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Use of osmotic dilators to facilitate induced midtrimester abortion: Clinical evaluations
CONTRACEPTION
USE OF OSMOTIC DILATORS TO FACILITATE INDUCED MIDTRIMESTER ABORTION: CLINICAL EVALUATIONS
Milagros Ronald
F. Atienza,
T. Burkman,
Theodore
M.D.
M.D.
M. King, M.D., Ph.D.
The Fertility Control Center Department of Gynecology and Obstetrics Johns Hopkins Medical Institutions Baltimore, Maryland
Abstract A number of studies evaluating an osmotic cervical dilator consisting of polyvinyl foam saturated with magnesium sulphate in women undergoing midtrimester abortion with intra-amniotic hyperosmolar urea plus prostaglandin F2a were completed. Comparisons with women receiving no pre-treatment with a laminaria tent or with one laminaria indicate that their use appears to shorten injectionabortion intervals, particularly in parous women, and reduce risk of endometritis and cervical laceration compared to women not receiving any type of device. The data suggests that two osmotic dilators may be more effective than one. Also, magnesium toxicity does not appear to be a substantial risk with their use. Submitted for publication August 16, 1984 Accepted for publication August 21, 1984
SEPTEMBER
1984 VOL. 30 NO. 3
215
CONTRACEPTION
In an effort to reduce both morbidity and hospitalization of women undergoing midtrimester abortion beyond 16 weeks duration gestation through the use of intra-amniotic hyperosmolar urea, the Fertility Control Center (FCC) of the Johns Hopkins Medical Institutions has completed a series of clinical studies(l).Recent information indicated that the use of hyperosmolar urea in conjunction with augmentation with intraamniotic prostaglandin F2a (PGF2a) produced injection-abortion Further, the intervals averaging between 12 and 17 hours. pre-injection use of laminaria tents appears to either maintain or reduce the occurrence of cervical laceration (at a rate between 0.5 to 1.4%) as a complication despite the shortened injection-abortion intervals. Most laminaria used in the United States are made of specifically prepared dried seaweed, the Laminaria japonica. These laminaria are highlv hvgroscopic and with absorption of fluid, they increase in mass-3 to 5-times the originai size. Thus by this mechanism or by altering the fluid characteristics of the cervix, they result in gradual dilatation of the cervix over several hours. Recently, a new osmotic cervical dilator consisting of of magnesium polyvinyl alcohol foam saturated with @.211gm sulphate to form a thin cylindrical tent (3 to 5mm diameter, The magnesium sulphate in 75mm length) has been prepared.* the dilator serves an an osmotic substance which retains fluid from the cervical tissue effecting a gradual dilatation Since these dilators can be made under conof the cervix. trolled conditions, concern about potential infectious sequelae with their use is less than with the use of Laminaria japonica. However, their use in conjunction with midtrimester The purpose of abortion procedures has not been evaluated. this study is to present the results of a series of experiments designed to test the efficacy and safety of these new osmotic cervical dilators. Methods The procedures and definitions used in the FCC have been extensively described previously(l,2). Therefore, this section will only highlight important aspects of our approach. For the studies described, only women requesting abortion between 16 and 21 weeks duration of gestation from the last Specific exclusions for the menstrual period were included. history of evaluation of the osmotic dilators included: threatened abortion in the current pregnancy, a previous cervical surgical procedure such as conization or cerclage,
*Lamicel,
216
Cabot Medical
Devices,
Langhorne,
SEPTEMBER
Pennsylvania
1984 VOL. 30 NO. 3
CONTRACEPTION
history or presence of renal insufficiency, or presence of a cardiac arrhythmia.
