The conservative aggressive management of placenta previa

OBSTETRICS

The conservative aggressive management of placenta previa DAVID B. COTTON, M.D. JOHN A. READ, M.D., LIEUTENANT COMMANDER, MC, USA RICHARD H. PAUL, M.D. EDWARD

J.

QUILLIGAN, M.D.

Los A ngelfs, California One hundred and seventy-three cases of placenta previa managed at the Women's Hospital of Los Angeles County-University of Southern California Medical Center from July, 1975, through June, 1978, were reviewed and compared to a similar series of cases studied in the same institution in 1969. The perinatal mortality of 12.6% was roughly one half of that in the earlier study. The fetal death rate did not change significantly, but the neonatal mortality was markedly less, especially in the 27-to-32-week range. Expectant management was employed in 65.8% of patients, as compared to 42.6% in 1969. The higher rate of expectant management was characterized by the aggressive use of antepartum transfusions in the face of moderate-to-severe bleeding in lieu of delivery, as well as the occasional use of tocolytic agents for inhibition of premature labor in the presence of vaginal bleeding. Elective termination of pregnancy utilizing the lecithin/sphingomyeUn (US) ratio for determination of pulmonary maturation also resulted in significantly less overall neonatal morbidity and mortality. These multiple factors appear to have contributed to a dramatic reduction in the perinatal mortality associated with placenta previa. (AM. J. OBSTET. GYNECOL. 137:687, 1980.)

c: oN s E R vAT I v E management of placenta previa introduced in 1945 1• 2 resulted in an appreciable im-

THE

From the Department of Obstetrics and Gynecology, University of Southern California School of Medicine, and Women's Hospital, Los Angeles County-University of Southern California Medical Center. Suppo·rted in part by Fellowship Training Grant No. HD09686-04from the National Institutes of Health. Presented at the District VIII Meeting of the American College of Obstetricians and Gynecologists, Seattle, Washington, September 19, 1979. Received for publication August 30, 1979. Remsed December 12, 1979. Aaepted December 31, 1979. Reprint request1: David B. Cotton, M.D., Department of Obstetrics and Gynecology, 1240 North Mission Road, Los Angeles, California 90033.

provement in perinatal survival. However, a review of Los Angeles County-University of Southern California's (LAC/USC) experience in 19693 revealed no significant decrease in the perinatal mortality in the intervening 20 years after popularization of expectant management. Since 1969, obstetric practice has undergone fundamental changes in the evaluation and treatment of the high-risk pregnancy. 4 Current emphasis is on individualization of care, with increasing reliance on biochemical"· 6 and biophysicaF- 9 methods of evaluating fetal well-being. The use of amniotic fluid phospholipid analysis for determination of pulmonary maturation in planning pregnancy termination has assumed a major role in modern obstetric management.10· 11 This study was undertaken in an attempt to evaluate the effectiveness of current techniques in the

687

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Table I. Fetal and neonatal mortality Number

%Mortality

Gestational age (weeks) Ll

22

12.6%* 6.3% 6.3% 87.4%

29.1 ± 6.8 29.5 ± 2.9

Deaths Fetal Neonatal

lit

II !52

36.2

±

3.0

± 893.6" 1,356.4 ± 609.2h 2.721.7 ± 738.2'

1.304.5

ilMean ±standard deviation. a-c, p < 0.0 l. b-e, p < 0.0 1. *Corrected for congenital anomalies, 12.2%. tOne set of twins. Table II. Mortality by gestational age ·Gestational age

(w~eks)

<27 Births Survivors Deaths Fetal Neonatal

8 0 8 6

2

>36 27

63

76

19

59

74

8

4 4 0

2

0 8

I I

management of placenta previa and to contrast the present approach with that described in 1969.:1

