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Clinical use of ultrasound in obstetrics and gynecology
ClinicSal use of ultrasound
in
obstetrics and gynecology E.
STEWART
TAYLOR,
HORACE
E.
KENNETH JO6EPH Denver,
THOMPSON, R.
H.
M.D. M.D.
GOTTESFELD, HOLMES,
M.D. M.D.
Colorado
During
c
the past three years ultrasound diagnostic procedures have been significant and useful aids in the clinical practice of obstetrics and gynecology at the University of Colorado Medical Center. The technique has had its most important applications in the preoperative diagnosis of hydatidiform mole, in the estimation of fetal maturity, and for localization of the placenta. Other areas of clinical application are in the diagnosis of multiple pregnancy, fetal position, and intrauterine fetal death. Approximately 10 per cent of our obstetric patients receive ultrasound diagnostic procedures. Ultrasound is used much less frequently in gynecology but does have value in the differential diagnosis of ascites, abdominal cysts, and pktoneal carcinomatosis.
I N 1 9 6 4 we presented the results of our experimental work in the diagnostic use of ultrasound in obstetrics and gynecology. During the intervening 3 years, ultrasound procedures have become significant and useful diagnostic aids in clinical practice. It is the purpose of this presentation to discuss the applications of ultrasonic diagnostic procedures to clinical obstetrics and gynecology at the University of Colorado Medical Center. In the clinical application of ultrasound to obstetrics and gynecology, we have used both the A scope and the compound contact scanner. The A scope has been used exclusively for the purpose of measuring the biparietal diameter of the fetus.7T * The compound contact scanner described previously is of two types.?, 7, * The first has a mechanically driven sectoring scanner which
is a fixed unit in the laboratory, and the second is a hand-controlled sectoring scanner, which is more versatile and is portable. These instruments use 1.75 to 2.25 megaherz transducers and emit sound with a pulse wave rate of 400 to 1,000 times per second. With the advent of diagnostic ultrasound, the use of x-ray for the diagnosis of many problems in pregnancy has been reduced in our hospital. Ultrasound has been used in 691 obstetric patients with diagnostic problems, out of a total obstetric group of 6,497, over the past 3 years, or approximately in 10 per cent of our obstetric cases. To date, there is no evidence of any toxic effect to the mother or fetus, either immediate or latent, as a result of this type of energy. The procedures are easily done with no discomfort to the patient. Clinical
From the Departments of Obstetrics Gynecology and Medicine, University Colorado Medical Center.
and of
studies
(Fig.
11
Estimation of fetal maturity. Seventy-four patients have been referred to the ultrasound laboratory for estimation of fetal maturity. This procedure is accomplished by the use of combined measurement of fetal biparietal
Presented at the Nineteenth Annual Meeting of the.Ame+can Gynecological &;ety, Phoenrx, Artzona, May 4-6,
671
Fig. 1. A, Normal Central
placenta
thorax
of fetus
at term.
previa. D, Hydatidiform
B, Thorax
in fetal
death
in utero
at 36 weeks.
(:,
mole at 18 weeks.
and chest diarneter.*l ’ The estimation of fetal weight by measuring the biparietal diameter, alone, is within plus or minus 454 grams of the actual weight of the infant in two thirds of the patients examined. Our studies show that infants with a biparietal diameter of 8.5 cm. or more will in 91 per cent of the cases weigh in excess of 2,500 grams; when the biparietal diameter is 9.0 cm. or greater, 97 per cent of the infants will weigh greater than 2,500 grams. By doing cross-sectional somagrams of the fetal thorax, it is possible to estimate within plus or minus 500 grams of the actual weight of the infant in 80 per cent of the cases. By combining the two methods, biparietal diameter and chest measurements, and taking an average of the two, an estimation of the fetal weight can be made within plus or minus 400 grams, in 82 per cent of the cases studied. Ultrasound has been particularly helpful in deciding fetal maturity in isoimmunization disease, in maternal diabetes, and in cases of elective repeat cesarean section. Although the accuracy of this determination is
somewhat limited, it is a helpful procedure when used in conjunction with the overall evaluation of the patient. The diagnostic accuracy of this procedure with regard to estimation of fetal weight in patients who were delivered within a week of the ultrasonic scan to determine if the fetus was greater than 2,500 grams, was demonstrated to be 94.7 per cent. In a group of 74 patients, there were 4 patients in whom errors were made. Detedtiien of f&d pasition. One hundred patients near term have been studied in order to determine fetal position when abdominal palpation was not diagnostic. This determination was frequently requested in conjunction with other diagnostic procedures such as placentography, estimation of fetal weight, and in suspected twins. Determination of fetal position is made by the use of the compound contact scanner. This procedure is easily accomplished, and is particularly helpful in the obese patient, or when the presenting part is not sufficiently engaged to make the diagnosis by vaginal examination. In our experience, ultrasound
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has been 100 per cent accurate in the diagnosis of fetal position. Multiple pregnancies. Eighty-two patients with a diagnosis of possible multiple pregnancy have been referred to our laboratory for examination. Twenty-two twin pregnancies and one set of triplets were delivered from this group with 21 twins and the one set of triplets being diagnosed by ultrasound. There was one error in diagnosis. Time of gestation in which this procedure was requested varied from 17 to 40 weeks. The diagnosis was incorrect in one case at 17 weeks’ gestation. Early in our experience with this procedure, it was not recognized that only the head and not the thorax could be visualized as early as the seventeenth gestational week, and two circular structures were seen on longitudinal cross-sectional examination of the abdomen. These were thought to be head and thorax, rather than two infant heads. Since that time, we have learned that before the twenty-second week of gestation, it is difficult to demonstrate the fetal chest clearly. We found this procedure for the diagnosis of twins to be 98.8 per cent accurate, there being but one false negative report. Intrauterine fetal death. Roentgenographic evidence of fetal death may not be demonstrable for three to 10 days following death, or may not be demonstrable at all if the death of the fetus has taken place before skeletal calcification.l, 5, 6 Fifty-nine patients have been referred to the ultrasound laboratory from July, 1965, to April, 1967, for the purpose of evaluating fetal viability. Four patients have been lost to follow-up, 23 patients were felt to have viable fetuses, and 32 were diagnosed as having fetal death in utero. Three errors in diagnoses were made. In the first patient, the initial somagram was that of a viable fetus, but a later somagmm showed changes of fetal death, A viable fetus was born to this patient. The second showed failure of growth on two different scans early in gestation and the patient was not seen again. A viable infant was ultimately delivered. The third patient, diabetic,
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was felt to have an intrauterine fetal death as evidenced by ultrasound, fetal ECG, and a negative pregnancy test. Shortly afterward, the uterus showed evidence of growth and fetal heart tones were heard by one examiner. The mother was subsequently delivered of a macerated 980 gram stillborn fetus. The somagraphic pattern of intrauterine fetal death is not fully understood. The picture that is obtained probably represents changes in the acoustical impedance following cellular death and secondary changes in the intracellular and extracellular fluid volumes. The pattern was first shown in 1965 to have value as a laboratory adjuvant in the diagnosis of intrauterine death.3 There are several problems that arise in the diagnosis of fetal death. The first is that before calcification has occurred, the somagram pattern of fetal death is one in which there is a relative absence of fetal parts. Early pregnancies, before the fourteenth week, many occasionally give this same appearance, so that in early pregnancy we advise taking serial somagrams a week apart to determine if there is evidence of fetal development. Following calcification of the fetus (fourteenth week), we have been able to demonstrate fetal death in as little as 6 hours after the clinical diagnosis is suspected, if we have a previous normal somagram on that particular patient. If no previous normal somagrams are available, we prefer to obtain later somagrams in 48 to 72 hours after a suspected intrauterine fetal death. This is especially true in those patients with pregnancies complicated by maternal diabetes or Rh isoimmunization, since fetal edema may produce a pattern similar to that of fetal death. The diagnosis of intrauterine fetal death should not be made from one somagram scan. We feel that serial somagrams should be taken. Our accuracy rate for ultrasonic diagnosis of intrauterine fetal death has been 94.5 per cent. We have had three false positive diagnoses. Placentography. Three to 5 patients are scanned by ultrasound each week for placenta localization. In the initial publication
