Operative vaginal deliveryAuthorsElisabeth K Wegner, MDIra M Bernstein, MDSection EditorCharles J Lockwood, MD, MHCMDeputy EditorVanessa A Barss, MD, FACOGDisclosures: Elisabeth K Wegner, MD Nothing to disclose. Ira M Bernstein, MD Nothing to disclose. Charles J Lockwood, MD, MHCM Consultant/Advisory Boards: Celula [Aneuploidy screening (Prenatal and cancer DNA screening tests in development)]. Vanessa A Barss, MD, FACOG Nothing to disclose.Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence.Conflict of interest policyAll topics are updated as new evidence becomes available and our peer review process is complete.Literature review current through: Jul 2015. | This topic last updated: Jun 26, 2015.NEWER VERSION OF TOPIC MESSAGEINTRODUCTION — Operative vaginal delivery refers to a delivery in which the operator uses forceps or a vacuum device to assist the mother in transitioning the fetus to extrauterine life. The instrument is applied to the fetal head and then the operator uses traction to extract the fetus, typically during a contraction while the mother is pushing.The first instrumental deliveries were performed to extract fetuses from parturients who were at high risk of maternal mortality due to prolonged and/or obstructed labor. In these cases, saving the mother's life took precedence over possible harm to the fetus. The focus of these procedures has changed as a result of modern obstetrical practices that have drastically reduced the risk of intrapartum maternal mortality and major morbidity. Decisions regarding use of instrumental delivery are now based primarily upon the fetal/neonatal impact of these procedures and are weighed against the alternative options of cesarean birth, expectant management (prolonging the second stage), and augmentation of contractions with oxytocin.INCIDENCE — In the United States, 3.5 percent of all deliveries are accomplished via an operative vaginal approach [1]. The overall rate of operative vaginal delivery has been diminishing, but the proportion of operative vaginal deliveries conducted by vacuum assisted births has been increasing and is more than four times the rate of forceps assisted births. Forceps deliveries account for 1 percent of vaginal births and vacuum deliveries account for about 4 percent of vaginal births.In recent years, the success rate for operative vaginal deliveries has been quite high (99 percent) [2]. This likely reflects appropriate choice

of candidates for this intervention. However, the wide range of operative vaginal delivery rates (1 to 23 percent), both across and within geographic regions in the United States, suggests that evidence based guidelines for operative vaginal delivery are either inadequate or randomly applied [3].INDICATIONS — An American College of Obstetricians and Gynecologists (ACOG) practice bulletin outlined the following indications for operative vaginal delivery (forceps or vacuum), recognizing that no indication is absolute; cesarean delivery is also an option in these clinical settings [4]:●Prolonged second stage of labor – For nulliparous women, a

prolonged second stage has been defined as no progress (descent, rotation) after ≥4 hours with epidural anesthesia and ≥3 hours without epidural anesthesia [5]. For multiparous women, a prolonged second stage has been defined as no progress (descent, rotation) after ≥3 hours with epidural anesthesia and ≥2 hours without epidural anesthesia.

In the past, shortening the second stage was an acceptable option, independent of any specific maternal or fetal indications, because early studies suggested the risk of fetal morbidity was higher when the second stage of labor exceeded two hours. More recent evidence does not support this practice. The ability of fetal heart rate monitoring to identify the fetus who is not tolerating labor has generally made the arbitrary termination of labor because of any elapsed period of time unwarranted [4,6-9]. The maternal risks of a prolonged second stage (eg, pelvic floor injury, postpartum hemorrhage) appear to be increased but are more related to instrumental intervention than the specific length of the second stage [7-12]. (See 'Maternal complications' below.)

●Nonreassuring fetal status – Suspicion of immediate or potential fetal

compromise (eg, nonreassuring fetal heart rate pattern, abruption) is an indication for use of forceps or vacuum when expeditious vaginal delivery can be readily accomplished; otherwise, cesarean delivery may be the safer and more effective option.

●Maternal cardiac or neurological disease – Forceps or vacuum can

be used to shorten the second stage of labor if the Valsalva maneuver is contraindicated because of maternal cardiovascular or neurologic disease, or if pushing is ineffective because of maternal neurological or muscular disease.

PREREQUISITES — The operator should be experienced in operative vaginal delivery. This individual should determine the following prerequisites prior to application of instruments (table 1) [4,13]:●The cervix is fully dilated.

●The membranes are ruptured.

●The head is engaged.

●Fetal presentation, position, station, and any asynclitism are known. The fetus must be in a cephalic presentation (unless the purpose is to use forceps to assist in delivery of an after-coming head).

If fetal presentation or position is uncertain, intrapartum ultrasound examination should be performed, as it is more accurate than digital examination in this setting. Sonographic visualization of fetal intracranial structures, including the cerebellum, orbits, and midline falx, can be used to confirm fetal head position. In two studies, digital examination incorrectly defined fetal head position in over 20 percent of cases about to undergo operative vaginal delivery [14,15]. However, in a randomized trial, ultrasound assessment of head position did not reduce maternal or neonatal morbidity compared with standard clinical care [15].

