Forceps Delivery 

Updated: Jun 15, 2020
Author: Michael G Ross, MD, MPH; Chief Editor: Christine Isaacs, MD 

Overview

Practice Essentials

Forceps are instruments designed to aid in the delivery of the fetus by applying traction to the fetal head. Many different types of forceps have been described and developed. Generally, forceps consist of 2 mirror image metal instruments that are maneuvered to cradle the fetal head and are articulated, after which traction is applied to effect delivery.

Forceps have 4 major components, as follows:

  • Blades: The blades grasp the fetus. Each blade has a curve to fit around the fetal head. The blades are oval or elliptical and can be fenestrated (with a hole in the middle) or solid. Many blades are also curved in a plane 90° from the cephalic curve to fit the maternal pelvis (pelvic curve).

  • Shanks: The shanks connect the blades to the handles and provide the length of the device. They are either parallel or crossing.

  • Lock: The lock is the articulation between the shanks. Many different types have been designed.

  • Handles: The handles are where the operator holds the device and applies traction to the fetal head.

See the image below.

An illustration of Simpson forceps. An illustration of Simpson forceps.

History of the Procedure

The history of obstetrical forceps is long and, often, colorful. Sanskrit writings from approximately 1500 BC contain evidence of single and paired instruments; Egyptian, Greek, Roman, and Persian writings and pictures refer to forceps that were originally used for extraction following fetal demise to save the mother’s life.

The credit for the invention of the precursor of the modern forceps to be used on live infants goes to Peter Chamberlen of England (circa 1600). Modifications have led to more than 700 different types and shapes of forceps. In 1745, William Smellie described the accurate application to the occiput, rather than the previously performed pelvic application, regardless of the position of the head. In 1845, Sir James Simpson developed a forceps that was designed to appropriately fit both cephalic curvatures and pelvic curvatures. In 1920, Joseph DeLee further modified that instrument and advocated the prophylactic forceps delivery. In an era in which many women labored and delivered under heavy sedation, forceps deliveries became common.

In current obstetrical practice, the use of forceps has become much less common. Clinical studies performed before the 1970s suggested that the risk of fetal morbidity and mortality was higher when the second stage of labor exceeded 2 hours.[1] With contemporary obstetrical management, morbidity rates no longer increase with longer labors if fetal surveillance is reassuring. Thus, the length of the second stage of labor alone is no longer an absolute indication for operative termination of labor, although it remains an indication in the American College of Obstetricians and Gynecologists (ACOG) publications.[2]

Other factors were also at work to decrease the use of forceps deliveries. In particular, the availability of blood products and greater choices in antibiotics helped make cesarean delivery a safe alternative to operative vaginal deliveries. In the 1980s, information became available suggesting that some forceps deliveries (midforceps deliveries) may be associated with an increased risk of fetal morbidity, though this issue remains controversial. These factors combined to greatly reduce the appeal of forceps delivery. Currently, many obstetrical training programs in North America struggle to teach forceps delivery. Problems include the lack of adequate personnel comfortable with teaching forceps-assisted vaginal deliveries, changes in consumer attitudes, and the demand for natural delivery. In addition, many practitioners fear litigation if a forceps-assisted delivery results in a poor outcome.

Epidemiology

United States data

The frequency of operative vaginal deliveries is now estimated to be less than 5% of all vaginal deliveries. Most of these are vacuum deliveries with forceps deliveries comprising less than 1% of total deliveries. According to Bofill et al, trained fellows of the American College of Obstetricians and Gynecologists (ACOG) were more likely to be taught vacuum extraction, and they use vacuum extraction as their instrument of choice for operative vaginal deliveries.[3]

When forceps deliveries are performed, the Simpson forceps (see image below) is the instrument most commonly used for outlet- and low-forceps deliveries. Other types of forceps are also available; one specialized type is the Piper forceps, which is used in the delivery of the after-coming head in breech vaginal deliveries. It is designed to decrease traction on the fetal neck during breech delivery. Multiple other types of forceps have been designed to rotate the fetal head or for unusual maternal pelvic or fetal head shapes. For detailed information on other forceps procedures, the reader is directed to the book Dennen's Forceps Deliveries.[1]