674 Taylor et al.
on placental somagraphy, placental position was located accurately in 97 per cent of 116 patients.2 Since that time, an additional 108 patients with accurate delivery records have been studied to April 1, 1967. Of the 108, 86 cases were referred for vaginal bleeding and 22 patients were referred for the purpose of helping the individual doing amniotic fluid sampling direct the needle away from the placenta. There were 4 errors in placental location. The diagnosis of partial placenta previa was made by ultrasound in
Table I. Results Over-a!1 accuracy Obstetric
(70)
uses
Fetal position Multiple gestation Hydatidiform mole Placental location Fetal weight (great-r than 2,500 grams) Fetal death
Fig. 2. A, Generalized
False jositive
False negative
100 98.8 98.7 97 94.7
0 0 0 2
0 1 1 5
94.5
3
0
Normal bowel carcinomatosia
2 cases, but at delivery, the etiology of the bleeding was felt to be a. marginal placentai sinus rupture. In the other 2, the diagnosis of low-lying placenta was made by ultrasound, but a partial previa and central placenta previa were diagnosed by cesarean section. In the remaining 104 cases, the placentas were accurately located. The accuracy rate for placenta localization remains at 97 per cent. The technique still poses some problems in the evaluation of a posteriorly implanted placenta without any lateral excrescences. There is also difficulty in diagnosing central placenta previa. Hydatidifarm mole. The most useful place of ultrasound in obstetrics and gynecology is in the differentiation of molar pregnancy from a normal pregnancy.* As of April 1, 1967, we have examined 78 patients for the presence or absence of molar tissue. Nineteen of these 78 patients showed positive evidence of hydatidiform mole. We have had one false negative molar preg-
.I.--r.~ i. -I “I. _C, Uteri& pattern. B, XM~~&rioma of iary. of peritoneum from serous cystadenocarcinoma.
fibromyimas.
D,
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nancy which was diagnosed as a missed abortion by ultrasound. With our present experience this film would now be read as a molar pregnancy. There have been no false positive diagnoses of molar pregnancies. The accuracy rate for the diagnosis of hydatidiform mole, using ultrasound, is 98.7 per cent. A summarization of the accuracy of diagnosis of obstetric conditions is given in Table I. Gynecology (Fig. 2). As the sound beam passes through the body, echoes reflect at any tissue interface where there is a change in acoustical impedance. Unlike x-ray, where extreme changes in density are required to outline a structure, density changes as low as 1 per cent will cause sound reflection of sufficient amount to be detected and recorded. Because of these physical qualities of ultrasound, it is possible to outline soft tissue structures such as cysts and solid tumors and to differentiate between various body organs and abnormal conditions. Diagnostic ultrasound in gynecology does not have the same accuracy as it does in obstetrics. It does, however, serve a useful purpose when used in conjunction with other diagnostic procedures. Its value in gynecol-
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ogy has been described previously, in which the details of the differentiation of solid and cystic tumors, encysted and free abdominal fluid, and benign and malignant disease are prevented.‘O Twenty-nine patients have been referred to the laboratory over the past year for the purpose of helping establish or rule out pelvic tumors and cysts when the diagnosis was equivocal by abdominal and pelvic examination, or to differentiate between free and encysted fluid in the abdomen. In 22 instances, an exploratory operation was performed and the diagnoses confirmed. Thirteen of the patients had benign ovarian cysts, 7 patients had no pathology, 3 had uterine leiomyomas, 3 had pelvic carcinoma, 2 had grossly distended urinary bladders associated with pregnancy, and one had a retained abdominal placenta. The remaining patients have been followed and no pathology has been apparent. Ultrasound as yet has a very limited application to gynecologic diagnosis. Perhaps its most specific value has been in the differentiation of ascites, obesity, or an ovarian tumor where classical methods of physical examination cannot establish the diagnosis.
REFERENCES
1.
Caughey, A. F., Jr.: Obst. & Gynec. Surv. 16: 153. 1961. 2. Gottesfeld, K. R., Thompson, H. E., Holmes, J. H., and Taylor, E. S.: AM. J. OBST. & GYNEC. 96: 538, 1966. 3. Gottesfeld, K. R.: The Practical Application of Ultrasound in Obstetrics and Gynecolagy, in Diagnostic Ultrasound, Proceedings of the First International Conference, New York, 1966, Plenum Press, pp. 428449. 4. Gottesfeld, K. R., Taylor, E. S., Thompson, H. E., and Holmes, J. H.: Obst. & Gynec. in press. 5. Northway, W. H., and Walls, W. L.: Am. T. Roentaenol. 89: 1080. 1963. 6. Stewart,-A. M.: Brit.’ J. Radiol. 34: 187, 1961.
Discussion* DR. have
JOSEPH struggled
HOLMES,**
Denver,
Colorado.
I
personally with the development
‘This Discussion is to the papers by Taylor and also the paper by Hellman and associates. **By invitation.