Large infants, extreme molding, extension of the fetal head, pelvic deformities, and asynclitism may falsely suggest engagement of the vertex. In these cases, the leading bony part is at the ischial spines, although the biparietal diameter has not passed through the pelvic inlet. If ultrasound is not available, no more than one-fifth of the fetal head should be palpable abdominally if the vertex is engaged [16].

●The fetal size has been estimated and clinical pelvimetry indicates adequate mid and outlet pelvic dimensions, and no obstructions or contractures exist.

●Maternal anesthesia is satisfactory. Neuraxial anesthesia provides more effective analgesia than pudendal block [17].

●Maternal bladder is empty.

●The patient consents to the procedure. The risks of the procedure should be explained to the woman and documentation of the indication and maternal and fetal assessments should be made in the medical record [18]. The record should also document the informed consent discussion (with specific risks, benefits, and alternatives delineated), and that her questions were answered.

●The option of performing an immediate cesarean delivery is available if complications arise. Personnel for neonatal resuscitation are available, if needed.

We do not give antibiotic prophylaxis as there is no convincing evidence that it reduces infection in this setting [19].Contraindications — Most contraindications to instrumental delivery are related to the potential for unacceptable fetal risks. Fetal prematurity is a relative contraindication. Some other contraindications include known fetal demineralizing diseases (eg, osteogenesis imperfecta), fetal bleeding diatheses (eg, hemophilia, alloimmune thrombocytopenia), unengaged head, unknown fetal position, malpresentation (eg, brow, face), and suspected fetal-pelvic disproportion [20]. A nonreassuring fetal heart rate pattern is not a contraindication to operative vaginal delivery [4]. (See "Fetal blood sampling".)In addition, vacuum devices should not be used to assist delivery prior to 34 weeks of gestation because of the risk of fetal intraventricular hemorrhage [4]. Prior scalp sampling or multiple attempts at fetal scalp electrode placement are also relative contraindications to vacuum extraction since these procedures may increase the risk of cephalohematoma or external bleeding from the scalp wound [21-23].Minimum and maximum estimated fetal weight — There is no consensus regarding the minimum and maximum estimated fetal weights that should preclude operative vaginal delivery.Upper threshold — Instrumental delivery of the macrosomic infant may be associated with an increased risk of injury. As an example, a study of 2924 macrosomic infants (birth weight >4000 g) found the risk of persistent significant injury was higher after forceps than after spontaneous delivery (relative risk [RR] 2.6) or cesarean birth (RR 4.2), although the overall rate of persistent injury was low (0.3 percent) [24]. The risk of persistent injury at six months of age was seven-fold higher among macrosomic infants compared with appropriate-for-gestational-age (AGA) controls (birth weight 3000 to 3999 g) and was related to vaginal birth (operative or spontaneous). Persistent injury was not observed in infants delivered by cesarean delivery.

The authors did not recommend a policy of elective cesarean birth for

macrosomia because it would necessitate 148 to 258 cesarean deliveries to prevent a single persistent injury; avoidance of operative vaginal delivery would require 50 to 99 cesarean births per injury prevented. Furthermore, there is no precise method for determining which mothers have macrosomic infants prior to delivery. (See "Fetal macrosomia".)

A trial of labor and careful use of forceps or vacuum extraction are acceptable for most fetuses suspected to be macrosomic [4]. Under these circumstances, the obstetrician should be aware of the risk of shoulder dystocia, especially when the second stage of labor is prolonged. (See "Shoulder dystocia: Risk factors and planning delivery of at risk pregnancies".)Lower threshold — As discussed above, vacuum devices should not be used to assist delivery prior to 34 weeks of gestation (mean birth weight 2500 g [25]) because of increased risks of fetal intraventricular hemorrhage in premature infants. Premie sized forceps have been used on fetuses as small as 1000 g [26].

There are no prospective randomized trials examining the impact of prophylactic low forceps delivery in low birth weight infants. Observational studies have reported conflicting findings. In 1965, the Collaborative Study of Cerebral Palsy reported that prophylactic low forceps delivery was associated with neurologic benefits in infants between 1000 and 2500 g when compared to spontaneous vaginal or cesarean deliveries [27]. However, this report was limited by the lack of a rigorous statistical analysis.

Another study that performed immediate and later head ultrasound examinations of 230 infants with estimated fetal weights of less than 1750 g observed that the overall incidence of cerebral hemorrhage was the same after vaginal and cesarean deliveries (41 and 44 percent, respectively) [28]. However, a lower incidence of hemorrhage was noted after vaginal delivery with forceps (17 percent). More grades 3 to 4 hemorrhages were observed after vaginal birth without forceps and in cesarean births following active phase labor compared to other modes of delivery.

