Epidural and instrumental delivery (forceps and vacuum)

Epidural and instrumental delivery (forceps and vacuum)

Instrumental delivery – forceps and vacuum – are associated with high incidence of perineal tears and neonatal injury. While epidural increases the use of instrumental delivery, it does not result in the increased rate of its complications.

The latest Cochrane review that compared the effects and complications of epidural versus non-epidural pain relief in labor found that epidurals increase the risk of forceps or vacuum – jointly called instrumental vaginal delivery – to assist the delivery of the baby. On average, thirty eight percent more women with epidurals needed these procedures compared with those who had other treatments for their pain. What is the significance of these findings?

What is instrumental delivery?

Instrumental delivery implies the use of special devices to facilitate delivery. These devices may roughly be separated into two large groups: forceps and vacuum. Forceps exist in various makes and are introduced into the vagina of a laboring woman and applied onto the head of the neonate. By means of quite complicated maneuvers the neonate is pulled out by the person applying the forceps. Vacuum is more recent invention. A device in the shape of a cup is also introduced into the vagina, but only so that the cup fits on top of the baby’s head. The air from the cup is sucked out by the special suction tubing, and the cup sticks to the head, allowing to pull the baby out.

Brief history

The history of obstetrical forceps is long and, often, colorful. The earliest evidence of forceps use is found in Sanskrit documents from approximately 1500 BC, and many cultures – Egyptian, Greek, Roman, and Persian writings and pictures mention use of these instruments. In those times forceps were used to extract a dead baby in order to save the mother’s life.

First modern variant of forceps that was used for delivering live infants was developed by Peter Chamberlain of England around circa 1600. This first model underwent numerous modifications, and in 1745 the methodology of correct application of forceps was described for the first time by William Smellie. In 1845 famous obstetrician Sir James Simpson developed a forceps that was designed to better fit the head of the baby, and in 1920 Joseph DeLee further modified that instrument and advocated prophylactic forceps delivery. During that time heavy sedation was commonly used during labor for pain relief, and the use of forceps quickly became popular.

In modern days the use of forceps is less common, and there has been a decline in their use in the last twenty years or so. It is estimated that forceps are used in about 4 and vacuum in 8.5 percent of all deliveries. The main reason for it is change in indications. For example, before 1970s it was believed that if the second stage of labor lasted for longer than two hours the risk of the baby developing complications or even dying was unacceptably high. As obstetric management gradually changed and became safer, the length of the second stage is no longer an absolute indication for the use of forceps.

Indications

In general terms, instrumental delivery is done when there is any condition threatening the mother or the baby that is likely to be relieved by delivery. For example, if the mother has cardiac condition which is being compromised by straining and pushing and is likely to cause problems, instrumental delivery may be performed in order to shorten the second stage of labor and get the woman out of danger. It is also done when there is potential danger to the baby, such as premature separation of the placenta or worsening of the fetal heart rate.

Prolonged second stage is a relative indication for instrumental delivery and is limited to primiparous women this stage lasts more than two hours without or three hours with epidural analgesia. In experienced hands forceps can also be used for improving the position of the baby during labor.

Advances in the techniques of vacuum extraction are another reason for the decrease in the use of forceps. Even though vacuum is somewhat less efficient, it has various benefits. It causes less injury to the mother and the baby, does not require as much pain relief as forceps and those women who had vacuum generally have less pain afterwards.

In order to perform instrumental delivery certain conditions must be present. The head of the baby must be engaged in the birth canal, the cervix fully dilated, the membranes should be ruptured, the position of the baby’s head must be known, there should not be any disproportion between the baby’s head and the pelvis, the patient must have adequate pain relief, it can only be performed in adequate facilities and, finally, the person doing it must be fully competent in the use of these instruments. Proper pain relief is absolute condition for performing instrumental delivery.

Contraindications

Contraindications to forceps delivery are logical extension of the indications listed above. Refusal of the patient is absolute contra-indication to instrumental delivery. It must not be attempted if the cervix is not fully dilated, if it is impossible to determine the exact position of the baby (presentation) and in the presence of confirmed disproportion between the size of the baby’s head and the pelvis. Other contra-indications include inadequate facilities and qualifications of medical personnel, lack of experience of the operator and, last but not least, if there is no adequate pain relief provided to the patient. Finally, failed vacuum extraction the use of forceps is a relative contra-indication of the use of forceps.

