S. Zalányi, MD and G. Szegõdi, MD
Department of Obstetrics and Gynecology, Municipal Hospital, Keszthely, Hungary

To assess the impact of introduction of abdominal and transvaginal sonography on the diagnosis of spontaneous abortion and the implications on subsequent therapy.

Design:

A review of the number and distribution of the types of spontaneous abortions and their relation to the number of deliveries in 1986 and 1991. A prospective study of spontaneous abortions after introducing vaginal sonography in 1996 and a comparison of the three periods.

Setting:

Municipal hospital Keszthely. Hungary.

Methods:

Retrospective review of obstetric statistics. case records and histology findings of two calendar years. 1986. 1991 and prospective evaluations of the same parameters in 1997. Data were analyzed on an IBM compatible Pentium based computer. using Microsoft Excel statistical software.

Results:

The proportion of spontaneous first trimester abortions remained constant (around 12%) during the whole observation period. The frequency of diagnosing missed abortion increased significantly from 6.8% (1986) and 6.4% (1991) to 49.3% (1996) after the introduction of transvaginal sonography. Curettage was spared in two thirds of complete abortions (10 of 15) and missed abortion was successfully evacuated medically in 22 out of 25 cases.

Conclusions:

The spectrum of spontaneous abortion diagnosis significantly changed during the observation period with the majority of cases diagnosed as missed abortion and treated medically. The second most common diagnosis was complete abortion which did not require surgical intervention. These changes associated with the use of transvaginal sonography are similar to those that had occurred in the diagnosis and treatment of ectopic pregnancy approximately a decade ago.

Introduction:

There is a continuous shift in medical terminology, partly due to changing concepts of medical conditions and partly due to changing diagnostics. There are several examples in obstetrics and gynecology, the last and most notable being the diagnosis of ectopic pregnancy(1) which was driven by the introduction of sensitive pregnancy tests and improved ultrasound methods. These improvements were accompanied by a marked change in the treatment of this entity by laparoscopic(1), medical(2), and expectative(3) modalities gaining full acceptance by our community. A similar change seems to have occurred in the diagnosis and treatment of spontaneous abortion, but this is much less perceived and documented than the former. The purpose of this study is to describe the changes that have occurred in the diagnosis and treatment of spontaneous abortion during the last decade.

It is well known that more than half of human pregnancies are lost(4), but only about 15% are perceived as miscarriage and treated as such. Spontaneous abortion is further classified according to the presenting symptoms as threatened, inevitable, incomplete, and complete abortion. Unsuccessful pregnancies which do not present any symptoms have traditionally been classified as missed abortion(5). This terminology has recently been questioned(6) and alternative nomenclature has been suggested(7), but the term "missed abortion" is still widely used by the representatives of our specialty. The term "missed" refers to the missing uterine forces to expel the products of non-viable or anembryonic pregnancy. The confusion about the term "missed" may be understood if we refer to the original description of missed abortion as failure of pregnancy growth for 8 weeks with no accompanying cramps or bleeding. This was applicable more than a century ago when no HCG testing and no method to ascertaining viability was available. Today few women would accept the uncertainty of waiting 8 weeks or more for the outcome of their pregnancy, and no obstetrician would expose a patient to such an extended waiting period either. With improved pregnancy testing including ultrasound with transvaginal transducers the diagnosis of a non-viable pregnancy has accelerated, but the term "missed" remained unchanged. In this study, we set out to examine how the presenting symptoms, the diagnosis, and treatment of spontaneous abortion has changed during an 11 year period in the same hospital.

Methods:

To examine these changes three different calendar years, 1986, 1991, and 1997 were evaluated. The year 1986 was the last when no ultrasound equipment was available in the hospital, thus the diagnosis of abortion was based on clinical examinations and HCG levels. Treatment consisted of curettage preceded by dilatation if necessary. In August 1996 transvaginal ultrasound was introduced. Expectative treatment was based on the ultrasound diagnosis of complete abortion i.e. no retained products of pregnancy in the uterus(8).

The year 1991 was in the middle of the period when abdominal ultrasound examination and HCG tests were available for the diagnosis. Histology examination was performed in all cases; results were missing in only three. The age of patients, length of pregnancy, symptoms of abortion, methods, and length of treatment were retrieved from patient's records for the years 1986 and 1991 and prospectively recorded for 1997. Data were analyzed on a Pentium computer by Microsoft Excel 6.01 under Windows 95. Only first trimester abortions were considered for this study.

Results:

In 1986 there were 613 deliveries and 87 spontaneous abortions corresponding 12.4% of all pregnancies. The average length of non-viable pregnancy was 10.2 weeks. and average hospital stay was 3.6 days. In 9 cases HCG levels were determined. In three cases the histologic examination excluded pregnancy and in one ectopic pregnancy was suspected and confirmed during laparotomy.

