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Diagnostic value of arteriography in cases of placenta previa
Diagnostic value of arteriography in cases of placenta previa U. BORELL, M.D. I. FERNSTRCIM, M.D.
L. OHLSON, M.D. Stockholm, Sweden
AccoRD 1 N G to the literature the perinatal mortality associated with placenta previa is between 20 and 30 per cent, the principal cause being prematurity. The perinatal mortality from placenta previa can be reduced by early diagnosis of the condition, resulting in immediate admission and care of the patient in the hospital from the first "warning" hemorrhage until she has been delivered. There are only two methods by which the diagnosis placenta previa can be made with reasonable certainty, viz., vaginal palpation and radiography. However, localization of the placental site by the former method presents difficulties. Of the various radiologic methods available, arteriography has been used increasingly during the last decade and has been our method of choice. Table I shows the results achieved by earlier workers together with the complications observed, only those papers giving details of at least 10 cases were considered. All the investigators discussed in detail the reliability and the hazards of the method. No serious complications occurred and practically all considered arteriography to be of great diagnostic value. With the exception of Brink's 2 series the number of cases in the individual series has
thus far been too small to permit any definite conclusions to be drawn. Moreover, in many reports the arteriographic appearances were incompletely described and in several investigations they were not correlated with the clinical findings. During the years 1950 to 1955 we have been using arteriography to exclude placenta previa only in selected cases. Since 1955, we have been performing the procedure as a routine method of examination in all cases in which placenta previa was suspected, and, between 1955 and 1961, 160 patients were examined. This comparatively large number of cases prompted ,us to reinvestigate the hospital records and arteriograms of these subjects to obtain a better idea of the usefulness and hazards of arteriography. The results were considered sufficiently interesting to be reported. Present series
The present series included 160 patients who were admitted because of vaginal bleeding during the second half of pregnancy, pain was an associated symptom in 45 cases. Method
During the last two years the aim was to obtain filling of the ovarian arteries in addition to the uterine arteries in cases in which placenta previa was suspected. For this reason a modification of the technique described earlier1 • 3 was used. The modification con-
From the Women's Clinic and the Department of Diagnostic Roentgenology, Karolinska S jukhuset.
535
536
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June 1.;, 1963 & Gynec.
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A
sisted in introducing the catheter 30 em. instead of 17 em. The tip of the catheter then generally lies at the level of the point of origin of the ovarian artery from the aorta. The contrast medium was a 60 per cent solution of Urografin, * 70 ml. injected within 2 to 3 seconds. Two anteroposterior views of the abdomen were taken first (Figs. 1 A, Band 2 A, B). If ''Ten per cent sodium and 66 per cent methylglucamine salts of 3,5-diacetamido-2,4,6,-triiodobenzoic acid. Schering A·G , V\'.st Berlin, Germany.
intervillous spaces were demonstrated within the true pelvis another 70 ml. of the contrast medium was injected and a lateral view of the pelvis was taken (Fig. 2, C). The lateral view is of the utmost diagnostic importance since it determines whether the placenta is implanted on the anterior or posterior wall. Knowledge of this point is essential for the localization of the lower boundary of the placenta within the lower uterine segment. The schematic representation of the arteriograms taken on 2 pregnant subjects illustrates this very clearly (Fig. 3).
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B
Fig. 1. Arteriograms taken on a patient at term. Normal placental implantation. A, Anteroposterior view. Film taken immediately after completion of the injection of contrast medium. The pelvic arteries (arrows } a r e demonstra ted ; they appear to be ma rkedly widened . B, Anteroposterior view. Film taken 4 seconds after film A. Intervillous spaces a re outlined within the upper right portion of the corpus uteri.
The anteroposterior views 1, A and 1, B, which are practicaiiy identical, do not permit the correct diagnosis to be made. The lateral views 2, A and 2, B enable the position of the placenta to be determined. Results
Placental implantation diagnosed on clinical grounds. The cases were classified into 9 groups without knowledge of the radiologic diagnosis, basing the division on the hospital records of the findings at vaginal palpation, cesarean section, inspection of the
expelled placenta, and site of rupture of the membranes. In view of the difficulties which differential diagnosis between marginal placenta previa and partial placenta previa presents, the two types were included in the same group under the heading " partial placenta previa." Nor was central placenta previa classified separately, being included in the group of total placenta previa. Group I, normal implantation ; Group II, normal implantation or low-lying placenta ; Group III, low-lying placenta ; Group IV,
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low-lying placenta or partial placenta previa: Group V , any position between low-lying placenta and total placenta previa: Group VI , partial placenta previa: Group VIL
june 13, 1963 Am. j, Obst, & Gyncc.
partial or total placenta previa: Group VIII, total placenta previa; and Group IX, placental site indeterminate. Groups II , IV, V. and VII include the
Fig. 2, A . Arteriogram take n in th e te nth lunar month of pregnanc y o n a pa tient w ith plac enta previa. Anteroposterior view. Film ta ken immediately after completion of the inj ec tion of contrast medium. Th e pel vic arte ries and the ute rine arteries (a rrows ) are outlined .
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cases m which the position of the placenta could not be inferred with certainty from the clinical features and Group IX includes single cases in which it was not possible to
determine the implantation of the placenta on clinical grounds. Table II shows the classification of the cases on clinical grounds and the month of
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Fig. 2, B, Arteriogram in the tenth lunar month of pregnancy on a patient with placenta previa. Anteroposterior view. Film taken about 4 seconds after film A. Intervillous spaces are outlined within and above the true pelvis.
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Fig. 2, C , Arteriogram taken in the tenth lunar month of pregnancy on a patient with placenta previa. Lateral view. Film taken about 4 seconds aft er completion of the injection of contrast medium. Placental sinuses are see n to extend over the site of the internal os ( X) . Arrows point toward the fetal head ; (S) first sacral vertebra.
pregnancy in which the arteriography was performed. It is seen that the majority of patients were examined prior to the last lunar month and more than one third between the fifth and eighth lunar months of pregnancy. The table also shows that the placenta was situated in the lower uterine segment in one third of the patients. Treatment. Treatment was planned on the basis of the arteriographic appearances. The latter showed the placenta to be in the lower uterine segment in 4 7 cases; 44 of these patients were kept in the hospital until they had been delivered. If no vaginal bleeding occurred during their first week in the hospital, the patients were allowed to be mobile but were not allowed to leave the ward. The remaining 3 subjects had low-lying placenta. They were discharged and kept under observation as outpatient~.
