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Does the station of the fetal head during epidural analgesia affect labor and delivery?
International Journal of Gynecology & Obstetrics 64 Ž1999. 43᎐47
Article
Does the station of the fetal head during epidural analgesia affect labor and delivery? E. Sheiner a,U , E.K. Sheiner b , D. Segal a , M. Mazor a , O. Erez a , M. Katz a b
a Department of Obstetrics and Gynecology, Soroka Medical Center, Beer-She¨ a, Israel Faculty of Health Sciences Soroka Medical Center, Ben Gurion Uni¨ ersity of the Nege¨ , Beer-She¨ a, Israel
Received 28 April 1998; received in revised form 5 October 1998; accepted 16 October 1998
Abstract Objecti¨ e: To assess whether the station of the fetal head when lumbar epidural analgesia is administered influences the duration or the mode of delivery in low-risk laboring women. Methods: We prospectively evaluated 131 consecutive cases of low-risk parturients at term who requested intrapartum epidural analgesia. Obstetric outcome of 65 parturients who underwent epidural analgesia when the fetal head was low in the birth canal was compared to 66 patients whose fetal head station was above the ischial spine. Results: Both groups were similar in their obstetric characteristics. Cervical dilatation when performing the epidural analgesia was similar in both groups. The duration of labor and mode of delivery, as well as percentage of malpositions, were not significantly different in the two groups. Conclusions: The station of the fetal head while initiating epidural analgesia does not influence the duration of labor or the mode of delivery. Therefore, there is no justification to delay epidural analgesia in labor until the presenting fetal part is engaged. 䊚 1999 International Federation of Gynecology and Obstetrics Keywords: Epidural analgesia; Station; Labor; Mode of delivery
1. Introduction An important goal during labor is to provide safe and effective methods of analgesia for women
U
Corresponding author. Tel.: q972 7 6400774; fax: q972 7 6275338.
in pain. Undoubtedly, epidural analgesia is considered one of the best methods for pain relief during labor w1᎐4x. The data available with regard to the rate of instrumental deliveries in patients receiving epidural anesthesia is contradictory. Several authors have suggested that epidural analgesia prolongs labor w3᎐5x, and increases the number of operative w3,5,6x or assisted deliveries
0020-7292r99r$ - see front matter 䊚 1999 International Federation of Gynecology and Obstetrics P I I: S 0 0 2 0 - 7 2 9 2 Ž 9 8 . 0 0 2 2 5 - 2
44
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
w4x. However, others w7x in a prospective randomized study did not find that epidural analgesia prolonged labor or increased the frequency of instrumental deliveries. A relaxation of the pelvic floor due to the motor blockade resulting in cephalic malposition is an acceptable etiology for dystocia in patients with epidural analgesia w5,8,9x. Therefore, several authors have recommended that epidural analgesia should be started only at cervical dilatation ) 4 cm w10x, or when the fetal head is engaged in the birth canal w11x, in order to avoid malpositions or instrumental deliveries. On the contrary, others have concluded that early administration of epidural analgesia does not prolong labor or increase the incidence of operative deliveries, and that there is no justification in delaying epidural analgesia until labor advances w12᎐14x. The purpose of the present study is to examine whether the station of the fetal head when lumbar epidural analgesia is initiated influences the duration of labor or the mode of delivery, in low risk parturients. 2. Materials and methods The study was conducted between 1 May and 30 November 1997, after receiving the approval of the local ethics institutional review board of the Soroka University Medical Center. Included in the study were all term parturients who chose epidural analgesia, with a singleton fetus in cephalic presentation. The exclusion criteria were: clinical evidence of cephalopelvic disproportion Žwhere an elective cesarean section was performed., placental insufficiency, scarred uterus or advanced active stage of labor. Women were examined by an obstetrician for cervical dilatation and fetal head station just before epidural placement. A previous examination of a doctor or a midwife was taken as comparison for this examination. In order to control for cervical dilatation, we included only patients in early active stage of labor, i.e. cervical dilatation 4᎐5 cm, in the presence of regular uterine contractions. Station was defined according to The American College of Obstetricians and Gynecologists guidelines of 1988. Zero station was measured at the
