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Intravenous prostaglandins E2 and F2α for the induction of term labor
OBSTETRICS
Intravenous prostaglandins E, and F,, for the induction of term labor GERALD
G.
JOHN
C.
LEON
SPEROFF,
New
Haven,
ANDERSON,
HOBBINS,
M.D M.D.
M.D.
Connecticut
Prostaglandins Es and Ka and synthetic oxytocin were studied for eficacy and side effects in a double-blind protocol for the induction of labor at term in 100 women. That an inducibility scoring index should be part of each clinical oxytocin trial is evidenced by the fact that erroneous conclusions would have been drawn if it had not been used. All patients who were classified as having “easy inductions” were delivered independent of which drug they received; however, the 3 categories of graded “dificult inductions” reflected success rates from 93.3 to 40 per cent, depending upon dificulty of induction. Synthetic oxytocin and prostaglandin Ra were found to be equally eficacious in the dificult groups although more cases will be required to allow significant statistical analysis. Except for an increased incidence of innocuous uterine hypertonus, no significant side effects of prostaglandin infusions were noted.
in 2 aspects: ( 1) They were not doubleblind in nature; (2) no objective attempt was made to delineate the inducibility status. Therefore, a double-blind protocol was prepared in cooperation with The Upjohn Co. which included an inducibility scoring index as described by Bishop.”
HAS BEEN less than 2 years since the first significant series was published concerning the use of prostaglandins in the induction of labor in term human pregnancy.l An increasing number of investigators around the world have been devoting their efforts in an attempt to delineate the role of prostaglandins in labor and to assess their possible therapeutic value.2-4 It was evident at the outset that the early published series were lacking in protocol design
IT
From the Department of Obstetrics Gynecology, Yale University School Medicine. The Upjohn Company, Kalamazoo, Michigan, supplied the prostaglandins and financial support for this study. Received 1971.
for
publication
October
Patients
and
method
A score from 0 to 13 was possible-patients with a score of 6 or less were considered “difficult inductions” while those with a score of 7 or greater were considered “easy inductions” (Table I) . All 100 patients were accepted for the study whatever their Bishop score, unless they had a previous cesarean section, were grandmultiparas or primiparas, had ruptured membranes, or
and of
20, 382
Volume Number
112 3
PGE,
Table I. Bishop system for scoring inducibility Factor
Score
0
Dilation (cm.) Effacement (9’0) Station Consistency Position
Closed O-30 -3 Firm Posterior
Score
PGF2a:
for
induction
of
labor
383
of labor5
1
Score
1-2 40-50 -2 Medium Midposition
Table II. Dosage of initial
and
2
I
Score
3-4 60-70 -1, 0 Soft Anterior
5+ 80+ +l, +2 Total
3
Factor
Score
--score
-.--
protocol .___
I
Drug
(
Rate
30 pg/c.c.
PGFaa
oxytocin
40
mU./c.c.
were in labor, or if fetal death was evident. The fetal heart rate and uterine contractions were recorded continuously from a scalp electrode and transcervical open-end intra-amniotic catheter on a multichannel polygraph. Membranes were not ruptured for application of monitoring equipment until lf/2 hours of the study had been completed and then not until the patient was in good clinical labor and making progress. Maternal blood pressure, temperature, respirations, and pulse rate were obtained and recorded every hour or more frequently if indicated. Maternal blood was obtained for hematocrit, white blood cell count and differential, and platelet estimation before and the day following induction of labor. The neonate was assigned 1 and 5 minute Apgar scores and was observed for complications during the hospital stay. The infusion was given intravenously by electronic infusion pump per the dose schedule in Table II. The infusion rates were the same for all three drugs; synthetic oxytocin” prostaglandin F,ar ( PGF*(u), and prostaglandin E, (PGE,) in keeping with *Syntocinon, Sandoz Pharmaceuticals, Jersey, 10 United States Pharmacopeia centimeter.
(cdmin.) 0.05 0.1 0.2 0.05 0.1 0.2 0.05 0.1 0.2
3 pg/c.c.