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Method of delivery. Table III shows the method of delivery in the cases of low-lying placenta or placenta previa. Of the 11 patients with low-lying pl acenta, 8 were delivered vaginally and 3 by cesarean section. Of the 21 subjects with placenta previa, 20 were delivered by cesarean section ; in the remaining patient a severe hemorrhage was controlled by Braxton Hicks' maneuver. Maternal and infant mortality. Maternal mortality was nil although 19 infants were lost. Table IV shows the distribution of the perinatal mortality in the different groups together with the time of death in relation to arteriography. The causes of death are also detailed. In the 106 cases of normal placental implanta tion, 11 infants died. The main causes of death were as follows: debility in 6 cases due to premature separation of the placenta in 3 ; prolapse of the umbilical cord in 2; severe fetal malformation in 2; and erythroblastosis in 1. In 4 7 cases in which the placenta was wholly or partially in the lower uterine segment, 8 infants were lost ; the infant mortality being 17 per cent . The causes of perinatal death were prematurity in 7 cases and severe fetal malformation in 1. Of the 7 perinatal deaths due to prematurity, the postmortem examination revealed hyaline membra ne in 2 cases. No infant was lost in the 7 patients in whom it was impossible to determine with certainty whether the placenta was implanted in the body of the uterus or in the lower uterine segment. Arteriographic appearances. Placental implanta tion was regarded as normal if the anteroposterior view showed the intervillous spaces to be above a transverse plane a t the level of the promontory. If spaces were demonstrated below this level, a lateral view of the pelvis was usually taken in addition to the a nteroposterior view. The position of the placenta cannot be correctly assessed radiologically unless the site of the internal os is defined on the arteriogram. However, the radiologic determination of the site of the internal os presents
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Arteriography
difficulties because the latter varies from one patient to the other. In the present investigation the site of the internal os on the lateral projection was assumed to be on the axis of the true pelvis at a point which was about 5 em. below the pelvic inlet. Low-lying placenta was diagnosed if intervillous spaces did not extend to this point but extended posteriorly below the promontory or anteriorly below a point which was about 5 em. above the symphysis. Table V shows the arteriographic diagnoses. As was the case with the clinical findings it was not possible to infer the site of placental implantation with certainty from the arteriographic appearances in some patients. These were therefore placed in separate groups. Complications of arteriography. In no instance did arteriography give rise to renal complications. Also there were no noteworthy allergic reactions observed. In a few cases a hematoma developed at the site of puncture, but in no case was it sufficiently severe
to require specific treatment. Otherwise, neither puncture of the femoral artery nor the introduction of the catheter gave nse to any complications. As already mentioned, the cardinal cause of perinatal death is prematurity in cases of placenta previa. In reinvestigating the hospital records of the patients, special attention was given to the question of whether arteriography involved danger of inducing labor or causing hemorrhage sufficiently severe to necessitate artificial termination of pregnancy. Hemorrhage. In 13 of the 47 patients with placenta previa no vaginal hemorrhage occurred during the period between the radiologic examination and the commencement of labor. Twenty-five of the 47 subjects had episodes of vaginal bleeding during this period but in no instance was the bleeding more severe or frequent than that which took place prior to arteriography. In the remaining 9 subjects with placenta previa vaginal bleeding was more frequent and severe than that prior to the procedure. How-
1n
A,
Fig. 3. Schematic representation of the arteriograms taken on two pregnant patients. AI and A2, normal implantation on the anterior wall of the uterus. BI and B2, placenta previa lying in the posterior part of the lower uterine segment.
542 Borell, Fernstrom, and Ohlson
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ever, in 8 of the latter cases the vaginal bleeding occurred more than 5 days after the examination. It is therefore most unlikely that arteriography was the cause of it. Labor pains. Of the 47 patients with pia-
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Jun~ IJ, 1%:1 Obst. & Gynec.
centa previa 11 experienced labor pains within 48 hours of arteriography. In one case intrauterine fetal death had been diagnosed prior to the examination which had been performed in the ninth lunar month of pree;-
Table I. Diagnostic value and complications of arteriography in cases of placenta previa as reported in the literature Diagnostic value of arteriography
Name of author
Hartnett"
1948
Spanio et aJ.12 Norman'
1953 1953 1955 1958 1958 1960 1961
Fernstrom~
Sammons et aJ.to Hodge'1 Brink2 Solisch et aJ.ll
Complication>
68
Reliable
13
C nsatisfactory Reliable II Reliable II Reliable II One incorrect diagnosis Safe method Reliable Correct diagnosis in 9 cases; 0 in 4 cases. indeterminate
15
29 45 13 209 13
Labor sometimes ensued in patients near term if the contrast medium was sodium iodide Safe method 0
-··~-~-~·~--·
Table II. Classification of the cases according to the clinical diagnosis of placental implantation and the month of pregnancy in which arteriography was performed Lunar month of p_r_e...;.g_n,a_n...;cy'----.-·-l····O
Clinical diagnosis
·~5~....---6-,....l ·1-~--
Normal implantation Normal implantation or low-lying placenta Low-lying placenta Low-lying placenta or partial previa Any position between low-lying placenta and total previa Partial previa Partial or total previa Total previa Placental site indeterminate
2
10
a
1
9
-·I
Total
40
106
+
2
0 ll
')
26 1
3
3
2
Total
6
1 I 5
+
6
0 I
17
+2
5i
44
160
12 3 1 1
Table III. Method of delivery in cases of placenta previa
Position of placenta
Low-lying Low-lying or partial previa; any position between low-lying and total previa Partial previa; partial or total previa; total Total *Braxton Hicks'
man~uve1.
Spontaneous vaginal delivery
Cesarean section
Other methods of delivery
I
Total
3
0
11
13
0
!.)