level of the maternal ischial spines. High station was defined as less than zero station. Low station was characterized as equal or greater than zero station. Before epidural placement, patients received 500᎐1000 ml of lactated Ringer’s solution intravenously. An epidural catheter was introduced under local anesthesia at L2᎐L3 or L3᎐L4 interspace. A test dose of 1.5% lidocaine with epinephrine via the epidural catheter was added after its placement. The epidural analgesia was started by a bolus of 8᎐10 cm3 of 0.125% bupivacaine with 25 mg of pethidine, which was than repeated as needed. This combination has proved to provide adequate analgesia w15x. Maternal blood pressure and fetal heart rate were monitored. Clinical information was obtained by means of a structured interview regarding maternal age, number of pregnancies and deliveries, gestational age, family status Ži.e married, separated or divorced. and ethnic origin Ži.e Jewish or Bedouin Arabs.. Women were asked about the degree of pain experienced prior to the start of epidural analgesia, by using a visual analog scale ŽVAS.. VAS is a 10-cm line that is labeled ‘no pain’ at one end and ‘the worst possible pain’ at the other. The VAS is a quick, simple, easy tool to use, and has proven to be a sensitive, reliable method for pain measurement w16,17x. The assessment of the effectiveness of epidural analgesia was done the day after the delivery, in the postpartum wards. Position of the fetal occiput was assessed at delivery. Malposition was defined as occiput posterior or transverse. Oxytocin augmentation and the mode of delivery were noted, and when a cesarean section was performed, the indications were documented. Statistical analysis was performed with the SPSS package. 2 or Fisher’s exact test for comparison of proportions, and Student’s t-test for comparison of means were used. P- 0.05 was considered statistically significant. 3. Results A total of 131 women met the inclusion criteria. Of those, 65 received epidural analgesia when
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
the fetal head was engaged in the birth canal, while 66 received epidural analgesia when the fetal head was above the ischial spine. Table 1 presents selected maternal characteristics of the high and the low station groups. No statistically significant differences were found between the groups. Selected labor characteristics are displayed in Table 2. Again, both groups were similar with regard to analyzed variables. Mean cervical dilatation was 4.1" 0.3 in the low station group, and 4.1" 0.4 in the comparison group Ž Ps 0.620., thus allowing isolation of the effect of the station alone on labor and delivery outcome. Labor duration was comparable between the low and the high station groups Ž5.8" 5.2 and 4.3" 2.5, respectively.. The pain scores reported by the patients before Žmean visual analog scale score 8.7" 1.5 in the cases as compared to 8.9" 1.4 in the comparison group; Ps 0.442. and after analgesia Ž5.3" 2.7 in the study group as compared to 5.1" 3.2 in the comparison group; Ps 0.752. were similar. In addition, the incidence of malposition Ž10.8% in the low station group as compared to 7.6% in the high station. and the need for oxytocin augmentation Ž23.1% and 21.2% in the low and high station groups. was not significantly different in the two groups. The mode of delivery was similar between both groups. Most
45
patients delivered vaginally Ž86.2% in the low station group as compared to 0.3% in the high station group.. Likewise, the percentage of cesarean sections was comparable in both groups Ž7.7% in the low station group, as compared to 9.1% in the comparison group.. The indications for surgery, as shown in Table 3, did not differ in both groups of parturients. A separate analysis was done to nulliparous and multiparous patients. No significant differences were found with regard to the cervical dilatation, labor duration, the need for oxytocin augmentation and malpositions. In addition, the mode of delivery was comparable in this analysis. Among nulliparous women two patients had a cesarean section in the low station group vs. three in the comparison group, and three nulliparas had a vacuum delivery in both groups. Among multiparous women three patients in each group had a cesarean section, and one patient had a vacuum delivery in the low station group vs. two women in the high station group. 4. Discussion A retrospective cohort study w11x found malpo-
Table 1 Clinical characteristics of both groups Characteristics
Low station ŽS-0 and lower. Ž n s 65.
High station ŽS-1 and above. Ž n s 66.