In contrast, several other studies have suggested an increased risk of intraventricular hemorrhage with prophylactic low forceps [29-31] while one report on 1065 infants between 1000 to 2500 g identified no differences in neonatal outcome between the 394 infants delivered by low forceps and the 671 that delivered spontaneously [26].In summary, the evidence does not clearly identify a superior mode of delivery in cephalic presenting low birth weight infants and very little data address the very low birth weight infant. Reassuringly, larger trials

do not demonstrate any increase in neurologic injury with the use of low forceps in low birth weight infants, and a role for low forceps in clinically indicated situations would appear reasonable in this population. (See "Delivery of the preterm low birth weight singleton fetus".)Two forceps are available which are smaller in dimension than standard forceps and are intended for use in the low birth weight or very low birth weight populations. "Baby" Elliot and "baby" Simpson forceps are among these instruments. Unfortunately, we were unable to identify any published studies or manufacturer guidelines regarding the estimated fetal weights or gestational ages at which these instruments might be most useful.ALTERNATIVES — Possible alternatives to operative vaginal delivery are cesarean birth, expectant management (possibly with delayed pushing, maternal rest, change in maternal position, reduction in neuraxial anesthesia, emotional support), and augmentation of contractions with oxytocin. The choice depends upon the clinical situation, taking into account factors such as whether the fetal heart rate pattern is nonreassuring, the quality and frequency of contractions, estimated fetal size, and fetal position. (See "Overview of normal labor and protraction and arrest disorders" and "Shoulder dystocia: Risk factors and planning delivery of at risk pregnancies".)TRIAL OF INSTRUMENTAL DELIVERY — Although one can never be certain of a successful outcome, an operative vaginal delivery should only be considered when the likelihood of success is high, given there may be a higher rate of birth trauma after failed attempts at operative delivery [4,32,33]. As an example, in one study, the rates of subdural or cerebral hemorrhage, facial nerve injury, convulsions, central nervous system depression, and mechanical ventilation were higher in infants delivered by cesarean birth after a failed instrumental delivery than in those delivered by cesarean with no prior attempt at operative vaginal delivery (table 2) [34]. However, other studies have not shown adverse effects from failed operative vaginal delivery as long as cesarean delivery followed promptly [35]. No randomized trials have been performed comparing a trial of instrumental vaginal delivery (vacuum extraction or forceps) to immediate cesarean delivery for women with failure to progress in the second stage of labor.Multiple variables have been associated with an increased risk of failed operative delivery; two common causes are occiput posterior position and macrosomia [32,36-42]. Other purported factors include one fifth of the head palpable abdominally, the presenting part only as far as the ischial spines, excessive molding of the fetal head, protracted labor, and maternal obesity [32].CLASSIFICATION OF FORCEPS DELIVERIES — ACOG redefined the classification of forceps delivery in 1988 to better reflect the degree of difficulty and attendant risk (eg, lower fetal station and smaller degrees of head rotation are associated with reduced maternal and fetal

injury [43]) [4]. The criteria for different types of forceps deliveries are as follows [4]:●Outlet forceps – The application of forceps when the scalp is visible at the introitus without separating the labia, the fetal skull has reached the pelvic floor, the sagittal suture is in anteroposterior diameter or a right or left occiput anterior or posterior position, the fetal head is at or on the perineum, rotation does not exceed 45 degrees.

●Low forceps – The application of forceps when the leading point of the fetal skull is 2 cm or more beyond the ischial spines (ie, at least +2 cm station; the maximum possible distance beyond the ischial spines using this system is 5 cm), but not on the pelvic floor. Low forceps have two subdivisions: (a) rotation is 45 degrees or less (left or right occiput anterior to occiput anterior, or left or right occiput posterior to occiput posterior), and (b) rotation more than 45 degrees.

●Midforceps – The application of forceps when the head is engaged, but the leading point of the skull is higher than +2 cm station.

Under very unusual circumstances, such as the sudden onset of severe fetal or maternal compromise, application of forceps above +2 cm station may be attempted while simultaneously initiating preparations for a cesarean delivery in the event the forceps maneuver is unsuccessful. Under no circumstances, however, should forceps be applied to an unengaged presenting part or when the cervix is not completely dilated [4].

CHOICE OF INSTRUMENT — The choice of instrument is determined by level of training with the various forceps and vacuum equipment. Factors that might influence choice are the availability of the instrument, the degree of maternal anesthesia, and knowledge of the risks and benefits associated with each instrument. Differences between the two instruments in the types and rates of maternal and fetal morbidity are reviewed below (see 'Data from comparative trials' below).In general, vacuum delivery is probably safer than forceps for the mother, while forceps are probably safer than vacuum for the fetus. Vacuum devices are easier to apply, place less force on the fetal head, require less maternal anesthesia, result in less maternal soft tissue trauma, and do not affect the diameter of the fetal head compared to forceps. Fetal head rotation may occur secondary to fetal extraction.By comparison, the advantages of forceps are that they are unlikely to detach from the head, can be used on premature fetuses or to actively rotate the fetal head, result in less cephalohematoma and retinal