and history
The abortifacients used in all patients consisted of 135ml of a 59.7% concentration of urea plus 5mg of prostaglandin F2a (PGF2a) given intra-amniotically after removal of 100 to 200ml of amniotic fluid. Complete abortion was defined as passage of the fetus and placenta without instrumentation within 48 hours; incomplete abortion was defined as instrumental removal of the placenta after fetal abortion if the placenta was not passed within two hours or if bleeding or fever mandated earlier removal. Failed abortion was defined as failure to pass the fetus within 48 hours. Women in this category undergo vaginal evacuation to complete the procedure. To test the efficacy and safety of the osmotic dilators, a variety of experiments were performed. The first 10 women had their pre-insertion cervical canal diameter estimated with a K-Pratt dilator, a single 5mm osmotic dilator was then inserted, the osmotic dilator was then removed after 3 to 4 hours and the cervical canal diameter was then remeasured, and the injection procedure was carried out. Serum magnesium levels were also determined prior to insertion and at 2, 6, 12 and 24 hours post-insertion. The remaining women receiving osmotic dilators had either one or two 3 or 5mm diameter dilators inserted depending on ease of insertion 3 to 4 hours prior to the injection procedure and the dilators were left in place until fetal abortion. In addition, the first 6 patients receiving two dilators had serum magnesium levels determined prior to insertion and at 2, 6, 12 and 24 hours post-insertion. Two treatment dilators three to selected
cohorts of women presenting to the FCC undergoing with the same abortifacients without laminaria or or with the insertion of one Laminaria japonica four hours prior to injection and left in place were for comparison.
The serum magnesium levels were determined by atomic Statistical significance between absorption spectrometry. the various groups when assessing various outcome measures was carried out using the Student's t test and the Chi-Square test. Results Table I provides data on the clinical characteristics Although the women undergoing of the subjects in this study. abortion with the osmotic dilators had shorter mean durations of gestation, the differences were not felt to be of substanFor the first 10 patients who tial clinical significance.
SEPTEMBER
1984 VOL. 30 NO. 3
217
CONTRACEPTION
TABLE I Clinical Characteristics of Urea plus PGFZa(5mg) Patients* No.
Mean Age
Para 0
Para 1 or Greater
Mean Duration of Gestation(Weeks)
No laminaria tents
349
20.0 (13-40)
216
133
19.6 (14-24)
One laminaria tent
197
19.5 (13-38)
160
37
19.9 (16-22)
One osmotic dilator
21
21.3 (16-26)
9
12
18.2 (17-19)
Two osmotic dilators
69
19.9 (14-41)
33
36
18.1 (16-21)
*Ranges in parenthesis
218
SEPTEMBER
1984 VOL. 30 NO. 3
CONTRACEPTION
received only one osmotic dilator, the mean cervical diameter as estimated with K-Pratt dilators prior to insertion of an osmotic dilator was 5.3mm. After three or four hours of treatment and prior to injection, the mean cervical diameter had increased to 10.7mm (p(O.001). In addition, the serum magnesium levels at all times ranged between 1.3 and 1.9mg/lOOml (normal range for females 1.5 to 1.9mg/lOOml). Further, the serum magnesium levels for the 6 women in whom two osmotic dilators were left in place until fetal abortion occurred ranged from 1.4 to 1.9mg/lOOml. Table II provides a comparison of the injection-abortion intervals for the various study groups, by parity. Since there were no major differences in outcome for the women receiving only a single osmotic dilator regardless of duration of use, the two duration groups for a single dilator were combined for subsequent analysis. Except for the comparison of no laminaria to a single osmotic dilator, the use of any type of laminaria or osmotic dilator shortened the injection-abortion intervals for both the parity 0 and the parity 1 or greater women (~(0.05). For the parity 0 women, the difference in injection-abortion intervals between the two dilator and one dilator groups was significant (p
SEPTEMBER
1984 VOL. 30 NO. 3
219
CONTRACEPTION
TABLE II Injection-Abortion Intervals of Urea plus PGF2a(5mg) Patients Injection-Abortion Interval (Hours)* No.