Material and methods This study identified 173 cases of documented placenta previa from July, 1975, through June, 1978, among 38,398 deliveries, an incidence of I in 222 deliveries. It is of interest that a tentative diagnosis of placenta previa was made some time during pregnancy in 437 patients, but that only I73 patients fulfilled study criteria for placenta previa at the time of delivery. The criteria demanded that the diagnosis be made either by pelvic examination at the time of delivery or placental localization at the time of cesarean section. Classifications of the type of placenta previa were: (I) marginal, in which case the placenta bordered but did not encroach upon the cervical os; (2) partial, in which case the placenta covered a portion of the cervical os; and (3) total, in which case the placenta covered the os entirely. The degree of cervical dilatation at the time of diagnosis was variable, and classifications were made on the basis of the last examination. Complete information could not be obtained in four patients, so that values derived were calculated only from those patients with complete information for the variable being examined. All infants in this study weighed 500 grams or more. Statistical methods. The data were analyzed with the use of the Statistical Paclulgefor the Social Sciences and the Biomedical Computer Program-P Series on the IBM 370 computer at the University of Southern California

computer renter. Chi-square analyses with Yate's cor. rection were performed to test for differences in incidences between groups. Student's t test and one~way analyses of variance were employed to test for differ~ ences in means between groups. When more than two groups were being compared, Schefft~'s multiple comparison technique was used to detect which pairs of means differed. Furthermore, the z test for difference in two proportions was performed to compare our sample to that of Hibbard.'1

Results Population characteristics. The mean maternal age was 28.4 years (range, 15 to 43 years), with the mean gravidity and parity being 4.2 and 2.5, respectively. The usual association with multiparity was present in this study, with 4.9 times as many multiparas ( 14483.2%) having placenta previa as nulliparas (2916.8%). Thirty-seven percent of patients in this study had a history of a prior abortion, 14.6% had had a previous cesarean section, and 2.3% had had a placenta previa in earlier pregnancies. Mortality. Eleven fetal deaths (i.e., stillborns-6.3%) and II neonatal deaths (6.3%) occurred, for an overall perinatal mortality of 12.6% (corrected for congenital anomalies, 12.2%; Table 1). There was one set of twins that contributed two of the 11 fetal deaths. That particular pregnancy was a marginal previa with premature rupture of membranes and subsequent amnionitis that was treated by hysterectomy at 22 weeks' gestation. Gestational age. The effect of gestational age on mortality was analyzed by division into the following gestational age groups: less than 27 weeks, 27 to 32 weeks, 33 to 36 weeks, and more than 36 weeks (Table li). The perinatal mortality fell significantly with increasing gestational age: less than 27 weeks, I 00%: 27 to 32 weeks, 29.6%; 33 to 36 weeks. 6.3%; and more than 36 weeks, 2.6%. The occurrence of fetal and neonatal deaths is shown in Table II. Birth weight. Analysis of mortality by birth weight re-

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689

Table III. Mortality by birth weight Birth weight (grams) 500-1,000

1,001-1,500

1,501-2,000

2,001-2,500

2,501-3,000

3,001-3,500

>3,500

10

13 7 6

19 17 2 1 1

35 32 3 2

51 50

28 27

18 18 0 0 0

Births Survivors Deaths Fetal Neonatal

I

9 6 3

I

5

I I

I

0

l

l

0

Table IV. Comparison of types of placenta previa*

I

Total cases Perinatal deaths Mean gestational age (weeks) Mean birth weight (grams) Number of bleeds prior to delivery Estimated loss of blood antepartum (cc) Number of antepartum transfusions Estimated loss of blood at delivery (cc) Total estimated loss of blood for pregnancy (cc) Total units transfused Antepartum hospitalization days Postpartum hospitalization days *Mean

:!:

Partial

Total

53 8 35.6 ± 4.4 2,627.5 ± 897.8 3.2 ± 3.8 527.9 ± 508.3 0.2 ± 0.6 1.056.3 ± 818.7 1,582.3:!: 1,020.7 1.2±2.1 9.5 ± 14.6 6.0 ± 2.3

74 6

Marginal

45 8 34.6 ± 5.0 2,439.2 ± 974.0 2.8 ± 2.9 510.0 ± 422.5 0.1 ± 0.5 855.7 ± 410.3 1,351.2 ± 599.9 0.7 ± 1.4 7.0 ± 10.6 5.8 ± 2.0

NS NS NS NS NS NS NS

35.8 ± 3.2 2,557.6 ± 791.6 3.4 ± 4.1 697.3 ± 519.9 0.3 ± 0.7 1,315.5 ± 423.1 2,001.5 ± 1,520.6 1.9±3.1 11.2± 14.0 5.7 ± 1.8

p < O.Oit p < 0.05t NS NS

standard deviation.

t Marginal significantly less than total.