P value
Maternal age
27.04
27.02
NS
Ethnic origin Jewish Bedouins
54 Ž83.1%. 11 Ž16.9%.
56 Ž84.8%. 10 Ž15.2%.
NS
Family status Married Not married
64 Ž98.5%. 1 Ž1.5%.
65 Ž98.5%. 1 Ž1.5%.
NS
Nulliparity
37 Ž57%.
29 Ž44%.
NS
Gravidity
2.2" 1.8
2.8" 2.3
NS
Parity
1.8" 1.3
2.3" 1.7
NS
39.6" 1.1
39.9" 1.3
NS
Gestational age Žweeks.
Note. NS, not significant; data are expressed as means " S.D. or numbers and percentages.
46
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
Table 2 Labor characteristics Variables
Low station ŽS-0 and lower. Ž n s 65.
High station ŽS-1 and above. Ž n s 66.
P value
Cervical dilatation Žcm.
4.1" 0.3
4.1" 0.4
NS
Duration of labor Žhours.
5.8" 5.2
4.3" 2.5
NS
Pain before epidural ŽVAS score.
8.7" 1.5
8.9" 1.4
NS
Pain after epidural ŽVAS score.
5.3" 2.7
5.1" 3.2
NS
15 Ž23.1%.
14 Ž21.2%.
NS
7 Ž10.8%.
5 Ž7.6%.
NS
56 Ž86.2%.
55 Ž83.3%.
Cesarean section
5 Ž7.7%.
6 Ž9.1%.
Vacuum delivery
4 Ž6.1%.
5 Ž7.6%.
Oxytocin augmentation Occiput posterior or transverse position Mode of delivery Spontaneous delivery
NS
Note. NS, not significant; data are expressed as means " S.D. or numbers and percentages.
sitions of the fetal occiput and cesarean sections to be significantly more frequent when epidural analgesia was administered prior to engagement of the fetal head. In our study the duration of labor, as well as the mode of delivery were comparable between both groups. The epidural pharmacology was, however, different. In the above study w11x, the epidural contained bupivacaine alone. While given alone, a higher concentration of bupivacaine is required in order to achieve a proper pain relief. Thus, the relaxation of the pelvic floor is more likely to occur. Pelvic relaxation resulting from motor blockade is a well-
established mechanism for the high rates of malpositions associated with the epidural analgesia. Indeed, Stoddart et al. w9x evaluated the effect of two different concentrations of bupivacaine combined with fentanyl on the rate of instrumental delivery. They found a significantly higher rate of Kielland’s rotational forceps in women receiving a higher concentration of bupivacaine. The authors concluded that higher concentrations of bupivacaine, leading to a greater degree of motor block, are more likely to contribute to inadequate rotation of the fetal presenting part. On the contrary, another study w14x which evaluated the ef-
Table 3 Indications for cesarean section Low station ŽS-0 and lower. Ž n s 65.
High station ŽS-1 and above. Ž n s 66.
Non-progressive labor 1st stage
3
4
Non-progressive labor 2nd stage
1
1
Fetal distress
1
1
P value
NS Note. NS, not significant.
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
fects of early vs. late continuous epidural analgesia on instrumental deliveries, did not find the station of the fetal head to effect the incidence of instrumental deliveries, despite the usage of high concentrations of bupivacaine Ž0.5%.. A possible explanation for our results can be attributed to the use of pethidine in our medical center which allows for lower concentrations of bupivacaine. This study has a relatively small sample size, but we did not find any consistent trend towards an increased length of delivery or a higher rate of instrumental deliveries or cesarean sections. The prospective analysis allowed an accurate assessment of the cervical dilatation and station of the fetal presenting part at the start of epidural analgesia. The examinations were carried out just before the epidural placement. Unlike other studies in which analysis was retrospective, the vaginal examination was performed within 2 h of catheter placement w11x, thus allowing for further descent of the presenting part. The results of our study indicate that the station of the fetal head while initiating intrapartum epidural analgesia in early active stage of labor does not influence the duration of labor or the mode of delivery. Therefore, there is no justification to delay intrapartum epidural analgesia until the presenting fetal part is engaged in the birth canal.