Complications of instrumental delivery

Complications of instrumental delivery, maternal or/and neonatal, are relatively common and may be serious. Maternal complications are divided into early, happening immediately during of after labor, and late, developing days or weeks after childbirth. Forceps can cause lacerations of the cervix, vagina or perineum and, in severe cases, bladder. If episiotomy has been performed, the forceps may increase its size and lead to the increased blood loss. In very rare instances the use of forceps may cause the rupture of the uterus, which is a serious and potentially lethal complication. Late complications are related to injury to the tissues of the pelvis that support the organs located there and include urinary incontinence (leaky bladder), fecal incontinence (inability to control bowel movement), injuries to the anal sphincter and the prolapse of pelvic organs.

Complications with the baby also vary from mild to very serious. Most common are bruises and cuts on the baby’s head. Simple bruises are instrument marks and heal quickly. Other kind of bruising is cephalohematomas, the collection of blood under the periosteum, the covering of the scull bones. It looks like squishy swelling with distinct borders that feels as if there were a tiny water-filled balloon under the scalp. Over the first few days of life cephalohematoma becomes more defined and then slowly disappears.

In more serious cases the facial nerve can be injured. Yet more serious complications include scull fractures, intracranial hemorrhage (bleeding into the head), cerebral palsy, mental retardation and behavioral problems.

The reported incidence of complications is considerable. One of the latest reviews that included 508 women, of whom 200 had forceps delivery and 308 had vacuum extraction, the most common complication of these modes of delivery are tears of varying degrees, and their incidence is high. Third and fourth degree tears, which are the most severe, happened in 44.4 percent in those with forceps delivery and 27.9 percent in those who delivered by vacuum extraction. Overall 6.2 percent of all deliveries needed instrumental assistance.

Among neonates the rate of complications was less dramatic and consisted of mostly bruises and hematomas of the head. In 36.5 percent of the babies delivered by forceps bruises caused by the instrument were present, in those assisted by forceps only 10.7 percent had them. Cephalohematomas were present in 12.5 percent of babies in forceps deliveries and in 20.5 percent of those helped by vacuum. As mentioned earlier, as the rule these injuries heal without consequences.

Epidurals and instrumental delivery: complicated relationships

About 90 percent of women who had to be assisted by forceps had epidural (and 80% who had vacuum). It is not stated what percentage of those patients who delivered normally had epidural, but it is likely that among those who had instrumental delivery is was higher.

The intuitive conclusion is that epidurals lead to instrumental delivery, which in turn leads to complications, therefore labor epidural leads to complications. However, the interaction between epidural, instrumental delivery and its complications is not straightforward.

In the review mentioned above two other neonatal complications was observed, so called caput succedaneum and molding. Caput succedaneum (often just called caput) simply means the swelling of the baby’s head. Unlike cephalohematoma, this swelling is rather puffy and is caused not by trauma from forceps, but by the pressure on the baby’s head by the cervix or the vaginal wall during labor. Molding occurs when the head of a newborn is cone shaped and is often associated with the caput. Molding is typically the result of either prolonged or difficult labor, during which baby’s head is compressed and shaped this way. The significance of these phenomena is that they signify complicated or prolonged labor, and that probably was the main reason why instrumental delivery was performed. About 90% percent in the forceps and 80 percent in vacuum group also had episiotomies, another testimony of problematic labors.

The authors of the review also commented that it is likely that instrumental delivery is more likely to be attempted in those women who have working epidurals. Epidural eliminates pain, and the decision to resort to instrumental delivery is easier in patients with good pain relief provided by epidural.

In all likelihood serious complications described in association with the use of forceps or vacuum are not caused by instrumental manipulation. Rather the labors were complicated and traumatic, and that caused problems and not the use of forceps as such.

Clinical facts support this view. If epidural causes more instrumental deliveries and instrumental deliveries lead to severe tears, it would be logical to assume that the use of epidurals is associated with more tears. Clinical evidence does not support this logic. Considerable amount of research has been aimed at reducing complications during childbirth, and various risk factors for severe tears have been analyzed. Research consistently shows that main risk factors for severe perineal tears are the use of forceps, giving birth for the first time, large fetus and the presence of episiotomy. The presence of epidural is not associated with increased incidence of tears.