hemorrhage, and do not aggravate bleeding from scalp lacerations.A meta-analysis of randomized trials found that forceps were less likely to fail to achieve vaginal birth than vacuum (RR 0.65, 95% CI 0.45-0.94; 7 trials, 2419 participants), but with more maternal trauma [44]. The authors suggested use of vacuum extraction when a relatively easy procedure is anticipated (eg, occipito-anterior position with no signs of relative cephalopelvic disproportion).Vacuum — A meta-analysis of eight trials involving 1076 women compared soft (silicone, plastic, rubber) vacuum extractor cups to rigid (metal, plastic) ones [44]. Soft cups were more likely to fail in achieving vaginal delivery (OR 1.63, 95% CI 1.17-2.28). However, there were fewer scalp injuries and cephalohematomas with the soft cup and no differences between groups in regard to maternal injury. The authors concluded that metal or rigid cups were more suitable for occiput posterior, transverse, and difficult occiput anterior deliveries, whereas the soft cup was appropriate for uncomplicated deliveries.Two randomized prospective trials compared conventional vacuum devices to the Kiwi Omnicup. Both showed a statistically significant higher failure rate with the Kiwi Omnicup compared to conventional vacuum: failure rates in one trial were 30.1 and 19.2 percent, respectively [45], and in the other trial, failure rates were 34 and 21 percent, respectively [46].Forceps — A detailed discussion of the hundreds of types of instruments available for forceps delivery is beyond the scope of this review. In general, the instrument selected should have cephalic and pelvic curves appropriate to the size and shape of the fetal head, maternal pelvis, and planned procedure. Midpelvic deliveries are facilitated by an instrument that can be used with a traction handle (eg, Bill's axis traction handle) and a sliding lock is helpful when there is asynclitism. Simpson type forceps tend to fit a long molded head, Elliott or Tucker-McLane type forceps are better suited to a round unmolded head, and Kielland forceps are useful for rotations because of their minimal pelvic curve and sliding lock (picture 1A-F).Spatula — An unarticulated forceps (ie, Thierry spatula) has become popular in many European, African, and Latin American countries [47]. Outcome data are limited, but maternal and neonatal complication rates appear to be similar to, or slightly higher than, rates with other instruments [48,49].Odon device — A novel alternative instrument, the Odon device, was developed by the World Health Organization (WHO) for use in areas that have limited or no access to cesarean birth. The Odon device is undergoing the first phase of testing for safety and feasibility in Argentina and rural South Africa [50]. It is a low-cost device made of film-like polyethylene material that creates a sac filled with air that surrounds the entire head and enables extraction when traction is applied. It has the potential to be safer and easier to apply than

forceps/vacuum extractor for assisted deliveries. Videos showing application of the device and fetal extraction are available online (www.odondevice.org).APPLICATIONForceps — Appropriately applied forceps grasp the occiput anterior (OA) fetal head such that:●The long axis of the blades corresponds to the occipitomental diameter (figure 1)

●The tips of the blades lie over the cheeks (figure 2)

●The blades are equidistant from the sagittal suture, which should bisect a horizontal plane through the shanks

●The posterior fontanelle should be one finger breadth anterior to this plane

●Fenestrated blades should admit no more than one finger breadth between the heel of the fenestration and the fetal head

●No maternal tissue has been grasped.

Rotation, when needed, is performed between contractions. These deliveries are more difficult and associated with a higher risk of maternal and fetal complications than simple traction applied to the non- or minimally rotated vertex. Forceps application and rotation when the fetal vertex is not directly OA is beyond the scope of this topic review.To reduce the risk of laceration, forceps are disarticulated and removed when expulsion is certain, but before the widest diameter of the fetal head passes through the introitus. The vertex can then be delivered with no or minimal maternal assistance.Vacuum — The procedure for vacuum extraction is discussed in detail separately. (See "Procedure for vacuum assisted operative vaginal delivery".)Traction — Traction with forceps (or vacuum) should be steady (not rocking) and in the line of the birth canal. Traction should be exerted with each contraction and in conjunction with maternal expulsive efforts; the forceps can be relaxed between contractions to reduce fetal cranial compression. In most cases, progress is noted with the first or second pull and delivery occurs by the third or fourth pull [51]. The procedure

should be abandoned if descent does not occur with appropriate application and traction.An observational study of 560 vacuum assisted deliveries using an omnicup vacuum device with a traction force indicator found that 86 percent of extractions occurred with 11.5 kg (25 lbs) or less traction and 14 percent with greater than 11.5 kg traction [52]. A similar series found that neonatal scalp abrasion and cephalhematoma were more common in infants born with traction greater than 11.5 kg [53].SEQUENTIAL ATTEMPTS — ACOG has suggested that multiple attempts at operative vaginal delivery using different instruments (vacuum, different types of forceps) be avoided due to the greater potential for maternal and/or fetal injury [4]. Population-based data have shown increased maternal and neonatal risks from sequential application of vacuum and forceps [34,54-56], while a few small studies have not demonstrated increased risk, but these may be limited by their study sizes [35,57].In one large study, the incidence of subdural or cerebral hemorrhage in infants delivered by vacuum and forceps, vacuum alone, or forceps alone was approximately 21, 10, and 8, per 10,000 births, respectively [34]. These findings were corroborated by another analysis based upon state-wide birth certificate data [54], and a study on asymptomatic term infants who underwent routine magnetic resonance imaging within 48 hours of birth [55]. Nine of 111 asymptomatic infants had subdural hematomas with the highest proportion in the group exposed to failed vacuum followed by successful forceps delivery (five subdural hematomas among 18 infants). In addition, three subdural hematomas occurred in 49 infants spontaneously delivered from vertex presentation and one subdural hemorrhage occurred after a failed vacuum delivery. No subdurals were noted in the remaining infants (25 infants delivered by cesarean, 4 delivered by forceps, 13 delivered by vacuum, and 1 delivered by cesarean after failed forceps). All hematomas had resolved without clinical sequelae when reevaluated four weeks later. However, two other small studies did not show adverse effects from sequential use of vacuum and forceps, even when vaginal delivery was not achieved [35,57].For the mother, sequential use of vacuum and forceps has been associated with increased rates of third/fourth degree lacerations and postpartum hemorrhage [56].We feel sequential delivery may be appropriate in rare, carefully selected cases, as long as none of the indications for abandonment of operative delivery are present. We would not consider it a sequential delivery in situations where proper placement of forceps cannot be achieved or a vacuum device fails to achieve suction and no traction has been applied and then a second instrument is used (see 'When to abandon the procedure' below).WHEN TO ABANDON THE PROCEDURE — The decision to proceed