()
20
I*
21
10
36
8
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Arteriography
nancy. Labor commenced a few hours after arteriography. Four patients had experienced labor pains prior to the examination. The remaining 6 patients were at term. It may be assumed that labor commenced spontaneously in these 11 subjects. Fetal death. As already mentioned, 19 infants were lost (Table IV) but in no instance was perinatal death attributable to arteriography. The causes of death were prematurity in 15 cases, severe malformation in 3, and severe Rh immunization in 1 case. Radiation hazards. In discussing the possible risks of arteriography, special consideration must be given to the radiation hazards. The procedure imposes a much smaller radiation to the fetal gonads and the maternal ovaries than soft tissue radiography which is also used in the diagnosis of placenta previa; the parts of the fetus and maternal ovaries lying within the field of radiation receive less than 1 r. Correlation of the arteriographic diagnosis with the clinical diagnosis. Table VI shows
that the artcriographic diagnosis accorded with the clinical diagnosis in 125 of the 160 cases in the present series. In 29 cases the arteriographic diagnosis slightly deviated from the clinical diagnosis. However, this did not vitiate the treatment of these patients. In 18 of the 29 cases arteriography enabled the diagnosis of the placental site to be made with greater certainty than the clinical diagnostic methods. In the remaining 11 the reverse was true. In 6 cases the arteriographic diagnosis disaccorded with the clinical diagnosis. In 2 of these the reason was omission of taking a lateral view in addition to the anteroposterior view, despite the fact that the latter showed the intervillous spaces to be below a transverse plane at the level of the promontory. In 1 of the 6 cases the reason was that the lower boundary of the placenta reached the region of Bandl's ring, making differentiation between normal implantation and lowlying placenta particularly difficult. In this instance normal implantation was diagnosed
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Table IV. Interval between arteriography and fetal death and causes of death Interval in days between arteriography and fetal death
Fetal weight (grams)
Cause of death
0
1,840
8 0 6
1,220 2,130 1,870
3
2,120
Debility; death during delivery; foot presentation Debility Debility; death 2 hours after delivery Debility; death during delivery; Braxton Hicks' maneuver Debility; anoxia
7 6 Unknown
2,360 1,800 1,810
Normal Normal Normal Nom1al Normal Normal Normal Normal Normal
19 39 13 5 16 1* 2*
1,500 3,210 960 830 1,170 1,150 1,180
Normal
25
Position of placenta Low-lying or partial previa Low-lying Low-lying Partial previa Low-lying or partial previa Total previa Total previa Total previa Normal
1
3
*Fetal death occurred before arteriography.
1,650
Multiple malformations Debility; hyaline membrane Debility; hyaline membrane Debility; premature separation of placenta; prolapse of umbilical cord Debility Rh immunization Debility; premature separation of placenta Debility; premature separation of placenta Debility; premature separation of placenta Debility Debility Multiple malformations Debility; asphyxia; cornm·pssion of umbilical cord; breech
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clinically while the arteriographic appear-
pams m conjunction with the injection of
ances suggested low·-lying placenta. The in-
the contrast mediun1. In 15 cases not in-
correct arteriographic diagnosis resulted in inadequate treatment of the patient. In the rC'maining 3, no or only a few intervillous spaces were demonstrated. This accounted for the incorrect arteriographic diagnosis. One of these indiYiduals experienced labor
eluded in this series, in which arteriography was performed during or between labor pains, the intervillous spaces either failed to opacify or filled unsatisfactorily in conjunction with uterine contraction. vVe were, therefore, inclined to believe that failure of or unsatisfactory demonstration of the intt~rvillous spaces was due to uterine contraction in these :l cases, being painless in 2. Ramsey and coworkers' made a similar observation in pregnant monkeys. They reported that uterine contractions prevented filling of the intervillous spaces.
Table V. Arteriographic diagnosis of placental site Position of .tJlacenta
No. of cases
Normal Normal or low-lying Low-lying Low-lying· or partial previa Any position between !ow-lying and total previa Partial previa Partial or total previa Total previa Placental site indeterminate
107 7
Tobl
160
15
Comment
:l
Various methods have been used for the
+
diagnosis of placenta previa. Many of them
5
have fallacies which may lead to erroneous interpretation of the findings. Vaginal palpation. Before delivery of the patient vaginal palpation is the only clinical
15
Table VI. Correlation of the arteriographic diagnosis with clinical diagnosis
Clinical dia~;nosis*
N
Arteriographic diagnosis according u•ith clinical diagnosis (No. of cases)
102
N-L
1'\-L L-P
0 L-T
2
P-T
0 II
u
3
Arteriographic diagnosis disaccording n•ith clinical diagnosi.r (No. of cases)
II
{j
11
N '>
:)
1\'-T
-t
0
1~
1 ')
N-L T P-T L-T
Total
106
L
')
p L L-P p P-T
p
1\i-T
N-L N L
L
T
Arteriographic diagnoxis slight!)' deviating from clinical diagnosis (No. of cases)
'
,)
0 ')
~
N
N L
17 I)
1
----~--
Total
125
29
6
160
-------*N Sormal implantation; N-L, no1mal implantation or low-lying placenta; L, IO\v-lying placenta; L-P, lo\\-lying placenta pa/ttal previa~ L-T. any position betV~.een 10\\--lying plaC't'nta and total prt>via; P, pal'tial p~t•vJa; P-T. partial or total ptc\ia: T, total p1 evia; N-T, placental site indeterminate.