Forceps have 4 major components, as follows (see the image below)[2] :

  • Blades - The blades grasp the fetal head, and each one is curved to fit around the head; they can be oval or elliptical and can be fenestrated (with a hole in the middle) or solid; many blades are also curved in a plane 90° from the cephalic curve to fit the maternal pelvis (pelvic curve).
  • Shanks - The shanks connect the blades to the handles and provide the length of the device; they are either parallel or crossing.
  • Lock - The lock is the articulation between the shanks; many different types have been designed.
  • Handles - The handles allow the operator to hold the device and to apply traction to the fetal head.
Simpson forceps, labeled to show parts of the inst Simpson forceps, labeled to show parts of the instrument. This version has a fenestrated blade.

 

Presentation

Forceps delivery is classified according to the level and position of the head in the birth canal at the time the forceps are applied. In 1965, the ACOG issued a classification of low/outlet forceps, mid forceps, and high forceps. The low/outlet forceps categories were strictly defined and applied when the fetal scalp was visible or when the scalp had reached the pelvic floor, and only when the sagittal suture was in the anteroposterior diameter of the pelvis. In contrast, the category of mid forceps was very broad. It included many positions of the fetal head, and stations from engagement at zero station to the perineum.

When the safety of midforceps deliveries came into question in the 1980s, the ACOG redefined the classification of forceps deliveries to better define which procedures posed a significant fetal risk.[2]  The revised classification uses the level of the leading bony point of the fetal head, in centimeters, measured from the level of the maternal ischial spines, to define station (-5 to 5 cm).

ACOG criteria for types of forceps deliveries

The ACOG classification of types of forceps delivery is as follows:

  • Outlet forceps: (1) The scalp is visible at the introitus, without separating the labia. The fetal skull has reached the pelvic floor. (2) The sagittal suture is in anteroposterior diameter, right or left occiput anterior or posterior position (ie, the fetal head is at or on the perineum and rotation does not exceed 45º).

  • Low forceps: The leading point of the fetal skull is at a station greater than or equal to +2 cm and is not on the pelvic floor. Low forceps deliveries without rotation are performed with a rotation of less than 45º; the procedure is described as beginning with rotation if the rotation is of more than 45º.

  • Mid forceps: The station is above +2 cm, but the head is engaged. Attempted vaginal deliveries from this station are rarely attempted and are associated with an increased rate of morbidity compared with Cesarean delivery in the second stage of labor.[4]

  • High forceps: This is not included in the classification. Previous systems classified high-forceps deliveries as procedures performed when the head is not engaged. High-forceps deliveries are not recommended.

Obstetrical pelvic evaluation (clinical pelvimetry)

The important points of interest are emphasized as follows:

  • The type (ie, gynecoid, android, anthropoid, platypoid) and adequacy of the pelvis for delivery of the fetus can be estimated clinically, with an assessment of the bony pelvis. It should be emphasized that adequate pelvic size depends not only on the pelvis but also on the size and presentation of the fetus.

  • The distance between the bottom of the symphysis pubis and the sacral promontory is measured by digital examination and is defined as the diagonal conjugate. The obstetrical conjugate, the distance from the mid symphysis to the sacral promontory, is estimated by subtracting 1.5-2 cm from the diagonal conjugate. This is used to assess the adequacy of the pelvic inlet in the anterior-posterior dimension.

  • Unfortunately, no clinical means are available to measure the mid pelvis; these measurements can only be obtained with detailed imaging studies, which themselves have not demonstrated clinical efficacy. During the examination, one may have a high index of suspicion of a contracted mid pelvis if the sacrospinous ligament is short, the sidewalls are convergent, and the concavity of the sacrum is very shallow.

  • The pelvic outlet is also important, with assessments potentially including the distance between the ischial tuberosities and the pubic angle.

  • For the purpose of assessing a patient for forceps application, one should confirm the pelvic adequacy at the time of delivery.

Indications

Indications for operative vaginal deliveries are identical for forceps and vacuum extractors. No indication for operative vaginal delivery is absolute.

The following indications apply when no contraindications exist:

  • Prolonged second stage: This includes nulliparous woman with failure to deliver after 2 hours without, and 3 hours with, conduction anesthesia. It also includes multiparous woman with failure to deliver after 1 hour without, and 2 hours with, conduction anesthesia.