Mean
Range
No laminaria
213
17.0
6-45
One laminaria
160
12.0
4-46
9
18.3
9-34
30
12.5
4-40
133
16.3
3-46
One laminaria
37
13.9
4-44
One osmotic dilator
12
14.2
4-25
Two osmotic dilators
37
11.4
3-31
No laminaria
346
16.7
3-46
One laminaria
Parity:
0
One osmotic dilator Two osmotic dilators Parity:
1 or greater
No laminaria
Total Groups
197
12.3
4-46
One osmotic dilator
21
16.0
4-34
Two osmotic dilators
67
11.9
3-40
*From intra-amniotic injection of medication to abortion of fetus
220
SEPTEMBER 1984VOL.30NO.3
CONTRACEPTION
TABLE III Clinical Outcome of Urea plus PGF2a(5mg) Patients No.
Complete Abortion /, No.
Incomplete Ahortion Failure r-- Kx---z NO.
No laminaria
349
222
63.6
124
35.5
3
0.0
One laminaria
197
140
71.1
55
27.9
2
I.O
One osmotic dilator
21
8
38.1
13
61.9
0
0 0
Two osmotic dilators
69
42
60.9
25
36.2
2
7.9
TABLE IV Complications of Urea plus PGFZa(5mg) Patients
Hemorrhage (500~~ or need for curettage)
No Laminaria (349 cases)
One Laminaria (197 cases)
Osmot%?Dilator (21 casts)
Osmot T?Dilators (69 cases)
NO.
%
No.
%
No.
%
No.
%
8.9
7
3.6
4
19.0
9
13.0
31
Endometritis Hospitalization
6
1.7
2
1.0
0
0.0
0
r) .
11
3.2
2
1.0
0
0.0
0
0.0
Transverse
3
0.9
1
1.0
0
0.0
0
0.0
Vertical
5
1.4
2
0.5
0
0.0
1
1.5
Outpatient
il
Cervical Laceration
SEPTEMBER
1984 VOL. 30 NO. 3
221
CONTRACEPTION
Discussion A prior study has shown that the use of osmotic dilators prior to first trimester suction abortion significantly reduces the force needed to dilate the cervix(3).The current study was conducted to evaluate their use in women undergoing midtrimester amnioinfusion abortion. As shown in this study, their use compares favorably with the use of a single Laminaria japonica. The use of two osmotic dilators, at least in parous women, appears to be even more effective. In addition, the use of osmotic dilators also appears to reduce endometritis when compared to women not receiving any laminaria. Although the reasons are not clear, the shortening of the injectionabortion interval probably is important. Also, the use of any type of cervical dilating device appears to reduce but not eliminate the risk of cervical laceration. The reasons for the variation in incomplete abortion rates as well as rates of hemorrhage are unclear. However, the data suggests that the use of two osmotic dilators reduces the occurrence of both these problems when compared with only one osmotic dilator. Finally, the measurements of serum magnesium levels in this study do not indicate that magnesium toxicity is a serious risk with the use of these devices in pregnant women. In conclusion, the use of osmotic dilators in women undergoing midtrimester abortion with hyperosmolar urea and PGF2a appears to shorten injection-abortion intervals and reduce risk of endometritis and cervical laceration compared to women not receiving any type of pre-abortion cervical device. The data also suggests that the use of two osmotic dilators may be more effective than either a single osmotic dilator or Laminaria japonica particularly in parous women. In addition, the use of two dilators appearsto reduce the risk of hemorrhage and incomplete abortion when compared to a Magnesium toxicity does not appear single osmotic dilator. to be a substantial risk with the use of osmotic dilators.
222
SEPTEMBER 1984VOL.30N0.3
CONTRACEPTION
References 1.
Burkman RT, King TM, Atienza MF: Hyperosmolar urea in second trimester abortion In:Second Trimester Abortion: Perspectives After a Pecade of Experience (Berger GS, Brenner WE, Keith LG, Editors). John Wright, PSG, Inc., Boston, 1981
2.
Burkman RT, Atienza MF, King TM, Tonascia JA, Pang JCK, Whitmore AJ: Hyperosmolar urea for elective midtrimester abortion: experience in 1913 cases. Amer J. Obstet. Gynecol 131:10, 1978
3.
