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.     

Fetal heart rate and neonatal condition related to epidural analgesia in women reaching the second stage of labour

The relationship between epidural analgesia and a number of labour and delivery factors, relevant to fetal and neonatal condition, was considered in a prospective study of 200 labours reaching the second stage of labour. The group was representative of the hospital population with regard to the proportion of nulliparous women, the incidence of instrumental vaginal deliveries and the incidence of epidural analgesia (37%). The 8% of labours requiring fetal blood sampling during the first stage, and the labours with fetal heart rate (FHR) decelerations in the hour prior to second stage (25%) and during pushing (50%) were significantly more likely to have been given an epidural. Nulliparity (55%), induced labour (34%), a first stage longer than eight hours (37%), a second stage longer than 60 min (43%), maternal pushing for longer than 36 min (50%), forceps delivery (28%) and a 1 min Apgar score less than 7 (12%) were also factors associated with significantly higher rates of epidural analgesia whereas meconium (15%), a small baby (16%) and umbilical arterial metabolic acidaemia (13%) were not. FHR decelerations in labours reaching the second stage with an epidural reflect adjustments to fetal cardiovascular control and not acidaemia.     

Malpositions and malpresentations of the fetal head

Nearly 95% of fetuses at term present with the vertex and with such a presentation, the vast majority of women progress well in labour and have a spontaneous vaginal delivery. Any presentations other than vertex can lead to difficulties in labour and hence are called as malpresentations.Malpresentations of fetal head occur due to extension of the fetal head causing brow or face to present during labour. Malpositions of fetal head result when the occiput persists in a lateral or posterior position. Malpresentations and malpositions 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 fetal malpresentations or malpositions are diagnosed. Although vaginal delivery is possible in many cases, caesarean section becomes necessary when the malposition or malpresentation persists and labour fails to progress.     

Fever in labour and neonatal encephalopathy: a prospective cohort study

Objective To determine whether the reported association of maternal fever with neonatal encephalopathy is independent of other associated intrapartum risk factors.
Design Prospective cohort study.
Setting Dublin teaching hospital delivery ward.
Population 4915 low risk women in labour at 36-41 weeks of gestation.
Methods Using logistic regression with odds ratios and 95% confidence intervals, the incidence of neonatal encephalopathy and other neonatal outcomes of women who had an intrapartum fever >37.5° C was compared with those who did not.
Results The cohort comprised 33% of all deliveries during the study period. Neonatal encephalopathy was diagnosed in 3.25/1000 births. The incidence of intrapartum fever was 6.8%. Maternal fever was strongly associated with neonatal encephalopathy (crude OR 10.8, 95% CI 4.0-29.3). Univariate analysis showed maternal fever was associated with epidural analgesia, nulliparity, induction, longer labour, oxytocin administration, greater fetal birthweight and gestational age and instrumental vaginal delivery, but not with prolonged (>24hours) prelabour rupture of the membranes. The association of fever with neonatal encephalopathy persisted having adjusting for these covariates (adjusted OR 4.72, 95% CI 1.28-17.4).
Conclusions The relationship between maternal intrapartum fever and neonatal encephalopathy is independent of other known intrapartum risk factors. This provides further evidence for the role of inflammatory processes in the aetiology of neonatal neurological morbidity.     

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.     

A prospective randomised trial on the effect of position in the passive second stage of labour on birth outcome in nulliparous women using epidural analgesia