and associates
7. Taylor, E. S., Holmes, J. H., Thompson, H. E., and Gottesfeld, K. R.: AM. J. OBST. & GYNEC. 90: 655, 1964. 8. Thompson, H. E., Holmes, J. H., Gottesfeld, K. R., and Taylor, E. S.: AM. J. OBST. & GYNEC. 92: 44, 1965. 9. Thompson, H. E.: Studies of Fetal Growth by Ultrasound, in Diagnostic Ultrasound, Proceedings of the First International Conference, New York, 1966, Plenum Press, pp. 416-427. H. E., Holmes, J, H., Gottesfeld, 10. Thompson, K. R., and Taylor, E. S.: AM. J. OBST. & GYNEC. In press. 4200 East Ninth Denver, Colorado
Avenue
of this technique since 1951, and thus it is fying to see it finally develop as a useful nostic procedure. I would like to make specific references to the papers presented also make a few general comments which be of interest to those who may attempt
grati-
diagsome and might to use
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ct
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diagnostic ultrasound in the next few months. An unmentioned application of diagnostic ultrasound is in evaluating the patient with repeated spontaneous abortion. Dr. Ian Donald of Glasgow claims that he can visualize the dcvelopment of the fetus from the third week up to the eleventh week. Then there is a period between the eleventh week and the fourteeenth week when the echo pattern of the developing embryo is obscured by the placental echo pattern. After the fourteenth week the baby can then be followed in its development throughout the remainder of pregnancy. According to Dr. Donald, one factor in proper development of the fetus is the site of ovum implantation in the uterus. I think we all realize that there is some danger in expressing fetal growth as a function of weight change when we are making such actual measurements as biparietal diameter, occipital-frontal circumference, or chest size. This is an error we make in internal medicine when we try to express blood volume measurements as cubic centimeters per kilogram, because you cannot expect a direct relationship. I would suggest as the ultrasonic techniques improve, that the ultimate aim should be to express fetal growth and development in terms of what we actually can measure, for example, chest size or liver size. The difference shown by Dr. Hellman, between measurements of the biparietal diameter made by the A and B ultrasound techniques, is probably not a true difference. Nor does Dr. Taylor’s presentation of his ultrasonic results as per cent of correct diagnoses paint a true picture of the capabilities of ultrasound. When good ultrasonic pictures (somagrams) are obtained by the B-scan technique, then there is little doubt of the diagnosis and of the fetal measurements. However, with current equipment and examining techniques, we are still getting between 10 and 20 per cent poor pictures, and when we make an interpretation from inadequate somagrams, the errors are much greater. It is difficult to specify in every instance why the picture is inadequate. The inadequate pictures might be related to such factors as variations in brightness of the oscilloscope screen, variations in positioning of the patient, improper sensitivity settings, differences in equipment performanceas (for example, alterations in voltage or tube performance) differences in tissue structure which alter the rate of the transmission of sound.
11t the pres<*nt stage of development of ult~ ;Isonic diagnostic techniques, it is particularly irnportant to standardize equipment operation and examining methods. For example, in the fetal death problem presented by Dr. Taylor, when he examines pictures taken at sequential time intervals, he must be sure that the equipment is performing exactly the same for each examination. Otherwise, proper interpretation of the successive pictures is impossible. I cannot emphasize tot) strongly the need for developing standards which make it possible for the technician to check the equipment operation daily and also to profile each new piece of equipment, such as a transducer, before it is incorporated into the routine diagnostic operation. We have devised several types of standards filling them with castor oil to simulate attenuation of tissues. One standard contains small spherical balls which are spaced at different distances in the castor oil-filled tube. Thus, by comparing the echo signals received from the three spheres, it is possible to determine equipment performance at different depths within the human body and to determine the precise sensitivity settings required to reproduce previous studies. A smaller castor oilfilled tube is used to calibrate tissue measurcments. Another important standardization is the X-Y axis alignment. When this alignment is not proper, the outline of various parts of the fetal head do not form a perfect oval, but the linear traces overlap improperly. With such misalignment, it is impossible to obtain proper measurements of the fetal head. Another example of improper X-Y alignment is overlapping of the echo lines representing a trace of the posterior edge of the liver and gallbladder. Simpler standards are used to check the equipment every day or once a week. A large plastic box with many different target patterns is used to profile all characteristics of a transducer before it is placed in our system. Spheres spaced at several different distances apart will determine the degrre of resolution obtained. A series of targets at spaced intervals from the transducer will determine the near and distant limitations. In addition to standardization of equipment, we must standardize examining and scanning procedures. For example, the type of picture obtained can be altered significantly by changes in sensitivity settings of the receiver. This is iilustrated in Fig. 1, which shows the same liver echo pattern displayed at four different sensitivity settings. As you will note: there is quite a difference
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Fig. 1. Live
echo pattern
displayed
at four
different
sensitivity
in obstetrics
. .
Fig. 2. Correlation mission
of
Iliffe
between Publications,
required Ltd.,
sensitivity setting London, England.
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settings.
.
.
.
and
l
.
l
.
.
. . l a’
.
and surface Ultrasonics
area. (Reprinted 5: 65, 1967.1
by
per-
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et al.
in the type of picture obtained and, thus, before making a proper interpretation, the physician must consider the suspected pathology in relation to sensitivity settings. In some instances, the sensitivity setting can be changed to accentuate suspected pathology. This is comparable to x-ray, where a chest picture can appear quite different when the equipment settings arc changed. At the present time, we have not developed a technique for properly setting the sensitivity dials and other equipment parameters in accordance with body build and tissue characteristics (fat or muscle). This, as you know, is done very carefully in x-ray with established charts which show the proper settings for each patient based on body size or other physical measurements. Preliminary work in our laboratory indicates that a different sensitivity setting is required for patients of different body build. We used as a criteria of proper sensitivity setting, good delineation of the posterior edge of the liver. You will note from Fig. 2 that there seems to be a definite correlation between the required sensitivity setting and the surface area. It is always possible to change electronic variables to improve the ultrasonic picture when you use the equipment for examining only one diagnostic area, such as the pregnant abdomen. When one develops equipment that can be applied to visualizing all areas of the body, then you sacrifice some precision for examining a particular anatomic area. One example of this is use of time-varied gain (TVG). TVG reprepresents an automatic change in sensitivity setting from time of pulsing so that the near echo signals which will obscure the picture are eliminated and only the more distant signals are displayed on the screen. A modification of TVG is depth control, where near signals are displayed as usual but more distant signals are amplified by increasing receiver sensitivity. This makes it possible to look at more distance anatomic structures within the body in a more effective fashion. It is also apparent from the illustrations shown in both papers that our diagnostic percentages will improve as the individuals interpreting the pictures gain more experience. This is to be expected if one realizes that it takes at least 3 years to train a radiology resident. Dr. Taylor was rather modest in describing the diagnostic results with gynecologic lesions. Our residents on the medical ward feel that
ultrasound has been most useful in providing diagnostic information regarding abdominal masses. Dr. Taylor discussed these results from the standpoint of the etiology of the pathologic lesion. However, ultrasound can provide certain structural information which helps in arriving at a correct diagnosis when considered with othrt clinical information. Ultrasound can delineate the precise size of the lesion and show whether the mass contains organized or disorganized structures. Furthermore, there is some evidence in both our own work and the studies of Dr. Donald that if in the case of a tumor we vary the ultrasonic frequency, different types of tumors will give different echo displays. This may represent another advantage which ultrasound will have over radiology in the future. As regards toxicity of diagnostic ultrasound, all reported tissue destruction occurs at power levels above 1 watt per square centimeter. No toxicity has been reported at the power levels used in diagnostic ultrasound, namely 0.004 watt per square centimeter or below. At these power levels there has been no evidence of toxicity on the reproductive systems in animal studies done in our laboratory and in the laboratories of Dr. Sundgren and Dr. Smythe. No genetic effects on hamsters and mice have been demonstrated in two reports. There may be a level of ultrasound, possibly between 0.5 and 0.7 watt per square centimeter which may stimulate fetal growth. In order to further reduce the power levels used, we are currently devising a system which would set receiver sensitivity at maximum and reduce pulse power to provide changes in picture intensity. This technique should further reduce the power levels required. This is very feasible and can be easily incorporated into the present diagnostic systems. With several commercial companies currently producing ultrasonic diagnostic equipment, there is serious need for setting up training programs in this country for both physicians and technicians. We have currently &en discussing this problem with the Public Health Service. Such training programs are essential if this new ultrasonic technique is to achieve proper stature among physicians and provide additional diagnostic aids for the development of American medicine. DR. HORACE THOMPSON, Denver, Colorado. In the preparation of a paper such as the one presented by Dr. Taylor, many details and interesting points are difficult to include. For this
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Fig.