  • Suspicion of immediate or potential fetal compromise in the second stage of labor.

  • Shortening of the second stage for maternal benefits: Maternal indications include, but are not limited to, exhaustion, bleeding, cardiac or pulmonary disease, and history of spontaneous pneumothorax.

  • In skilled hands, fetal malpositions, including the after-coming head in breech vaginal delivery, can be indications for forceps delivery.

Prerequisites for forceps delivery include the following:

  • The head must be engaged.

  • The cervix must be fully dilated and retracted.

  • The position of the head must be known.

  • Clinical assessment of pelvic capacity should be performed. No disproportion should be suspected between the size of the head and the size of the pelvic inlet and mid pelvis.

  • The membranes must be ruptured.

  • The patient must have adequate analgesia.

  • Adequate facilities and supportive elements should be available.

  • The operator should be competent in the use of the instruments and the recognition and management of potential complications. The operator should also know when to stop so as not to force the issue.

Relevant Anatomy

Planes and diameters of the pelvis

For obstetrical purposes, the pelvis is described as having 3 imaginary planes: plane of the inlet, plane of the mid pelvis, and plane of the pelvic outlet. See the images below.

The anterior view of a pelvis. The anterior view of a pelvis.
The inferior view of a pelvis. The inferior view of a pelvis.
The sagittal section of a pelvis. The sagittal section of a pelvis.

For the plane of the inlet, the following 4 diameters have been described.

  • Anteroposterior diameter: This is the distance between the sacral promontory and the symphysis pubis; it is designated the obstetrical conjugate. This conjugate normally measures approximately 10 cm or more, but it may be shortened considerably in an abnormal pelvis.

  • Transverse diameter: This is the greatest distance between the linea terminalis on either side of the pelvis. This imaginary line usually intersects the obstetrical conjugate at a point approximately 4 cm in front of the promontory.

  • Two oblique diameters: Each of these diameters extends from one of the sacroiliac joints to the iliopectineal eminence on the opposite side of the pelvis. These diameters normally average less than 13 cm each.

The plane of the mid pelvis is the plane of the smallest dimensions. This plane is extremely important following engagement of the head in obstructed labor. The interspinous diameter (usually >10 cm) is the smallest diameter of the pelvis.

The plane of the pelvic outlet consists of 2 triangular areas created from the connection of an imaginary line between the 2 ischial tuberosities. The apex of the posterior triangle is at the tip of the sacrum, and the apex of the anterior triangle is under the pubic arch. The following 3 diameters of the outlet are of importance:

  • Anteroposterior diameter: This is normally 9.5-11.5 cm and extends from the lower margin of the symphysis pubis to the tip of the sacrum.

  • Transverse diameter: This is commonly 11 cm and is the distance between the inner edges of the ischial tuberosities.

  • Posterior sagittal diameter: This usually exceeds 7 cm and extends from the tip of the sacrum to a right-angle intersection with the line between the ischial tuberosities.

Relevant terminology

Relevant terms are listed below:

  • Engagement: This occurs when the biparietal diameter in a vertex position passes through the plane of the pelvic inlet. Thus, the widest part of the fetal head has entered the true pelvis. Engagement is generally achieved when the leading bony point of the skull has reached the level of the ischial spines (0 station).

  • Presentation: This is the description of the presenting fetal part occupying the maternal pelvic inlet (eg, cephalic, breech, shoulder).

  • Lie: This term describes the relationship between the fetal longitudinal axis and the maternal longitudinal axis (eg, longitudinal, oblique, transverse).

  • Position: This term describes the relationship of the fetal presenting part to the maternal pelvis.

  • Asynclitism: This term describes the condition when the fetal head is turned in the maternal pelvis such that one parietal bone is closer to the pelvic outlet.

Determination of position

For cephalic presentations, the reference point is the occiput, whereas in breech presentations, the reference point is the sacrum. Position is always described in reference to the maternal right or left side of the pelvis.

Determination of the position is crucial in forceps application and traction. The fontanels and sutures are used to determine the position. The finding that the fontanels are not easily palpable is not uncommon; this may occur because of distortion, molding, or caput formation.