OBJECTIVE: To determine whether the rate of instrumental birth in nulliparous women using epidural analgesia is affected by maternal position in the passive second stage of labour. DESIGN: A pragmatic prospective randomised trial. SETTING: Consultant maternity unit in the Midlands. PARTICIPANTS: One hundred and seven nulliparous women using epidural analgesia and reaching the second stage of labour with no contraindications to spontaneous birth. INTERVENTIONS: The lateral versus the supported sitting position during the passive second stage of labour. MEASUREMENTS: Mode of birth, incidence of episiotomy, and perineal suturing. FINDINGS: Recruitment was lower than anticipated (107 vs. 220 planned). Lateral position was associated with lower rates of instrumental birth rate (lateral group 33%; sitting group 52%; p=0.05, RR 0.64, CI for RR: 0.40-1.01; Number-needed-to-treat (NNT)=5), of episiotomy (45% vs. 64%; p=0.05, RR 0.66, CI for RR: 0.44-1.00, NNT=5), and of perineal suturing (78% vs. 86%; p=0.243, RR 0.75, CI for RR 0.47-1.17). The odds ratio for instrumental birth in the sitting group was 2.2 (CI 1.00-4.6). Logistic regression of potential confounder variables was undertaken, due to a large variation in maternal weight between the randomised groups. Of the nine possible confounders tested, only position of the baby's head at full dilation affected the risk of instrumental birth significantly (p=0.4, OR 2.7 where the fetal head was in the lateral or posterior position). Maternal weight did not appear to have any effect. The odds ratio for instrumental delivery for women randomised to the sitting position was slightly higher within the logistic regression model (adjusted OR 2.3). KEY CONCLUSIONS: Women randomised to the lateral position had a better chance of a spontaneous vaginal birth than those randomised to the supported sitting position. Position of the babies head at full dilation had an additional effect on mode of birth. These effects are not conclusively generalizable. RECOMMENDATIONS FOR PRACTICE: The lateral position is likely to be at best beneficial, and at the worst no less harmful than the sitting position for most women and their babies who meet the criteria set for this study. Conclusive evidence for or against the technique should be established using larger trials.     

Digital rotation from occipito-posterior to occipito-anterior decreases the need for cesarean section

OBJECTIVE: Our purpose was to study prospectively the efficacy of digital rotation in reducing the prevalence of persistent occipito-posterior position (POP) and its consequences. STUDY DESIGN: Sixty-one women with a singleton pregnancy were enrolled prospectively between July 2003 and July 2004. They were in the second stage of labor with the fetal head engaged in the occipito-posterior position. During the first period of the study women were allowed to continue labor without intervention (group I); during the second period, digital rotation was performed (group II). RESULTS: In group I 15% of the fetuses were delivered in the occipito-anterior position and 27% underwent spontaneous vaginal delivery, as opposed to 93% and 77%, respectively, when the procedure was performed-an increase in spontaneous vaginal delivery among the group undergoing rotation of more than 50% (p<0.0001). Cesarean section was performed in 23% and vacuum in 50% when the procedure was not performed (group I) in contrast to 0% and 23%, respectively, in the group undergoing rotation (0.0001). CONCLUSION: Digital rotation should be considered when managing the labor of a fetus in the occipito-posterior position. The maneuver successfully rotates the fetus reducing the need for cesarean section, instrumental delivery, and other complications associated with POP.     

The use of forceps delivery in own analysis

OBJECTIVES: The clinical analysis of deliveries ended by forceps over the period of ten years. DESIGN: Review of perinatal outcome and indications to use outlet and low forceps or midforceps. MATERIALS AND METHODS: Author analysed 137 forceps deliveries in comparison to control group of 250 normal, vaginal labours. Obstetrical history, indications to use vaginal operation, duration of labour, hospitalisation time, newborns state in Apgar score or arterial cord pH, PaO2, and fetal or maternal injures were statistically analysed. The American College of Obstetricians and Gynecologists (ACOG) 1988 forceps classification be adopted for deliveries. Using outlet, low forceps and midforceps concerned with vaginal operation. RESULTS: The common indications to use outlet or low forceps were prolonged second stage of labour. The most frequent indication for the midforceps was a risk of fetal asphyxia and neonatal hypoxia. A major fetal injury occurred in midforceps, particularly with fetal head rotations. Furthermore, midforceps delivery increased incidence of maternal perineal trauma. The outlet or low forceps was safe for fetal outcome and trauma of the birth canal in comparison to normal vaginal delivery. CONCLUSIONS: The prophylactic use of outlet or low forceps has beneficial impact on the neonate because it shortens second stage of labour and decreased the incidence of neonatal hypoxia. The midforceps delivery increased a perinatal disorders and using cesarean section are better for child and mother.     