PGE,
Synthetic
Concentration
Hanover, U. per
New cubic
/
Dose
(per 1.5 3.0
min.) I% P!&!
6.0 /.+z! 0.15 0.3
/.Lg Pg
0.6 fig 2 mu. 4 mu. 8 mu.
1
Duration
(hr.) 0.5 8.0 4.0 0.5 8.0 4.0 0.5 8.0 4.0
the double-blind protocol. After using this schedule with 5 patients, verbal information from Karim,6 who was using up to 10 pg per minute of PGF*(Y, suggested that we were probably using an under-dose. Therefore, the protocol was altered to increase the maximum dosage rate for PGF,cK from 6 to 10 pg per minute while PGE, was doubled to 1.2 pg per minute. Because of results poorer than expected, the administration was changed to the schedule in Table III after studying 21 patients. Factors under consideration to account for the discrepancies in results included the greater mean weight of our patient group (=z 10 kilograms), the possible genetic difference in response to prostaglandins by African Bantus, the exclusion of patients with dead fetuses or ruptured membranes from our group, the greater parity of patients in Karim’s study, and finally the lack of an initial objective examination for inducibility of labor. The concentrations of the prostaglandins were increased, the duration of the infusion was decreased to 10 hours, and the maximal dose was increased to 40 and 4.8 pg per minute of F,a and ES, respectively, and for synthetic oxytocin to 16 mu. per minute. The rates were increased according to the schedule only if adequate
384
Anderson,
Table III.
Hobbins,
and Speroff
February 1, 1972 Am. J. Obstet. Gynecol.
Dosage and rates of administration
Drug
Concentration
PGFza
1 Rate
50 pg/c.c.
PGEa
20 mU./c.c.
Table IV. Success rates for synthetic oxytocin, PGF,(u, and PGE, in 79 patients Drug
Synthetic oxytocin PGFza PGEe
Totals
Percentage success
No. of successes
(c.c./min.)
/
D ose (per
2.5 5.0 10.0 20.0 40.0 0.3
0.05 0.1 0.2 0.4 0.8 0.05 0.1 0.2 0.4 0.8 0.05 0.1 0.2 0.4 0.8
6.0 pg/c.c.
Synthetic oxytocin
of second alteration
No.of
23 35 5
27 46 6
79.75
63
79
Resulis
The results obtained after studying 21 patients under the first two protocols are shown in Fig. 1. We see that all 4 patients with a score of 7 or greater were delivered (as indicated by a circle), while in the difficult induction (Bishop score of 6 or less) group, only 4 of 17 patients were delivered. Early in the study, PGE, was withdrawn because of shelf instability; therefore, most comparisons will concern synthetic oxytocin and PGF2a in the 79 patients since the final alteration of the protocol. The over-all success rate for the 3 drugs was 79.75 per cent (Table IV). The success rate for synthetic oxytocin was 85.19 per cent; for PGF,cr, 79.6 per cent; and for PGE2, 83.4 per cent. In the patients with a Bishop score of 6 or less (Table V), a success rate of 91 per cent with synthetic oxyto& and 93.3 per cent with PFG,a was
1
Duration
pg Pg .ug fig pg kg
(hr.)
0.5 0.5 1.0 4.0 4.0 0.5 0.5 1.0 4.0 4.0 0.5 0.5 1.0 4.0 4.0
2.4 fig 4.8 /+c 1 mu. 2 mu. 4 mu. 8 mu. 16 mu.
Table V. Per cent of successful inductions in 55 patients grouped according to difficulty of induction. Successful induction per number of patients in parentheses Bishop score Drug
Synthetic PGFza
clinical progress in labor was not brought about at the previous level.
min.)