During 1991 78 spontaneous abortions and 630 deliveries were recorded (11.0%). In 31 cases ultrasound and in 12 cases HCG examination was performed. Five cases of missed abortion were diagnosed on ultrasound. A posteriori cases may be considered complete abortions, because no chorionic elements were identified on histologic examination. The hospital stay (3.4 days) remained constant.

During 1997, 69 spontaneous abortions (12.0 %) and 505 deliveries were recorded. Ultrasound examination was performed in 62 out of 69 cases. In 42 cases the pregnancy was non-viable and 15 were considered complete abortion. Out of these 15 patients 10 were spared curettage. No chorionic element were identified in 3 of the 5 cases of curettage. Out of the 42 cases of non-viable pregnancies 34 had no symptoms (i.e. missed abortion) and were offered medical treatment (9). Of them 25 accepted Misoprostol treatment and 22 aborted without surgical intervention (10). Out of the 20 patients, who had surgical evacuation, no chorionic tissue was identified on histology in 7 cases, but these patients had an earlier ultrasound scan which demonstrated an intrauterine gestational sac effectively ruling out ectopic pregnancy. The average hospital stay decreased to 2.3 days, due to the reduced time necessary to establish diagnosis and the omission of surgical intervention in most cases of complete abortion.

Discussion:

The frequency of spontaneous abortion remained relatively constant (around 12%) during the observation period, which is at the lower end of the range published in the literature (11). This may be related to the omission of second trimester abortions from our material. The completed weeks of non-viable pregnancy significantly decreased from 10.2 to 9.35 and 8.87 from 1986 to 1997, together with hospital stay from 3.57 to 2.35 days. Both phenomena are explained on the basis of improved diagnostics. Ultrasound examinations introduced after 1986 in this hospital enabled the diagnosis of unsuccessful pregnancies earlier and substantially reduced the treatment period.

The reporting rate of missed abortion changed most significantly. Standard transabdominal ultrasound examination aided by transvaginal sonography improved the diagnosis of non-viable pregnancies before symptoms appeared. Therefore many pregnancies destined to abort later were diagnosed as missed abortions approximately 10 days earlier. While the diagnosis of missed abortion was established in less than 7% of the cases during the first two periods examined, it became the most frequent diagnosis in almost half of the cases of unsuccessful pregnancies.

Similarly, complete abortion was diagnosed only retrospectively by histologic examination during 1986 and 1991. but was diagnosed on ultrasound in 15 cases plus in another four on histology, representing the second most common diagnosis in 1997. The ultrasonographic diagnosis of complete abortion enabled us to observe the majority of these patients without surgical intervention. The classic threatened. inevitable and incomplete forms of abortion are thus restricted to a fraction of cases.

Year	1986	1991	1997
Age (years)	27.46 ±7.42	27.65 ± 6.53	28.03 ± 6.95
Completed Weeks of Pregnancy	10.0 ± 1.96	9.35 ±2 .46	8.87 ± 2.47 a
Length of Treatment (days)	3.57 ± 2.57	3.40 ± 1.46	2.35± 0.56 b
Spontaneous abortion rate (%)	87 (12.4)	78 (11.0)	69 (12.0)
Missed abortion rate ( %)	6.8	6.4	49.3 c

Table I. Frequency and course of spontaneous abortions in relation to maternal age, completed weeks of pregnancy, and length of treatment during three selected observation periods. Values are given as means ± standard deviation or as percentages (%). Significance a: p= 0.002. b: p= 0.00014 (Student´s t test) c: p= 0.0001 (c2).

 

In conclusion: the introduction of ultrasonography, especially transvaginal transducers, greatly improved the diagnosis of unsuccessful pregnancies in the first trimester. These were diagnosed as missed abortions according to the principles of the original description of this entity, although the original waiting period was substantially reduced from two months to several days. This observation is most valuable today, when both patients and clinicians strive to reach definitive diagnosis and treatment as soon as possible. Most patients chose medical treatment instead of surgical evacuation. Ultrasound examination also enabled the diagnosis of complete abortion and its expectative treatment in two thirds of the cases, again diminishing the need for surgical intervention and general anesthesia. All these changes are as dramatic as those in the diagnosis and treatment of ectopic pregnancy, but much less perceived or discussed by our community. We suggest that the term missed abortion is as useful in today's obstetrics as it used to be twelve decades ago, although its definition needs to be modified inasmuch that the original waiting period of 8 weeks be reduced to the time necessary to establish the diagnosis of non viable pregnancy