with operative vaginal delivery is ongoing and decided moment by moment based on assessment of the success of the various steps in the procedure. Operative vaginal delivery should be abandoned if it is difficult to apply the instrument, descent does not easily proceed with traction, or the baby has not been delivered within a reasonable time (eg, 15 to 20 minutes) [16]. Some experts have recommended abandoning the procedure after three pulls. A cohort study found that 82 percent of completed operative deliveries occurred with one to three pulls, and that pulling more than three times was associated with infant trauma in 45 percent of such deliveries [58]. Based on these data, it seems prudent to abandon the procedure if good instrument placement is followed by no progress in descent over three attempts. If descent has occurred and delivery is clearly imminent, then proceeding with instrumental delivery after three pulls may be appropriate and less morbid than a cesarean delivery of an infant with its head on the perineum.The operator should not be fixated on affecting a vaginal delivery. It is essential that the operator be willing to abandon a planned or attempted operative delivery and have the ability to perform a cesarean birth if evaluation or reevaluation of the clinical status shows that an instrumental delivery is contraindicated (eg, the fetal head is not engaged, the position is uncertain, the procedure is not succeeding).It is important to remember to examine the mother for possible tissue trauma after a failed attempt at operative delivery, as well as after successful attempts.OUTCOME AFTER FAILED PROCEDURES — A secondary analysis of an observational study of women who underwent second stage cesarean delivery compared outcomes of infants delivered abdominally after a failed attempt at operative vaginal delivery (n = 640) with those who underwent cesarean delivery without such attempts (n = 2549) [59]. Overall, a failed operative delivery was associated with significantly higher rates of umbilical pH <7.0 (4.7 versus 1.7 percent), Apgar score ≤3 at 5 minutes (1.7 versus 0.6 percent), seizures in the first 24 hours of life (0.9 versus 0.1 percent), and hypoxic ischemic encephalopathy (HIE) (1.1 versus 0.1 percent).The authors attributed these differences, at least in part, to the higher proportion of nonreassuring fetal heart rate tracings as the indication for cesarean in the attempted operative vaginal delivery group (18 versus 14 percent); unfortunately, the indications for attempted instrument delivery were not reported. There was no evidence of fetal cranial trauma in neonates with HIE, which suggests that the HIE was related to the nonreassuring fetal status rather than trauma. This hypothesis is supported by the observation that significant differences in neonatal outcome did not occur when the instrumental procedures were performed for indications other than a nonreassuring tracing (eg, dystocia); however, the number of adverse events in these settings was

small, with a wide confidence interval around the odds ratio. This study did not report outcomes of pregnancies in which attempted operative vaginal delivery was successful; incorporating these data might change the overall results reported for attempted operative vaginal delivery and impact conclusions about the safety of attempting this procedure. Data from randomized trials which include outcomes of all women undergoing attempted operative vaginal delivery are needed before one can conclude that a failed instrumental delivery has any adverse neonatal effects.RISKS — Maternal and fetal complication rates depend on a number of factors, which are not entirely independent. These include parity, forceps/cup position, head position at application, and station.Data from comparative trials — The risks associated with operative vaginal delivery need to be evaluated with respect to appropriate control groups and reasonable alternative procedures. This was illustrated by a study assessing the incidence of intracranial hemorrhage related to labor and mode of delivery in 583,340 singleton infants born to nulliparous women in California (table 3) [34]. The rate of subdural or cerebral hemorrhage associated with vacuum extraction was equivalent to that associated with forceps use or cesarean delivery during labor, but higher than after spontaneous delivery or a cesarean delivery performed prior to labor. This suggests that the intrapartum indication for intervention was the major risk factor for this complication, rather than mode of delivery. (See "Clinical manifestations and diagnosis of intraventricular hemorrhage in the newborn".)Comparative data on the risks of instrumental delivery are illustrated by the following examples from large studies:●A meta-analysis of 10 trials comparing vacuum with forceps delivery found vacuum deliveries were associated with less maternal soft tissue trauma (OR 0.41, 95% CI 0.33-0.50), required less general and regional anesthesia, and resulted in fewer cesarean deliveries [60]. However, use of a vacuum device was less likely to result in successful vaginal delivery than forceps. The lower cesarean delivery rate after attempted vacuum extraction was likely due to follow-up trial of forceps, whereas failed forceps typically resulted in a cesarean delivery. Patient selection may have also been a factor; the vacuum approach may have been used in patients more likely to deliver with minimal assistance.