0.6 clg 1.2 /kg
cases
85.19 79.6 83.4
of protocol
Bishop score
Bishop score
(O/o)
3-4 57% (4/7)
5-6 91% (llA2)
40 % (2/5)
56% (g/16)
9.3% (14/15)
o-1-2
oxytocin
seen in patients with Bishop scores 5 or 6; the rate was 57 per cent with synthetic oxytocin and 56 per cent with PGF,cu in patients with Bishop scores of 3 or 4; and it was 40 per cent with PGFza in patients with Bishop scores of 0, 1, or 2 (no patients fell into this category in the synthetic oxytocin group). The mean duration of labor was shorter in the difficult group with the use of PGF,a by 1.8 hours and by 1.25 hours in the easy group. This approaches statistical significance (P = 0.06, + test) only if one compares adequate-sized comparable groups such as those with a Bishop score of 5 or 6. The form, frequency, and intensity of contractions were indistinguishable in the 3 groups. However, 7 patients developed transient periods of hypertonus (base-line intrauterine pressure > 15 mm. Hg) or tachysystole (frequency of contractions
Volume Number
112 3
PGE,
2
EEFF
0 0 E E
E r fz V ul
5 6 -
-
ES
x m H a
8
Bishop score
Synthetic oxytocin
O-6 7-13
9.17 5.75
EFSSS
for
induction
of
labor
385
__---
I
.I
PGF,a
Difference
7.77 4.5
1.4 1.25
F
- -OOE ------
7
Pi 0
PGF,a
Table VI. Mean duration of labor and difference (in‘hours) in 73 patients who received synthetic oxytocin or PGF,e grouped according to inducibility of labor -_..-..- - ..~_
1 = +J
and
00 0 0 E S
12
13
Fig. 1. Drugs used in first 21 patients. S = synthetic oxytocin, F = PGFaq E = PGEZ, 0 = delivered. greater than 2 per minute) at various infusion rates; 2 were receiving PGEz and 5 received PGF,(u. In only one case was the fetal heart rate affected-the patient was receiving PGF,a: at 10 pg per minute and had participated in the study for 3yz hours. The drug was discontinued, and the fetal heart rate returned to normal along with the establishment of a uterine tonus of 10 to 15 mm. Hg within 5 minutes. Contractions continued, and the patient was spontaneously delivered of an Apgar 8 to 9 infant one hour later. The cesarean section rate was 1 per cent, the procedure occurring 3 days after a study failure with synthetic oxytocin for cephalopelvic disproportion. There was no significant effect discernible on the following parameters: maternal vital signs, Apgar scoring, neonatal follow-up,
hemogram, maternal gastrointestinal symptoms, or blood loss. Nine of our patients had a past or present history of asthma; however, no attacks occurred during the infusion. Comment The most recent publication on prostaglandins in the induction of labor was the work of Beazley and associates’ in which PGE, and synthetic oxytocin were used in a double-blind study in 300 patients. They found a 73 per cent success rate in each group and concluded that PGE, was no more efficacious than synthetic oxytocin in inducing labor. However, an inducibility index was not utilized. Our over-all success rate (Table IV) for the 3 drugs was 79.75 per cent. The success rate for synthetic oxytocin was 85.19 per cent; for PGF,e 76.01 per cent, and for PGE,, 83.4 per cent. Once again, all patients with a Bishop score of 7 or greater were delivered no matter what drug they received, indicating that these patients may skew effacacy results. At this point, synthetic oxytocin still appears more effective; however, if the results are broken down further according to the inducibility scoring categories (Table V). it can be seen that more low Bishop score patients were present in the PGF,(w group and that results in the Score 3 to 4 and Score 5 to 6 groups were essentially identical. No “very difficult” patients fell into the synthetic oxytocin group, but 2 of 5 in that category were delivered with PGF,a. Without a scoring index, false conclusions might have been drawn at this point. Table VI compares the infusion-delivery interval in successful inductions in the
386
Anderson,
Hobbins,
and
February 1, 1972 Am. J. Obstet. Gynecol.