One study specifically addressed the question if epidurals increase the risk of maternal and neonatal complications. It was confined to 1009 women with uncomplicated pregnancy. According to the findings of the study, “epidural analgesia showed no evidence of a detrimental effect on the integrity of the birth-canal and on neonatal outcome during spontaneous vaginal delivery.” In other words, the incidence of tears and neonatal injury was the same among those with epidural and without.

The association of epidural analgesia with instrumental delivery is difficult to study because of wide variations in the use of instrumental delivery from hospital to hospital: in women without epidurals it varies between 4 and 60 percent. In teaching hospitals the use of instrumental delivery is likely to be higher for training purposes.

Current Cochrane Database review on epidural vs. non-epidural analgesia in labor also demonstrated that though epidural analgesia in labor may lead to the increased use of forceps and vacuum, it did not result in increased instrumental delivery for dystocia. The latter is the term for difficult or abnormal labor, the one that leads to serious complications.

Epidural anesthesia may in some instances lead to muscle weakness and interfere with the ability to push during the second stage. If it occurs, forceps or vacuum are used to facilitate delivery of the baby. In this scenario instrumental delivery does not lead to complications in the mother or the baby.

Strength of local anesthetic is important

If muscle weakness leads to more frequent need of instrumental delivery then reducing the concentration of local anesthetic in epidural mixture may to some extent mitigate this undesirable side-effect. Indeed, this has been demonstrated in the trial published in 2001.

The study was conducted in the UK6. 1054 women who requested epidural for their labor were randomly assigned to three groups, according to the epidural technique. Traditional epidural was maintained with 10 ml boluses of 0.25% bupivacaine when needed, a standard technique at the time. Combined spinal-epidural: small dose of spinal bupivacaine and fentanyl was followed by boluses of 0.1% bupivacaine with fentanyl at 2 ug/ml. In Low Dose Infusion group epidural was initiated and maintained with 0.1% bupivacaine and fentanyl 2 ug/ml.

The proportion of women who had to undergo caesarean section was not different between the groups, about 28%. However, there was difference between the rates of instrumental delivery: 37% in traditional epidural, 29% in combined spinal-epidural and 28% in low dose infusion group. In other words, the use of less concentrated local anesthetic resulted in about 36% decrease in instrumental delivery.

The issue of epidural associated with higher risk of instrumental delivery is typical for many issues regarding labor epidural in general. There are many factors that determine the use of forceps and vacuum, and the presence of epidural is just one of them. The composition of epidural mixture is also important for reducing this undesirable side-effect. In recent decade 0.2% ropivacaine has become standard local anesthetic in labor epidurals. However, currently reported rates of instrumental delivery has been derived from earlier studies where other local anesthetics – potentially affecting muscle strength to larger degree – were used. 0.1% bupivacaine has been shown to be associated with lower rates of instrumental delivery. On the other hand, 0.2% ropivacaine is likely to affect muscle strength to even lesser degree, and we could expect instrumental delivery rates to be lower. Obviously, further studies are needed to obtain definite statistics.

References:

1. Anim-Somuah M, Smyth R, Howell C. Epidural versus non-epidural or no analgesia in labour. Cochrane Database of Systematic Reviews 2005, Issue 4. Art. No.: CD000331. DOI: 10.1002/14651858.CD000331.pub2.

2. Ross MG et al. Forceps Delivery. http://www.emedicine.com/MED/topic3284.htm Updated: Jun 3, 2010.

3. JH. Johnson, R Figueroa, D Garry, A Elimian, D Maulik. Immediate Maternal and Neonatal Effects of Forceps and Vacuum-Assisted Deliveries. Obstet Gynecol 2004;103:513– 8.

4. LM Christianson, VE Bovbjerg, EC McDavitt, KL Hullfish. Risk factors for perineal injury during delivery. Am J Obstet Gynecol. 2003 Jul; 189(1):255-60.

5. B Bodner-Adler, K Bodner, O Kimberger, P Wagenbichler, A Kaider, P Husslein, K Mayerhofer. The effect of epidural analgesia on obstetric lacerations and neonatal outcome during spontaneous vaginal delivery. Arch Gynecol Obstet (2003) 267:130–133.

6. Comparative Obstetric Mobile Epidural Trial (COMET) Study Group UK. Effect of low-dose mobile versus traditional epidural techniques on mode of delivery: a randomised controlled trial. Lancet 2001; 358: 19–23.

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Dr. Eugene Smetannikov is a practicing anesthesiologist with the interest in obstetric anesthesia. He is the author of the most comprehensive book on the subject, The Truth About Labor Epidural