Neonates delivered by vacuum extraction had more neonatal cephalohematoma (OR 2.38) and retinal hemorrhages (OR 1.99) than those delivered by forceps [60]. These problems generally are not associated with long-term complications (see 'Maternal complications' below).

●

A population-based analysis of singleton births in the United States provided crude morbidity/mortality data for over 11 million unassisted, forceps assisted, and vacuum assisted births (table 4) [61]. Vacuum-assisted deliveries were associated with significantly lower rates of birth injury, seizures, and assisted ventilation than forceps-assisted deliveries, after adjustment for confounders; neonatal death rates were equivalent.

State-based data for California and New Jersey are shown in the tables (table 5 and table 6) [34,61]. Although patients contained in these reports might represent a biased sample, relative to the choice of tool for operative vaginal delivery, it seems likely that this is a reasonable representation of injuries to be expected with the application of the different tools, given current clinical indications for different types of operative vaginal delivery.

Maternal complicationsShort-term — Short-term maternal risks from instrumental delivery include pain at delivery, perineal pain at 24 hours, lower genital tract lacerations and hematomas, urinary retention and incontinence, anemia, anal incontinence, and rehospitalization [62-67]. A randomized trial reported at least one adverse maternal outcome (periurethral/labial laceration, vaginal laceration, 3rd or 4th degree laceration, vulvar or vaginal hematomas, or cervical lacerations) occurred in 48 percent of forceps, 36 percent of silastic vacuum extractor, and 22 percent of Mityvac vacuum extractor deliveries [68]. Severe maternal trauma is primarily associated with rotational and midforceps operations [43,69]; direct bladder injury, ureteral lacerations/transections, and uterine rupture have been reported in such cases [70].Although maternal complications can occur with spontaneous delivery, they are more likely to be associated with vacuum or forceps delivery. This was illustrated by a retrospective review of 50,210 vaginal deliveries and a cohort study of 87,267 vaginal deliveries in which the rates of third and fourth degree lacerations were: spontaneous delivery (2 percent), vacuum extraction (10 to 11 percent), and forceps delivery (17 to 20 percent) [71,72].Additional maternal morbidities occur when episiotomy is performed at the time of the operative vaginal delivery. These morbidities include an increased risk of postpartum hemorrhage and perineal infection, and a greater need for moderate or strong analgesia [73].Most studies show performing an episiotomy (midline [74,75] or mediolateral [76,77]) appears to increase, rather than decrease, the risk of perineal trauma [74-78] when employed in association with operative vaginal deliveries. As an example, a study that calculated odds ratios (OR) for severe perineal laceration in nulliparous women undergoing various types of delivery reported [75]:

●Vacuum extraction without episiotomy (OR 9.4)●Forceps delivery without episiotomy (OR 23.2)●Vacuum extraction with episiotomy (OR 34.7)●Forceps delivery with episiotomy (OR 41.8)

Similar results have been reported in multiparous women.However, one large cohort study found that mediolateral episiotomy during operative vaginal delivery protected against anal sphincter injury [79]. Of note, the only randomized trial comparing routine versus restrictive episiotomy did not show a difference in outcomes, including anal sphincter tear or postpartum hemorrhage [80].Rates of third and fourth degree lacerations have decreased over several decades in the US [81]. Observational data suggest that more than 50 percent of this reduction can be accounted for by decreased use of forceps and episiotomy [82]. The effects of episiotomy are discussed in more detail separately. (See "Approach to episiotomy".)Fetal position also has an impact on the risk of maternal trauma during delivery [83-85]. The rate of rectal injury is higher for instrumental delivery from the occiput posterior (OP) compared with the occiput anterior (OA) position (for forceps delivery: 72 versus 54 percent; for vacuum delivery: 33 versus 27 percent) [83]. A logistic regression model adjusting for a number of factors showed that OP was four times more likely than OA to be associated with anal sphincter injury; the unadjusted rates of anal sphincter injury for the OP and OA positions were 42 and 22 percent, respectively [84].It should be noted that surgical trauma is intrinsic to all cesarean deliveries. Although spontaneous vaginal delivery is less traumatic for the mother than operative vaginal delivery, the latter is associated with less short-term maternal morbidity than cesarean delivery. As an example, a retrospective analysis of 358 midforceps and 486 cesarean deliveries reported febrile morbidity followed 25 percent of cesareans, but only 4 percent of forceps deliveries, and all cases of thromboembolism occurred in women who underwent cesarean delivery [86]. Unexpected cervical and vaginal lacerations and episiotomy extensions occurred in 45 percent of forceps deliveries, while 21 percent of women delivered by cesarean had an unexpected hysterotomy extension.Long-term — Long-term maternal sequelae from operative delivery are primarily related to potential disturbances in urinary and anal function, such as urinary incontinence, fecal incontinence, pelvic organ prolapse, and, occasionally, fistula formation. As an example, a trial that randomly assigned 75 women to forceps or vacuum delivery and surveyed them

