cm or more. An occiput transverse position in 24 (28%) cases was diagnosed accurately, with the need for additional ultrasonic information only in the presence of scalp edema. Distinguishing between a persistent occiput posterior (15 cases, 17%) or anterior (47 cases, 55%) position was often inexact by palpation alone. Combined clinical and ultrasonic impressions allowed for a significantly more precise diagnosis. Ultrasonic imaging allowed for more security while waiting, more confidence with midforceps application, or a prompter decision for cesarean section, depending on the head position.     

Le suivi échographique de la deuxième partie du travail

In the second stage of labor, fetal head rotation and fetal head position are determinant for the management of labor to attempt a vaginal delivery or a cesarean section. However, digital examination is highly subjective. Nowadays, delivery rooms are often equipped with compact and high performance ultrasound systems. The clinical examination can be easily completed by quantified and reproducible methods. Transabdominal ultrasonography is a well-known and efficient way to determine the fetal head position. Nevertheless, ultrasound approach to assess fetal head descent is less widespread. We can use translabial or transperineal way to evaluate fetal head position. We describe precisely two different types of methods: the linear methods (3 different types) and the angles of progression (4 different types of measurement). Among all those methods, the main pelvic landmarks are the symphysis pubis and the fetal skull. The angle of progression appears promising but the assessment was restricted to occipitoanterior fetal position cases. In the coming years, ultrasound will likely play a greater role in the management of labor.     

Impact on delivery outcome of ultrasonographic fetal head position prior to induction of labor

OBJECTIVE: To assess clinical and sonographic fetal head position before induction of labor, position at delivery, and whether occiput posterior (OP) position is associated with adverse delivery outcome. METHODS: Abdominal palpation and ultrasonographic fetal head and spine position were determined at 36 weeks or more of gestation in 289 women immediately before induction of labor and the head position at delivery noted. Chi-square, Mann-Whitney U tests, and logistic regression were used to assess whether OP position was associated with cesarean delivery. RESULTS: Ninety-seven (36%) of 270 women with full outcome data had an OP position on ultrasonography before induction of labor. Of these 97 women, eight (8%) were OP at delivery. Sixty-eight percent of the 25 OP positions at delivery occurred due to a mal-rotation from a non-OP position during labor. Logistic regression showed that OP position before induction of labor was not an independent predictor of cesarean delivery (odds ratio 1.75, 95% confidence interval 0.97-3.15, P=.06). CONCLUSION: Two thirds of OP positions at delivery after induction of labor occur due to a mal-rotation in labor from a non-OP position. Ultrasonography is an easy method of assessing fetal head position before induction of labor. In clinical practice, its usefulness is limited by the fact that, contrary to conventional teaching, OP position before induction of labor does not appear to be associated with an increased risk of cesarean delivery. LEVEL OF EVIDENCE: II.     

胎儿体重对持续性枕后位产程特征和分娩结局影响的分析

目的:探讨胎儿体重对持续性枕后位产程特征和分娩结局的影响.方法:对2005年12月至2009年12月在本院产科住院分娩228例持续性枕后位产妇的临床资料进行回顾性分析,根据新生儿出生体重分为对照组112例(胎儿体重≥2500 g且＜3500 g)和研究组116例(胎儿体重≥3500 g且＜4250 g).并将两组产程特征、母儿结局进行分析比较.结果:两组产妇产程异常(宫口扩张延缓、停滞,胎头下降延缓、停滞)发生率、临床干预(体位矫正、手转胎头)成功率、剖宫产率、母儿并发症(产后出血、产褥病率、胎儿窘迫、新生儿窒息)发生率差异均有统计学意义(P＜0.05).结论:持续性枕后位产程处理中充分考虑胎儿的体重因素,对于胎儿估计体重≥3500 g的枕后位病例应积极临床干预,干预失败应放宽手术指征,以降低母儿并发症发生率.     