Volume 86 Number4
method available for the diagnosis of placenta previa. The method has several disadvantages: first, it does not permit the correct diagnosis to be made unless the internal os is sufficiently dilated to admit a finger and the placenta reaches or completely covers the internal os; second, blood clot may simulate placental tissue to the touch. Not until labor has commenced and labor pains have caused dilatation of the cervical canal is it possible to gain a fair idea of the position of the placenta in relation to the internal os. Moreover, vaginal palpation may cause severe uterine hemorrhage. Radiologic methods. Radiologic methods have been widely used in the diagnosis of placenta previa, particularly cystography and soft tissue radiography. These two methods are both reliable if performed during the last lunar month of pregnancy. Earlier in pregnancy, when the first symptoms of placenta previa usually appear, they are unreliable. Moreover, soft tissue radiography cannot be used in cases of polyhydramnios and interpretation of the radiographic appearances may be difficult in cases of multiple pregnancy and transverse lie. Cystography is of no value in cases of oblique, transverse, or breech presentations and in instances of multiple pregnancy cystograms may be difficult to interpret. Arteriography. Arteriography permits the determination of the placental position irrespective of the type of presentation, maturity of pregnancy, or the presence of polyhydramnios. In the present investigation the arteriographic diagnosis accorded with the clinical diagnosis in the majority of the cases (97 per cent). Arteriography was performed on many patients in this series at a stage of pregnancy in which neither vaginal palpation, cystography, nor soft tissue radiography would have enabled the correct diagnosis to be made. It is advisable to avoid the performance of arteriography during uterine contractions because it was found that they may prevent satisfactory filling of the intervillous spaces and this may result in incorrect interpreta-
Arteriography in cases of placenta previa
545
tion of the arteriographic appearances. As uterine contractions may be painless and are then difficult to diagnose, it is expedient to give the patient a relaxant prior to the examination. During the last 6 months all patients were given 5 mg. of isoxsuprine intramuscularly 10 minutes before arteriography. In our experience puncture of the artery and the injection of contrast medium did not give rise to any complications, either in the mother or fetus. Since a maximum of
Table VII. Position of maternal ovaries in relation to the spine between the eighth and tenth lunar months of pregnancy Position of ovaries in relation to the spine
No. of ovarzes
At the level of L-4 At the level of L-5 At the level of S-1
8 21
7
Table VIII. Comparison between the measurements of the cross sectional areas of the ovarian and uterine arteries Combined measurements of cross sectional areas of the right and left ovarian arteries (mm.t)
0.8 0.8 0.8 0.8 1.6 1.8 1.8
2.6
3.1 3.9
3.9
4.9 4.9 4.9 4.9 4.9
6.2 6.7 8.0
8.0 9.8
10.2 11.4 12.0
Combined measurements of cross sectional areas of the right and left uterine arUries (mm.') 8.0 9.8
14.2 16.7 14.2 19.2 22.2 14.6 14.2 8.0
12.0 9.8 10.2 12.0 14.2 14.2 14.2 6.2 4.9 10.2 22.2
14.2
3.1 8.0
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three films are required the radiation risks are minimal. With the exposure data used the maternal ovaries and the parts of the fetus which were inside the field of radiation received 0.3 r, respectively, per exposure. This dose can be reduced by adjusting the light beam diaphragm so that the upper border of the field of radiation is at the level of L-5-S-l. The fetal gonads are then invariably outside the field of radiation in instances of cephalic presentation. This also applies to the maternal ovaries in many cases. The latter observation was made in 18 cases of uterine pregnancy in which arteriography revealed the position of the maternal ovaries (Table VII\. The position of the maternal ovaries was in good agreement with that reported by Hibbard.'' The present investigation has shown that the demonstration of the ovarian arteries in addition to the uterine arteries is of utmost importance in cases in which placenta previa is suspected on clinical grounds, because the former may take part in the blood supply of the uterus during pregnancy. This was proved in 24 of the 160 cases by measuring crosssectional areas of the ovarian and uterine arteries directly from the films. These measurements showed that the ovarian arteries were remarkably wide as compared with the uterine arteries (Table VIII). It was found that the quantity of contrast medium injected also played an important part in the demonstration of the intervillous spaces. In our hands, injection of 70 mi. of a 60 per cent solution of Urografin resulted in clear visualization of the intervillous spaces and did not have any untoward effects on the patient. According to some authors arteriography performed for localization of the placental site is an extremely difficult procedure which should only be carried out by experienced and specially trained radiologists. In our opinion the technique is not more difficult than arteriography of other structures, e.g., renal arteriography, etc. None of the radiologists of the staff of the Department of Diagnostic Roentgenology of this hospital
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had any difficulty in learning it. We do not support Duncan Reid's 9 view who, in discussing placentography in his textbook of obstetrics and gynecology, wrote: ". . . attempts have also been made to visualize the placenta by arteriography utilizing either the femoral and iliac arteries or the aorta. This formidable procedure, although furnishing interesting information relative to the anatomical changes of the uterine artery in pregnancy, seems too hazardous, impractical, and unnecessary as a diagnostic procedure." As already mentioned, the perinatal mortality associated with placenta previa is generally quoted between 20 and :10 per cent. The corresponding figure in the present series was 17 per cent. There probably are many explanations for this rather low rate. One explanation may be that arteriography permitted early diagnosis of the condition and this made possible prompt admission of the subject and care in hospital until she had been delivered. Care of the patient in hospital throughout the pregnancy is essential to try to avoid hemorrhage which may be sufficiently severe to cause premature delivery. Another possible explanation is that 36 of the 47 patients with low-lying placenta or placenta previa were delivered by cesarean section. Arteriography was also of practical ;·alue in the cases in which it disclosed normal placental implantation because the patients rould be confidently kept under observation as outpatients.
Summary
Arteriography was performed in 160 cases in which placenta previa was suspected on clinical grounds. In 97 per cent the procedure enabled the correct diagnosis to be made. No noteworthy complications attributable to the examination occurred. Arteriography permits early diagnosis of placenta previa and thereby makes possible prompt admission of the patient and care in hospital until she has been delivered. Maternal mortality was nil, and the perinatal death rate was I 7 per cent.
Volume 86 Number4
REFERENCES
1. Borell, U., and Fernstrom, I.: In Abrams, 2. 3. 4. 5. 6.
Herbert 1., editor: Angiography, Boston, 1961, Little, Brown & Company. Brink, D.: J. Obst. & Gynaec. Brit. Emp. 67: 437, 1960. Fernstrom, I.: Acta radio!. suppl. 122, 1955. Hartnett, L. J.: AM. J. OnsT. & GYNEC. 55: 940, 1948. Hibbard, B. M.: Brit. J. Radio!. 34: 387, 1961. Hodge, K. E.: Am. J. Roentgen a!. 80: 651, 1958.
Arteriography rn cases of placenta previa
547
7. Norman, 0.: Brit. J. Radio!. 26:. 393, 1953. 8. Ramsey, E. M., Corner, G. W., Jr., Donner, M. W., and Stran, H. M.: Proc. Nat. Acad. Sc. 46: 100'3, 1960. 9. Reid, D.: Obstetrics, Philadelphia, 1962, W. B. Saunders Company, p. 558. 10. Sammons, B. P., et a!.: Am. J. Roentgenol. 80: 664, 1958. 11. Solisch, G. I., Masterson, J. G., and Hellman, L. M.: AM. J. OnsT. & GYNEC. 81: 57, 1961. 12. Spanio, P., and Nejedly, C.: Minerva ginec. 5: 573, 1953.
L. OHLSON, M.D. Stockholm, Sweden
AccoRD 1 N G to the literature the perinatal mortality associated with placenta previa is between 20 and 30 per cent, the principal cause being prematurity. The perinatal mortality from placenta previa can be reduced by early diagnosis of the condition, resulting in immediate admission and care of the patient in the hospital from the first "warning" hemorrhage until she has been delivered. There are only two methods by which the diagnosis placenta previa can be made with reasonable certainty, viz., vaginal palpation and radiography. However, localization of the placental site by the former method presents difficulties. Of the various radiologic methods available, arteriography has been used increasingly during the last decade and has been our method of choice. Table I shows the results achieved by earlier workers together with the complications observed, only those papers giving details of at least 10 cases were considered. All the investigators discussed in detail the reliability and the hazards of the method. No serious complications occurred and practically all considered arteriography to be of great diagnostic value. With the exception of Brink's 2 series the number of cases in the individual series has
thus far been too small to permit any definite conclusions to be drawn. Moreover, in many reports the arteriographic appearances were incompletely described and in several investigations they were not correlated with the clinical findings. During the years 1950 to 1955 we have been using arteriography to exclude placenta previa only in selected cases. Since 1955, we have been performing the procedure as a routine method of examination in all cases in which placenta previa was suspected, and, between 1955 and 1961, 160 patients were examined. This comparatively large number of cases prompted ,us to reinvestigate the hospital records and arteriograms of these subjects to obtain a better idea of the usefulness and hazards of arteriography. The results were considered sufficiently interesting to be reported. Present series
The present series included 160 patients who were admitted because of vaginal bleeding during the second half of pregnancy, pain was an associated symptom in 45 cases. Method
During the last two years the aim was to obtain filling of the ovarian arteries in addition to the uterine arteries in cases in which placenta previa was suspected. For this reason a modification of the technique described earlier1 • 3 was used. The modification con-
From the Women's Clinic and the Department of Diagnostic Roentgenology, Karolinska S jukhuset.
535
536
Borell, Fernstrom, and Ohlson
Am.
June 1.;, 1963 & Gynec.
J. ObsL
A
sisted in introducing the catheter 30 em. instead of 17 em. The tip of the catheter then generally lies at the level of the point of origin of the ovarian artery from the aorta. The contrast medium was a 60 per cent solution of Urografin, * 70 ml. injected within 2 to 3 seconds. Two anteroposterior views of the abdomen were taken first (Figs. 1 A, Band 2 A, B). If ''Ten per cent sodium and 66 per cent methylglucamine salts of 3,5-diacetamido-2,4,6,-triiodobenzoic acid. Schering A·G , V\'.st Berlin, Germany.
intervillous spaces were demonstrated within the true pelvis another 70 ml. of the contrast medium was injected and a lateral view of the pelvis was taken (Fig. 2, C). The lateral view is of the utmost diagnostic importance since it determines whether the placenta is implanted on the anterior or posterior wall. Knowledge of this point is essential for the localization of the lower boundary of the placenta within the lower uterine segment. The schematic representation of the arteriograms taken on 2 pregnant subjects illustrates this very clearly (Fig. 3).
Volume 86 Number4
Arteriography
1n
cases of placenta previa
537
B
Fig. 1. Arteriograms taken on a patient at term. Normal placental implantation. A, Anteroposterior view. Film taken immediately after completion of the injection of contrast medium. The pelvic arteries (arrows } a r e demonstra ted ; they appear to be ma rkedly widened . B, Anteroposterior view. Film taken 4 seconds after film A. Intervillous spaces a re outlined within the upper right portion of the corpus uteri.
The anteroposterior views 1, A and 1, B, which are practicaiiy identical, do not permit the correct diagnosis to be made. The lateral views 2, A and 2, B enable the position of the placenta to be determined. Results
Placental implantation diagnosed on clinical grounds. The cases were classified into 9 groups without knowledge of the radiologic diagnosis, basing the division on the hospital records of the findings at vaginal palpation, cesarean section, inspection of the
expelled placenta, and site of rupture of the membranes. In view of the difficulties which differential diagnosis between marginal placenta previa and partial placenta previa presents, the two types were included in the same group under the heading " partial placenta previa." Nor was central placenta previa classified separately, being included in the group of total placenta previa. Group I, normal implantation ; Group II, normal implantation or low-lying placenta ; Group III, low-lying placenta ; Group IV,
538
Borell, Fernstrom, and Ohlson
low-lying placenta or partial placenta previa: Group V , any position between low-lying placenta and total placenta previa: Group VI , partial placenta previa: Group VIL
june 13, 1963 Am. j, Obst, & Gyncc.
partial or total placenta previa: Group VIII, total placenta previa; and Group IX, placental site indeterminate. Groups II , IV, V. and VII include the
Fig. 2, A . Arteriogram take n in th e te nth lunar month of pregnanc y o n a pa tient w ith plac enta previa. Anteroposterior view. Film ta ken immediately after completion of the inj ec tion of contrast medium. Th e pel vic arte ries and the ute rine arteries (a rrows ) are outlined .
Volume 86 Number 4
Arieriography
cases m which the position of the placenta could not be inferred with certainty from the clinical features and Group IX includes single cases in which it was not possible to
determine the implantation of the placenta on clinical grounds. Table II shows the classification of the cases on clinical grounds and the month of
1n
cases of placenia prev1a
539
Fig. 2, B, Arteriogram in the tenth lunar month of pregnancy on a patient with placenta previa. Anteroposterior view. Film taken about 4 seconds after film A. Intervillous spaces are outlined within and above the true pelvis.
540
Borell, Fernstrom, and Ohlson
Fig. 2, C , Arteriogram taken in the tenth lunar month of pregnancy on a patient with placenta previa. Lateral view. Film taken about 4 seconds aft er completion of the injection of contrast medium. Placental sinuses are see n to extend over the site of the internal os ( X) . Arrows point toward the fetal head ; (S) first sacral vertebra.
pregnancy in which the arteriography was performed. It is seen that the majority of patients were examined prior to the last lunar month and more than one third between the fifth and eighth lunar months of pregnancy. The table also shows that the placenta was situated in the lower uterine segment in one third of the patients. Treatment. Treatment was planned on the basis of the arteriographic appearances. The latter showed the placenta to be in the lower uterine segment in 4 7 cases; 44 of these patients were kept in the hospital until they had been delivered. If no vaginal bleeding occurred during their first week in the hospital, the patients were allowed to be mobile but were not allowed to leave the ward. The remaining 3 subjects had low-lying placenta. They were discharged and kept under observation as outpatient~.
June ,\m .
.f. Ob' t.