Speroff
difficult and easy groups for synthetic oxytocin and PGF?(u. As can be seen, the mean duration of labor was shortened in the difficult group with the use of PGF,(u by 1.4 hours and by 1.25 hours in the easy group. A comparison of the time needed from beginning of infusion to the start of adequate clinical labor as determined by cervical effacement and dilatation indicated that the shortening of labor in the difficult PGF,cu group was mainly due to a shortening of the latent phase of labor. The following is concluded: 1. Studies involving the efficacy of oxytocic drugs should include a semiobjective scoring index in order to compare patients with similar scoring indices, As indicated by our study, this of necessity calls for a series of sufficient size to allow significant statistical comparisons of small subgroups. 2. With the dosages administered to these patients, PGF,a was as effective as oxy-
tocin for inducing labor if patients with comparable cervical characteristics are compared. Changes in dose rates or infusion times may yield different results. 3. PGF?a thus far seems to be as safe as synthetic oxytocin in terms of effects on maternal vital signs, fetal heart rate, and neonatal condition. The uterus does seem to be more sensitive to alterations in dosage rates of PGF,cu than to synthetic oxytocin; however, careful adjustment of dosage rates in response to uterine contractions and fetal heart rate has essentially eliminated significant hypertonus or tachysystolia in our hands, no episodes having occurred in the last 40 cases. 4. The mean infusion-delivery interval in the PGF,a! group was shorter in both the easy and difficult induction groups. This trend indicates the only possible advantage noted thus far for PGF,a over synthetic oxytocin.
REFERENCES
1.
2.
3.
Karim, S. M. M., Trussel, R. R., Hillier, K., K., and Patel, R. C.: J. Obstet. Gynaecol. Br. Commonw. 76: 769, 1969. Bygdeman, M., Kwon, S. U., Mukherjee, T., and Wiqvist, N.: AM. J. OBSTET. GYNECOL. 102: 317, 1968. Embrey, M. B.: J. Obstet. Gynaecol. Br. Commonw. 76: 783, 1969.
4. 5. 6.
Roth-Brandel, stet. Gynecol. Bishop, E. H.: Karim, S. M. 487, 1971.
U., and Adams, A.: Acta ObStand. (SuppI.) 49: 9, 1970. Obstet. Gynecol. 24: 266, 1964. M.: Ann. N. Y. Acad. Sci. 180:
7. Beazley, J. M., Dewhurst, J.: J. Obstet. 193, 1970.
Gynaecol.
C. J., and Gillespie, Br.
Commonw.
77:
Intravenous prostaglandins E, and F,, for the induction of term labor GERALD
G.
JOHN
C.
LEON
SPEROFF,
New
Haven,
ANDERSON,
HOBBINS,
M.D M.D.
M.D.
Connecticut
Prostaglandins Es and Ka and synthetic oxytocin were studied for eficacy and side effects in a double-blind protocol for the induction of labor at term in 100 women. That an inducibility scoring index should be part of each clinical oxytocin trial is evidenced by the fact that erroneous conclusions would have been drawn if it had not been used. All patients who were classified as having “easy inductions” were delivered independent of which drug they received; however, the 3 categories of graded “dificult inductions” reflected success rates from 93.3 to 40 per cent, depending upon dificulty of induction. Synthetic oxytocin and prostaglandin Ra were found to be equally eficacious in the dificult groups although more cases will be required to allow significant statistical analysis. Except for an increased incidence of innocuous uterine hypertonus, no significant side effects of prostaglandin infusions were noted.
in 2 aspects: ( 1) They were not doubleblind in nature; (2) no objective attempt was made to delineate the inducibility status. Therefore, a double-blind protocol was prepared in cooperation with The Upjohn Co. which included an inducibility scoring index as described by Bishop.”
HAS BEEN less than 2 years since the first significant series was published concerning the use of prostaglandins in the induction of labor in term human pregnancy.l An increasing number of investigators around the world have been devoting their efforts in an attempt to delineate the role of prostaglandins in labor and to assess their possible therapeutic value.2-4 It was evident at the outset that the early published series were lacking in protocol design
IT
From the Department of Obstetrics Gynecology, Yale University School Medicine. The Upjohn Company, Kalamazoo, Michigan, supplied the prostaglandins and financial support for this study. Received 1971.