Maternal Temperature Elevation and Occiput Posterior Position at Birth Among Low‐Risk Women Receiving Epidural Analgesia

Introduction: To evaluate the relationship between maternal temperature elevation and occiput posterior position at birth as well as the association of fetal head position and temperature elevation on method of birth among women receiving epidural analgesia. Methods: We conducted a secondary analysis of data from the Fetal Orientation during Childbirth by Ultrasound Study (FOCUS), which used serial ultrasounds to evaluate the effect of epidural anesthesia on fetal position at birth in low‐risk women. The current analysis was limited to the 1428 study participants who received epidural analgesia. Results: In our population, 47% (n = 669) of women had a maximum intrapartum temperature greater than or equal to 99.6°F (37.6°C). The prevalence of fetal occiput posterior position at admission did not differ between women who later developed temperature elevations (24.4%) and those who did not (23.6%, P= .70). Women who developed an elevated temperature greater than or equal to 99.6°F (37.6°C) had an increased risk of occiput posterior fetal head position at birth regardless of the amount of temperature elevation (odds ratio [OR]= 2.0; 95% confidence interval [CI], 1.5‐2.8); the association persisted after control for potentially confounding factors (adjusted OR = 1.5; 95% CI, 1.1‐2.1). The cesarean birth rate among women with both temperature elevation and occiput posterior position at birth was more than 12 times the rate of women with neither risk factor (adjusted OR = 12.6; 95% CI, 7.5‐21.2). Discussion: Intrapartum temperature elevation among women receiving epidural analgesia, even if only to 99.6°F (37.6°C), is associated with approximately a 2‐fold increase in the occurrence of occiput posterior fetal head position at birth. Additionally, although this observational study cannot establish causal links, our findings suggest that the relationship between epidural‐related intrapartum temperature elevation and occiput posterior position at birth could contribute to an increased cesarean birth rate among women receiving epidural analgesia for pain relief in labor.     

Occipito-posterior fetal head position, maternal and neonatal outcome

The purpose of this review is to summarize the available evidence on occipito-posterior fetal head position and maternal and neonatal outcome. The occipito-posterior fetal head position is the most common malposition, but there are not so many data about it in literature. Its incidence is ranging from 1.8% by Fitzpatrick, to 4.6% and 5.5% by Yancey and Sizer, to 6% by Ponkey. Only two trials studied the occipito-posterior associated factors. There are lower incidence of premature rupture of membrane, arterial hypertension pregnancy-induced, induced labour, increased of episiotomy, instrumental delivery and a decreased of vaginal birth without a difference in neonatal Apgar, and with a neonatal bigger weight. The occipito-posterior fetal head position persistence compared to anterior position, has a statistically significant association with low maternal stature, previous cesarean section, longer first and second stage of labour, oxytocin augmentation, epidural analgesia, instrumental vaginal delivery, chorion-amniositis, vaginal perineal injures, loss of blood and post partum infections. A highest incidence of occipito-posterior fetal head position may depend by nulliparity, malnutrition with pelvic deformity, pelvic immaturity in the teenager and anterior placenta. Epidural analgesia is a risk factor for fetal head malposition. The majority of occipito-posterior fetal head positions is not due to a malrotation, but to a persistence in this position of the fetal head. In fact, this persistence leads to a failure of the fetal head rotation. The prolonged second stage is often the result of occipito-posterior fetal head position and instrumental delivery is required. The traditional vaginal examination is not useful for the determination of fetal head position, so and instrumental method is needed, such as ultrasound, for a correct evaluation of fetal head position, particularly if a vaginal instrumental delivery is necessary. This is recommended by the Canadian Society of Obstetrics and Gynecology. The evaluation of fetal head position is important in the prediction of labour induction.     

Malpositions and malpresentations of the fetal head

In normal labour, the fetal head presents with the occiput in lateral position in early stages of labour followed by anterior rotation in advanced labour. Malpositions of fetal head result when the occiput persists in a lateral or posterior position while malpresentations occur due to extension of the fetal head causing brow or face to present. Malpresentations of fetal head are usually diagnosed in labour and are associated with difficult labour and increased risk of operative intervention. Regular systematic clinical examinations to monitor progress of labour and fetal wellbeing are necessary once the diagnosis is confirmed. Although vaginal delivery is possible in many cases, caesarean section becomes necessary when the malposition or malpresentation persists and labour fails to progress.     