Fig.
1. Somagrams
of patient
2. Abdominal
pregnancy.
with
in obstetrics
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triplets.
reason, I would like to show you somagrams on 2 patients that I thought were particularly interesting. Both of these patients were included in the reported group. Fig. 1 represents serial somagrams taken at 2 cm. intervals from the top of the fundus to the symphysis of a patient with triplets approximately 30 weeks pregnant. Starting at the upper left corner you will note the outline of one fetal
head. Continuing downward in the same row, a second head is also outlined. As we progress from above downward and to the right in the third row, the thorax in all 3 infants is demonstrated. In the last row, lower picture, the head of the third infant is demonstrated. Fig. 2 represents three somagrams of a patient with an abdominal pregnancy. Somagram
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A was taken before the infant was delivered by laparotomy and is a longitudinal cross-section taken along the midline. It demonstrates the fetal head, the enlarged uterus, and the placenta. These structures are labeled in the picture. At the time of operation, the infant was macerated and had been dead approximately 2 weeks. The placenta was essentially avascular at this time and was implanted retroperitoneally on the posterior surface of the posterior parietal peritoneum and on the posterior surface of the uterus and broad ligaments. It was impossible to remove the placenta safely at this time so the infant was delivered, the placenta left intact, and the abdomen closed. Somagram 2, B was taken 3 weeks postoperatively and outlines the placental tissue and the amniotic cavity containing a homogeneous material. The patient was followed in the clinic for the next 9 months and the abdominal mass did not decrease in size. The patient complained of lower abdominal pain and pressure. On this basis, it was decided to again explore the abdomen. At this time the placenta was removed, and the amniotic cavity was found to contain approximately 1,000 cc. of clear green fluid.
Somagram 2, C was taken 2 days Itefore tttc: second operation and clearly outlines the larq: cystic mass found at surgery which was the Auidfilled amniotic cavity. It is now 2 weeks since operation and additional somagrams will be obtained in the near future to complete the follow-up. DR. LOUIS HELLMAN, Brooklyn, 1C’ew York. I am very honored to have Dr. Holmes discuss my paper this afternoon. We is not very old as far as age goes, but he is one of the old men in the field of ultrasonics and one of the real authorities in this area. Some of his origina pictures, those taken with the water bath, are among the best that have ever been made. If you have a chance to visit Dr. Holmes’ laboratory or Dr. Taylor’s, I can assure you that you will be we11 received and have a profitable visit. By showing some odd pictures, Dr. Holmes gave me a chance to show one of my very best. This slide is a transverse scan of young woman 9 weeks pregnant. The early implanted ovum, a hoilow sphere, filled with fluid and its projecting villi are clearly demonstrable (Fig. 1) . I would like to reinforce Dr. Holmes’ statement about standardization. I neither understand his sensitivity figures, nor does he comprehend mine. Furthermore, a lot of the conventions
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are in disagreement, for example, Dr. Donald’s pictures are reversed from the ones we use in this country. We need standardization of terminology and of equipment. Our equipment is standardized weekly in the same manner that Dr. Holmes uses. Although the equipment shows little tendency to drift, the standardization is important. Furthermore, this complicated apparatus needs a part-time engineer to keep it in operating order. The question of the difference between A and B scan is clinically quite important. A machine to do an A scan is relatively cheap, while that necessary to do a B scan costs between fifteen and twenty thousand dollars. Finally, just a word about testing for safety of the apparatus in pregnancy. We are testing our apparatus on tissue cultures of fetal cells, studying the rates and normalcy of mitotic division. I do not suppose the energies we are using will affect these tissues, but it is important that we make absolutely sure in this matter. DR. HAROLD TOVELL, New York, New York. During the last 5 years, in our laboratory we have been using ultrasonic techniques for both gynecologic and obstetric diagnoses. Besides providing information which cannot be obtained by any other means, ultrasonography proved to be a valuable adjunct or a preferable alternative to other diagnostic methods presently at our disposal. Biparietal cephalometry using the A-scan method as originally proposed by Donald is subject to some errors, both in technique and interpretation. This has recently been shown in a prenatal series of biparietal measurements studied by Kohorn at Yale where about 80 per cent were within 3 m. of accuracy, 60 per cent within 2 mm., and some 15 per cent showed an error greater than 4 mm., when compared with caliper measurements performed postnatally. The optical averaging method introduced by McKinney in 1965 for echo encephalography has been subsequently applied in our Bioacoustical Laboratory at Woman’s Hospital by Dr. Lajos von Micsky for fetal biparietal cephalometry. According to some preliminary studies, this technique seems to improve the accuracy of this biometric procedure. In contradistinction to A-scan cephalometry, where the signals appear as “pips,” i.e., vertical deflections of the time base line, optical averaging stykography displays the echoes in the in-
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tensity modulated mode. In order to achieve this, the plane of the A scan is electronically rotated 90 degrees, thus displaying as luminous dots only the peaks of the “pips.” While the transducer is minimally rocked about its point of contact on the abdomen, the derived ultrasonic image, comprising a row of light spots of varying intensity, is electronically swept across the face of the cathode ray tube. A Polaroid camera with time exposure records the signal information as a series of linear traces, the intensity and thickness of which are proportional to the returned energy. Since the strongest signals are reflected by the proximal and distal walls of the fetal head and its midline structures, the sonograph and camera sensitivity can be so adjusted that only traces corresponding to these anatomic landmarks are photographed, thereby permitting an unequivocal precise measurement of the biparietal diameter. This technical modification in our hands in some 15 cases studied to date measures the biparietal diameter with an accuracy of plus or minus 1 mm. It is emphasized that in order to exclude any error of interpretation, all optical averaging tracings in biparietal cephalometry should reveal the midline echo. The method of cephalopelvic periography, or area measurement, employed in our laboratory involves the planimetric area determination of the transverse tomogram of the fetal head that shows the same occipitofrontal and biparietal diameters as previously determined by optical averaging stykography method. The direction and dimensions of these two diameters can only be precisely determined by A scan in a breech presentation or where the fetal head is easily maneuverable such as a floating head or in some cases of polyhydramnios. While the two diameters are not in the same plane, they fall within the width of the transducer and thus delimit a well-defined anatomic segment of the fetal head. So far, it would appear that the correlation of these precise measurements with the area of the pelvic inlet, as measured by x-ray pelvimetry, permits a more reliable estimation of cephalopelvic relationships than has hitherto been possible. DR. TAYLOR (Closing). In the 3 years past, ultrasound diagnostic procedures in our own practice and our own medical school setting can be summarized as follows: This diagnostic procedure is the final judg-
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ment as to whether a patient does or dots not have a hydatidiform mole. We have discarded all other methods for making this final diagnosis before treatment. The other area in which I think it is now indispensable is in localization of the placenta before proceeding with amniocentesis or intrauterine transfusion.
‘I‘hc last arc~r for which we USC it e\ cry week is in confirming a judgment about the matut-it! of a given infant who is to be delivered from a mother who is diabetic or from a patient who has had a previous ccsarean section; and, in some other instances, where a judgment has to be made as to whether a fetus is mature or not.
in
obstetrics and gynecology E.