for
publication
October
Patients
and
method
A score from 0 to 13 was possible-patients with a score of 6 or less were considered “difficult inductions” while those with a score of 7 or greater were considered “easy inductions” (Table I) . All 100 patients were accepted for the study whatever their Bishop score, unless they had a previous cesarean section, were grandmultiparas or primiparas, had ruptured membranes, or
and of
20, 382
Volume Number
112 3
PGE,
Table I. Bishop system for scoring inducibility Factor
Score
0
Dilation (cm.) Effacement (9’0) Station Consistency Position
Closed O-30 -3 Firm Posterior
Score
PGF2a:
for
induction
of
labor
383
of labor5
1
Score
1-2 40-50 -2 Medium Midposition
Table II. Dosage of initial
and
2
I
Score
3-4 60-70 -1, 0 Soft Anterior
5+ 80+ +l, +2 Total
3
Factor
Score
--score
-.--
protocol .___
I
Drug
(
Rate
30 pg/c.c.
PGFaa
oxytocin
40
mU./c.c.
were in labor, or if fetal death was evident. The fetal heart rate and uterine contractions were recorded continuously from a scalp electrode and transcervical open-end intra-amniotic catheter on a multichannel polygraph. Membranes were not ruptured for application of monitoring equipment until lf/2 hours of the study had been completed and then not until the patient was in good clinical labor and making progress. Maternal blood pressure, temperature, respirations, and pulse rate were obtained and recorded every hour or more frequently if indicated. Maternal blood was obtained for hematocrit, white blood cell count and differential, and platelet estimation before and the day following induction of labor. The neonate was assigned 1 and 5 minute Apgar scores and was observed for complications during the hospital stay. The infusion was given intravenously by electronic infusion pump per the dose schedule in Table II. The infusion rates were the same for all three drugs; synthetic oxytocin” prostaglandin F,ar ( PGF*(u), and prostaglandin E, (PGE,) in keeping with *Syntocinon, Sandoz Pharmaceuticals, Jersey, 10 United States Pharmacopeia centimeter.
(cdmin.) 0.05 0.1 0.2 0.05 0.1 0.2 0.05 0.1 0.2
3 pg/c.c.
PGE,
Synthetic
Concentration
Hanover, U. per
New cubic
/
Dose
(per 1.5 3.0
min.) I% P!&!
6.0 /.+z! 0.15 0.3
/.Lg Pg
0.6 fig 2 mu. 4 mu. 8 mu.
1
Duration
(hr.) 0.5 8.0 4.0 0.5 8.0 4.0 0.5 8.0 4.0
the double-blind protocol. After using this schedule with 5 patients, verbal information from Karim,6 who was using up to 10 pg per minute of PGF*(Y, suggested that we were probably using an under-dose. Therefore, the protocol was altered to increase the maximum dosage rate for PGF,cK from 6 to 10 pg per minute while PGE, was doubled to 1.2 pg per minute. Because of results poorer than expected, the administration was changed to the schedule in Table III after studying 21 patients. Factors under consideration to account for the discrepancies in results included the greater mean weight of our patient group (=z 10 kilograms), the possible genetic difference in response to prostaglandins by African Bantus, the exclusion of patients with dead fetuses or ruptured membranes from our group, the greater parity of patients in Karim’s study, and finally the lack of an initial objective examination for inducibility of labor. The concentrations of the prostaglandins were increased, the duration of the infusion was decreased to 10 hours, and the maximal dose was increased to 40 and 4.8 pg per minute of F,a and ES, respectively, and for synthetic oxytocin to 16 mu. per minute. The rates were increased according to the schedule only if adequate
384
Anderson,
Table III.
Hobbins,
and Speroff
February 1, 1972 Am. J. Obstet. Gynecol.
Dosage and rates of administration
Drug
Concentration
PGFza
1 Rate
50 pg/c.c.
PGEa
20 mU./c.c.
Table IV. Success rates for synthetic oxytocin, PGF,(u, and PGE, in 79 patients Drug
Synthetic oxytocin PGFza PGEe
Totals
Percentage success
No. of successes
(c.c./min.)
/
D ose (per
2.5 5.0 10.0 20.0 40.0 0.3
0.05 0.1 0.2 0.4 0.8 0.05 0.1 0.2 0.4 0.8 0.05 0.1 0.2 0.4 0.8
6.0 pg/c.c.