five years postpartum reported 47 percent had some degree of urinary incontinence and 20 percent had loss of bowel control "sometimes" or "frequently" [87]. The long-term rates of morbidity were similar regardless of the instrument used to assist delivery. This study was limited by the lack of a control group of women who underwent cesarean delivery following a dysfunctional labor.Any increase in risk of long-term maternal morbidity from different types of operative vaginal delivery cannot be accurately quantitated and compared because of the lack of adequate randomized trials with appropriate control groups. The most appropriate control group when evaluating sequelae of operative vaginal delivery is probably cesarean delivery during dysfunctional labor because prelabor cesarean delivery and spontaneous vaginal delivery are not possible alternatives to instrumental delivery in the setting of labor complications. Data from longitudinal cohort studies suggest that cesarean delivery after full dilation is associated with less urinary incontinence, anal incontinence, and prolapse symptoms than operative vaginal delivery, but these differences were not consistently statistically significant [88,89]. The relationships between method of delivery and long-term risk of pelvic relaxation and urinary and fecal incontinence are discussed in detail separately. (See "Effect of pregnancy and childbirth on anal sphincter function and fecal incontinence" and "Urinary incontinence and pelvic organ prolapse associated with pregnancy and childbirth".)Risk of recurrent operative vaginal delivery — Mode of delivery after a previous operative vaginal delivery has not been extensively evaluated. A three-year follow-up study that surveyed women who had undergone a successful, term, operative vaginal delivery in the second stage reported 42 of 54 (78 percent) women achieved vaginal delivery in the subsequent pregnancy and 3 of the 54 (5.6 percent) women had another instrumental delivery [90]. Another study of nulliparas who underwent operative vaginal delivery for their first birth observed 4.7 percent had a repeat operative vaginal delivery in their subsequent delivery [91].Neonatal complicationsShort-term — Postdelivery, the neonatal care provider should be informed that the birth was attempted or assisted by vacuum or forceps. Since a serious complication, such as a subgaleal hematoma, can occur within hours of delivery, it is important that the infant care providers be informed by either a reliable charting method or direct notification. A prospective study that follows 79 term infants after vacuum assisted delivery found all delivery related complaints were identified within the first 10 hours of life [92].The short-term complications to the fetus from operative vaginal delivery are usually caused by head compression and traction on the fetal intracranial structures, face, and scalp, but may be caused by suboptimal instrument placement [93]. The most serious complication is

intracranial hemorrhage. The relative frequency of intracranial hemorrhage according to type of delivery and labor status was best illustrated in a study of 583,340 singleton infants born to nulliparous women in California (table 5) [34]. Similar trends have been reported by others [94]. Other complications include: bruises, abrasions and lacerations, facial nerve palsy, cephalohematoma, retinal hemorrhage, subgaleal hemorrhage, and skull fracture [16,95].Virtually all of these complications can also occur in the course of a spontaneous vaginal delivery, but the incidence is lower than with instrumental delivery. The reported incidence of each complication varies widely and depends on a number of factors, such as the equipment used (metal, plastic, vacuum, forceps), fetal station, and the experience of the operator.●Vacuum-assisted deliveries – The incidence of serious neonatal

complications with vacuum extraction is approximately 5 percent [96]. Torsion and traction of the vacuum cup can cause fetal scalp abrasions and lacerations, separation of the scalp from underlying structures leading to cephalohematoma, subgaleal hematoma (26 to 45 per 1000 vacuum deliveries [4]), intracranial hemorrhage, hyperbilirubinemia, and retinal hemorrhage (figure 3) [34,52,97]. In general, the incidence of retinal hemorrhage is higher for vacuum-assisted than for spontaneous vaginal or cesarean deliveries (75, 33, and 7 percent, respectively) [98]. These hemorrhages typically resolve without sequelae within four weeks of birth. Cephalohematoma, in particular, is more common after vacuum-assisted extraction than forceps delivery (approximately 15 versus 2 percent) (table 6) [60,61,68]. A study of 913 term newborns who were successfully delivered using a vacuum device, and who had a skull x-ray and head ultrasound, reported skull fracture in 46 (5 percent) [99]. All of the fractures were linear (nondepressed) and no infant was symptomatic.

Death from intracranial hemorrhage has been reported. The Food and Drug Administration (FDA) issued an advisory (May 21, 1998) regarding the possibility of two major life-threatening complications following use of vacuum assisted devices: (1) subgaleal hematoma (ie, collection of blood between the aponeurosis covering the scalp and the periosteum; blood can extend across suture lines and beneath the scalp and into the neck) and (2) intracranial hemorrhage (subdural, subarachnoid, intraventricular, and/or intraparenchymal hemorrhage) [100]. The FDA also recommended these devices be used only when a specific obstetric indication is present and when five criteria could be met (table 7).

Shoulder dystocia also appears to be more common with vacuum-

assisted than forceps deliveries [61,101]. This is likely the reason that vacuum-assisted deliveries are at higher risk of brachial plexus injury than forceps-assisted deliveries or cesarean delivery [94].

●Forceps-assisted deliveries – Short-term complications resulting from

forceps deliveries include skin markings and lacerations, external ocular trauma, intracranial hemorrhage, subgaleal hematomas, hyperbilirubinemia, retinal hemorrhage, lipoid necrosis, nerve injury, skull fractures, and death [20,34,96,102]. Facial palsies (table 6) [94,102] and depressed skull fractures [102], in particular, are more common with use of forceps than vacuum devices; both complications can also occur after a non-instrumental delivery.