STEWART
TAYLOR,
HORACE
E.
KENNETH JO6EPH Denver,
THOMPSON, R.
H.
M.D. M.D.
GOTTESFELD, HOLMES,
M.D. M.D.
Colorado
During
c
the past three years ultrasound diagnostic procedures have been significant and useful aids in the clinical practice of obstetrics and gynecology at the University of Colorado Medical Center. The technique has had its most important applications in the preoperative diagnosis of hydatidiform mole, in the estimation of fetal maturity, and for localization of the placenta. Other areas of clinical application are in the diagnosis of multiple pregnancy, fetal position, and intrauterine fetal death. Approximately 10 per cent of our obstetric patients receive ultrasound diagnostic procedures. Ultrasound is used much less frequently in gynecology but does have value in the differential diagnosis of ascites, abdominal cysts, and pktoneal carcinomatosis.
I N 1 9 6 4 we presented the results of our experimental work in the diagnostic use of ultrasound in obstetrics and gynecology. During the intervening 3 years, ultrasound procedures have become significant and useful diagnostic aids in clinical practice. It is the purpose of this presentation to discuss the applications of ultrasonic diagnostic procedures to clinical obstetrics and gynecology at the University of Colorado Medical Center. In the clinical application of ultrasound to obstetrics and gynecology, we have used both the A scope and the compound contact scanner. The A scope has been used exclusively for the purpose of measuring the biparietal diameter of the fetus.7T * The compound contact scanner described previously is of two types.?, 7, * The first has a mechanically driven sectoring scanner which
is a fixed unit in the laboratory, and the second is a hand-controlled sectoring scanner, which is more versatile and is portable. These instruments use 1.75 to 2.25 megaherz transducers and emit sound with a pulse wave rate of 400 to 1,000 times per second. With the advent of diagnostic ultrasound, the use of x-ray for the diagnosis of many problems in pregnancy has been reduced in our hospital. Ultrasound has been used in 691 obstetric patients with diagnostic problems, out of a total obstetric group of 6,497, over the past 3 years, or approximately in 10 per cent of our obstetric cases. To date, there is no evidence of any toxic effect to the mother or fetus, either immediate or latent, as a result of this type of energy. The procedures are easily done with no discomfort to the patient. Clinical
From the Departments of Obstetrics Gynecology and Medicine, University Colorado Medical Center.
and of
studies
(Fig.
11
Estimation of fetal maturity. Seventy-four patients have been referred to the ultrasound laboratory for estimation of fetal maturity. This procedure is accomplished by the use of combined measurement of fetal biparietal
Presented at the Nineteenth Annual Meeting of the.Ame+can Gynecological &;ety, Phoenrx, Artzona, May 4-6,
671
Fig. 1. A, Normal Central
placenta
thorax
of fetus
at term.
previa. D, Hydatidiform
B, Thorax
in fetal
death
in utero
at 36 weeks.
(:,
mole at 18 weeks.
and chest diarneter.*l ’ The estimation of fetal weight by measuring the biparietal diameter, alone, is within plus or minus 454 grams of the actual weight of the infant in two thirds of the patients examined. Our studies show that infants with a biparietal diameter of 8.5 cm. or more will in 91 per cent of the cases weigh in excess of 2,500 grams; when the biparietal diameter is 9.0 cm. or greater, 97 per cent of the infants will weigh greater than 2,500 grams. By doing cross-sectional somagrams of the fetal thorax, it is possible to estimate within plus or minus 500 grams of the actual weight of the infant in 80 per cent of the cases. By combining the two methods, biparietal diameter and chest measurements, and taking an average of the two, an estimation of the fetal weight can be made within plus or minus 400 grams, in 82 per cent of the cases studied. Ultrasound has been particularly helpful in deciding fetal maturity in isoimmunization disease, in maternal diabetes, and in cases of elective repeat cesarean section. Although the accuracy of this determination is
somewhat limited, it is a helpful procedure when used in conjunction with the overall evaluation of the patient. The diagnostic accuracy of this procedure with regard to estimation of fetal weight in patients who were delivered within a week of the ultrasonic scan to determine if the fetus was greater than 2,500 grams, was demonstrated to be 94.7 per cent. In a group of 74 patients, there were 4 patients in whom errors were made. Detedtiien of f&d pasition. One hundred patients near term have been studied in order to determine fetal position when abdominal palpation was not diagnostic. This determination was frequently requested in conjunction with other diagnostic procedures such as placentography, estimation of fetal weight, and in suspected twins. Determination of fetal position is made by the use of the compound contact scanner. This procedure is easily accomplished, and is particularly helpful in the obese patient, or when the presenting part is not sufficiently engaged to make the diagnosis by vaginal examination. In our experience, ultrasound
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has been 100 per cent accurate in the diagnosis of fetal position. Multiple pregnancies. Eighty-two patients with a diagnosis of possible multiple pregnancy have been referred to our laboratory for examination. Twenty-two twin pregnancies and one set of triplets were delivered from this group with 21 twins and the one set of triplets being diagnosed by ultrasound. There was one error in diagnosis. Time of gestation in which this procedure was requested varied from 17 to 40 weeks. The diagnosis was incorrect in one case at 17 weeks’ gestation. Early in our experience with this procedure, it was not recognized that only the head and not the thorax could be visualized as early as the seventeenth gestational week, and two circular structures were seen on longitudinal cross-sectional examination of the abdomen. These were thought to be head and thorax, rather than two infant heads. Since that time, we have learned that before the twenty-second week of gestation, it is difficult to demonstrate the fetal chest clearly. We found this procedure for the diagnosis of twins to be 98.8 per cent accurate, there being but one false negative report. Intrauterine fetal death. Roentgenographic evidence of fetal death may not be demonstrable for three to 10 days following death, or may not be demonstrable at all if the death of the fetus has taken place before skeletal calcification.l, 5, 6 Fifty-nine patients have been referred to the ultrasound laboratory from July, 1965, to April, 1967, for the purpose of evaluating fetal viability. Four patients have been lost to follow-up, 23 patients were felt to have viable fetuses, and 32 were diagnosed as having fetal death in utero. Three errors in diagnoses were made. In the first patient, the initial somagram was that of a viable fetus, but a later somagmm showed changes of fetal death, A viable fetus was born to this patient. The second showed failure of growth on two different scans early in gestation and the patient was not seen again. A viable infant was ultimately delivered. The third patient, diabetic,
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was felt to have an intrauterine fetal death as evidenced by ultrasound, fetal ECG, and a negative pregnancy test. Shortly afterward, the uterus showed evidence of growth and fetal heart tones were heard by one examiner. The mother was subsequently delivered of a macerated 980 gram stillborn fetus. The somagraphic pattern of intrauterine fetal death is not fully understood. The picture that is obtained probably represents changes in the acoustical impedance following cellular death and secondary changes in the intracellular and extracellular fluid volumes. The pattern was first shown in 1965 to have value as a laboratory adjuvant in the diagnosis of intrauterine death.3 There are several problems that arise in the diagnosis of fetal death. The first is that before calcification has occurred, the somagram pattern of fetal death is one in which there is a relative absence of fetal parts. Early pregnancies, before the fourteenth week, many occasionally give this same appearance, so that in early pregnancy we advise taking serial somagrams a week apart to determine if there is evidence of fetal development. Following calcification of the fetus (fourteenth week), we have been able to demonstrate fetal death in as little as 6 hours after the clinical diagnosis is suspected, if we have a previous normal somagram on that particular patient. If no previous normal somagrams are available, we prefer to obtain later somagrams in 48 to 72 hours after a suspected intrauterine fetal death. This is especially true in those patients with pregnancies complicated by maternal diabetes or Rh isoimmunization, since fetal edema may produce a pattern similar to that of fetal death. The diagnosis of intrauterine fetal death should not be made from one somagram scan. We feel that serial somagrams should be taken. Our accuracy rate for ultrasonic diagnosis of intrauterine fetal death has been 94.5 per cent. We have had three false positive diagnoses. Placentography. Three to 5 patients are scanned by ultrasound each week for placenta localization. In the initial publication