Jj ,
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& <.ynt'C.
Method of delivery. Table III shows the method of delivery in the cases of low-lying placenta or placenta previa. Of the 11 patients with low-lying pl acenta, 8 were delivered vaginally and 3 by cesarean section. Of the 21 subjects with placenta previa, 20 were delivered by cesarean section ; in the remaining patient a severe hemorrhage was controlled by Braxton Hicks' maneuver. Maternal and infant mortality. Maternal mortality was nil although 19 infants were lost. Table IV shows the distribution of the perinatal mortality in the different groups together with the time of death in relation to arteriography. The causes of death are also detailed. In the 106 cases of normal placental implanta tion, 11 infants died. The main causes of death were as follows: debility in 6 cases due to premature separation of the placenta in 3 ; prolapse of the umbilical cord in 2; severe fetal malformation in 2; and erythroblastosis in 1. In 4 7 cases in which the placenta was wholly or partially in the lower uterine segment, 8 infants were lost ; the infant mortality being 17 per cent . The causes of perinatal death were prematurity in 7 cases and severe fetal malformation in 1. Of the 7 perinatal deaths due to prematurity, the postmortem examination revealed hyaline membra ne in 2 cases. No infant was lost in the 7 patients in whom it was impossible to determine with certainty whether the placenta was implanted in the body of the uterus or in the lower uterine segment. Arteriographic appearances. Placental implanta tion was regarded as normal if the anteroposterior view showed the intervillous spaces to be above a transverse plane a t the level of the promontory. If spaces were demonstrated below this level, a lateral view of the pelvis was usually taken in addition to the a nteroposterior view. The position of the placenta cannot be correctly assessed radiologically unless the site of the internal os is defined on the arteriogram. However, the radiologic determination of the site of the internal os presents
cases of placenta previa
541
Volume 86 Number4
Arteriography
difficulties because the latter varies from one patient to the other. In the present investigation the site of the internal os on the lateral projection was assumed to be on the axis of the true pelvis at a point which was about 5 em. below the pelvic inlet. Low-lying placenta was diagnosed if intervillous spaces did not extend to this point but extended posteriorly below the promontory or anteriorly below a point which was about 5 em. above the symphysis. Table V shows the arteriographic diagnoses. As was the case with the clinical findings it was not possible to infer the site of placental implantation with certainty from the arteriographic appearances in some patients. These were therefore placed in separate groups. Complications of arteriography. In no instance did arteriography give rise to renal complications. Also there were no noteworthy allergic reactions observed. In a few cases a hematoma developed at the site of puncture, but in no case was it sufficiently severe
to require specific treatment. Otherwise, neither puncture of the femoral artery nor the introduction of the catheter gave nse to any complications. As already mentioned, the cardinal cause of perinatal death is prematurity in cases of placenta previa. In reinvestigating the hospital records of the patients, special attention was given to the question of whether arteriography involved danger of inducing labor or causing hemorrhage sufficiently severe to necessitate artificial termination of pregnancy. Hemorrhage. In 13 of the 47 patients with placenta previa no vaginal hemorrhage occurred during the period between the radiologic examination and the commencement of labor. Twenty-five of the 47 subjects had episodes of vaginal bleeding during this period but in no instance was the bleeding more severe or frequent than that which took place prior to arteriography. In the remaining 9 subjects with placenta previa vaginal bleeding was more frequent and severe than that prior to the procedure. How-
1n
A,
Fig. 3. Schematic representation of the arteriograms taken on two pregnant patients. AI and A2, normal implantation on the anterior wall of the uterus. BI and B2, placenta previa lying in the posterior part of the lower uterine segment.
542 Borell, Fernstrom, and Ohlson
Am.
ever, in 8 of the latter cases the vaginal bleeding occurred more than 5 days after the examination. It is therefore most unlikely that arteriography was the cause of it. Labor pains. Of the 47 patients with pia-
J.
Jun~ IJ, 1%:1 Obst. & Gynec.
centa previa 11 experienced labor pains within 48 hours of arteriography. In one case intrauterine fetal death had been diagnosed prior to the examination which had been performed in the ninth lunar month of pree;-
Table I. Diagnostic value and complications of arteriography in cases of placenta previa as reported in the literature Diagnostic value of arteriography
Name of author
Hartnett"
1948
Spanio et aJ.12 Norman'
1953 1953 1955 1958 1958 1960 1961
Fernstrom~
Sammons et aJ.to Hodge'1 Brink2 Solisch et aJ.ll
Complication>
68
Reliable
13
C nsatisfactory Reliable II Reliable II Reliable II One incorrect diagnosis Safe method Reliable Correct diagnosis in 9 cases; 0 in 4 cases. indeterminate
15
29 45 13 209 13
Labor sometimes ensued in patients near term if the contrast medium was sodium iodide Safe method 0
-··~-~-~·~--·
Table II. Classification of the cases according to the clinical diagnosis of placental implantation and the month of pregnancy in which arteriography was performed Lunar month of p_r_e...;.g_n,a_n...;cy'----.-·-l····O
Clinical diagnosis
·~5~....---6-,....l ·1-~--
Normal implantation Normal implantation or low-lying placenta Low-lying placenta Low-lying placenta or partial previa Any position between low-lying placenta and total previa Partial previa Partial or total previa Total previa Placental site indeterminate
2
10
a
1
9
-·I
Total
40
106
+
2
0 ll
')
26 1
3
3
2
Total
6
1 I 5
+
6
0 I
17
+2
5i
44
160
12 3 1 1
Table III. Method of delivery in cases of placenta previa
Position of placenta
Low-lying Low-lying or partial previa; any position between low-lying and total previa Partial previa; partial or total previa; total Total *Braxton Hicks'
man~uve1.
Spontaneous vaginal delivery
Cesarean section
Other methods of delivery
I
Total
3
0
11
13
0
!.)