Nicolaides KH, Welch CC, MacPherson MBA, Johnson LA et -- al: Lamicel: a new technique for cervical dilatation before first trimester abortion. Brit J. Obstet. Gynecol. 90:475, 1983
SEPTEMBER 1984VOL.30NO.3
223
USE OF OSMOTIC DILATORS TO FACILITATE INDUCED MIDTRIMESTER ABORTION: CLINICAL EVALUATIONS
Milagros Ronald
F. Atienza,
T. Burkman,
Theodore
M.D.
M.D.
M. King, M.D., Ph.D.
The Fertility Control Center Department of Gynecology and Obstetrics Johns Hopkins Medical Institutions Baltimore, Maryland
Abstract A number of studies evaluating an osmotic cervical dilator consisting of polyvinyl foam saturated with magnesium sulphate in women undergoing midtrimester abortion with intra-amniotic hyperosmolar urea plus prostaglandin F2a were completed. Comparisons with women receiving no pre-treatment with a laminaria tent or with one laminaria indicate that their use appears to shorten injectionabortion intervals, particularly in parous women, and reduce risk of endometritis and cervical laceration compared to women not receiving any type of device. The data suggests that two osmotic dilators may be more effective than one. Also, magnesium toxicity does not appear to be a substantial risk with their use. Submitted for publication August 16, 1984 Accepted for publication August 21, 1984
SEPTEMBER
1984 VOL. 30 NO. 3
215
CONTRACEPTION
In an effort to reduce both morbidity and hospitalization of women undergoing midtrimester abortion beyond 16 weeks duration gestation through the use of intra-amniotic hyperosmolar urea, the Fertility Control Center (FCC) of the Johns Hopkins Medical Institutions has completed a series of clinical studies(l).Recent information indicated that the use of hyperosmolar urea in conjunction with augmentation with intraamniotic prostaglandin F2a (PGF2a) produced injection-abortion Further, the intervals averaging between 12 and 17 hours. pre-injection use of laminaria tents appears to either maintain or reduce the occurrence of cervical laceration (at a rate between 0.5 to 1.4%) as a complication despite the shortened injection-abortion intervals. Most laminaria used in the United States are made of specifically prepared dried seaweed, the Laminaria japonica. These laminaria are highlv hvgroscopic and with absorption of fluid, they increase in mass-3 to 5-times the originai size. Thus by this mechanism or by altering the fluid characteristics of the cervix, they result in gradual dilatation of the cervix over several hours. Recently, a new osmotic cervical dilator consisting of of magnesium polyvinyl alcohol foam saturated with @.211gm sulphate to form a thin cylindrical tent (3 to 5mm diameter, The magnesium sulphate in 75mm length) has been prepared.* the dilator serves an an osmotic substance which retains fluid from the cervical tissue effecting a gradual dilatation Since these dilators can be made under conof the cervix. trolled conditions, concern about potential infectious sequelae with their use is less than with the use of Laminaria japonica. However, their use in conjunction with midtrimester The purpose of abortion procedures has not been evaluated. this study is to present the results of a series of experiments designed to test the efficacy and safety of these new osmotic cervical dilators. Methods The procedures and definitions used in the FCC have been extensively described previously(l,2). Therefore, this section will only highlight important aspects of our approach. For the studies described, only women requesting abortion between 16 and 21 weeks duration of gestation from the last Specific exclusions for the menstrual period were included. history of evaluation of the osmotic dilators included: threatened abortion in the current pregnancy, a previous cervical surgical procedure such as conization or cerclage,
*Lamicel,
216
Cabot Medical
Devices,
Langhorne,
SEPTEMBER
Pennsylvania
1984 VOL. 30 NO. 3
CONTRACEPTION
history or presence of renal insufficiency, or presence of a cardiac arrhythmia.