Synthetic oxytocin
of second alteration
No.of
23 35 5
27 46 6
79.75
63
79
Resulis
The results obtained after studying 21 patients under the first two protocols are shown in Fig. 1. We see that all 4 patients with a score of 7 or greater were delivered (as indicated by a circle), while in the difficult induction (Bishop score of 6 or less) group, only 4 of 17 patients were delivered. Early in the study, PGE, was withdrawn because of shelf instability; therefore, most comparisons will concern synthetic oxytocin and PGF2a in the 79 patients since the final alteration of the protocol. The over-all success rate for the 3 drugs was 79.75 per cent (Table IV). The success rate for synthetic oxytocin was 85.19 per cent; for PGF,cr, 79.6 per cent; and for PGE2, 83.4 per cent. In the patients with a Bishop score of 6 or less (Table V), a success rate of 91 per cent with synthetic oxyto& and 93.3 per cent with PFG,a was
1
Duration
pg Pg .ug fig pg kg
(hr.)
0.5 0.5 1.0 4.0 4.0 0.5 0.5 1.0 4.0 4.0 0.5 0.5 1.0 4.0 4.0
2.4 fig 4.8 /+c 1 mu. 2 mu. 4 mu. 8 mu. 16 mu.
Table V. Per cent of successful inductions in 55 patients grouped according to difficulty of induction. Successful induction per number of patients in parentheses Bishop score Drug
Synthetic PGFza
clinical progress in labor was not brought about at the previous level.
min.)
0.6 clg 1.2 /kg
cases
85.19 79.6 83.4
of protocol
Bishop score
Bishop score
(O/o)
3-4 57% (4/7)
5-6 91% (llA2)
40 % (2/5)
56% (g/16)
9.3% (14/15)
o-1-2
oxytocin
seen in patients with Bishop scores 5 or 6; the rate was 57 per cent with synthetic oxytocin and 56 per cent with PGF,cu in patients with Bishop scores of 3 or 4; and it was 40 per cent with PGFza in patients with Bishop scores of 0, 1, or 2 (no patients fell into this category in the synthetic oxytocin group). The mean duration of labor was shorter in the difficult group with the use of PGF,a by 1.8 hours and by 1.25 hours in the easy group. This approaches statistical significance (P = 0.06, + test) only if one compares adequate-sized comparable groups such as those with a Bishop score of 5 or 6. The form, frequency, and intensity of contractions were indistinguishable in the 3 groups. However, 7 patients developed transient periods of hypertonus (base-line intrauterine pressure > 15 mm. Hg) or tachysystole (frequency of contractions
Volume Number
112 3
PGE,
2
EEFF
0 0 E E
E r fz V ul
5 6 -
-
ES
x m H a
8
Bishop score
Synthetic oxytocin
O-6 7-13
9.17 5.75
EFSSS
for
induction
of
labor
385
__---
I
.I
PGF,a
Difference
7.77 4.5
1.4 1.25
F
- -OOE ------
7
Pi 0
PGF,a
Table VI. Mean duration of labor and difference (in‘hours) in 73 patients who received synthetic oxytocin or PGF,e grouped according to inducibility of labor -_..-..- - ..~_
1 = +J
and
00 0 0 E S
12
13
Fig. 1. Drugs used in first 21 patients. S = synthetic oxytocin, F = PGFaq E = PGEZ, 0 = delivered. greater than 2 per minute) at various infusion rates; 2 were receiving PGEz and 5 received PGF,(u. In only one case was the fetal heart rate affected-the patient was receiving PGF,a: at 10 pg per minute and had participated in the study for 3yz hours. The drug was discontinued, and the fetal heart rate returned to normal along with the establishment of a uterine tonus of 10 to 15 mm. Hg within 5 minutes. Contractions continued, and the patient was spontaneously delivered of an Apgar 8 to 9 infant one hour later. The cesarean section rate was 1 per cent, the procedure occurring 3 days after a study failure with synthetic oxytocin for cephalopelvic disproportion. There was no significant effect discernible on the following parameters: maternal vital signs, Apgar scoring, neonatal follow-up,