Table V. Ultrasound diagnosis of placenta previa in 124 patients Type ofprevia found at delivery

Ultrascmographic diagnosis Marginal1.3:!: 1.7*

Marginal Partial Total

I

Partial1.4 ± 1.97*

I

previa 0.2 ± 0.9"'

4 2 37

3 4 2

0 23 6

24 8 ll

No evidencet of

Tota/1.4 ± 2.5"'

*Mean ±standard deviation of ultrasound-to-delivery interval in weeks. tlmplantation was posterior in four, anterior in three, and total in two.

Table VI. Placenta previa: Expectant management vs. immediate delivery (Maternal parameters*)

Delivered immediately (n Expectant management (n P value *Mean

::!:

=

58) 112)

Gestational age at diagnosis

age at delivery

blood antepartum

Estimated loss of

Antepartum hospitali%/Jtitm days

Overall maternaJ morbidity

35.4 ± 5.3 32.4 ± 4.3 p< 0.01

35.9:!: 5.0 35.1 ± 5.0 NS

488.8 ± 426.6 651.3 ± 523.6 p < 0.05

0.5 ± 2.8 14.2 ± 14.3 p < 0.01

77.6% (45) 82.3% (93) NS

Gestational

standard deviation.

vealed a perinatal mortality of 4.6% (four fetal deaths and three neonatal deaths) in infants weighing more than 1,500 grams, as compared to 65.2% (seven fetal deaths and eight neonatal deaths) in those weighing less than 1,500 grams (Table III). A more detailed review of the effects of both gestational age and birth weight on mortality will be discussed under Comment when contrasting this study with that of Hibbard. 3

Clinical features.

Type of previa. The type of placenta previa was determined and stated at the time of delivery in all but one case. There were 45 marginal previas, 53 partial previas, and 7 4 total previas. When total placenta previas were compared to marginal previas, the significant findings were an increase in the total estimated loss of blood for the pregnancy (p < 0.01), total number of

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Table VII. Placenta previa: Expectant management vs. immediate delivery (fetal parameters)

Delivered immediately (n = 58) Expectant management (n = II3t) P value

RDS

Anemia

Infection

%Perinatal deaths

Birth weight (grams*)

No

I Yes

No

I Yes

No

24.1% (7 SB: 7 NND) 7.1% (4 SB; 4 NND) p < 0.()1

2,593.3 ± 1,045.8

43

8

44

7

50

2,523.8 ± 782.5

68

41

84

25

87

NS

p< 0.01

NS

I Yes

Hyperbilirubinemia No

j

Yes

50

22

p < O.Dl

80

Hypoglycemia No

I

Yes

50

29

p <0.01

99

10

NS

SB = Stillborn. NND = Neonatal deaths. *Mean± standard deviation. tOne set of twins.

units transfused (p < 0.01), and incidence of maternal anemia (p < 0.05). There was also an increase in fetal infection in the total previa group in comparison to the partial previa group (p < 0.05). The degree of previa was not related to mortality, overall fetal or maternal morbidity, gestational age at delivery, birth weight, initial presentation of bleeding, estimated loss of blood prior to delivery, or indications for termination of the pregnancy (Table IV). Clinical presentation. There were 170 patients in whom the initial type of clinical presentation could be ascertained. In 12 patients (7.0%), the discovery of placenta previa was made incidentally. They were not in labor and had no bleeding at the time of diagnosis. In this group, eight were diagnosed by ultrasound, three at the time of vaginal examination, and one at the time of repeat cesarean section. Bleeding in the absence of labor occurred in 70.6% of the patients. An additional 20.6% had evidence of uterine activity as well as cl.inically significant bleeding. Only 1.8% did not have significant bleeding in the presence of labor. Complications associated with placenta previa. Fetal malpresentation was present in approximately one third of patients-breech in 24, and transverse lie in 35, compared to vertex in 113 (twins undetermined). Cord prolapse occurred in 1. 7% and premature rupture of the membranes in 11.0% of the patients. Illustrating the continued maternal danger with placenta previa is the fact that seven patients had a placenta accreta, an incidence of one in 25; and eight patients underwent a hysterectomy, an incidence of one in 22. Among those patients undergoing hysterectomy, three had a marginal previa, two had a partial previa, and one had a total previa. The indications for hysterectomy were placenta accreta in five, postpartum hemorrhage in two, and sepsis in one. One hundred and seven of 174 (61.8%) babies in this study were male, which confirms previous observations. 12