The impact of a trial of instrumental delivery in theatre on neonatal outcome

Objective  To observe the effect of a trial of instrumental delivery in theatre on outcome for mother and baby.
Design  A prospective observational study.
Methods  Relevant maternal and neonatal data were collected for all instrumental deliveries of singleton viable pregnancies delivered over a three month period.
Population  Two hundred and twenty nine consecutive deliveries conducted by ventouse or forceps because of fetal distress or dystocia.
Setting  The maternity unit of a teaching hospital delivering around 6000 women annually.
Main outcome measures  The decision-to-delivery intervals (DDI), mode of delivery and neonatal condition at birth.
Results  Sixty (26%) deliveries were managed as a trial in theatre, 46 (77%) because of prolonged second stage, with malposition being a factor in 39, and 14 (23%) because of fetal distress. The mean ± SD DDI for these 60 deliveries was 59.2 ± 20.4 minutes (median 58 minutes) compared with 21.2 ± 9.0 minutes (median 20 minutes) for 169 delivered in the labour room ( P < 0.0001). Of these 169 deliveries, 168 were delivered within 46 minutes and 1 delivered by caesarean section at 60 minutes. Nine women (13%) ultimately delivered by caesarean section, eight following a trial in theatre; in seven, there was malposition. Deliveries following a trial had slightly less favourable cord blood gas results.
Conclusions  Trial of instrumental delivery takes two to three times longer than delivery in the labour room; fetal malposition was the major indication for the trial of instrumental delivery and reason for failed delivery. Adopting the recent guidelines of the Royal College of Obstetricians and Gynaecologists, at least 107 (47%) should have been managed as a trial in theatre. The added delay in delivery could be damaging to an already hypoxic fetus, and the use of a trial should be individually assessed.     

Effects of maternal analgesia and anesthesia on the fetus and the newborn

Continuous electronic fetal heart rate (FHR) monitoring is part of routine care for laboring patients under either systemic or locoregional analgesia. Opioid systemic analgesia (mainly meperidine in early labor), yet less frequently used in our country, is associated with a decrease in FHR-variability and worse acid-base and neonatal status compared to epidural or combined spinal epidural analgesia. Although epidural analgesia may cause maternal hypotension and fever, longer second stage of labour and more instrumental vaginal deliveries, these potentially adverse factors appear to be outweighed by benefits on clinical and neonatal acid-base status when compared with maternal opioid systemic analgesia. The mechanisms by which epidural or spinal analgesia may affect fetal well-being include maternal hypotension and/or uterine hyperactivity. All these undesirable side effects which may induce severe intrapartum fetal distress must be adequately detected and treated with intrauterine resuscitation techniques, including correction of maternal hypotension and/or the use of tocolytics agents. Reinstallation of electronic fetal monitoring at arrival in the operating room before cesarean section for suspected fetal hypoxia may be helpful to choose better anesthetic technique and try to avoid general anesthesia associated with increased maternal morbidity and mortality.     

A vaginal delivery protocol for the term breech infant utilizing ball pelvimetry

Ball pelvimetry has been utilized at the Medical Center Hospital of Vermont to evaluate infants with breech presentation for vaginal delivery. That technique provided measurements of both the fetal head volume and maternal pelvic capacity so that relative fetomaternal relationships could be established. Between January 1979 and December 1981, 107 patients in spontaneous labor with term pregnancy were evaluated with the protocol. Inadequate pelvimetry and hyperextension of the fetal head occurred in 21 patients (20%). Of the 86 patients who were allowed to labor, 51 (59%) had a vaginal delivery. The total cesarean section rate was 52%. Vaginal delivery in our highly selected patient population did not increase neonatal morbidity. There were no neonatal deaths.     

Does epidural anesthesia affect the course of labor and delivery?

The progress of labor ideally leads to a normal, spontaneous, vaginal delivery. Many factors--maternal, fetal, obstetrical and anesthetic--may collectively contribute to delaying or precluding an ideal outcome. Adverse outcomes of labor and delivery must be clearly defined in terms of maternal, fetal, or neonatal morbidity or mortality, and should be distinguished from abnormal data (such as fetal heart rate, duration of labor, and incidence of low forceps deliveries) that are only indirectly related to outcome. Epidural anesthesia is not a singular phenomenon. Variations and subtle nuances in the administration of epidural anesthesia create a vast array of potential anesthetic regimens. To discover the anesthetic methods that provide excellent analgesia with no adverse effects on the course of labor is an ideal goal that has not yet been achieved. To approach this goal, the answers to several questions are needed. Are study patient groups adequately matched for risk factors? Are obstetrical practices well-defined with respect to elective versus indicated use of instrumental or cesarean delivery methods? Do the risks of instrumental delivery outweigh the benefit of perineal analgesia associated with epidural anesthesia? Is it possible to provide optimal analgesia throughout stage two labor without tending to increase the risk of instrumental delivery? Can delayed pushing during stage two labor increase the probability of spontaneous vaginal delivery with continuous epidural anesthesia? Well-controlled clinical trials and refinements in both anesthetic and obstetric techniques are necessary to resolve such issues so that every parturient (and fetus) may undergo a safe and painless delivery.     