Influence of persistent occiput posterior position on delivery outcome.

OBJECTIVE: To evaluate the influence of intrapartum persistent occiput posterior position of the fetal head on delivery outcome and anal sphincter injury, with reference to the association with epidural analgesia. METHODS: We conducted a prospective observational study of 246 women with persistent occiput posterior position in labor during a 2-year period, compared with 13,543 contemporaneous vaginal deliveries with occiput anterior position. RESULTS: The incidence of persistent occiput posterior position was significantly greater among primiparas (2.4%) than multiparas (1.3%; P <.001; 95% confidence interval 1.4, 2.4) and was associated with significantly higher incidences of prolonged pregnancy, induction of labor, oxytocin augmentation of labor, epidural use, and prolonged labor. Only 29% of primiparas and 55% of multiparas with persistent occiput posterior position achieved spontaneous vaginal delivery, and the malposition was associated with 12% of all cesarean deliveries performed because of dystocia. Persistent occiput posterior position was also associated with a sevenfold higher incidence of anal sphincter disruption. Despite a high overall incidence of use of epidural analgesia (47% versus 3%), the institutional incidence of persistent occiput posterior position was lower than that reported 25 years ago. CONCLUSION: Persistent occiput posterior position contributed disproportionately to cesarean and instrumental delivery, with fewer than half of the occiput posterior labors ending in spontaneous delivery and the position accounting for 12% of all cesarean deliveries for dystocia. Persistent occiput posterior position leads to a sevenfold increase in the incidence of anal sphincter injury. Use of epidural analgesia was not related to the malposition.     

The Fetal Occiput Posterior Position: State of the Science and a New Perspective

Abstract: Background: The fetal occiput posterior position poses challenges in every aspect of intrapartum care—prevention, diagnosis, correction, supportive care, labor management, and delivery. Maternal and newborn outcomes are often worse and both physical and psychological traumas are more common than with fetal occiput anterior positions. The purpose of this paper is to describe nine prevailing concepts that guide labor and birth management with an occiput posterior fetus, and summarize evidence to clarify the state of the science. Methods: A search was conducted of the databases of PubMed and the Cochrane Library. Additional valuable information was obtained from obstetric and midwifery textbooks, books and websites for the public, conversations with maternity care professionals, and years of experience as a doula. Results: Nine prevailing concepts are as follows: (1) prenatal maneuvers rotate the occiput posterior fetus to occiput anterior; (2) it is possible to detect the occiput posterior fetus prenatally; (3) a fetus who is occiput anterior at the onset of labor will remain in that position throughout labor; (4) back pain in labor is a reliable sign of an occiput posterior fetus; (5) the occiput posterior fetus can be identified during labor by digital vaginal examination; (6) an ultrasound scan is a reliable way to detect fetal position; (7) maternal positions facilitate rotation of the occiput posterior fetus; (8) epidural analgesia facilitates rotation; (9) manual rotation of the fetal head to occiput anterior improves the rate of occiput anterior deliveries. Concepts 1, 2, 3, 4, 5, and 8 have little scientific support whereas concepts 6, 7, and 9 are supported by promising evidence. Conclusions: Many current obstetric practices with respect to the occiput posterior position are unsatisfactory, resulting in failure to identify and correct the problem and thus contributing to high surgical delivery rates and traumatic births. The use of ultrasound examination to identify fetal position is a method that is far superior to other methods, and has the potential to improve outcomes. Research studies are needed to examine the efficacy of midwifery methods of identification, and the effect of promising methods to rotate the fetus (simple positional methods and digital or manual rotation). Based on the findings of this review, a practical approach to care is suggested. (BIRTH 37:1 March 2010)     