w4x
w5x
w6x
w7x
w8x
w9x
w10x w11x
w12x
Acknowledgements The authors want to thank the midwifes Sue Shachar, Leslie Tannenbaum and Adrienne Neta for the valuable remarks on the paper.
w13x
w14x
References w1x Morgan B, Bulpitt CJ, Clifton P, Lewis PJ. Effectiveness of pain relief in labor: survey of 1000 mothers. Br Med J 1982;285:689᎐690. w2x Philipsen T, Jensen NH. Maternal opinion about analgesia in labor and delivery. A comparison of epidural blockade and intramuscular pethidine. Eur J Obstet Gynecol Reprod Biol 1990;34:205᎐210. w3x Ramin SM, Gambling DR, Lucas MJ, Sharma SK, Sidawi
w15x
w16x w17x
47
JE, Leveno KJ. Randomized trial of epidural versus intravenous analgesia during labor. Obstet Gynecol 1995;86:783᎐789. Robinson JO, Rosen M, Evans JM, Revill SI, David H, Rees GAD. Maternal opinion about analgesia for labor. Anaesthesia 1980;35:1173᎐1181. Thorp JA, Hu DH, Albin RM et al. The effect of intrapartum epidural analgesia on nulliparous labor: a randomized, controlled, prospective trial. Am J Obstet Gynecol 1993;169:851᎐858. Thorp JA, Parisi VM, Boylan PC, Johnston DA. The effect of continuous epidural analgesia on cesarean section for dystocia in nulliparous women. Am J Obstet Gynecol 1989;161:670᎐675. 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;33:27᎐33. Saunders NJ, Spiby H, Gilbert L et al. Oxytocin infusion during second stage of labor in primiparous women using epidural analgesia: a randomised double-blind placebo-controlled trial. Br Med J 1989;299:1423᎐1426. Stoddart AP, Nicholson KEA, Popham PA. Low dose bupivacainerfentanyl epidural infusions in labor and mode of delivery. Anaesthesia 1994;49:1087᎐1090. Clark RB. Conduction anesthesia. Clin Obstet Gynecol 1981;24:601᎐617. Robinson CA, Macones GA, Roth NW, Morgan MA. Does station of the fetal head at epidural placement affect the position of the fetal vertex at delivery? Am J Obstet Gynecol 1996;175:991᎐994. Chestnut DH, Vincent R, McGrath JM, Choi WW, Bates JN. Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are receiving intravenous oxytocin? Anesthesiology 1994;80:1193᎐1200. Chestnut DH, McGrath JM, Vincent R et al. Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are in spontaneous labor? Anesthesiology 1994;80:1201᎐1208. Ohel G, Harats H. Epidural anesthesia in early compared with advanced labor. Int J Gynaecol Obstet 1994;45:217᎐219. Hardley G, Perkins G. The addition of pethidine to epidural bupivacaine in labor, effect of changing bupivacaine strength. Anaesth Intensive Care 1992;20:151᎐155. Scott J, Huskisson EC. Graphic representation of pain. Pain 1976;2:175᎐184. Chapman CR, Casey KL, Dubner R, Foley KM, Gracely RH, Reading AE. Pain measurement: an overview. Pain 1985;22:1᎐31.