The position can be determined by finding the location of the sagittal suture and its relationship to the posterior portion of the ear, if palpable. If the sagittal suture is in a U formation, an anterior asynclitism presentation should be suspected (ie, presentation of the anterior parietal bone of the fetal head). Conversely, if the sagittal suture is in the shape of an inverted U, this may indicate posterior asynclitism (ie, posterior parietal bone) presentation.

Most fetuses can be delivered by forceps if they are in or can be maneuvered (manually or by forceps) into an occiput anterior or posterior position.

Correct determination of the position may be the most important step prior to forceps application.

Contraindications

The following are contraindications to forceps-assisted vaginal deliveries:

  • Any contraindication to vaginal delivery (see Normal Labor and Delivery)

  • Refusal of the patient to verbally consent to the procedure

  • Cervix not fully dilated or retracted

  • Inability to determine the presentation and fetal head position

  • Inadequate pelvic size

  • Confirmed cephalopelvic disproportion

  • Unsuccessful trial of vacuum extraction (relative contraindication)

  • Absence of adequate anesthesia/analgesia

  • Inadequate facilities and support staff

  • Inexperienced operator

 

Workup

Diagnostic Studies

The decision for forceps delivery is often made in the second stage of labor when transport of the mother to other units is not practical and imaging studies may not be available quickly enough. Although x-ray pelvimetry and pelvic magnetic resonance imaging and computed tomography have been shown to help in defining the pelvic anatomy, their usefulness has not been demonstrated in predicting successful vaginal delivery.

Ultrasonographic evaluation of the fetus may be of value in gathering information prior to a forceps delivery, although it is not required prior to forceps-assisted delivery. Ultrasonography can be used to estimate fetal size as well as to assess the position of the fetal head.

No specific laboratory test is used prior to forceps delivery.

In general, evaluation of the patient for forceps delivery is purely clinical.

 

Treatment

Preoperative Details

Reviewing the indications for operative vaginal delivery and confirming the presence of all the prerequisites for forceps application are crucial steps. In particular, the presentation, position, and station of the presenting part must be reconfirmed just before the procedure.

Maternal verbal consent should be obtained prior to the forceps attempt, although the procedure may need to be performed emergently or after the mother has been medicated. If a planned forceps delivery is to be performed (ie, for maternal medical indications), counseling and consent may be completed prior to the onset of active labor.

The type of forceps to be used depends on the specific indications and conditions. The most commonly used forceps are Simpson forceps, which are used to deliver a molded fetal head, as is commonly seen in nulliparous women. Also commonly used are Tucker-McLane forceps, which have a more rounded cephalic curve, more suitable for the unmolded fetal head commonly seen in multiparous women. Kjelland forceps are made for rotation of the fetal head and lack a pelvic curve. Many instruments are available with the Luikart modification (pseudo-fenestrated).

An illustration of Simpson forceps. An illustration of Simpson forceps.
An illustration of Kjelland forceps with a Luikart An illustration of Kjelland forceps with a Luikart modification.
An illustration of Simpson forceps with a Luikart An illustration of Simpson forceps with a Luikart modification.

The decision of what type of anesthesia is used should be made before initiating the delivery. An adequate level of anesthesia should be in effect before forceps application. Although published reports suggest that using only local infiltration anesthesia to the perineal body is enough, the authors believe that this type of anesthesia may be less than adequate. Very few women can tolerate forceps application without, at a minimum, pudendal block anesthesia. Attempts to "force the issue" with inadequate anesthesia may be intolerable to the mother. Pudendal block anesthesia may be augmented with intravenous sedation.

Adequate anesthesia is also achievable with regional or general anesthesia. Regional anesthesia is often used; general anesthesia is usually reserved for very unusual emergency situations. With the former, the patient should be prepared and draped after the anesthesia has been delivered via epidural or spinal injection. With the latter, the surgeon should be ready, with the patient properly draped, before administration of general anesthesia.

The bladder should be emptied in preparation for forceps operative deliveries, regardless of the type of anesthesia used.