Long-term — Acute fetal injuries with potential long-term sequelae include intracranial hemorrhage (subdural, subarachnoid, intraventricular and/or intraparenchymal hemorrhage) [103] and neuromuscular injury; however, these sequelae are rare.Developmental outcome appears to be equivalent for both forceps and vacuum assisted births. In one trial, 313 maternal-infant pairs were randomly assigned to delivery by forceps or vacuum extraction and followed for five years [87]. There was no difference in child development between the groups. Another randomized trial of 300 women delivered by forceps or vacuum evaluated the infants at nine months of age and found no differences in infant testing results, such as hearing or vision [104]. Both of these trials lacked a comparison to infants delivered spontaneously or by cesarean delivery. A third trial compared neurodevelopmental outcome at age 5 for children born by successful instrumental vaginal delivery, failed instrumental delivery, and cesarean delivery in the second stage of labor [105]. Neurodevelopmental morbidity was low with no significant differences among the three groups, but the study was underpowered.One of the few follow-up evaluations comparing outcome at school age after operative or spontaneous delivery among 3413 five year-olds found no differences in cognitive testing [106]. This series included 1192 forceps deliveries, of which 114 were midforceps. Another study compared the neurological outcome of 295 10-year-old children delivered by vacuum extraction with that of 302 children delivered spontaneously in the same hospital by the same doctors and matched for maternal age, gestational age, and birthweight [107]. Both groups had similar results for tests of fine and gross motor control, perceptual integration, behavioral maturity, scholastic performance, speech ability, and self-care. In addition, a national cohort study of 126,032 sixteen year olds born as nonanomalous vertex singletons ≥34 weeks of gestation to Swedish-born parents noted that those delivered by vacuum extraction had slightly lower mean mathematics test scores

than children born vaginally without instruments after adjustment for major confounders, but similar scores to those born by intrapartum cesarean delivery [108].Lastly, a cohort study of almost 25,000 births did not find any association between forceps delivery and adult epilepsy [109].USE OF VACCUM OR FORCEPS AT CESAREAN DELIVERY — (See "Management of deeply engaged and floating fetal presentations at cesarean delivery".)SUMMARY AND RECOMMENDATIONS●For each patient, the risks and benefits of operative vaginal delivery need to be balanced against those for cesarean delivery and less invasive interventions. Situations where operative vaginal delivery may be preferable to cesarean delivery or less invasive interventions include prolonged second stage of labor despite intervention with less invasive measures, nonreassuring fetal status where expeditious delivery is desirable, and maternal cardiac or neurological diseases where pushing (Valsalva) needs to be avoided. Nonmedically indicated shortening of the second stage is not an indication for operative vaginal delivery. (See 'Indications' above.)

●Before resorting to an operative vaginal delivery, the clinician should ensure that prerequisites are met (eg, head is engaged, membranes ruptured, presentation and position known, anesthesia is satisfactory, the fetus is of appropriate gestational age and size, maternal bladder is empty) and there are no contraindications (eg, malpresentation, fetal bleeding diathesis). (See 'Prerequisites' above.)

●Forceps deliveries are classified as outlet, low, or mid, depending on the fetal station and degree of head rotation. (See 'Classification of forceps deliveries' above.)

●There is inadequate evidence upon which to base a recommendation for use of either vacuum or forceps for all circumstances when operative vaginal delivery is attempted. In general, vacuum devices are easier to apply, place less force on the fetal head, require less maternal anesthesia, and do not increase the diameter of the fetal head compared to forceps. By comparison, the advantages of forceps are that they are unlikely to detach from the head, can be sized to a premature cranium, may be used for a rotation, and do not aggravate bleeding from scalp lacerations. (See 'Choice of instrument' above.)

Vacuum should not be applied to fetuses less than 34 weeks of

gestation.

For women who are to undergo an operative vaginal delivery at greater than 34 weeks and have a high likelihood of success (eg, outlet procedure), we suggest use of vacuum over forceps because of lower maternal morbidity (Grade 2C). When success is uncertain, primary use of forceps may reduce the morbidity associated with combined sequential instrumental delivery. (See 'Choice of instrument' above and 'Sequential attempts' above.)

●Vacuum assisted deliveries are associated with an increased risk of neonatal cephalohematomata and retinal hemorrhage compared with forceps or spontaneous deliveries. These complications generally resolve without sequelae. Forceps assisted deliveries cause significantly more acute maternal injury and fetal facial nerve injury than vacuum assisted operative deliveries or spontaneous deliveries. (See 'Risks' above.)

●The decision to proceed with operative vaginal delivery is ongoing and decided moment by moment based on assessment of the success of the various steps in the procedure. Operative vaginal delivery should be abandoned if it is difficult to apply the instrument, descent does not easily proceed with traction, or the baby has not been delivered within a reasonable time (eg, 15 to 20 minutes) or after three pulls with no progress. (See 'When to abandon the procedure' above.)

●It is unclear whether a failed attempt at operative vaginal delivery followed by cesarean delivery is associated with a poorer neonatal outcome than cesarean delivery without the attempt. (See 'Outcome after failed procedures' above.)

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109 Murphy DJ, Libby G, Chien P, et al. Cohort study of forceps delivery and the risk of epilepsy in adulthood. Am J Obstet Gynecol 2004; 191:392.

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