Kielland产钳在持续性枕后位中的应用

目的 评估Ｋｉｅｌｌａｎｄ产钳对持续性枕后位进行反置上钳旋转胎头的安全性及可行性。方法 对１００例胎头双顶径已达或已过坐骨棘水平的持续性枕后位产妇,用Ｋｉｅｌｌａｎｄ产钳进行反置上钳旋转胎头产钳术。结果 成功率１００％,母体软产道损伤１７％,新生儿损伤１２％,无会阴Ⅲ度裂伤,无后穹窿,宫颈,膀胱损伤及子宫破裂,无新生儿颅内出血及死亡等严重并发症,结论 Ｋｉｅｌｌａｎｄ产钳反置上钳旋转胎头术用于双顶     

Study Protocol. IDUS -- Instrumental delivery & ultrasound. A multi-centre randomised controlled trial of ultrasound assessment of the fetal head position versus standard care as an approach to prevent morbidity at instrumental delivery

ABSTRACT: BACKGROUND: Instrumental deliveries are commonly performed in the United Kingdom and Ireland, with rates of 12 -- 17% in most centres. Knowing the exact position of the fetal head is a pre-requisite for safe instrumental delivery. Traditionally, diagnosis of the fetal head position is made on transvaginal digital examination by delineating the suture lines of the fetal skull and the fontanelles. However, the accuracy of transvaginal digital examination can be unreliable and varies between 20% and 75%. Failure to identify the correct fetal head position increases the likelihood of failed instrumental delivery with the additional morbidity of sequential use of instruments or second stage caesarean section. The use of ultrasound in determining the position of the fetal head has been explored but is not part of routine clinical practice. METHODS: A multi-centre randomised controlled trial is proposed. The study will take place in two large maternity units in Ireland with a combined annual birth rate of 13,500 deliveries. It will involve 450 nulliparous women undergoing instrumental delivery after 37 weeks gestation. The main outcome measure will be incorrect diagnosis of the fetal head position. A study involving 450 women will have 80% power to detect a 10% difference in the incidence of inaccurate diagnosis of the fetal head position with two-sided 5% alpha. DISCUSSION: It is both important and timely to evaluate the use of ultrasound to diagnose the fetal head position prior to instrumental delivery before routine use can be advocated. The overall aim is to reduce the incidence of incorrect diagnosis of the fetal head position prior to instrumental delivery and improve the safety of instrumental deliveries.Trial registrationCurrent Controlled Trials ISRCTN72230496.     

Diagnosis and intervention for occiput posterior malposition

OBJECTIVES: To evaluate diagnostic methods used to detect occiput posterior and to describe the efficacy of posturing to enhance rotation from occiput posterior to occiput anterior. DATA SOURCES: Keyword search using PubMed, CINAHL, Cochrane Review, and Dissertation Abstracts International. STUDY SELECTION: Studies published from 1996 to 2006 (except one published in 1983) that focused on the use of ultrasonography versus digital vaginal examination to diagnose fetal position and maternal posturing to enhance rotation from occiput posterior to occiput anterior. DATA EXTRACTION: Eight prospective studies regarding malposition diagnosis were reviewed and analyzed for error rates and predictors affecting ability to detect fetal position; five randomized controlled trials were evaluated for effects of various maternal postures on fetal rotation from occiput posterior to occiput anterior. DATA SYNTHESIS: If fetal malposition is accurately diagnosed in early labor, subsequent nursing management can focus on rotation toward occiput anterior position, leading to a safer delivery for mother and baby. CONCLUSIONS: Antepartum ultrasonography is more accurate than digital vaginal examination in diagnosing fetal malposition; however, its efficacy needs to be further explored using randomized controlled trials and cost-benefit analyses before routine use is recommended. Furthermore, Sims' posture on the same side as the fetal spine is recommended during labor to enhance rotation from occiput posterior to occiput anterior.     