Diagnosis. Ultrasound. The sole modality, other than double set-up, for the antepartum diagnosis of placenta previa was ultrasound. One hundred and twenty-four patients were diagnosed by ultrasonic methods: static, 83; realtime, 32; and both static and real-time, nine. Placental localization was correctly determined as to anterior or posterior implantation in all but three of the 124 patients. However, there were nine ultrasonic examinations (seven static, two real-time) that failed to diagnose placenta previa, a false negative rate of 7.3%, or one in 14. The accuracy of the ultrasonic method in predicting the degree of placenta previa was: marginal, 55.8%; partial, 79.3%; and total, 86.0% (Table V). These examinations were done by multiple observers utilizing various techniques, and the time interval from the scan to delivery was variable, as can be seen from Table V. A comparison between patients who had ultrasonic examinations with a false negative diagnosis, those with a correct diagnosis, and those who had no such examinations revealed no significant differences in perinatal mortality. For entrance into this study, all patients had to have confirmation of placenta previa at delivery. Therefore, it was not possible to estimate the false positive rate in ultrasonic diagnosis of placenta previa. Double set-up. One hundred and seventeen patients had a double set-up performed to confirm the suspected diagnosis of placenta previa. There were eight deaths and 109 living infants in the double set-up group as compared to 14 deaths and 43 living infants in the group in which no double set-up was performed, a significantly lower mortality in the double set-up group (p < 0.01). There was no significant increase in the estimated loss of blood antepartum or at .delivery in those who had a double set-up compared to those who did not. There were 44 patients (25.9%) with unsuspected

Management of placenta previa 691

Volume 137 Number 6

Hypo-

calcemia No

I Yes

46

5

82

27

Seizures

Other

Overall fetal morbidity

Apgars

I Yes

No

I Yes

No

I Yes

49

2

38

13

37

14

5.5/6.8

105

4

73

36

41

68

6.0/7.6

No

p < 0.05

NS

NS

p < 0.01

1/s minute

NS

placenta previa who inadvertently underwent vaginal examination without double set-up. In this group, three patients had life-threatening hemorrhage with digital examination. There was no significant increase in perinatal mortality in this group compared to the entire study population.

Management. Initial treatment. There were 170 patients in whom initial treatment could be ascertained from the hospital chart. Sixty-six percent ( 112) of patients were managed expectantly, and 34.1% (58) were delivered immediately (Table VI). Four fetal and four neonatal deaths occurred in the expectant group, a perinatal mortality of 7 .I%. This was significantly lower than the perinatal mortality of 24.1% in the immediately delivered group (seven fetal and seven neonatal deaths, p < 0.01). This significance remained when the perinatal mortality among the immediately delivered group was corrected for four patients who presented with a fetal death which occurred prior to the diagnosis of placenta previa (p < 0.05). A comparison between those delivered .immediately and those managed expectantly revealed no significant differences in mean gestational age at delivery, birth weight, estimated loss of blood at initial presentation, estimated loss of blood at delivery, total estimated loss of blood for the pregnancy, or maternal morbidity (cystitis, anemia, wound infection, endometritis, pulmonary embolus, thrombophlebitis, clotting disorder, or transfusion reaction). The expectantly managed group, however, was diagnosed at an earlier fetal age, had significantly more bleeding episodes prior to delivery, greater antepartum loss of blood, as well as more frequent fetal morbidity, including respiratory distress syndrome (RDS), infection, hyperbilirubinemia, hypocalcemia. and prolonged hospitalization days (p < 0.05, Table VII). Surprisingly, there was no significant difference in the mean Apgar scores or risk of fetal