hemogram, maternal gastrointestinal symptoms, or blood loss. Nine of our patients had a past or present history of asthma; however, no attacks occurred during the infusion. Comment The most recent publication on prostaglandins in the induction of labor was the work of Beazley and associates’ in which PGE, and synthetic oxytocin were used in a double-blind study in 300 patients. They found a 73 per cent success rate in each group and concluded that PGE, was no more efficacious than synthetic oxytocin in inducing labor. However, an inducibility index was not utilized. Our over-all success rate (Table IV) for the 3 drugs was 79.75 per cent. The success rate for synthetic oxytocin was 85.19 per cent; for PGF,e 76.01 per cent, and for PGE,, 83.4 per cent. Once again, all patients with a Bishop score of 7 or greater were delivered no matter what drug they received, indicating that these patients may skew effacacy results. At this point, synthetic oxytocin still appears more effective; however, if the results are broken down further according to the inducibility scoring categories (Table V). it can be seen that more low Bishop score patients were present in the PGF,(w group and that results in the Score 3 to 4 and Score 5 to 6 groups were essentially identical. No “very difficult” patients fell into the synthetic oxytocin group, but 2 of 5 in that category were delivered with PGF,a. Without a scoring index, false conclusions might have been drawn at this point. Table VI compares the infusion-delivery interval in successful inductions in the
386
Anderson,
Hobbins,
and
February 1, 1972 Am. J. Obstet. Gynecol.
Speroff
difficult and easy groups for synthetic oxytocin and PGF?(u. As can be seen, the mean duration of labor was shortened in the difficult group with the use of PGF,(u by 1.4 hours and by 1.25 hours in the easy group. A comparison of the time needed from beginning of infusion to the start of adequate clinical labor as determined by cervical effacement and dilatation indicated that the shortening of labor in the difficult PGF,cu group was mainly due to a shortening of the latent phase of labor. The following is concluded: 1. Studies involving the efficacy of oxytocic drugs should include a semiobjective scoring index in order to compare patients with similar scoring indices, As indicated by our study, this of necessity calls for a series of sufficient size to allow significant statistical comparisons of small subgroups. 2. With the dosages administered to these patients, PGF,a was as effective as oxy-
tocin for inducing labor if patients with comparable cervical characteristics are compared. Changes in dose rates or infusion times may yield different results. 3. PGF?a thus far seems to be as safe as synthetic oxytocin in terms of effects on maternal vital signs, fetal heart rate, and neonatal condition. The uterus does seem to be more sensitive to alterations in dosage rates of PGF,cu than to synthetic oxytocin; however, careful adjustment of dosage rates in response to uterine contractions and fetal heart rate has essentially eliminated significant hypertonus or tachysystolia in our hands, no episodes having occurred in the last 40 cases. 4. The mean infusion-delivery interval in the PGF,a! group was shorter in both the easy and difficult induction groups. This trend indicates the only possible advantage noted thus far for PGF,a over synthetic oxytocin.
REFERENCES
1.
2.
3.
Karim, S. M. M., Trussel, R. R., Hillier, K., K., and Patel, R. C.: J. Obstet. Gynaecol. Br. Commonw. 76: 769, 1969. Bygdeman, M., Kwon, S. U., Mukherjee, T., and Wiqvist, N.: AM. J. OBSTET. GYNECOL. 102: 317, 1968. Embrey, M. B.: J. Obstet. Gynaecol. Br. Commonw. 76: 783, 1969.
4. 5. 6.
Roth-Brandel, stet. Gynecol. Bishop, E. H.: Karim, S. M. 487, 1971.
U., and Adams, A.: Acta ObStand. (SuppI.) 49: 9, 1970. Obstet. Gynecol. 24: 266, 1964. M.: Ann. N. Y. Acad. Sci. 180:
7. Beazley, J. M., Dewhurst, J.: J. Obstet. 193, 1970.
Gynaecol.
C. J., and Gillespie, Br.
Commonw.
77: