CONTRACEPTION
INTRAUTERINE DEVICE AND ECTOPIC PREGNANCY R. Erkkola and P. Liukko Department of Obstetrics and Gynecology University Central Hospital SF 20520 TURKU 52, Finland
ABSTRACT
In Turku, Finland, 345 ectopic pregnancies were diagnosed in the period 1966 - 1975. Calculated from the number of deliveries, the incidence of ectopic pregnancy was 0.60 % in 1966 - 70, and 1.08 % in 1971 - 75. This difference is significant (p < 0.001). During the period studied, 59 cases of ectopic pregnancy presented with an intrauterine device _in situ, thus accounting for 17 % of the total number seen. The use of intrauterine devices increased considerably after 1972. From that year, 29 % of all ectopic pregnancies occurred with an intrauterine device in situ. Our findings accord well with other investigations,which emphasize the major role of intrauterine devices in raising the incidence of ectopic pregnancy.
Accepted for publication September 29, 1977
DECEMBER 1977 VOL. 16 NO. 6
569
CONTRACEPTION
INTRODUCTION The incidence of ectopic pregnancy has been shown to have risen in some countries (1, 2). Intrauterine contraceptive devices (IUDs) have been considered the most important cause of this increase (1, 2). In Finland the use of IUDs was rather limited in the 1960's but exact numbers are not known. Since 1972 the number of insertions has increased considerably and for example in Turku, Finland and its surroundings (pop. 250,000), approximately 11,000 Copper Ts and 8,000 Dalkon shields were inserted during 1972 - 75. The rapid increase in the number of IUDs was felt to be reflected in the incidence of ectopic pregnancy and therefore the following study was undertaken. MATERIALS
AND METHODS
A total of 345 ectopic pregnancies was diagnosed in Turku during 1966 - 75. Information on the method of contraception was obtained from case histories and if no data were found, patients were interviewed. Where an IUD had been used, the type of device was ascertained from the patient or the doctor who performed the insertion. Data from this period on deliveries as well as on spontaneous and induced abortions were collected from the Turku hospitals. The history regarding previous abdominal operations or pelvic inflammatory diseases (PID) was recorded.
RESULTS Table I shows the annual number of pregnancies and deliveries in Turku with the annual number of ectopic pregnancies and anndal incidence calculated from the total number of deliveries and pregnancies. In the decade 1966 - 75 the mean incidence of ectopic pregnancy was 0.88 % of deliveries and 0.66 % of pregnancies. During the decade the annual rise of incidences hasbeen significant as presented in Table I. The incidence in the consecutive S-year periods is presented in Table II. During the latter period the incidence of ectopic pregnancy was significantly (p < 0.001) higher when calculated from the total number of deliveries. Table III presents the annual number of ectopic pregnancies with IUDs in situ during the study period. There-were 59 ectopic pregnancierw=IUDs (17.1 % of all ectopic pregnancies). The increase in the number of ectopic pregnancies has been significant (p < 0.001). When the consecutive 5-year periods again are compared, during the latter period the number of ectopic pregnancies is significantly higher (X1 = 27.45, p < 0.001). Table IV presents ent IUDs.
570
the number of ectopic pregnancies
with differ-
DECEMBER 1977 VOL. 16 NO. 6
CONTRACEPTION
A previous abdominal operation was performed to 28.3 % (81 patients) in the group without IUD and to 25.4 % (15 patients) in the IUD group. The difference is not significant. Forty-nine patients (17.1 %) in the group without IUD claimed to have had a previous PID whereas in the IUD group only 3 patients (5.1 %) gave the same history. The difference is significant (x2 =,3.90, p < 0.05). l,c Table I
Year
Deliveries, pregnancies and ectopic pregnancies in Turku, Finland in 1966 - 75. The linear regressions of annual incidences are presented below the Table.
Incidence of ectopics(%) Nullbec of deliveriespregnanciesectopics frandeliveries*pregnancies**
1966 4074 1967 3944 4104 1968 1969 3960 1970 3945 1971 3830 1972 3640 1973 3540 1974 3991 1975 4162 Total 39190 * 2 Y
=
4641 4585 4784 4873 5263 5512 5348 5452 5964 6100 52522
23 28 24 28 34 39 30 39 53 47 345 ** 2
0.81
Y
b" = 0.46 0.08 t8 = 5.84 P < 0.001
0.56 0.71 0.58 0.71 0.86 1.02 0.82 1.10 1.33 1.13 0.88
;: = 0.46 0.03 tg = 3.87 P < 0.01
The incidence of ectopic pregnancies in consecutive 5-year periods.
Years
Incidence of ectopic pregnancies (%) from deliveries* pregnancies**
*2 = 17.62 x1 P ( 0.001
0.66
= 0.65
Table II
1966-70 1971-75
0.50 0.61 0.50 0.57 0.65 0.71 0.56 0.72 0.89 0.77
0.68 (1:146) 1.09 (1:92)
0.57 (1:176) 0.73 (1:136) ** 2 = 5.23 x1 P < 0.05
DECEMBER 1977 VOL. 16 NO. 6
571
CONTRACEPTION
Table III Number of ectopic pregnancies with IUD and proportion of all ectopic pregnancies in Turku in 1966 - 15. Below the Table the linear regression of the annual incidence is presented.
Year
Ectopic pregnancies
1966 1967 1968 1969 1970 1971 1972 1973 1974 1975
23 28 24 28 34 39 30 39 53 41
1 2 2 6 8 14 15 11
4.2 7.1 5.9 15.4 26.6 35.9 28.8 23.4
345
59
17.1
Total *
Ectopic pregnancies
with IUD
Incidence* (%) 0 0
2 Y
=
0.8
ts = 5.63
;: = 6.56 3.81
Table IV
P
< 0.001
Number of ectopic pregnancies
IUD Lippes loop Dalkon shield Copper T Saf-T coil Copper 7 Bow Inhiband
with different
IUDs.
Number of ectopics 26 14 10 4 2 2 1
DISCUSSION The incidence of ectopic pregnancy varies considerably in different parts of the world. The highest figures come from Jamaica, where there is one ectopic pregnancy in 28 deliveries, whereas in some areas of the United States the figure is only one tenth of this (2). In Finland the incidence of ectopic pregnancy has fluctuated during this century.
572
DECEMBER 1977 VOL. 16 NO. 6
CONTRACEPTION
1901 - 29 the incidence was 0.4 - 1.4 % (3) and in 1930 it varied annually between land2 % (4) when calculated in Helsinki from the number of deliveries. The present incidence in the third largest city in Finland is very close to those figures. In this study, however, a significant increase in the incidence of ectopic pregnancy was found when consecutive 5-year periods were compared. Thus our findings are parallel to the trend observed in England (1).
::
In England it has been estimated that the risk of ectopic pregnancy with IUDs is six-fold in comparison with other pregnancies (5). The present study shows that ectopic pregnancies with IUDs account for 29 % of all ectopic pregnancy during the last 4 years. This together with ectopic pregnancies occurring during the use of low dose progestogens (6) is enough to explain the increased incidence found in this study. It is not quite clear if IUDs really cause ectopic pregnancies. From a theoretical point of view it is understandable that IUDs inhibit intrauterine pregnancy but have little influence upon extrauterine pregnancy. Since the rate of conception is high among IUD users, they are also more exposed to the risk of ectopic pregnancy. It is not certain whether IUDs decrease the motility of the oviduct but this is also a possible cause of ectopic pregnancy. It has been furthermore suggested that PID is 5 times more common among IUD users than in other women (7) and this may increase the risk of ectopic pregnancy. Inourstudy, however, the patients having an ectopic pregnancy when the IUD was in situ had had significantly less PID than the patiezshaving an ectopic pregnancy without IUD. This is probably due to the selection of the patients when the insertion of IUD is considered, since the use of IUD is generally avoided if the woman has a history of previous PIDs. This finding of a low PID rate in patients using IUD suggests that the PID is not of decisive importance as an etiological factor when an ectopic pregnancy occurs during IUD use. In this study ectopic pregnancies were found to occur during use of all registered types of IUD?.. Because the numbers of insertions and the continuation rate for different IUDs can not be estimated reliably enough, it is impossible to make comparisons between the risk associated with different types of IUD. Our impression is that the number of ectopic pregnancies closely reflects the number of insertions of individual IUDs.
DECEMBER 1977 VOL. 16 NO. 6
573
CONTRACEPTION
REFERENCES 1. Beral, V. An epidemiological study on recent trends in ectopic pregnancy. Br J Obstet Gynaecol 82: 175, 1975. 2. Hallat, J.G. Ectopic pregnancy associated with intrauterine device: a study of seventy cases. Am J Obstet Gynecol 125: 754, 1976. 3. Apajalahti, A. Zur inflanunatorischen Athiologie der Tubenschwangerschaft. Acta Sot Med Fenn (Duodecim) B: 16, 1931. 4. Kinnunen, 0. and Jgrvinen, P. Some aspects on ectopic pregnancy, its treatment and results. Duodecim (Helsinki) 68: suppl 23, 1952. 5. Vessey, M.P., Johnson, B., Doll, R. and Peto, R. Outcome of pregnancy in women using an intrauterine device. Lancet 1: 495, 1974. 6. Liukko, P., Erkkola, R. and Laakso, L. Ectopic pregnancies during use of low-dose progestogens for oral 16:575,1977. contraception. Contraception 7. Editorial: Risk of pelvic infection associated intrauterine devices. Br Med J 2: 717, 1976.
574
with
DECEMBER 1977 VOL. 16 NO. 6
INTRAUTERINE DEVICE AND ECTOPIC PREGNANCY R. Erkkola and P. Liukko Department of Obstetrics and Gynecology University Central Hospital SF 20520 TURKU 52, Finland
ABSTRACT
In Turku, Finland, 345 ectopic pregnancies were diagnosed in the period 1966 - 1975. Calculated from the number of deliveries, the incidence of ectopic pregnancy was 0.60 % in 1966 - 70, and 1.08 % in 1971 - 75. This difference is significant (p < 0.001). During the period studied, 59 cases of ectopic pregnancy presented with an intrauterine device _in situ, thus accounting for 17 % of the total number seen. The use of intrauterine devices increased considerably after 1972. From that year, 29 % of all ectopic pregnancies occurred with an intrauterine device in situ. Our findings accord well with other investigations,which emphasize the major role of intrauterine devices in raising the incidence of ectopic pregnancy.
Accepted for publication September 29, 1977
DECEMBER 1977 VOL. 16 NO. 6
569
CONTRACEPTION
INTRODUCTION The incidence of ectopic pregnancy has been shown to have risen in some countries (1, 2). Intrauterine contraceptive devices (IUDs) have been considered the most important cause of this increase (1, 2). In Finland the use of IUDs was rather limited in the 1960's but exact numbers are not known. Since 1972 the number of insertions has increased considerably and for example in Turku, Finland and its surroundings (pop. 250,000), approximately 11,000 Copper Ts and 8,000 Dalkon shields were inserted during 1972 - 75. The rapid increase in the number of IUDs was felt to be reflected in the incidence of ectopic pregnancy and therefore the following study was undertaken. MATERIALS
AND METHODS
A total of 345 ectopic pregnancies was diagnosed in Turku during 1966 - 75. Information on the method of contraception was obtained from case histories and if no data were found, patients were interviewed. Where an IUD had been used, the type of device was ascertained from the patient or the doctor who performed the insertion. Data from this period on deliveries as well as on spontaneous and induced abortions were collected from the Turku hospitals. The history regarding previous abdominal operations or pelvic inflammatory diseases (PID) was recorded.
RESULTS Table I shows the annual number of pregnancies and deliveries in Turku with the annual number of ectopic pregnancies and anndal incidence calculated from the total number of deliveries and pregnancies. In the decade 1966 - 75 the mean incidence of ectopic pregnancy was 0.88 % of deliveries and 0.66 % of pregnancies. During the decade the annual rise of incidences hasbeen significant as presented in Table I. The incidence in the consecutive S-year periods is presented in Table II. During the latter period the incidence of ectopic pregnancy was significantly (p < 0.001) higher when calculated from the total number of deliveries. Table III presents the annual number of ectopic pregnancies with IUDs in situ during the study period. There-were 59 ectopic pregnancierw=IUDs (17.1 % of all ectopic pregnancies). The increase in the number of ectopic pregnancies has been significant (p < 0.001). When the consecutive 5-year periods again are compared, during the latter period the number of ectopic pregnancies is significantly higher (X1 = 27.45, p < 0.001). Table IV presents ent IUDs.
570
the number of ectopic pregnancies
with differ-
DECEMBER 1977 VOL. 16 NO. 6
CONTRACEPTION
A previous abdominal operation was performed to 28.3 % (81 patients) in the group without IUD and to 25.4 % (15 patients) in the IUD group. The difference is not significant. Forty-nine patients (17.1 %) in the group without IUD claimed to have had a previous PID whereas in the IUD group only 3 patients (5.1 %) gave the same history. The difference is significant (x2 =,3.90, p < 0.05). l,c Table I
Year
Deliveries, pregnancies and ectopic pregnancies in Turku, Finland in 1966 - 75. The linear regressions of annual incidences are presented below the Table.
Incidence of ectopics(%) Nullbec of deliveriespregnanciesectopics frandeliveries*pregnancies**
1966 4074 1967 3944 4104 1968 1969 3960 1970 3945 1971 3830 1972 3640 1973 3540 1974 3991 1975 4162 Total 39190 * 2 Y
=
4641 4585 4784 4873 5263 5512 5348 5452 5964 6100 52522
23 28 24 28 34 39 30 39 53 47 345 ** 2
0.81
Y
b" = 0.46 0.08 t8 = 5.84 P < 0.001
0.56 0.71 0.58 0.71 0.86 1.02 0.82 1.10 1.33 1.13 0.88
;: = 0.46 0.03 tg = 3.87 P < 0.01
The incidence of ectopic pregnancies in consecutive 5-year periods.
Years
Incidence of ectopic pregnancies (%) from deliveries* pregnancies**
*2 = 17.62 x1 P ( 0.001
0.66
= 0.65
Table II
1966-70 1971-75
0.50 0.61 0.50 0.57 0.65 0.71 0.56 0.72 0.89 0.77
0.68 (1:146) 1.09 (1:92)
0.57 (1:176) 0.73 (1:136) ** 2 = 5.23 x1 P < 0.05
DECEMBER 1977 VOL. 16 NO. 6
571
CONTRACEPTION
Table III Number of ectopic pregnancies with IUD and proportion of all ectopic pregnancies in Turku in 1966 - 15. Below the Table the linear regression of the annual incidence is presented.
Year
Ectopic pregnancies
1966 1967 1968 1969 1970 1971 1972 1973 1974 1975
23 28 24 28 34 39 30 39 53 41
1 2 2 6 8 14 15 11
4.2 7.1 5.9 15.4 26.6 35.9 28.8 23.4
345
59
17.1
Total *
Ectopic pregnancies
with IUD
Incidence* (%) 0 0
2 Y
=
0.8
ts = 5.63
;: = 6.56 3.81
Table IV
P
< 0.001
Number of ectopic pregnancies
IUD Lippes loop Dalkon shield Copper T Saf-T coil Copper 7 Bow Inhiband
with different
IUDs.
Number of ectopics 26 14 10 4 2 2 1
DISCUSSION The incidence of ectopic pregnancy varies considerably in different parts of the world. The highest figures come from Jamaica, where there is one ectopic pregnancy in 28 deliveries, whereas in some areas of the United States the figure is only one tenth of this (2). In Finland the incidence of ectopic pregnancy has fluctuated during this century.
572
DECEMBER 1977 VOL. 16 NO. 6
CONTRACEPTION
1901 - 29 the incidence was 0.4 - 1.4 % (3) and in 1930 it varied annually between land2 % (4) when calculated in Helsinki from the number of deliveries. The present incidence in the third largest city in Finland is very close to those figures. In this study, however, a significant increase in the incidence of ectopic pregnancy was found when consecutive 5-year periods were compared. Thus our findings are parallel to the trend observed in England (1).
::
In England it has been estimated that the risk of ectopic pregnancy with IUDs is six-fold in comparison with other pregnancies (5). The present study shows that ectopic pregnancies with IUDs account for 29 % of all ectopic pregnancy during the last 4 years. This together with ectopic pregnancies occurring during the use of low dose progestogens (6) is enough to explain the increased incidence found in this study. It is not quite clear if IUDs really cause ectopic pregnancies. From a theoretical point of view it is understandable that IUDs inhibit intrauterine pregnancy but have little influence upon extrauterine pregnancy. Since the rate of conception is high among IUD users, they are also more exposed to the risk of ectopic pregnancy. It is not certain whether IUDs decrease the motility of the oviduct but this is also a possible cause of ectopic pregnancy. It has been furthermore suggested that PID is 5 times more common among IUD users than in other women (7) and this may increase the risk of ectopic pregnancy. Inourstudy, however, the patients having an ectopic pregnancy when the IUD was in situ had had significantly less PID than the patiezshaving an ectopic pregnancy without IUD. This is probably due to the selection of the patients when the insertion of IUD is considered, since the use of IUD is generally avoided if the woman has a history of previous PIDs. This finding of a low PID rate in patients using IUD suggests that the PID is not of decisive importance as an etiological factor when an ectopic pregnancy occurs during IUD use. In this study ectopic pregnancies were found to occur during use of all registered types of IUD?.. Because the numbers of insertions and the continuation rate for different IUDs can not be estimated reliably enough, it is impossible to make comparisons between the risk associated with different types of IUD. Our impression is that the number of ectopic pregnancies closely reflects the number of insertions of individual IUDs.
DECEMBER 1977 VOL. 16 NO. 6
573
CONTRACEPTION
REFERENCES 1. Beral, V. An epidemiological study on recent trends in ectopic pregnancy. Br J Obstet Gynaecol 82: 175, 1975. 2. Hallat, J.G. Ectopic pregnancy associated with intrauterine device: a study of seventy cases. Am J Obstet Gynecol 125: 754, 1976. 3. Apajalahti, A. Zur inflanunatorischen Athiologie der Tubenschwangerschaft. Acta Sot Med Fenn (Duodecim) B: 16, 1931. 4. Kinnunen, 0. and Jgrvinen, P. Some aspects on ectopic pregnancy, its treatment and results. Duodecim (Helsinki) 68: suppl 23, 1952. 5. Vessey, M.P., Johnson, B., Doll, R. and Peto, R. Outcome of pregnancy in women using an intrauterine device. Lancet 1: 495, 1974. 6. Liukko, P., Erkkola, R. and Laakso, L. Ectopic pregnancies during use of low-dose progestogens for oral 16:575,1977. contraception. Contraception 7. Editorial: Risk of pelvic infection associated intrauterine devices. Br Med J 2: 717, 1976.
574
with
DECEMBER 1977 VOL. 16 NO. 6