anemia between the two groups . .Eighteen percent of infants had fetal anemia in this study, 78.1% of whom were in the expectantly managed group. Analysis of the selection process for expectant versus immediate delivery demonstrated that moderate-tosevere bleeding did not preclude expectant management. There were 32 patients in whom the estimated Joss of blood at the first hemorrhage was greater than 500 cc, and one-half of those were managed expectantly (Table VIII). This trend of aggressively pursuing expectant management was supported by the fact that the mean diagnosis-to-delivery time i.n this group was 16.8 :t 16.8 days (range, I to 4R days). Furthermore, there were 48 expectantly managed patients in whom the total estimated antepartum loss of blood was greater than 500 cc (Table IX). Although not statistically significant, there was a trend toward increased survival in this expectant! y managed group, which assumes importance considering their earlier age at diagnosis. Outpatient management was instituted in 41 patients. There were no significant differences in perinatal outcome between the 41 patients managed as outpatients and the 71 patients expectantly managed with continuous hospitalization. However, the vast majority of patients initially sent home were rehospitalized for significant bleeding and were kept in the hospital until delivery, with only seven patients being discharged home more than twice. Overall, in 67.89( of the 112 expectantly managed patients, delivery was postponed for more than 3 days, and for more than 7 days in 50.1%. Antepartum transfusions. Antepartum transfusions were employed in 27 of 112 expectantly managed patients in lieu of delivery. There was no fetal or neonatal death in any patient receiving an antepartum transfusion. Anemia and cystitis were the only significant maternal complications in the transfused group (p < 0.05). Perhaps of more importance was the fact that 10 of 27 infants of transfused mothers had anemia (required transfusion or hemoglobin \e~s than 13.0 grams). Inhibition of labor. Bleeding in the presence of premature labor did not absolutely contraindicate tocolysis in this series. Fourteen patients received a tocolytic agent (magnesium sulfate, three; isoxsuprine, six; alcohol, five) for premature labor in the presence of vaginal bleeding. Five of the 14 patients had an estimated antepartum loss of blood of more than 1,000 cr (Table X). No patient received a tocolytic agent in the presence of vaginal bleeding of sufficient magnitude to cause ma· ternal hypotension, or in whom the amount of blood

692 Cotton et al. Am.

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Table VIII. Placenta previa: Expectant managemem vs. immediate delivery (estimated amount of first hemorrhage)

H<

,.

•

Amount of blood lost (cc)

10

X

0

i>O

< z

<

,,

~

•o

f

Delivered

None Spotting (<250) Mild (251-500) Moderate (501-1 ,000) Severe(> 1,000) Total

J(o

Expectantly managed

immedia~ly

4

6 25

60 32

II 10

13

;\ ll2

6 58

71

Table IX. Placenta previa: Expectant management vs. immediate delivery (total estimated antepartum loss of blood)

10

(,l STAT tON A\ Af.f i"'t·+· ~ 1

Fig. 1. The.percentage of perinatal deaths in each gestational age group is compared between 1969 and 1979, with the total number of cases in eafh group indicated.

replaced could not equal that lost. No patient who received a tocolytic agent in this series had a fetal or neonatal death. Whereas the mean gestational age at diagnosis of this group was 30.4 ± 4 .0 weeks, the mean gestational age at delivery was 33.8 ± 3 .0 weeks. In those patients managed expectantly with either tocolysis (14), antepartum transfusion (27), or both (41), there were no perinatal losses. Indication for termination of pregnancy. In the current study, termination of pregnancy was for the following reasons: labor (21 patients); hemorrhage (29); labor and hemorrhage (52); elective (42); and miscellaneous (29). A comparison between these groups revealed a significantly higher mean Apgar score and decreased neonatal morbidity and perinatal mortality in the electively terminated group (Table XI; p < 0.05). These data were compared with Hibbard's study 3 in Table XII. Since his study had no labor-plus-hemorrhage group, the mortality for the labor-plus-hemorrhage group was added to both labor and hemorrhage groups separately for purposes of comparison. Assessment offetal lung maturation. The choice of elective termination of pregnancy is traditionally based on assessment of gestational age and estimation of birth weight. The recent development of the lecithin/ sphingomyelin (LIS) ratio 10 has provided additional information for the decision-making process. An investigation of the impact of the LIS ratio on placenta previa revealed no perinatal deaths in the 44 patients undergoing amniocentesis and determination of the LIS ratio. Two infants with LIS ratios greater than 2.0 developed RDS . One of these infants had anemia and

Amount of blood lost (cc) 0-500 501-1,000 I ,00 l-1,500 I ,501-2,000 2,001-2,500 Total

Delivered immediately Number

l

Expectant managemmt

Died

39 14

10 2 2 0 0 I4

4 I

0 58

Number

I Died

64 28 14 4

5 I 0 2*

2 I 12

8

()

No significant difference in mortality between groups. *Twins.