Article
Does the station of the fetal head during epidural analgesia affect labor and delivery? E. Sheiner a,U , E.K. Sheiner b , D. Segal a , M. Mazor a , O. Erez a , M. Katz a b
a Department of Obstetrics and Gynecology, Soroka Medical Center, Beer-She¨ a, Israel Faculty of Health Sciences Soroka Medical Center, Ben Gurion Uni¨ ersity of the Nege¨ , Beer-She¨ a, Israel
Received 28 April 1998; received in revised form 5 October 1998; accepted 16 October 1998
Abstract Objecti¨ e: To assess whether the station of the fetal head when lumbar epidural analgesia is administered influences the duration or the mode of delivery in low-risk laboring women. Methods: We prospectively evaluated 131 consecutive cases of low-risk parturients at term who requested intrapartum epidural analgesia. Obstetric outcome of 65 parturients who underwent epidural analgesia when the fetal head was low in the birth canal was compared to 66 patients whose fetal head station was above the ischial spine. Results: Both groups were similar in their obstetric characteristics. Cervical dilatation when performing the epidural analgesia was similar in both groups. The duration of labor and mode of delivery, as well as percentage of malpositions, were not significantly different in the two groups. Conclusions: The station of the fetal head while initiating epidural analgesia does not influence the duration of labor or the mode of delivery. Therefore, there is no justification to delay epidural analgesia in labor until the presenting fetal part is engaged. 䊚 1999 International Federation of Gynecology and Obstetrics Keywords: Epidural analgesia; Station; Labor; Mode of delivery
1. Introduction An important goal during labor is to provide safe and effective methods of analgesia for women
U
Corresponding author. Tel.: q972 7 6400774; fax: q972 7 6275338.
in pain. Undoubtedly, epidural analgesia is considered one of the best methods for pain relief during labor w1᎐4x. The data available with regard to the rate of instrumental deliveries in patients receiving epidural anesthesia is contradictory. Several authors have suggested that epidural analgesia prolongs labor w3᎐5x, and increases the number of operative w3,5,6x or assisted deliveries
0020-7292r99r$ - see front matter 䊚 1999 International Federation of Gynecology and Obstetrics P I I: S 0 0 2 0 - 7 2 9 2 Ž 9 8 . 0 0 2 2 5 - 2
44
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
w4x. However, others w7x in a prospective randomized study did not find that epidural analgesia prolonged labor or increased the frequency of instrumental deliveries. A relaxation of the pelvic floor due to the motor blockade resulting in cephalic malposition is an acceptable etiology for dystocia in patients with epidural analgesia w5,8,9x. Therefore, several authors have recommended that epidural analgesia should be started only at cervical dilatation ) 4 cm w10x, or when the fetal head is engaged in the birth canal w11x, in order to avoid malpositions or instrumental deliveries. On the contrary, others have concluded that early administration of epidural analgesia does not prolong labor or increase the incidence of operative deliveries, and that there is no justification in delaying epidural analgesia until labor advances w12᎐14x. The purpose of the present study is to examine whether the station of the fetal head when lumbar epidural analgesia is initiated influences the duration of labor or the mode of delivery, in low risk parturients. 2. Materials and methods The study was conducted between 1 May and 30 November 1997, after receiving the approval of the local ethics institutional review board of the Soroka University Medical Center. Included in the study were all term parturients who chose epidural analgesia, with a singleton fetus in cephalic presentation. The exclusion criteria were: clinical evidence of cephalopelvic disproportion Žwhere an elective cesarean section was performed., placental insufficiency, scarred uterus or advanced active stage of labor. Women were examined by an obstetrician for cervical dilatation and fetal head station just before epidural placement. A previous examination of a doctor or a midwife was taken as comparison for this examination. In order to control for cervical dilatation, we included only patients in early active stage of labor, i.e. cervical dilatation 4᎐5 cm, in the presence of regular uterine contractions. Station was defined according to The American College of Obstetricians and Gynecologists guidelines of 1988. Zero station was measured at the