Some authors have advocated the routine use of prophylactic antibiotics prior to operative vaginal delivery. This recommendation is based on a study that found a decreased incidence of perineal wound infections in treated patients.[5]  The patients in the study had a high incidence of mediolateral episiotomies, which are not commonly used in the United States. The American College of Obstetricians and Gynecologists (ACOG) recommends that prophylactic antibiotics be considered for patients with a planned episiotomy associated with an operative vaginal delivery.[2]

Intraoperative Details

Application of the forceps

The most crucial point of forceps delivery is knowledge of the presentation position of the fetus. The term pelvic application is used when the left blade is applied on the left side of the pelvis and the right blade is applied on the right side of the pelvis, regardless of the fetal position. Pelvic application is never to be used as a substitute for knowledge of the fetal position; inappropriate pelvic application may cause maternal harm.

Once again, emphasizing that forceps delivery is skill- and training-dependent is important. The operator must have a clear understanding of his or her own capabilities, as well as the safe limits of the procedure, and must not exceed either of these.

Application technique

After ensuring proper anesthesia and an empty bladder, the fetal position is again checked prior to introducing the instrument. The presence of the sagittal suture in the anteroposterior diameter of the pelvic outlet is confirmed, and the left forceps blade is introduced into the posterior half of the left side of the pelvis and is guided to the appropriate position along the fetal head.

The left handle is held in the left hand (Simpson The left handle is held in the left hand (Simpson forceps).
The left blade is introduced into the left side of The left blade is introduced into the left side of the pelvis.

The placement and guidance are performed by the operator's right hand in the maternal pelvis. The left blade is left in place to stand freely or is held in place without pressure by an assistant. The right blade is introduced into the right side of the pelvis in the same fashion.

The left blade is in place and the right blade is The left blade is in place and the right blade is introduced by the right hand.

At all times, attention should be given to avoiding the use of excessive force. At the beginning of the application, the blades should be held like a pencil, almost in a vertical position; as the blades are introduced into the vagina, they are brought to a horizontal position. Avoiding levering or forcing the blade with the nonvaginal hand is critical. The fingers in the vagina should only guide the blades and should not apply pressure on or displace the fetal head. The application of the forceps is generally not performed during a uterine contraction; however, properly placed blades may be left in place if a contraction ensues during placement.

After proper placement of the left blade, it should lie almost parallel to the floor. With insertion of the right blade, the forceps should lock without pressure.

When the occiput is not directly anterior, applying the blade to the lower half of the fetal head first to avoid turning the head to a transverse position with the first blade application is desirable. At times, this requires placement of the right blade first.

Appropriateness of application

In a proper cephalic application, the long axis of the blades corresponds to the occipitomental diameter, with the ends of the blades lying over the posterior cheeks (see image below); the blades should lie symmetrically on both sides of the head. The sagittal suture of the fetal head will be in the middle, and the blades will be equidistant from the sagittal and occipital sutures. At no time should any part of the forceps cover any midline structure. The forceps should lock easily with minimal force and stand parallel to the plane of the floor. The appropriateness of application should be confirmed before applying traction.

The forceps have been locked. The inset shows a le The forceps have been locked. The inset shows a left occipitoanterior fetal position.

Traction with forceps and episiotomy

During an indicated forceps delivery, traction is applied during contractions. The instrument may be used to maintain the station of the fetal head between contractions. In an emergency, applying continuous traction may be necessary until the fetal head delivers.

After confirming proper forceps application, traction starts parallel to the plane of horizon and is then elevated to an almost vertical position as the fetal head extends, and the forceps are removed as the fetal head delivers through the perineum.

An illustration of a forceps delivery technique. An illustration of a forceps delivery technique.
An illustration of horizontal traction with the op An illustration of horizontal traction with the operator seated.
An illustration of upward traction. An illustration of upward traction.

The amount of traction should be the least necessary to accomplish safe fetal head descent. In biomechanical studies, safe limits of 45 pounds in primiparas and 30 pounds in multiparas have been suggested, though there is no consensus on the amount of traction force.[6] The angle of traction is as important as the force applied in effecting delivery. Knowing when to stop and abandon the procedure is a matter of experience; however, assuming that everything has been done according to proper protocols, if no progress is observable in 3 traction attempts, abdominal delivery should be considered.