Table X. Placenta previa: Expectant management vs. immediate delivery (tocolysis) Total antepartum loss of blood (cc) 0-500 501-1,000 1,00 1-l ,500 l ,50I-2,000 2,001 -2,500 Total

Tocolytic agent 2

7

2 I

2 14

No tocolytic agent 101 35 16 4 0

156

hypovolemia at delivery. There was no explanation for why the other infant developed RDS. Antepartum surveillance. There were no significant differences in perinatal mortality between patients monitored with estriols (20), nonstress tests (1 5), or intrapartum fetal monitoring (93) and those not evaluated by these parameters. However, these numbers are too small to be meaningful. Mode of delivery. Only six patients had a vaginal delivery in this series (two stillborn infants, two neonatal deaths, and two livirig infants). As a result, meaningful comparisons between vaginal and abdominal delivery could not be made. There were 113 low transverse, 31 low vertical, and 13 classical uterine incisions in the cesarean section

Management of placenta previa

Volume 137 Sumher fi

693

Table XI. Comparison of indications for termination*

Number of patients Perinatal deaths Mean gestational age Mean birth weight Number of prior bleeds Estimated loss of blood antepartum

Labor

Hemorrhage

Labor and hnnorrhage

Elective

21

29 0

52 10

42 0

34.3 2,286.0 2.3 352.4

4 ± 4.4 ± 855.3 ± 2.5 ± 341.1

37.1 2.3 2,969.9 ± 811.5 3.3 ± 4.9 834.5 ± 526.5

34.6 2,343.9 3.2 737.5

± 4.1 ± 898.5

± 3.2 ± 446.9

37.5 ± 2.0 2,938.1 ± 558.1 3.2 ± 3.4 ~~46.3 ± 352.7

29 8 31H 2,!93.8 3.7 625.0

± 5.2

± 917.8 ± 4.4 ± 615.6

*Mean -o: standard deviation.

Table XII. Comparison of perinatal mortality by indication for termination, 1969*

Hemorrhage Labor Elective Miscellaneous Total

165 147 156 12 480

36.4 29.7 7.1 33.0 24.8

29t 2lt 42 29 173

p < (LOI p < 0.05 p < 0.01 NS p 0.01

12.3 19.1 9.0 27.5 12.6

*Reference :l. tPerinatal mortality for labor and hemorrhage (10 of 52) added to each group for purposes of comparison.

group. The type of incision could not be determined in I 0 patients .. There were no meaningful differences between groups as to estimated loss of blood, postoperative morbidity, or incidence of fetal anemia. The ::)5 patients who underwent elective cesarean section prior to labor bad significantly fewer instances of fetal anemia than the others (2.9% [one] vs. 27.7% [31]) and fewer instances of RDS (11.4% [four] vs. 40.2% [ 45] when compared to the overall study group (p < 0.05), but had no significant decrease in maternal morbidity. Seven patients had their pregnancy electively terminated after minimal uterine activity or bleeding thar made up the remainder of the 42 patients in the electively terminated group. Type of anesthesia. General anesthesia was employed in 164 patients and epidural anesthesia in seven, with two patients receiving only local anesthesia. There were no significant differences in morbidity or mortalit.y in either mother or fetus, but the numbers of patient.s who did not receive general anesthesia are too small to make meaningful comparisons of subgroups.

Comment This stud) was undertaken in an effort to determine the effectiveness of current therapeutic modalities in the management of placenta previa and to contrast current treatment and outcome with those described in 1969.'1 This was done with the realization that changes in obstetric techniques cannot be clearly separated from the impact of the modern neonatal intensive-care unit.

Table XIII. Placenta previa: Comparison of older* and recent findings 11948-195311962-196611975-1978

Age Parity Nulliparous Under age 20 Over age 40 Incidence Vaginal examinations Placentography Ultrasound Total previas Termination indication-hemorrhage Gestational age at onset of bleeding Proportion of stillbirths Perinatal mortality Expectant treatment

27.5 3.3 6.1 6.0 4.5 l-223 87.0 39.0

29.0 3.6 5.4 6.2 4.5 1-206 87.0 36.0

24.1 27.0

27.2 24.7

70.7 43.0 54.9

34.7

34.7

32.3

32.0

35.0

50.0

24.9 42.8

24.7

12.6 65.8

42.~

28.4 2.5 16.9 6.9 4.0 1-222 78.9

*Reference 3.

