産科領域における超音波断層法の応用

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タイトル別名
  • Application of ultrasonic scanning in obstetrics.

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Since the advent of the real time B-mode scanner, ultrasonic diagnosis has become indispensable in the field of obstetrics for fetal diagnosis on the basis of observation of the fetal movement. In this paper, the authors discuss the key points of ultrasonic diagnosis and the findings which require caution when this technique is employed for the diagnosis of the diseases frequently seen in the obstetric clinic.<br>In the early diagnosis of a normal pregnancy, the key points are the detection of the gestational sac and its gradual enlargement with the passage of time, and detection of the fetal heart movement and fetal movement. For the diagnosis of abortion and determination of the prognosis, the key points are detection of the growth, shape and position of the gestational sac, and the chorionic findings. Diagnosis of multiple pregnancies can be achieved during the 5th to 6th weeks of gestation on the basis of the number of gestational sacs, while after the 7th week of gestation the number of fetal (embryonic) heart movements can be employed, and once the fetus is sufficiently developed for the body parts to be distinguished, the number of fetal heads can be counted. However, care must be taken to distinguish such fetal sac appearances as double decidual sacs, uterus bicornis, and blighted twins. For the diagnosis of the fetal appendages, the early placenta can be distinguished by its partial projection into the amniotic cavity, while the developed placenta can be recognized as a mass structure in which a fine granular echo is covered by a fibrous echo. Hydatidiform moles, especially early hydatidiform moles and atypical hydatidiform moles, can be distinguished as a small cyst structure which occupies a deformed amniotic cavity and as an amorphous structure which also contains retained fluid. For the diagnosis of abnormalities of the site of placental attachment, evidence can be gained from the positional relationship between the inferior margin of the placenta and the upper edge of the cervical canal, and at the same time it is necessary to distinguish hypertrophic decidua and local thickening of the myometrium since these events can resemble a placenta previa. In addition, caution is required concerning the suitability of application of the bladder-filling method. The diagnosis of premature detachment of a normal-position placenta can be made on the basis of the presence of a retroplacental hematoma. Ectopic pregnancies can be identified with a high rate of accuracy on the basis of findings of a gravid uterus, even while an intrauterine pregnancy is ruled out, findings of extrauterine attachment of conceptus or a gravid swelling, and findings of a Douglas' cul-de-sac gravid mass or fluid retention.<br>In consideration of the above points, it is clear that sonography has become one of the most important diagnostic aids in obstetrics for the successful management of the perinatal period. Thus, it is suggested that it is necessary for physicians to achieve a thorough understanding of the obstetrical significance of the various findings provided by this technique during the course of pregnancy.

収録刊行物

  • 医療

    医療 41 (4), 336-340, 1987

    一般社団法人 国立医療学会

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