Episiotomy may be performed when the perineum is distended by the fetal head. There is some evidence that episiotomy use may protect the rectal sphincter,[7]  although in the United States routine episiotomy is not favored.[2]

A median or mediolateral episiotomy may be perform A median or mediolateral episiotomy may be performed at this point. A left mediolateral episiotomy is shown here.

With forceps delivery, less opportunity exists for the maternal tissues to stretch, and episiotomy may be performed to allow a more rapid delivery. The utility of episiotomy in preventing short- and long-term maternal injury is controversial.[8]

As the fetal head crowns, the forcep blades are disarticulated and removed (see the image below), and the remainder of the delivery proceeds as for a spontaneous vaginal delivery.

An illustration of disarticulation of the branches An illustration of disarticulation of the branches of the forceps; beginning modified Ritgen maneuver.

Postoperative Details

After a forceps delivery, thorough examination of both the mother and the newborn is advisable. Maternal cervical, vaginal, and perineal lacerations must be excluded. In addition, maternal vulvar edema may be significant. Most operators institute measures such as perineal ice to ameliorate this. Pain medication is also advisable. These patients are at increased risk for hemorrhage, and a postoperative hemogram should be obtained and the condition corrected as needed.

Before discharge, pelvic and rectal examinations may help confirm the integrity of pelvic organs and may exclude such entities as pelvic hematoma, rectal tears, and misplaced sutures. Diagnostic studies should be obtained as needed. Antibiotics can be considered for patients who experience third- or fourth-degree perineal lacerations.[2]

The newborn must be examined for lacerations, bruising, and other injuries. The pediatric service should be made aware of the circumstances of delivery.

Follow-up

In the absence of specific forceps-related complications, a follow-up postpartum examination within 4-6 weeks, according to the usual protocol for postpartum care, with a thorough pelvic examination, is usually sufficient.

Complications

Either mother or infant may experience complications related to a forceps-assisted delivery. Research into forceps delivery complications is hampered by a number of potential biases: Maternal and fetal complications have been reported to vary depending on skill and judgment of the operator; however, this is difficult or impossible to quantify. In addition, there is the problem of the comparison group; complication rates are often quoted in comparison to normal deliveries, but forceps deliveries are often performed in patients with complicated pregnancies or abnormal labors.

Early maternal complications include lacerations and bleeding. Even with appropriate use, forceps deliveries may be associated with an increased risk of perineal tears,[9] possibly due to the more rapid stretching of the tissues with delivery of the fetal head. One center was able to reduce the incidence of serious (third- or fourth-degree) perineal tears at operative vaginal delivery by a series of interventions.[10] The incidence of serious tears was reduced from 41% to 26% using a policy of increased use of vacuum delivery (from 16% to 29% of instrumental deliveries), use of mediolateral episiotomy, and changes in forceps technique. In addition to overt perineal tears, forceps deliveries have been associated with an increased incidence of tears of the levator ani, and this can be demonstrated by pelvic ultrasound.[11, 12]

Late maternal complications are largely related to damage to the pelvic support tissues; this damage may occur in the form of anatomic deficits, such as fistulae, or in defects in rectal sphincter function, due to both tears and nerve damage at the time of delivery. The finding of an increased risk of fecal incontinence after forceps delivery has been confirmed by numerous studies.[13] In one study, the rate of fecal incontinence was increased to 23% after an instrumental delivery (80% of these were forceps deliveries).[14]

As described above, the degree of increase is dependent on the comparison group, as the risk of incontinence after a normal spontaneous delivery was only 1.4%, whereas the use of an epidural anesthetic followed by a vaginal delivery was associated with a 6% risk. The same authors found that instrumental deliveries were associated with an increased risk of both damage to the rectal sphincter and with reduced pudendal nerve conduction velocity; not all patients with abnormal testing had symptoms. Whereas some authors have suggested that mediolateral episiotomy may reduce the risk of anal sphincter injury,[15]  others have demonstrated no benefit of routine episiotomy.[16]