674 Taylor et al.
on placental somagraphy, placental position was located accurately in 97 per cent of 116 patients.2 Since that time, an additional 108 patients with accurate delivery records have been studied to April 1, 1967. Of the 108, 86 cases were referred for vaginal bleeding and 22 patients were referred for the purpose of helping the individual doing amniotic fluid sampling direct the needle away from the placenta. There were 4 errors in placental location. The diagnosis of partial placenta previa was made by ultrasound in
Table I. Results Over-a!1 accuracy Obstetric
(70)
uses
Fetal position Multiple gestation Hydatidiform mole Placental location Fetal weight (great-r than 2,500 grams) Fetal death
Fig. 2. A, Generalized
False jositive
False negative
100 98.8 98.7 97 94.7
0 0 0 2
0 1 1 5
94.5
3
0
Normal bowel carcinomatosia
2 cases, but at delivery, the etiology of the bleeding was felt to be a. marginal placentai sinus rupture. In the other 2, the diagnosis of low-lying placenta was made by ultrasound, but a partial previa and central placenta previa were diagnosed by cesarean section. In the remaining 104 cases, the placentas were accurately located. The accuracy rate for placenta localization remains at 97 per cent. The technique still poses some problems in the evaluation of a posteriorly implanted placenta without any lateral excrescences. There is also difficulty in diagnosing central placenta previa. Hydatidifarm mole. The most useful place of ultrasound in obstetrics and gynecology is in the differentiation of molar pregnancy from a normal pregnancy.* As of April 1, 1967, we have examined 78 patients for the presence or absence of molar tissue. Nineteen of these 78 patients showed positive evidence of hydatidiform mole. We have had one false negative molar preg-
.I.--r.~ i. -I “I. _C, Uteri& pattern. B, XM~~&rioma of iary. of peritoneum from serous cystadenocarcinoma.
fibromyimas.
D,
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nancy which was diagnosed as a missed abortion by ultrasound. With our present experience this film would now be read as a molar pregnancy. There have been no false positive diagnoses of molar pregnancies. The accuracy rate for the diagnosis of hydatidiform mole, using ultrasound, is 98.7 per cent. A summarization of the accuracy of diagnosis of obstetric conditions is given in Table I. Gynecology (Fig. 2). As the sound beam passes through the body, echoes reflect at any tissue interface where there is a change in acoustical impedance. Unlike x-ray, where extreme changes in density are required to outline a structure, density changes as low as 1 per cent will cause sound reflection of sufficient amount to be detected and recorded. Because of these physical qualities of ultrasound, it is possible to outline soft tissue structures such as cysts and solid tumors and to differentiate between various body organs and abnormal conditions. Diagnostic ultrasound in gynecology does not have the same accuracy as it does in obstetrics. It does, however, serve a useful purpose when used in conjunction with other diagnostic procedures. Its value in gynecol-
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ogy has been described previously, in which the details of the differentiation of solid and cystic tumors, encysted and free abdominal fluid, and benign and malignant disease are prevented.‘O Twenty-nine patients have been referred to the laboratory over the past year for the purpose of helping establish or rule out pelvic tumors and cysts when the diagnosis was equivocal by abdominal and pelvic examination, or to differentiate between free and encysted fluid in the abdomen. In 22 instances, an exploratory operation was performed and the diagnoses confirmed. Thirteen of the patients had benign ovarian cysts, 7 patients had no pathology, 3 had uterine leiomyomas, 3 had pelvic carcinoma, 2 had grossly distended urinary bladders associated with pregnancy, and one had a retained abdominal placenta. The remaining patients have been followed and no pathology has been apparent. Ultrasound as yet has a very limited application to gynecologic diagnosis. Perhaps its most specific value has been in the differentiation of ascites, obesity, or an ovarian tumor where classical methods of physical examination cannot establish the diagnosis.
REFERENCES
1.
Caughey, A. F., Jr.: Obst. & Gynec. Surv. 16: 153. 1961. 2. Gottesfeld, K. R., Thompson, H. E., Holmes, J. H., and Taylor, E. S.: AM. J. OBST. & GYNEC. 96: 538, 1966. 3. Gottesfeld, K. R.: The Practical Application of Ultrasound in Obstetrics and Gynecolagy, in Diagnostic Ultrasound, Proceedings of the First International Conference, New York, 1966, Plenum Press, pp. 428449. 4. Gottesfeld, K. R., Taylor, E. S., Thompson, H. E., and Holmes, J. H.: Obst. & Gynec. in press. 5. Northway, W. H., and Walls, W. L.: Am. T. Roentaenol. 89: 1080. 1963. 6. Stewart,-A. M.: Brit.’ J. Radiol. 34: 187, 1961.
Discussion* DR. have
JOSEPH struggled
HOLMES,**
Denver,
Colorado.
I
personally with the development
‘This Discussion is to the papers by Taylor and also the paper by Hellman and associates. **By invitation.
and associates
7. Taylor, E. S., Holmes, J. H., Thompson, H. E., and Gottesfeld, K. R.: AM. J. OBST. & GYNEC. 90: 655, 1964. 8. Thompson, H. E., Holmes, J. H., Gottesfeld, K. R., and Taylor, E. S.: AM. J. OBST. & GYNEC. 92: 44, 1965. 9. Thompson, H. E.: Studies of Fetal Growth by Ultrasound, in Diagnostic Ultrasound, Proceedings of the First International Conference, New York, 1966, Plenum Press, pp. 416-427. H. E., Holmes, J, H., Gottesfeld, 10. Thompson, K. R., and Taylor, E. S.: AM. J. OBST. & GYNEC. In press. 4200 East Ninth Denver, Colorado
Avenue
of this technique since 1951, and thus it is fying to see it finally develop as a useful nostic procedure. I would like to make specific references to the papers presented also make a few general comments which be of interest to those who may attempt
grati-
diagsome and might to use
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ct
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diagnostic ultrasound in the next few months. An unmentioned application of diagnostic ultrasound is in evaluating the patient with repeated spontaneous abortion. Dr. Ian Donald of Glasgow claims that he can visualize the dcvelopment of the fetus from the third week up to the eleventh week. Then there is a period between the eleventh week and the fourteeenth week when the echo pattern of the developing embryo is obscured by the placental echo pattern. After the fourteenth week the baby can then be followed in its development throughout the remainder of pregnancy. According to Dr. Donald, one factor in proper development of the fetus is the site of ovum implantation in the uterus. I think we all realize that there is some danger in expressing fetal growth as a function of weight change when we are making such actual measurements as biparietal diameter, occipital-frontal circumference, or chest size. This is an error we make in internal medicine when we try to express blood volume measurements as cubic centimeters per kilogram, because you cannot expect a direct relationship. I would suggest as the ultrasonic techniques improve, that the ultimate aim should be to express fetal growth and development in terms of what we actually can measure, for example, chest size or liver size. The difference shown by Dr. Hellman, between measurements of the biparietal diameter made by the A and B ultrasound techniques, is probably not a true difference. Nor does Dr. Taylor’s presentation of his ultrasonic results as per cent of correct diagnoses paint a true picture of the capabilities of ultrasound. When good ultrasonic pictures (somagrams) are obtained by the B-scan technique, then there is little doubt of the diagnosis and of the fetal measurements. However, with current equipment and examining techniques, we are still getting between 10 and 20 per cent poor pictures, and when we make an interpretation from inadequate somagrams, the errors are much greater. It is difficult to specify in every instance why the picture is inadequate. The inadequate pictures might be related to such factors as variations in brightness of the oscilloscope screen, variations in positioning of the patient, improper sensitivity settings, differences in equipment performanceas (for example, alterations in voltage or tube performance) differences in tissue structure which alter the rate of the transmission of sound.