level of the maternal ischial spines. High station was defined as less than zero station. Low station was characterized as equal or greater than zero station. Before epidural placement, patients received 500᎐1000 ml of lactated Ringer’s solution intravenously. An epidural catheter was introduced under local anesthesia at L2᎐L3 or L3᎐L4 interspace. A test dose of 1.5% lidocaine with epinephrine via the epidural catheter was added after its placement. The epidural analgesia was started by a bolus of 8᎐10 cm3 of 0.125% bupivacaine with 25 mg of pethidine, which was than repeated as needed. This combination has proved to provide adequate analgesia w15x. Maternal blood pressure and fetal heart rate were monitored. Clinical information was obtained by means of a structured interview regarding maternal age, number of pregnancies and deliveries, gestational age, family status Ži.e married, separated or divorced. and ethnic origin Ži.e Jewish or Bedouin Arabs.. Women were asked about the degree of pain experienced prior to the start of epidural analgesia, by using a visual analog scale ŽVAS.. VAS is a 10-cm line that is labeled ‘no pain’ at one end and ‘the worst possible pain’ at the other. The VAS is a quick, simple, easy tool to use, and has proven to be a sensitive, reliable method for pain measurement w16,17x. The assessment of the effectiveness of epidural analgesia was done the day after the delivery, in the postpartum wards. Position of the fetal occiput was assessed at delivery. Malposition was defined as occiput posterior or transverse. Oxytocin augmentation and the mode of delivery were noted, and when a cesarean section was performed, the indications were documented. Statistical analysis was performed with the SPSS package. 2 or Fisher’s exact test for comparison of proportions, and Student’s t-test for comparison of means were used. P- 0.05 was considered statistically significant. 3. Results A total of 131 women met the inclusion criteria. Of those, 65 received epidural analgesia when
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
the fetal head was engaged in the birth canal, while 66 received epidural analgesia when the fetal head was above the ischial spine. Table 1 presents selected maternal characteristics of the high and the low station groups. No statistically significant differences were found between the groups. Selected labor characteristics are displayed in Table 2. Again, both groups were similar with regard to analyzed variables. Mean cervical dilatation was 4.1" 0.3 in the low station group, and 4.1" 0.4 in the comparison group Ž Ps 0.620., thus allowing isolation of the effect of the station alone on labor and delivery outcome. Labor duration was comparable between the low and the high station groups Ž5.8" 5.2 and 4.3" 2.5, respectively.. The pain scores reported by the patients before Žmean visual analog scale score 8.7" 1.5 in the cases as compared to 8.9" 1.4 in the comparison group; Ps 0.442. and after analgesia Ž5.3" 2.7 in the study group as compared to 5.1" 3.2 in the comparison group; Ps 0.752. were similar. In addition, the incidence of malposition Ž10.8% in the low station group as compared to 7.6% in the high station. and the need for oxytocin augmentation Ž23.1% and 21.2% in the low and high station groups. was not significantly different in the two groups. The mode of delivery was similar between both groups. Most
45
patients delivered vaginally Ž86.2% in the low station group as compared to 0.3% in the high station group.. Likewise, the percentage of cesarean sections was comparable in both groups Ž7.7% in the low station group, as compared to 9.1% in the comparison group.. The indications for surgery, as shown in Table 3, did not differ in both groups of parturients. A separate analysis was done to nulliparous and multiparous patients. No significant differences were found with regard to the cervical dilatation, labor duration, the need for oxytocin augmentation and malpositions. In addition, the mode of delivery was comparable in this analysis. Among nulliparous women two patients had a cesarean section in the low station group vs. three in the comparison group, and three nulliparas had a vacuum delivery in both groups. Among multiparous women three patients in each group had a cesarean section, and one patient had a vacuum delivery in the low station group vs. two women in the high station group. 4. Discussion A retrospective cohort study w11x found malpo-
Table 1 Clinical characteristics of both groups Characteristics
Low station ŽS-0 and lower. Ž n s 65.
High station ŽS-1 and above. Ž n s 66.
P value
Maternal age
27.04
27.02
NS
Ethnic origin Jewish Bedouins
54 Ž83.1%. 11 Ž16.9%.
56 Ž84.8%. 10 Ž15.2%.
NS
Family status Married Not married
64 Ž98.5%. 1 Ž1.5%.
65 Ž98.5%. 1 Ž1.5%.
NS
Nulliparity
37 Ž57%.
29 Ž44%.
NS
Gravidity
2.2" 1.8
2.8" 2.3
NS
Parity
1.8" 1.3
2.3" 1.7
NS
39.6" 1.1
39.9" 1.3
NS
Gestational age Žweeks.
Note. NS, not significant; data are expressed as means " S.D. or numbers and percentages.
46
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
Table 2 Labor characteristics Variables
Low station ŽS-0 and lower. Ž n s 65.
High station ŽS-1 and above. Ž n s 66.
P value
Cervical dilatation Žcm.
4.1" 0.3
4.1" 0.4
NS
Duration of labor Žhours.