Although urinary incontinence is common in women during the immediate postpartum period (4 months), forceps delivery is associated with an increased incidence.[17] The long-term consequence of forceps on urinary incontinence remains unknown. Despite the concern for potential forceps complications, forceps have a relatively low risk of adverse outcome when used by experienced operators. Even Kjelland rotational deliveries, which are now uncommonly performed, are successful in up to 95% of appropriately chosen cases with rates of maternal complications equivalent to vacuum delivery.[18]

Forceps deliveries are associated with an increased incidence of forceps marks and bruising of the fetal face,[9] occurring in 17% of infants delivered by forceps.[19] Most of these injuries are trivial, but forceps delivery may also be associated with fetal injuries leading to long-term disability; transient or permanent facial nerve injuries have been reported in up to 0.5% of forceps-assisted deliveries. The facial palsy is most often mild and resolves without therapy.[20]

More concerning, the incidence of intracranial bleeding is increased with forceps delivery, with odds ratios between 2 and 4 being reported. Skull fractures have been reported with forceps deliveries; one report documented a rate of 1 per 4500.[21] Shoulder dystocia has been reported in association with forceps delivery; however, many studies have not found this association.[22] In addition, cerebral palsy and subtly lower IQ (2.5 points) have been described in infants delivered by forceps; however, it is not apparent whether the association of shoulder dystocia and fetal central nervous system (CNS) injury is with the forceps delivery per se, or with prolonged and difficult labors.

Towner et al examined the risk of intracranial hemorrhage in 583,340 live-born singleton infants born to nulliparous women between 1992 and 1994 and weighing between 2500 g and 4000 g. One third of the infants were delivered by operative techniques. Although the rate of intracranial hemorrhage was higher among infants delivered by vacuum extraction or forceps, as compared to those delivered spontaneously, the rate was similar to that of cesarean delivery during labor. These results suggest that the common risk factor for intracranial hemorrhage is abnormal labor rather than operative delivery per se.[23]

Despite the potential complications, when used appropriately forceps deliveries are as safe as vacuum deliveries to the neonate.[24] A study found that the rate of overall neurologic injury (seizures, intraventricular hemorrhage, and subdural hematoma) was lower with forceps deliveries than with either vacuum delivery or cesarean delivery in labor.[25]

Finally, the risk of maternal and fetal complications is increased if a forceps delivery is attempted after a failed vacuum extraction. The risk of maternal vaginal laceration and hemorrhage was increased in one study, with the relative risk of a fourth-degree tear being 11 when compared with normal delivery.[26] One study found an odds ratio of 7 for CNS bleeding, and an odds ratio of 4 for neonatal seizures in infants delivered via a combined procedure,[23]  whereas another found an increase in the incidence of brachial plexus injuries and facial nerve injuries.[26]

At least some of this excess risk is related to the risk associated with a failed instrumental delivery, as the risk for neonatal morbidity has been reported to be the same for patients after a failed vacuum extraction regardless of whether the next option was forceps or cesarean delivery.[27] If one elects to use forceps following a trial of vacuum, pelvic capacity and the risk/benefit should be carefully assessed.

Outcome and Prognosis

The use of forceps has been associated with long-term maternal and fetal morbidity. The remaining question is whether the association implies causality. In one study, the use of forceps electively was not associated with an increase in maternal or fetal morbidity in patients who were randomly assigned to delivery spontaneously or by forceps.[28] Unfortunately, this study contained only 50 patients and thus was underpowered to find the kind of serious morbidities described. This study also does not address the more frequent case, in which forceps delivery is used urgently as an alternative to cesarean delivery.

Future and Controversies

The future of forceps deliveries is in doubt. Information developed in the 1980s suggests that fetal outcome may be poor after at least some forceps deliveries. Other data suggest that long-term compromise of the maternal rectal sphincter is a common sequela of forceps delivery. In view of the discussions of the merits of cesarean delivery on demand for preservation of maternal pelvic musculature, the place of forceps deliveries in obstetrical practices has been questioned.

Given the current state of knowledge, it is the position of the American College of Obstetricians and Gynecologists that forceps delivery remains an acceptable and safe option for delivery.[2]  However, recent birth certificate data from the United States report a total forceps rate of 0.7%.[29] These data suggest that experience and skill with forceps delivery have become difficult to obtain, leading to concerns about the survival of the procedure.