11t the pres<*nt stage of development of ult~ ;Isonic diagnostic techniques, it is particularly irnportant to standardize equipment operation and examining methods. For example, in the fetal death problem presented by Dr. Taylor, when he examines pictures taken at sequential time intervals, he must be sure that the equipment is performing exactly the same for each examination. Otherwise, proper interpretation of the successive pictures is impossible. I cannot emphasize tot) strongly the need for developing standards which make it possible for the technician to check the equipment operation daily and also to profile each new piece of equipment, such as a transducer, before it is incorporated into the routine diagnostic operation. We have devised several types of standards filling them with castor oil to simulate attenuation of tissues. One standard contains small spherical balls which are spaced at different distances in the castor oil-filled tube. Thus, by comparing the echo signals received from the three spheres, it is possible to determine equipment performance at different depths within the human body and to determine the precise sensitivity settings required to reproduce previous studies. A smaller castor oilfilled tube is used to calibrate tissue measurcments. Another important standardization is the X-Y axis alignment. When this alignment is not proper, the outline of various parts of the fetal head do not form a perfect oval, but the linear traces overlap improperly. With such misalignment, it is impossible to obtain proper measurements of the fetal head. Another example of improper X-Y alignment is overlapping of the echo lines representing a trace of the posterior edge of the liver and gallbladder. Simpler standards are used to check the equipment every day or once a week. A large plastic box with many different target patterns is used to profile all characteristics of a transducer before it is placed in our system. Spheres spaced at several different distances apart will determine the degrre of resolution obtained. A series of targets at spaced intervals from the transducer will determine the near and distant limitations. In addition to standardization of equipment, we must standardize examining and scanning procedures. For example, the type of picture obtained can be altered significantly by changes in sensitivity settings of the receiver. This is iilustrated in Fig. 1, which shows the same liver echo pattern displayed at four different sensitivity settings. As you will note: there is quite a difference
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Fig. 1. Live
echo pattern
displayed
at four
different
sensitivity
in obstetrics
. .
Fig. 2. Correlation mission
of
Iliffe
between Publications,
required Ltd.,
sensitivity setting London, England.
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settings.
.
.
.
and
l
.
l
.
.
. . l a’
.
and surface Ultrasonics
area. (Reprinted 5: 65, 1967.1
by
per-
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et al.
in the type of picture obtained and, thus, before making a proper interpretation, the physician must consider the suspected pathology in relation to sensitivity settings. In some instances, the sensitivity setting can be changed to accentuate suspected pathology. This is comparable to x-ray, where a chest picture can appear quite different when the equipment settings arc changed. At the present time, we have not developed a technique for properly setting the sensitivity dials and other equipment parameters in accordance with body build and tissue characteristics (fat or muscle). This, as you know, is done very carefully in x-ray with established charts which show the proper settings for each patient based on body size or other physical measurements. Preliminary work in our laboratory indicates that a different sensitivity setting is required for patients of different body build. We used as a criteria of proper sensitivity setting, good delineation of the posterior edge of the liver. You will note from Fig. 2 that there seems to be a definite correlation between the required sensitivity setting and the surface area. It is always possible to change electronic variables to improve the ultrasonic picture when you use the equipment for examining only one diagnostic area, such as the pregnant abdomen. When one develops equipment that can be applied to visualizing all areas of the body, then you sacrifice some precision for examining a particular anatomic area. One example of this is use of time-varied gain (TVG). TVG reprepresents an automatic change in sensitivity setting from time of pulsing so that the near echo signals which will obscure the picture are eliminated and only the more distant signals are displayed on the screen. A modification of TVG is depth control, where near signals are displayed as usual but more distant signals are amplified by increasing receiver sensitivity. This makes it possible to look at more distance anatomic structures within the body in a more effective fashion. It is also apparent from the illustrations shown in both papers that our diagnostic percentages will improve as the individuals interpreting the pictures gain more experience. This is to be expected if one realizes that it takes at least 3 years to train a radiology resident. Dr. Taylor was rather modest in describing the diagnostic results with gynecologic lesions. Our residents on the medical ward feel that
ultrasound has been most useful in providing diagnostic information regarding abdominal masses. Dr. Taylor discussed these results from the standpoint of the etiology of the pathologic lesion. However, ultrasound can provide certain structural information which helps in arriving at a correct diagnosis when considered with othrt clinical information. Ultrasound can delineate the precise size of the lesion and show whether the mass contains organized or disorganized structures. Furthermore, there is some evidence in both our own work and the studies of Dr. Donald that if in the case of a tumor we vary the ultrasonic frequency, different types of tumors will give different echo displays. This may represent another advantage which ultrasound will have over radiology in the future. As regards toxicity of diagnostic ultrasound, all reported tissue destruction occurs at power levels above 1 watt per square centimeter. No toxicity has been reported at the power levels used in diagnostic ultrasound, namely 0.004 watt per square centimeter or below. At these power levels there has been no evidence of toxicity on the reproductive systems in animal studies done in our laboratory and in the laboratories of Dr. Sundgren and Dr. Smythe. No genetic effects on hamsters and mice have been demonstrated in two reports. There may be a level of ultrasound, possibly between 0.5 and 0.7 watt per square centimeter which may stimulate fetal growth. In order to further reduce the power levels used, we are currently devising a system which would set receiver sensitivity at maximum and reduce pulse power to provide changes in picture intensity. This technique should further reduce the power levels required. This is very feasible and can be easily incorporated into the present diagnostic systems. With several commercial companies currently producing ultrasonic diagnostic equipment, there is serious need for setting up training programs in this country for both physicians and technicians. We have currently &en discussing this problem with the Public Health Service. Such training programs are essential if this new ultrasonic technique is to achieve proper stature among physicians and provide additional diagnostic aids for the development of American medicine. DR. HORACE THOMPSON, Denver, Colorado. In the preparation of a paper such as the one presented by Dr. Taylor, many details and interesting points are difficult to include. For this
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Fig.