Epidural analgesia and fetal head malposition at vaginal delivery

OBJECTIVE: To determine if nulliparas who delivered with on-demand epidural analgesia are more likely to have malpositioning of the fetal vertex at delivery than women delivered during a period of restricted epidural use. METHODS: A retrospective cohort of nulliparous women with spontaneous labor delivered during a 12-month period immediately before the availability of on-demand labor epidural analgesia was compared with a similar group of nulliparas delivered after labor epidural analgesia was available on request. The primary outcome variable was a non-occiput anterior position or malpositioned fetal head at vaginal delivery. RESULTS: The frequency of epidural use increased from 0.9% before epidural analgesia became available on demand to 82.9% afterward. Fetal head malpositioning at vaginal delivery occurred in 26 of 434 (6.0%) women delivered in the before period compared with 29 of 511 (5.7%) in the after period (relative risk 0.95, 95% confidence interval 0.6, 1.6). No statistically significant difference in the incidence of fetal head malpositioning was present after patients were stratified by mode of delivery (Mantel-Haenszel weighted relative risk 0.94, 95% confidence interval 0.6, 1.4). The study sample size provided 85% power to detect a two-fold increase in the incidence of fetal malpositioning from a baseline rate of 6% associated with on-demand epidural use. CONCLUSION: Providing on-request labor epidural analgesia to nulliparas in spontaneous labor did not result in a clinically significant increase in the frequency of fetal head malpositioning at vaginal delivery.     

Estimating the impact of pelvic immaturity and young maternal age on fetal malposition

Objective

Fetal malposition, specifically occiput posterior and transverse (OP/OT), is associated with higher intra-partum morbidity. We tested the hypothesis that young maternal age and pelvic immaturity are risk factors for fetal malposition.

Methods

In a cohort study of all nulliparous teen (??18?years) deliveries over a 4-year period at one institution, fetal head position at time of delivery was collected and correlated with maternal characteristics and outcome data. Using Risser staging observations, pelvic maturity age was set at 16, and accordingly, the women were divided into two groups (younger vs. older teens). Analysis was performed using Fisher??s exact, student t test, and logistic regression modeling.

Results

Older teen mothers (16?C18?years, n?=?609) had higher rates of malposition (22 vs. 12?%, p?=?0.02) when compared with younger teens (??15?years, n?=?98). Among all women with a malpositioned fetus, older teens had a higher body mass index (BMI: 32.6?±?6.7 vs. 28.5?±?3.5, p?=?0.04) and subsequent need for cesarean delivery (69 vs. 33?%, p?=?0.02) when compared with their younger counterparts. Although younger teens were more successful in having a vaginal delivery (67?%) with an OP/OT position, it was at the expense of a 25?% rate of severe perineal laceration (third/fourth degree).

Conclusion

Obesity, and not young maternal age or pelvic immaturity, is associated with fetal malposition. The direct association with increasing pre-pregnancy BMI and the long-term impacts of the high rates of cesarean delivery in this young population underscores the need for more public health focus.     

再谈头位阴道助产术

头先露的阴道助产术包括产钳助产术和胎头负压吸引术。在第二产程中判断胎头位置及胎方位是阴道助产成功的关键。胎头最低位置于坐骨棘2 cm以下,胎方位为枕前位者,助产风险相对小。产科医生要严格把握阴道助产的手术指征,并与患者充分沟通。临床医生的判断能力,培训经历以及临床经验是助产成功的重要因素。     

