|Epidural analgesia minimally lengthens labor and does not increase the risk of cesarean delivery
Pregnant women commonly pose questions such as “Does epidural prolong my labor?” ” Do I have increased chances of forceps delivery?” These are simple questions but with a very complex answer. The influence of epidural analgesia on the course of labor continues to generate a debate within the anesthesia community and even more so outside of it. The literature is divided on this issue. Obstetricians, midwives, lay labor personnel, patients, hospital administrators, insurance executives, media reporters, and health care policy makers are all participating in this debate. Despite lack of evidence to support their claims, a vocal minority indict epidural analgesia to be an important cause of cesarean delivery.
There are several confounding factors that prevents the scientific community to determine a real answer to this apparently simple question. Some of them are as follows.
A major factor involves ethical issues. An ideal study (prospective double blind randomized study) would necessitate women coming for childbirth randomly to be divided into two groups. One would receive epidural for childbirth and the other would not. However, today, it is unethical to deny epidural anesthesia to a woman who requests this type of pain relief. Moreover, obstetricians may request epidural analgesia when they encounter a possible difficult labor in a woman. Even if women were randomly allocated to each of the two groups, initially, at the beginning of the study, there is a possibility that women can cross over to the epidural group from the I.V method due to inadequate pain relief during the course of the labor. Ethically, one can not deny this request for the sake of a study.
Ideally, the evaluators in a study should be blinded to the method of analgesia to eliminate bias. Insurmountable problem is posed by the practical impossibility of blinding patients, obstetricians, nurses, and anesthesiologists to the presence or absence of a functional epidural block. Because of proceeding with operative delivery is ultimately a subjective, clinical decision made by the obstetrician, the absence of masking may be important. Obstetricians and midwives may not treat their patients with epidural analgesia the same way that they treat those without it. For example, forceps-assisted delivery may be more common among patients with epidural analgesia, partly because obstetricians know their patients will be comfortable and have relaxed pelvic musculature for the procedure.
This is another factor that makes this issue very complex and probably invalidate retrospective studies (studying the outcome of women who received the type of anesthesia based on their choice rather than random allocation). There are inherent differences in the women who seek epidural anesthesia from those who do not. Woman who select epidural analgesia in labor are frequently nulliparous (first baby), tend to come to the hospital earlier in labor, have their baby much higher in the abdomen, have a big baby, and may have a slow labor itself. All of these factors contribute towards increasing the duration of labor with or without epidural analgesia.
Some of the studies have been severely underpowered meaning that the number of patients in each group were not sufficient enough to really validate the results of the studies.
Because of several limitations, one has to view the results of any study presented with a pinch of salt. Nonetheless, even in the absence of truly double blind randomized studies with enough power in them, it is possible to draw some conclusions using sophisticated statistical methods (Meta-analysis).
In order to overcome the difficulties of an underpowered study (a study with not enough number to strengthen the results of an individual study) a meta-analysis of several studies (obtaining answers from analyzing several similar studies) was undertaken that showed the following findings:(1)
The final conclusion, therefore, is as follows:
The appearance of several well-conducted, prospective, randomized trials have helped to confirm the opinion of most anesthesiologists and a growing number of obstetricians, that epidural analgesia only minimally lengthens labor and does not increase the risk of cesarean delivery.
Patients receiving epidural analgesia have longer labors. A difference on an average of about 60 minutes of longer labor in the epidural group as compared with the systemic I.V method. However, patient satisfaction and neonatal outcome are better after epidural than I.V method of providing childbirth pain relief.
Table 2: Sentinel event studies comparing C/S rate before and after a rapid change in epidural availiability
1. Segal S, Birnbach D. Epidurals and cesarean deliveries: A new look to an old problem. Editorial. Anesthesia and Analgesia 2000;94:775.
2. Halpern SH, Leightonm BL, Ohisson A, Barrett JF, Rice A. Effect of epidural vs parenteral opioid analgesia on the progress of labor. JAMA 1996;280;2105.
3. Segal S. Epidrual analgesia and the progress and outcome of labor and delivery. Problems in Anesthesia. 1999;11:324.
4. Thorp JA, Hu DH, Albin RM, et al. The effect of intrapartum epidural analgesia on nulliparous labor: a randomized, controlled, prospective trial. Obstet Gynecol 1993;169:851-8.
5. Ramin SM, Gambling DR, Lucas MJ, Sharma SK et al. Randomized trial of epidural versus intravenous analgesia during labor. Obstet Gynecol 1995;86:783-9.
5. Philipsen T, Jensen NH. Epidural block or parenteral pethidine as analgesic in labor: a randomized study concerning progress in labor and instrumental deliveries. Eur J Obstet Gynecol Reprod Biol 1989;30:27-33.
6. Sharma SK, Sidawi JE, Ramin SM, Lucas MJ, Laveno KJ, et al. Cesarean delivery; a randomized trial of epidural versus patient-controlled meperidine analgesia during labor. Anesthesiology 1997;87:487-94.
7. Bofill JA, Vincent RD, Ross EL, et al. Nulliparous active labor, epidural analgesia, and cesarean delivery for dystocia. Am J Obstet Gynecol 1997;177:1465-70.
8. Clarke A. Carr D. Loyd G, Cook V, Spinnato J. The influence of epidural analgesia on cesarean delivery rates: a randomized, prospective clinical trial. Am J Obstet Gynecol 1998;179:1527-33.
9. Wong CA. The influence of analgesia on labor- is it related to primary cesarean rates? Semin Perinatol 2012;36:353-6.