Fig.
1. Somagrams
of patient
2. Abdominal
pregnancy.
with
in obstetrics
and
gynecology
679
triplets.
reason, I would like to show you somagrams on 2 patients that I thought were particularly interesting. Both of these patients were included in the reported group. Fig. 1 represents serial somagrams taken at 2 cm. intervals from the top of the fundus to the symphysis of a patient with triplets approximately 30 weeks pregnant. Starting at the upper left corner you will note the outline of one fetal
head. Continuing downward in the same row, a second head is also outlined. As we progress from above downward and to the right in the third row, the thorax in all 3 infants is demonstrated. In the last row, lower picture, the head of the third infant is demonstrated. Fig. 2 represents three somagrams of a patient with an abdominal pregnancy. Somagram
680
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A was taken before the infant was delivered by laparotomy and is a longitudinal cross-section taken along the midline. It demonstrates the fetal head, the enlarged uterus, and the placenta. These structures are labeled in the picture. At the time of operation, the infant was macerated and had been dead approximately 2 weeks. The placenta was essentially avascular at this time and was implanted retroperitoneally on the posterior surface of the posterior parietal peritoneum and on the posterior surface of the uterus and broad ligaments. It was impossible to remove the placenta safely at this time so the infant was delivered, the placenta left intact, and the abdomen closed. Somagram 2, B was taken 3 weeks postoperatively and outlines the placental tissue and the amniotic cavity containing a homogeneous material. The patient was followed in the clinic for the next 9 months and the abdominal mass did not decrease in size. The patient complained of lower abdominal pain and pressure. On this basis, it was decided to again explore the abdomen. At this time the placenta was removed, and the amniotic cavity was found to contain approximately 1,000 cc. of clear green fluid.
Somagram 2, C was taken 2 days Itefore tttc: second operation and clearly outlines the larq: cystic mass found at surgery which was the Auidfilled amniotic cavity. It is now 2 weeks since operation and additional somagrams will be obtained in the near future to complete the follow-up. DR. LOUIS HELLMAN, Brooklyn, 1C’ew York. I am very honored to have Dr. Holmes discuss my paper this afternoon. We is not very old as far as age goes, but he is one of the old men in the field of ultrasonics and one of the real authorities in this area. Some of his origina pictures, those taken with the water bath, are among the best that have ever been made. If you have a chance to visit Dr. Holmes’ laboratory or Dr. Taylor’s, I can assure you that you will be we11 received and have a profitable visit. By showing some odd pictures, Dr. Holmes gave me a chance to show one of my very best. This slide is a transverse scan of young woman 9 weeks pregnant. The early implanted ovum, a hoilow sphere, filled with fluid and its projecting villi are clearly demonstrable (Fig. 1) . I would like to reinforce Dr. Holmes’ statement about standardization. I neither understand his sensitivity figures, nor does he comprehend mine. Furthermore, a lot of the conventions
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are in disagreement, for example, Dr. Donald’s pictures are reversed from the ones we use in this country. We need standardization of terminology and of equipment. Our equipment is standardized weekly in the same manner that Dr. Holmes uses. Although the equipment shows little tendency to drift, the standardization is important. Furthermore, this complicated apparatus needs a part-time engineer to keep it in operating order. The question of the difference between A and B scan is clinically quite important. A machine to do an A scan is relatively cheap, while that necessary to do a B scan costs between fifteen and twenty thousand dollars. Finally, just a word about testing for safety of the apparatus in pregnancy. We are testing our apparatus on tissue cultures of fetal cells, studying the rates and normalcy of mitotic division. I do not suppose the energies we are using will affect these tissues, but it is important that we make absolutely sure in this matter. DR. HAROLD TOVELL, New York, New York. During the last 5 years, in our laboratory we have been using ultrasonic techniques for both gynecologic and obstetric diagnoses. Besides providing information which cannot be obtained by any other means, ultrasonography proved to be a valuable adjunct or a preferable alternative to other diagnostic methods presently at our disposal. Biparietal cephalometry using the A-scan method as originally proposed by Donald is subject to some errors, both in technique and interpretation. This has recently been shown in a prenatal series of biparietal measurements studied by Kohorn at Yale where about 80 per cent were within 3 m. of accuracy, 60 per cent within 2 mm., and some 15 per cent showed an error greater than 4 mm., when compared with caliper measurements performed postnatally. The optical averaging method introduced by McKinney in 1965 for echo encephalography has been subsequently applied in our Bioacoustical Laboratory at Woman’s Hospital by Dr. Lajos von Micsky for fetal biparietal cephalometry. According to some preliminary studies, this technique seems to improve the accuracy of this biometric procedure. In contradistinction to A-scan cephalometry, where the signals appear as “pips,” i.e., vertical deflections of the time base line, optical averaging stykography displays the echoes in the in-
Ultrasound
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681
tensity modulated mode. In order to achieve this, the plane of the A scan is electronically rotated 90 degrees, thus displaying as luminous dots only the peaks of the “pips.” While the transducer is minimally rocked about its point of contact on the abdomen, the derived ultrasonic image, comprising a row of light spots of varying intensity, is electronically swept across the face of the cathode ray tube. A Polaroid camera with time exposure records the signal information as a series of linear traces, the intensity and thickness of which are proportional to the returned energy. Since the strongest signals are reflected by the proximal and distal walls of the fetal head and its midline structures, the sonograph and camera sensitivity can be so adjusted that only traces corresponding to these anatomic landmarks are photographed, thereby permitting an unequivocal precise measurement of the biparietal diameter. This technical modification in our hands in some 15 cases studied to date measures the biparietal diameter with an accuracy of plus or minus 1 mm. It is emphasized that in order to exclude any error of interpretation, all optical averaging tracings in biparietal cephalometry should reveal the midline echo. The method of cephalopelvic periography, or area measurement, employed in our laboratory involves the planimetric area determination of the transverse tomogram of the fetal head that shows the same occipitofrontal and biparietal diameters as previously determined by optical averaging stykography method. The direction and dimensions of these two diameters can only be precisely determined by A scan in a breech presentation or where the fetal head is easily maneuverable such as a floating head or in some cases of polyhydramnios. While the two diameters are not in the same plane, they fall within the width of the transducer and thus delimit a well-defined anatomic segment of the fetal head. So far, it would appear that the correlation of these precise measurements with the area of the pelvic inlet, as measured by x-ray pelvimetry, permits a more reliable estimation of cephalopelvic relationships than has hitherto been possible. DR. TAYLOR (Closing). In the 3 years past, ultrasound diagnostic procedures in our own practice and our own medical school setting can be summarized as follows: This diagnostic procedure is the final judg-
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ment as to whether a patient does or dots not have a hydatidiform mole. We have discarded all other methods for making this final diagnosis before treatment. The other area in which I think it is now indispensable is in localization of the placenta before proceeding with amniocentesis or intrauterine transfusion.
‘I‘hc last arc~r for which we USC it e\ cry week is in confirming a judgment about the matut-it! of a given infant who is to be delivered from a mother who is diabetic or from a patient who has had a previous ccsarean section; and, in some other instances, where a judgment has to be made as to whether a fetus is mature or not.