5.8" 5.2
4.3" 2.5
NS
Pain before epidural ŽVAS score.
8.7" 1.5
8.9" 1.4
NS
Pain after epidural ŽVAS score.
5.3" 2.7
5.1" 3.2
NS
15 Ž23.1%.
14 Ž21.2%.
NS
7 Ž10.8%.
5 Ž7.6%.
NS
56 Ž86.2%.
55 Ž83.3%.
Cesarean section
5 Ž7.7%.
6 Ž9.1%.
Vacuum delivery
4 Ž6.1%.
5 Ž7.6%.
Oxytocin augmentation Occiput posterior or transverse position Mode of delivery Spontaneous delivery
NS
Note. NS, not significant; data are expressed as means " S.D. or numbers and percentages.
sitions of the fetal occiput and cesarean sections to be significantly more frequent when epidural analgesia was administered prior to engagement of the fetal head. In our study the duration of labor, as well as the mode of delivery were comparable between both groups. The epidural pharmacology was, however, different. In the above study w11x, the epidural contained bupivacaine alone. While given alone, a higher concentration of bupivacaine is required in order to achieve a proper pain relief. Thus, the relaxation of the pelvic floor is more likely to occur. Pelvic relaxation resulting from motor blockade is a well-
established mechanism for the high rates of malpositions associated with the epidural analgesia. Indeed, Stoddart et al. w9x evaluated the effect of two different concentrations of bupivacaine combined with fentanyl on the rate of instrumental delivery. They found a significantly higher rate of Kielland’s rotational forceps in women receiving a higher concentration of bupivacaine. The authors concluded that higher concentrations of bupivacaine, leading to a greater degree of motor block, are more likely to contribute to inadequate rotation of the fetal presenting part. On the contrary, another study w14x which evaluated the ef-
Table 3 Indications for cesarean section Low station ŽS-0 and lower. Ž n s 65.
High station ŽS-1 and above. Ž n s 66.
Non-progressive labor 1st stage
3
4
Non-progressive labor 2nd stage
1
1
Fetal distress
1
1
P value
NS Note. NS, not significant.
E. Sheiner et al. r International Journal of Gynecology & Obstetrics 64 (1999) 43᎐47
fects of early vs. late continuous epidural analgesia on instrumental deliveries, did not find the station of the fetal head to effect the incidence of instrumental deliveries, despite the usage of high concentrations of bupivacaine Ž0.5%.. A possible explanation for our results can be attributed to the use of pethidine in our medical center which allows for lower concentrations of bupivacaine. This study has a relatively small sample size, but we did not find any consistent trend towards an increased length of delivery or a higher rate of instrumental deliveries or cesarean sections. The prospective analysis allowed an accurate assessment of the cervical dilatation and station of the fetal presenting part at the start of epidural analgesia. The examinations were carried out just before the epidural placement. Unlike other studies in which analysis was retrospective, the vaginal examination was performed within 2 h of catheter placement w11x, thus allowing for further descent of the presenting part. The results of our study indicate that the station of the fetal head while initiating intrapartum epidural analgesia in early active stage of labor does not influence the duration of labor or the mode of delivery. Therefore, there is no justification to delay intrapartum epidural analgesia until the presenting fetal part is engaged in the birth canal.
w4x
w5x
w6x
w7x
w8x
w9x
w10x w11x
w12x
Acknowledgements The authors want to thank the midwifes Sue Shachar, Leslie Tannenbaum and Adrienne Neta for the valuable remarks on the paper.
w13x
w14x
References w1x Morgan B, Bulpitt CJ, Clifton P, Lewis PJ. Effectiveness of pain relief in labor: survey of 1000 mothers. Br Med J 1982;285:689᎐690. w2x Philipsen T, Jensen NH. Maternal opinion about analgesia in labor and delivery. A comparison of epidural blockade and intramuscular pethidine. Eur J Obstet Gynecol Reprod Biol 1990;34:205᎐210. w3x Ramin SM, Gambling DR, Lucas MJ, Sharma SK, Sidawi
w15x
w16x w17x
47
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