and history
The abortifacients used in all patients consisted of 135ml of a 59.7% concentration of urea plus 5mg of prostaglandin F2a (PGF2a) given intra-amniotically after removal of 100 to 200ml of amniotic fluid. Complete abortion was defined as passage of the fetus and placenta without instrumentation within 48 hours; incomplete abortion was defined as instrumental removal of the placenta after fetal abortion if the placenta was not passed within two hours or if bleeding or fever mandated earlier removal. Failed abortion was defined as failure to pass the fetus within 48 hours. Women in this category undergo vaginal evacuation to complete the procedure. To test the efficacy and safety of the osmotic dilators, a variety of experiments were performed. The first 10 women had their pre-insertion cervical canal diameter estimated with a K-Pratt dilator, a single 5mm osmotic dilator was then inserted, the osmotic dilator was then removed after 3 to 4 hours and the cervical canal diameter was then remeasured, and the injection procedure was carried out. Serum magnesium levels were also determined prior to insertion and at 2, 6, 12 and 24 hours post-insertion. The remaining women receiving osmotic dilators had either one or two 3 or 5mm diameter dilators inserted depending on ease of insertion 3 to 4 hours prior to the injection procedure and the dilators were left in place until fetal abortion. In addition, the first 6 patients receiving two dilators had serum magnesium levels determined prior to insertion and at 2, 6, 12 and 24 hours post-insertion. Two treatment dilators three to selected
cohorts of women presenting to the FCC undergoing with the same abortifacients without laminaria or or with the insertion of one Laminaria japonica four hours prior to injection and left in place were for comparison.
The serum magnesium levels were determined by atomic Statistical significance between absorption spectrometry. the various groups when assessing various outcome measures was carried out using the Student's t test and the Chi-Square test. Results Table I provides data on the clinical characteristics Although the women undergoing of the subjects in this study. abortion with the osmotic dilators had shorter mean durations of gestation, the differences were not felt to be of substanFor the first 10 patients who tial clinical significance.
SEPTEMBER
1984 VOL. 30 NO. 3
217
CONTRACEPTION
TABLE I Clinical Characteristics of Urea plus PGFZa(5mg) Patients* No.
Mean Age
Para 0
Para 1 or Greater
Mean Duration of Gestation(Weeks)
No laminaria tents
349
20.0 (13-40)
216
133
19.6 (14-24)
One laminaria tent
197
19.5 (13-38)
160
37
19.9 (16-22)
One osmotic dilator
21
21.3 (16-26)
9
12
18.2 (17-19)
Two osmotic dilators
69
19.9 (14-41)
33
36
18.1 (16-21)
*Ranges in parenthesis
218
SEPTEMBER
1984 VOL. 30 NO. 3
CONTRACEPTION
received only one osmotic dilator, the mean cervical diameter as estimated with K-Pratt dilators prior to insertion of an osmotic dilator was 5.3mm. After three or four hours of treatment and prior to injection, the mean cervical diameter had increased to 10.7mm (p(O.001). In addition, the serum magnesium levels at all times ranged between 1.3 and 1.9mg/lOOml (normal range for females 1.5 to 1.9mg/lOOml). Further, the serum magnesium levels for the 6 women in whom two osmotic dilators were left in place until fetal abortion occurred ranged from 1.4 to 1.9mg/lOOml. Table II provides a comparison of the injection-abortion intervals for the various study groups, by parity. Since there were no major differences in outcome for the women receiving only a single osmotic dilator regardless of duration of use, the two duration groups for a single dilator were combined for subsequent analysis. Except for the comparison of no laminaria to a single osmotic dilator, the use of any type of laminaria or osmotic dilator shortened the injection-abortion intervals for both the parity 0 and the parity 1 or greater women (~(0.05). For the parity 0 women, the difference in injection-abortion intervals between the two dilator and one dilator groups was significant (p
SEPTEMBER
1984 VOL. 30 NO. 3
219
CONTRACEPTION
TABLE II Injection-Abortion Intervals of Urea plus PGF2a(5mg) Patients Injection-Abortion Interval (Hours)* No.
Mean
Range
No laminaria
213
17.0
6-45
One laminaria
160
12.0
4-46
9
18.3
9-34
30
12.5
4-40
133
16.3
3-46
One laminaria
37
13.9
4-44
One osmotic dilator
12
14.2
4-25
Two osmotic dilators
37
11.4
3-31
No laminaria
346
16.7
3-46
One laminaria
Parity:
0
One osmotic dilator Two osmotic dilators Parity:
1 or greater
No laminaria
Total Groups
197
12.3
4-46
One osmotic dilator
21
16.0
4-34
Two osmotic dilators
67
11.9
3-40
*From intra-amniotic injection of medication to abortion of fetus
220
SEPTEMBER 1984VOL.30NO.3
CONTRACEPTION
TABLE III Clinical Outcome of Urea plus PGF2a(5mg) Patients No.