Asynclitism: a literature review of an often forgotten clinical condition

Asynclitism is defined as the “oblique malpresentation of the fetal head in labor”. Asynclitism is a clinical diagnosis that may be difficult to make; it may be found during vaginal examination. It is significant because it may cause failure of progress operative or cesarean delivery. We reviewed all literature for asynclitism by performing an extensive electronic search of studies from 1959 to 2013. All studies were first reviewed by a single author and discussed with co-authors. The following studies were identified: 8 book chapters, 14 studies on asynclitism alone and 10 papers on both fetal occiput posterior position and asynclitism. The fetal head in a laboring patient may be associated with some degree of asynclitism; this is seen as usual way of the fetal head to adjust to maternal pelvic diameters. However, marked asynclitism is often detected in presence of a co-existing fetal head malposition, especially the transverse and occipital posterior positions. Digital diagnosis of asynclitism is enhanced by intrapartum ultrasound with transabdominal or transperineal approach. The accurate diagnosis of asynclitism, in an objective way, may provide a better assessment of the fetal head position that will help in the correct application of vacuum and forceps, allowing the prevention of unnecessary cesarean deliveries.     

Induction of labour with a favourable cervix and/or pre-labour rupture of membranes

Premature rupture of membranes (PROM) occurs in 8% of term deliveries. In this situation labour induction with prostaglandins, compared with expectant management, results in a reduced risk of chorioamnionitis, neonatal antibiotic therapy, neonatal intensive care (NICU) admission, and increased maternal satisfaction. The use of prostaglandin is associated with an increased rate of diarrhoea and use of analgesia/anaesthesia. Compared with oxytocin, prostaglandin induction results in a lower rate of epidural use and internal fetal heart rate monitoring but a greater risk of chorioamnionitis, nausea, vomiting, more vaginal examinations, neonatal antibiotic therapy, NICU admission and neonatal infection. Women should be informed of the risks and benefits of each method of induction.Misoprostol is gaining increasing interest as an alternative induction agent. It appears to be an effective method of labour induction with term PROM. Further research is needed to identify the preferred dosage, route and interval of administration, and to assess uncommon maternal and neonatal outcomes.There has been limited research on the use of prostaglandins, including misoprostol, for induction of labour with a favourable cervix and intact membranes. Compared with intravenous oxytocin (with and without amniotomy), labour induction using vaginal prostaglandins in women with a favourable cervix (with and without PROM) results in a higher rate of vaginal delivery within 24 hours and increased maternal satisfaction. In women with a favourable cervix, artificial rupture of membranes followed by oral misoprostol has similar time to vaginal delivery compared with artificial rupture of membranes followed by oxytocin. Further research with prostaglandins, including misoprostol, is needed to evaluate other maternal and neonatal outcomes in women being induced with a favourable cervix.No form of prostaglandin induction in women with PROM or favourable cervix has proven clearly superior to oxytocin infusion.     

Abnormal labour

Cord prolapse is an obstetric emergency that complicates 0.1–1% of all deliveries with significant perinatal morbidity and mortality. Early diagnosis and swift management improves fetal outcomes. Immediate interventions include manual elevation of the presenting part, altered maternal position and filling of the bladder. Delivery is usually by Caesarean section unless the cervix is fully dilated when an instrumental delivery can be considered.Face presentation accounts for 0.2% of all live births. The overall vaginal delivery rate is 60–70% with the majority being in mento-anterior position. Those in persistent mento-posterior position usually require Caesarean section. Forceps delivery can be performed for prolonged second stage or abnormal CTG in mento-anterior position.Primary dysfunctional labour is very common. Interventions to consider include intravenous hydration, amniotomy and oxytocin. Oxytocin reduces the length of labour but does not alter the mode of delivery. Continuous fetal monitoring must be employed when utilizing oxytocin.     

Benefits of continuous infusion epidural analgesia throughout vaginal delivery

Two groups of nulliparous women with fetuses in singleton vertex presentation received continuous infusion epidural analgesia (EDA) with bupivacaine: group A (90 parturients) without infusion analgesia in the second stage of labor and group B (90 parturients) with infusion analgesia throughout delivery. The groups were compared regarding pain relief, duration of the second stage, persistent malrotation of the fetal head, and rate of instrumental vaginal delivery. The continuous infusion EDA gave satisfactory pain relief in 93.3% of the parturients in group A and 97.8% in group B. The duration of second stage was the same in both groups. There were more persistent malrotations of the fetal head in group A, but the malrotation did not affect the mode of delivery. The rate of instrumental vaginal delivery was 25.5% in both groups. The main cause of operative intervention was delay in the second stage. When the continuous infusion technique is used, it seems unreasonable to discontinue the EDA and thereby deprive the parturient of analgesia during the second stage.