()
20
I*
21
10
36
8
Volume 86 Number 4
Arteriography
nancy. Labor commenced a few hours after arteriography. Four patients had experienced labor pains prior to the examination. The remaining 6 patients were at term. It may be assumed that labor commenced spontaneously in these 11 subjects. Fetal death. As already mentioned, 19 infants were lost (Table IV) but in no instance was perinatal death attributable to arteriography. The causes of death were prematurity in 15 cases, severe malformation in 3, and severe Rh immunization in 1 case. Radiation hazards. In discussing the possible risks of arteriography, special consideration must be given to the radiation hazards. The procedure imposes a much smaller radiation to the fetal gonads and the maternal ovaries than soft tissue radiography which is also used in the diagnosis of placenta previa; the parts of the fetus and maternal ovaries lying within the field of radiation receive less than 1 r. Correlation of the arteriographic diagnosis with the clinical diagnosis. Table VI shows
that the artcriographic diagnosis accorded with the clinical diagnosis in 125 of the 160 cases in the present series. In 29 cases the arteriographic diagnosis slightly deviated from the clinical diagnosis. However, this did not vitiate the treatment of these patients. In 18 of the 29 cases arteriography enabled the diagnosis of the placental site to be made with greater certainty than the clinical diagnostic methods. In the remaining 11 the reverse was true. In 6 cases the arteriographic diagnosis disaccorded with the clinical diagnosis. In 2 of these the reason was omission of taking a lateral view in addition to the anteroposterior view, despite the fact that the latter showed the intervillous spaces to be below a transverse plane at the level of the promontory. In 1 of the 6 cases the reason was that the lower boundary of the placenta reached the region of Bandl's ring, making differentiation between normal implantation and lowlying placenta particularly difficult. In this instance normal implantation was diagnosed
1n
cases of placenta prev1a
543
Table IV. Interval between arteriography and fetal death and causes of death Interval in days between arteriography and fetal death
Fetal weight (grams)
Cause of death
0
1,840
8 0 6
1,220 2,130 1,870
3
2,120
Debility; death during delivery; foot presentation Debility Debility; death 2 hours after delivery Debility; death during delivery; Braxton Hicks' maneuver Debility; anoxia
7 6 Unknown
2,360 1,800 1,810
Normal Normal Normal Nom1al Normal Normal Normal Normal Normal
19 39 13 5 16 1* 2*
1,500 3,210 960 830 1,170 1,150 1,180
Normal
25
Position of placenta Low-lying or partial previa Low-lying Low-lying Partial previa Low-lying or partial previa Total previa Total previa Total previa Normal
1
3
*Fetal death occurred before arteriography.
1,650
Multiple malformations Debility; hyaline membrane Debility; hyaline membrane Debility; premature separation of placenta; prolapse of umbilical cord Debility Rh immunization Debility; premature separation of placenta Debility; premature separation of placenta Debility; premature separation of placenta Debility Debility Multiple malformations Debility; asphyxia; cornm·pssion of umbilical cord; breech
544
Borell, Fernstrom, and Ohlson
Am.
J.
June 15, 196:~ Ohst. & <:yncc.
clinically while the arteriographic appear-
pams m conjunction with the injection of
ances suggested low·-lying placenta. The in-
the contrast mediun1. In 15 cases not in-
correct arteriographic diagnosis resulted in inadequate treatment of the patient. In the rC'maining 3, no or only a few intervillous spaces were demonstrated. This accounted for the incorrect arteriographic diagnosis. One of these indiYiduals experienced labor
eluded in this series, in which arteriography was performed during or between labor pains, the intervillous spaces either failed to opacify or filled unsatisfactorily in conjunction with uterine contraction. vVe were, therefore, inclined to believe that failure of or unsatisfactory demonstration of the intt~rvillous spaces was due to uterine contraction in these :l cases, being painless in 2. Ramsey and coworkers' made a similar observation in pregnant monkeys. They reported that uterine contractions prevented filling of the intervillous spaces.
Table V. Arteriographic diagnosis of placental site Position of .tJlacenta
No. of cases
Normal Normal or low-lying Low-lying Low-lying· or partial previa Any position between !ow-lying and total previa Partial previa Partial or total previa Total previa Placental site indeterminate
107 7
Tobl
160
15
Comment
:l
Various methods have been used for the
+
diagnosis of placenta previa. Many of them
5
have fallacies which may lead to erroneous interpretation of the findings. Vaginal palpation. Before delivery of the patient vaginal palpation is the only clinical
15
Table VI. Correlation of the arteriographic diagnosis with clinical diagnosis
Clinical dia~;nosis*
N
Arteriographic diagnosis according u•ith clinical diagnosis (No. of cases)
102
N-L
1'\-L L-P
0 L-T
2
P-T
0 II
u
3
Arteriographic diagnosis disaccording n•ith clinical diagnosi.r (No. of cases)
II
{j
11
N '>
:)
1\'-T
-t
0
1~
1 ')
N-L T P-T L-T
Total
106
L
')
p L L-P p P-T
p
1\i-T
N-L N L
L
T
Arteriographic diagnoxis slight!)' deviating from clinical diagnosis (No. of cases)
'
,)
0 ')
~
N
N L
17 I)
1
----~--
Total
125
29
6
160
-------*N Sormal implantation; N-L, no1mal implantation or low-lying placenta; L, IO\v-lying placenta; L-P, lo\\-lying placenta pa/ttal previa~ L-T. any position betV~.een 10\\--lying plaC't'nta and total prt>via; P, pal'tial p~t•vJa; P-T. partial or total ptc\ia: T, total p1 evia; N-T, placental site indeterminate.