持续性枕后位的临床特点及分娩方式选择

目的探讨持续性枕后位的临床特点及分娩方式。方法采用回顾性分析方法，对1998年1月至2004年12月在重庆医科大学两所附属医院住院分娩的112例持续性枕后位（枕后位组）和112例枕前位（枕前位组）的临床资料进行分析，比较两组产程情况、分娩方式及母儿结局。结果两组头位分娩评分、第一产程、第二产程及总产程时间比较，差异有显著性意义（P〈0．05）。枕后位组产钳助产、剖宫产、会阴裂伤、产后出血、胎儿窘迫、新生儿窒息率等均明显高于枕前位组，差异均有显著性意义（P〈0．05）。枕后位组宫口扩张及胎头下降延缓和第二产程延长的发生率均高于枕前位组，差异均有显著性意义（P〈0．05）。剖宫产组富口扩张延缓、胎头下降停滞和第二产程延长的发生率明显高于阴道分娩组（P〈0．05）。而剖宫产组和阴道分娩组骨盆临界狭窄、潜伏期及活跃期延长的发生率比较，差异无显著性意义（P〉0．05）。结论持续性枕后位导致母儿并发症增加，及时处理并选择最佳分娩方式可减少母儿并发症的发生。     

产程中改变产妇体位矫正胎方位的探讨

目的：探讨产程中改变产妇体位以矫正胎方位的临床效果。方法：选择先兆临产至潜伏期经Ｂ超检查判断为枕后位的初产妇２４０例，随机分为两组，各１２０例。研究组在产程中指导产妇取侧俯卧位，利用胎儿重力、羊水浮力、子宫间歇收缩的合力作用，使胎头在下降时逐渐从枕后位转至枕前位娩出，并与对照组比较。结果：研究组１０６例（８８．３％）胎儿从枕后位转到枕前位经阴道娩出。剖宫产１４例（１１．７％）。对照组经阴道娩出仅２０例（１６．７％），剖宫产１００例（８３．３％）。两组比较，差异有非常显著性（Ｐ＜０．００１）。研究组第一产程平均时间３０２．６分钟，第二产程平均５９．８分钟。对照组第一产程平均４８３．７分钟，第二产程平均１５６．７分钟。两组比较，差异有极显著性（Ｐ＜０．０１）。结论：在产程中指导产妇取侧俯卧位矫正胎头枕后位是降低难产发生率的有效方法。     

Pelvic floor dysfunction,and effects of pregnancy and mode of delivery on pelvic floor

Pelvic floor dysfunction (PFD), although seems to be simple, is a complex process that develops secondary to multifactorial factors. The incidence of PFD is increasing with increasing life expectancy. PFD is a term that refers to a broad range of clinical scenarios, including lower urinary tract excretory and defecation disorders, such as urinary and anal incontinence, overactive bladder, and pelvic organ prolapse, as well as sexual disorders. It is a financial burden on the health care system and disrupts women's quality of life. Strategies applied to decrease PFD are focused on the course of pregnancy, mode and management of delivery, and pelvic exercise methods. Many studies in the literature define traumatic birth, usage of forceps, length of the second stage of delivery, and sphincter damage as modifiable risk factors for PFD. Maternal age, fetal position, and fetal head circumference are nonmodifiable risk factors. Although numerous studies show that vaginal delivery affects pelvic floor structures and their functions in a negative way, there is not enough scientific evidence to recommend elective cesarean delivery in order to prevent development of PFD. PFD is a heterogeneous pathological condition, and the effects of pregnancy, vaginal delivery, cesarean delivery, and possible risk factors of PFD may be different from each other. Observational studies have identified certain obstetrical exposures as risk factors for pelvic floor disorders. These factors often coexist; therefore, the isolated effects of these variables on the pelvic floor are difficult to study. The routine use of episiotomy for many years in order to prevent PFD is not recommended anymore; episiotomy should be used in selected cases, and the mediolateral procedures should be used if needed.     

Use of the soft, silicone obstetric vacuum cup for delivery of the fetal head at cesarean section

Delivery of the fetal head at cesarean section can sometimes be very difficult, and serious maternal and fetal complications may occur. Recently a new soft, silicone obstetric vacuum cup was introduced for use on the fetal head at vaginal delivery. In 35 cases the cup was used for delivery of the fetal head at cesarean section. It is an effective, harmless alternative to conventional devices, especially in aiding the delivery of the high-floating head occurring spontaneously or occurring after the head impacted deep in the pelvis is dislodged.