Complete Abortion /, No.
Incomplete Ahortion Failure r-- Kx---z NO.
No laminaria
349
222
63.6
124
35.5
3
0.0
One laminaria
197
140
71.1
55
27.9
2
I.O
One osmotic dilator
21
8
38.1
13
61.9
0
0 0
Two osmotic dilators
69
42
60.9
25
36.2
2
7.9
TABLE IV Complications of Urea plus PGFZa(5mg) Patients
Hemorrhage (500~~ or need for curettage)
No Laminaria (349 cases)
One Laminaria (197 cases)
Osmot%?Dilator (21 casts)
Osmot T?Dilators (69 cases)
NO.
%
No.
%
No.
%
No.
%
8.9
7
3.6
4
19.0
9
13.0
31
Endometritis Hospitalization
6
1.7
2
1.0
0
0.0
0
r) .
11
3.2
2
1.0
0
0.0
0
0.0
Transverse
3
0.9
1
1.0
0
0.0
0
0.0
Vertical
5
1.4
2
0.5
0
0.0
1
1.5
Outpatient
il
Cervical Laceration
SEPTEMBER
1984 VOL. 30 NO. 3
221
CONTRACEPTION
Discussion A prior study has shown that the use of osmotic dilators prior to first trimester suction abortion significantly reduces the force needed to dilate the cervix(3).The current study was conducted to evaluate their use in women undergoing midtrimester amnioinfusion abortion. As shown in this study, their use compares favorably with the use of a single Laminaria japonica. The use of two osmotic dilators, at least in parous women, appears to be even more effective. In addition, the use of osmotic dilators also appears to reduce endometritis when compared to women not receiving any laminaria. Although the reasons are not clear, the shortening of the injectionabortion interval probably is important. Also, the use of any type of cervical dilating device appears to reduce but not eliminate the risk of cervical laceration. The reasons for the variation in incomplete abortion rates as well as rates of hemorrhage are unclear. However, the data suggests that the use of two osmotic dilators reduces the occurrence of both these problems when compared with only one osmotic dilator. Finally, the measurements of serum magnesium levels in this study do not indicate that magnesium toxicity is a serious risk with the use of these devices in pregnant women. In conclusion, the use of osmotic dilators in women undergoing midtrimester abortion with hyperosmolar urea and PGF2a appears to shorten injection-abortion intervals and reduce risk of endometritis and cervical laceration compared to women not receiving any type of pre-abortion cervical device. The data also suggests that the use of two osmotic dilators may be more effective than either a single osmotic dilator or Laminaria japonica particularly in parous women. In addition, the use of two dilators appearsto reduce the risk of hemorrhage and incomplete abortion when compared to a Magnesium toxicity does not appear single osmotic dilator. to be a substantial risk with the use of osmotic dilators.
222
SEPTEMBER 1984VOL.30N0.3
CONTRACEPTION
References 1.
Burkman RT, King TM, Atienza MF: Hyperosmolar urea in second trimester abortion In:Second Trimester Abortion: Perspectives After a Pecade of Experience (Berger GS, Brenner WE, Keith LG, Editors). John Wright, PSG, Inc., Boston, 1981
2.
Burkman RT, Atienza MF, King TM, Tonascia JA, Pang JCK, Whitmore AJ: Hyperosmolar urea for elective midtrimester abortion: experience in 1913 cases. Amer J. Obstet. Gynecol 131:10, 1978
3.
Nicolaides KH, Welch CC, MacPherson MBA, Johnson LA et -- al: Lamicel: a new technique for cervical dilatation before first trimester abortion. Brit J. Obstet. Gynecol. 90:475, 1983
SEPTEMBER 1984VOL.30NO.3
223