Volume 86 Number4
method available for the diagnosis of placenta previa. The method has several disadvantages: first, it does not permit the correct diagnosis to be made unless the internal os is sufficiently dilated to admit a finger and the placenta reaches or completely covers the internal os; second, blood clot may simulate placental tissue to the touch. Not until labor has commenced and labor pains have caused dilatation of the cervical canal is it possible to gain a fair idea of the position of the placenta in relation to the internal os. Moreover, vaginal palpation may cause severe uterine hemorrhage. Radiologic methods. Radiologic methods have been widely used in the diagnosis of placenta previa, particularly cystography and soft tissue radiography. These two methods are both reliable if performed during the last lunar month of pregnancy. Earlier in pregnancy, when the first symptoms of placenta previa usually appear, they are unreliable. Moreover, soft tissue radiography cannot be used in cases of polyhydramnios and interpretation of the radiographic appearances may be difficult in cases of multiple pregnancy and transverse lie. Cystography is of no value in cases of oblique, transverse, or breech presentations and in instances of multiple pregnancy cystograms may be difficult to interpret. Arteriography. Arteriography permits the determination of the placental position irrespective of the type of presentation, maturity of pregnancy, or the presence of polyhydramnios. In the present investigation the arteriographic diagnosis accorded with the clinical diagnosis in the majority of the cases (97 per cent). Arteriography was performed on many patients in this series at a stage of pregnancy in which neither vaginal palpation, cystography, nor soft tissue radiography would have enabled the correct diagnosis to be made. It is advisable to avoid the performance of arteriography during uterine contractions because it was found that they may prevent satisfactory filling of the intervillous spaces and this may result in incorrect interpreta-
Arteriography in cases of placenta previa
545
tion of the arteriographic appearances. As uterine contractions may be painless and are then difficult to diagnose, it is expedient to give the patient a relaxant prior to the examination. During the last 6 months all patients were given 5 mg. of isoxsuprine intramuscularly 10 minutes before arteriography. In our experience puncture of the artery and the injection of contrast medium did not give rise to any complications, either in the mother or fetus. Since a maximum of
Table VII. Position of maternal ovaries in relation to the spine between the eighth and tenth lunar months of pregnancy Position of ovaries in relation to the spine
No. of ovarzes
At the level of L-4 At the level of L-5 At the level of S-1
8 21
7
Table VIII. Comparison between the measurements of the cross sectional areas of the ovarian and uterine arteries Combined measurements of cross sectional areas of the right and left ovarian arteries (mm.t)
0.8 0.8 0.8 0.8 1.6 1.8 1.8
2.6
3.1 3.9
3.9
4.9 4.9 4.9 4.9 4.9
6.2 6.7 8.0
8.0 9.8
10.2 11.4 12.0
Combined measurements of cross sectional areas of the right and left uterine arUries (mm.') 8.0 9.8
14.2 16.7 14.2 19.2 22.2 14.6 14.2 8.0
12.0 9.8 10.2 12.0 14.2 14.2 14.2 6.2 4.9 10.2 22.2
14.2
3.1 8.0
546
Borell, Fernstrom, and Ohlson
three films are required the radiation risks are minimal. With the exposure data used the maternal ovaries and the parts of the fetus which were inside the field of radiation received 0.3 r, respectively, per exposure. This dose can be reduced by adjusting the light beam diaphragm so that the upper border of the field of radiation is at the level of L-5-S-l. The fetal gonads are then invariably outside the field of radiation in instances of cephalic presentation. This also applies to the maternal ovaries in many cases. The latter observation was made in 18 cases of uterine pregnancy in which arteriography revealed the position of the maternal ovaries (Table VII\. The position of the maternal ovaries was in good agreement with that reported by Hibbard.'' The present investigation has shown that the demonstration of the ovarian arteries in addition to the uterine arteries is of utmost importance in cases in which placenta previa is suspected on clinical grounds, because the former may take part in the blood supply of the uterus during pregnancy. This was proved in 24 of the 160 cases by measuring crosssectional areas of the ovarian and uterine arteries directly from the films. These measurements showed that the ovarian arteries were remarkably wide as compared with the uterine arteries (Table VIII). It was found that the quantity of contrast medium injected also played an important part in the demonstration of the intervillous spaces. In our hands, injection of 70 mi. of a 60 per cent solution of Urografin resulted in clear visualization of the intervillous spaces and did not have any untoward effects on the patient. According to some authors arteriography performed for localization of the placental site is an extremely difficult procedure which should only be carried out by experienced and specially trained radiologists. In our opinion the technique is not more difficult than arteriography of other structures, e.g., renal arteriography, etc. None of the radiologists of the staff of the Department of Diagnostic Roentgenology of this hospital
c\m.
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Juue J:,, 1963 Obst. & Gynec.
had any difficulty in learning it. We do not support Duncan Reid's 9 view who, in discussing placentography in his textbook of obstetrics and gynecology, wrote: ". . . attempts have also been made to visualize the placenta by arteriography utilizing either the femoral and iliac arteries or the aorta. This formidable procedure, although furnishing interesting information relative to the anatomical changes of the uterine artery in pregnancy, seems too hazardous, impractical, and unnecessary as a diagnostic procedure." As already mentioned, the perinatal mortality associated with placenta previa is generally quoted between 20 and :10 per cent. The corresponding figure in the present series was 17 per cent. There probably are many explanations for this rather low rate. One explanation may be that arteriography permitted early diagnosis of the condition and this made possible prompt admission of the subject and care in hospital until she had been delivered. Care of the patient in hospital throughout the pregnancy is essential to try to avoid hemorrhage which may be sufficiently severe to cause premature delivery. Another possible explanation is that 36 of the 47 patients with low-lying placenta or placenta previa were delivered by cesarean section. Arteriography was also of practical ;·alue in the cases in which it disclosed normal placental implantation because the patients rould be confidently kept under observation as outpatients.
Summary
Arteriography was performed in 160 cases in which placenta previa was suspected on clinical grounds. In 97 per cent the procedure enabled the correct diagnosis to be made. No noteworthy complications attributable to the examination occurred. Arteriography permits early diagnosis of placenta previa and thereby makes possible prompt admission of the patient and care in hospital until she has been delivered. Maternal mortality was nil, and the perinatal death rate was I 7 per cent.
Volume 86 Number4
REFERENCES
1. Borell, U., and Fernstrom, I.: In Abrams, 2. 3. 4. 5. 6.
Herbert 1., editor: Angiography, Boston, 1961, Little, Brown & Company. Brink, D.: J. Obst. & Gynaec. Brit. Emp. 67: 437, 1960. Fernstrom, I.: Acta radio!. suppl. 122, 1955. Hartnett, L. J.: AM. J. OnsT. & GYNEC. 55: 940, 1948. Hibbard, B. M.: Brit. J. Radio!. 34: 387, 1961. Hodge, K. E.: Am. J. Roentgen a!. 80: 651, 1958.
Arteriography rn cases of placenta previa
547
7. Norman, 0.: Brit. J. Radio!. 26:. 393, 1953. 8. Ramsey, E. M., Corner, G. W., Jr., Donner, M. W., and Stran, H. M.: Proc. Nat. Acad. Sc. 46: 100'3, 1960. 9. Reid, D.: Obstetrics, Philadelphia, 1962, W. B. Saunders Company, p. 558. 10. Sammons, B. P., et a!.: Am. J. Roentgenol. 80: 664, 1958. 11. Solisch, G. I., Masterson, J. G., and Hellman, L. M.: AM. J. OnsT. & GYNEC. 81: 57, 1961. 12. Spanio, P., and Nejedly, C.: Minerva ginec. 5: 573, 1953.