The perinatal mortality of 12.6% in this study is approximately one half of that in Hibbard's study of placenta previa in 19693 (p < 0.01, Table XIII). A comparison was made with the 1969 study in an effort to determine the major reasons for the decrease in perinatal mortality. Analysis of the effect of gestational age on fetal mor· tality was accomplished by breaking mortality into gestational age groups: less than 27 weeks, 27 to 32 weeks, 33 to 36 weeks, and more than 36 weeks. There was a significant decline in fetal deaths in the 27 to 32-week

694 Cotton et al.

jul1 !5, l'll
100 90

!.t-)'I!A,UIY \O!II'' ..

\o,'l

c::J

tl•t·•·c=J

80 10 60

50 <0

30 20

'0

Fig. 2. The percentage of perinatal deaths in each weight group is compared between 1969 and 1979, with the total number of cases in each group indicated .

range ( 17.33% vs. 0%, p < 0.05). However, the overall percent of fetal deaths of 6.3% was not significantly improved from that of 8.3% of 1969. Although there has been no appreciable improvement in the fetal death rate, there has been marked improvement in the neonatal mortality, not only in the 27- to 32-week range (59.7%'vs. 29.6%, p < 0.05), but also in the 33- to 36week category (13.6% vs 0%, p < 0.01). There was no significant difference in outcome of infants delivered after 36 weeks' gestation (4.9% vs. 2.6%). Hence, perinatal mort
ferences in mean gestational age or birth weight between the two. The exact reasons for the decrease i~ the mortality and increase in morbidity in the expectantly managed group are not readily apparent from the data. However, those expectantly managed pregnancies that were electively terminated with use of the LIS ratio for determination of pulmonary maturatiGn had significantly less overall neonatal morbidity all~ perinatal mortality (p < 0.05) when compared to the ' rest of the study popt.ilation, when corrected for gestational age. If a patient with a placenta previa has a mature LIS ratio, elective termination should be implemented, in the realization that organ systems other than the pulmonary may not be fully mature. Thi~ approach averts subsequent maternal hemorrhage that may result in fetal morbidity and mortality at any time . The risk to the fetus is apparent from the fact that 18.7% of infants in this series incurred anemia, which emphasizes the need to always determine whether any fetal component is present in third-trimester bleeding. The higher rate of expectant management in this study group is attributed to the aggressive use of antepartum transfusions in the face of moderate-tosevere bleeding and to the use of tocolytic agents for inhibition of premature labor in the presence of vaginal bleeding. Interesting clinical features of this study include the fact that a history of prior abortion, previous placenta previa (fivefold increase in risk), or prior cesarean section (sixfold increase) enhanced the risk of developing a placenta previa. There was also an unexplained increase in the proportion of male infants in mothers having a placenta previa. Additionally, 7.0% ofpatients in this series were discovered fortuitously, perhaps underlining the need for a cautious examination in all}'

Management of placenta previa

Volume 137 t\umber ti

new pregnant patient hrst seen in the third trimester. The fact that 44 patients with unsuspected placenta previa underwent vaginal examination in the absence of a double set-up does Hot encourage us in any way to promote this approach, hut does point out that the vaginal examination in placenta previa is not invariably catastrophic. Ultrasound in this study correctly diagnosed placental implantation as to anterior or posterior in 97.6% of cases. Ultrasound overall correctly diagnosed the type of placenta previa found at delivery 67.8% of tht• time. These discrepancies may be explained by varying times between ultrasound diagnosis and delivery and var-iable degrees of cervical dilatation at the time of classification. It would appear, however, that with an incidence of one in 14 false negative ultrasonic diagnoses, a double set-up should generally be performed to confirm t hf:' diagnosis prior to commit-

695

ting the patient to an operative procedure or abandoning the diagnosis of placenta previa. The consenative management ol placenta previa, including the aggressive use of antepartum transfusion in the ca-;e of moderate-to-severe bkeding, inhibition of pt·f:'mature labor in the presence of \·aginal bleeding, and early elective termination of pregnancv utilizing amniotic phospholipid analysis, along with the development of the neonatal intensive care unH, appt~ars to have contributed to a dramatic reduction in the perinatal mortality of placenta previa. \\'e wish to extend special thanks to Sarah Schoentgen for help with statistical analysis and to Lyndon M. Hill and Kenneth R. Niswander for reviewing the manuscript. Our thanks are due also to Frank rvtanning and the ultrasound staff for their work.

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