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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5802_Библиотеки_им_академика_М_И_Перельмана.pdf
Obstetrics
366
Systolic/diastolic ratio in the umbilical artery
PREPARATION
Full bladder for transabdominal imaging in 2
nd
trimester.
POSITION
Mother is in the supine position. The spectral Doppler cursor is placed
on the umbilical artery at or just before the fetal insertion of the umbilical cord.
TRANSDUCER
Transabdominal: 3.0–6.0 MHz curvilinear transducer.
METHOD
Spectral Doppler ultrasound recording of the umbilical artery is
obtained:
Systolic/Diastolic Ratio = Peak Systolic Velocity/End Diastolic Velocity
APPEARANCE
A normal umbilical cord contains two arteries and one vein. The vein
is larger than the arteries. A single umbilical artery is associated with
fetal anomalies.
The vascular resistance of the fetal arteries decreases toward the end
of the pregnancy. Early subtle increases of resistance in circulation
in a compromised fetus may reect intrauterine growth retardation
(IUGR). However, the value of Doppler velocimetry in a low-risk fetus
(normal weight for gestational age) has not been proven.
A spectral Doppler
waveform of
an umbilical
artery, with
comprehensive
machinegenerated
measurements.
Systolic/diastolic ratio in the umbilical artery
MEASUREMENTS
16 6.07
20 5.24
24 4.75
28 3.97
30 3.80
32 3.57
34 3.41
36 3.15
38 3.10
40 2.68
41 2.55
42 3.21
FURTHER READING
Divon MY, Ferber A. Umbilical artery Doppler velocimetry—An
update, Sem Perinatol. 2001; 25:44–47.
Fogarty P, Beattie B, Harper A, Dornan J. Continuous wave Doppler
ow velocity waveforms from the umbilical artery in normal
pregnancy. J Perinat Med. 1990; 18:51–57.
367
Obstetrics
368
CEREBRAL VENTRICULAR
MEASUREMENTS
Lateral ventricle transverse atrial
measurement (atrial size)
PREPARATION
Full bladder for transabdominal imaging in 2
POSITION
Mother is in the supine position. A transventricular axial image of the
fetus is obtained through the thalami at the level of the smooth posterior margin of the choroid plexus.
TRANSDUCER
Transabdominal: 3.0–6.0 MHz curvilinear transducer.
METHOD
Strict axial plane: The midline structures should be equidistant from
the proximal and distal calvarial margins and perpendicular to the
ultrasound beam.
The transverse atrial measurement is taken at the conuence of the
body, occipital, and temporal horns of the lateral ventricles. The glomus of the choroid plexus is used to locate the atrium.
Calipers are placed on the inner to inner edges of the ventricle wall at its
widest part, and aligned perpendicular to the long axis of the ventricle.
APPEARANCE
The choroid plexi are high-reective structures lling the atria of the
lateral ventricles.
MEASUREMENTS
nd
trimester.
7.5 6–9 10
Lateral ventricle transverse atrial measurement (atrial size)
The strict axial plane demonstrates the choroid plexus (arrow) and the position to measure
atrial size (Vp, between cursors).
369
FURTHER READING
Almog B, Gamzu R, Achiron R, Fainaru O, Zalel Y. Fetal
lateral ventricular width: What should be its upper limit? A
prospective cohort study and reanalysis of the current and
previous data. J Ultrasound Med. 2003; 22:39–43.
Filly RA, Cardoza JD, Goldstein RB, Barkovich AJ. Detection of
fetal central nervous system anomalies: A practical level of effort
for a routine sonogram. Radiology. 1989; 172:403–408.
Guibaud L. Fetal cerebral ventricular measurement and
ventriculomegaly: Time for procedure standardization.
Ultrasound Obstet Gynecol. 2009; 34:127–130.
Obstetrics
370
Cisterna magna measurements
PREPARATION
Full bladder for transabdominal imaging 2
nd
trimester.
POSITION
Mother is in the supine position. A transcerebellar view of fetus is
taken.
PROBE
Transabdominal: 3.0–6.0 MHz curvilinear transducer.
METHOD
Maximum anteroposterior diameter of the cerebrospinal uid (CSF)
space between cerebellum and occiput is measured.
APPEARANCE
Fluid-lled space between cerebellum and occiput.
MEASUREMENTS
5mm 2–8 mm 10 mm
Absence of the cisterna magna is suggestive of Chiari malformation.
Mega-cisterna magna (> 10 mm) is associated with chromosomal
abnormalities but can be normal.
The cerebellum (Cereb, between
cursors) lies anterior to the
measured CSF space (CM,
between cursors).
Cisterna magna measurements
FURTHER READING
Mahony BS, Callen PW, Filly RA, Hoddick WK. The fetal cisterna
magna. Radiology. 1984; 153:773–776.
Brown RN. Reassessment of the normal fetal cisterna magna during
gestation and an alternative approach to the denition of cisterna
magna dilatation. Fetal Diag Therap. 2013; 34:44– 49.
371
Obstetrics
372
Thoracic circumference
PREPARATION
Full bladder for transabdominal imaging in 2
nd
trimester.
POSITION
Mother is in the supine position. Axial image of thorax is obtained at
the level of the four-chamber view of the heart with the spine in a true
cross section.
TRANSDUCER
Transabdominal: 3.0–6.0 MHz curvilinear transducer.
METHOD
The thoracic circumference is obtained between the outer edge of the
spine and ribs but inside the skin at the level of the four-chamber view
of the heart.
APPEARANCE
Transaxial view through the thorax showing four cardiac chambers.
The transaxial view with four cardiac chambers (arrow) allows for an accurate thoracic
circumference measurement.
Thoracic circumference
MEASUREMENTS
The normal thoracic (TC) to abdominal circumference (AC) ratio is
0.89–1.0 TC/AC. A ratio of < 0.8 is associated with pulmonary hypoplasia. However, the lung area to body weight ratio is a better predictor of pulmonary hypoplasia.
FURTHER READING
Johnson A, Callan NA, Bhutani VK et al. Ultrasonic ratio of fetal
thoracic to abdominal circumference: An association with
fetal pulmonary hypoplasia. Am J Obstet Gynecol. 1987;
157:764–769.
Lessoway VA, Schulzer M, Wittmann BK, Gagnon FA, Wilson
RD. Ultrasound fetal biometry charts for a North American
Caucasian population. J Clin Ultrasound. 1998; 26:433–453.
373
Obstetrics
374
Renal pelvis diameter
PREPARATION
Full bladder for transabdominal imaging in the 2
nd
trimester.
POSITION
The mother is in the supine position. Transverse image of fetal abdomen is obtained at mid-renal level.
TRANSDUCER
Transabdominal: 3.0–6.0 MHz curvilinear transducer.
METHOD
Anteroposterior of the renal pelvis diameter is measured.
APPEARANCE
Fluid-lled structure in the center of the renal sinus.
Image of the renal pelvis diameter (between cursors) of the right kidney.
Renal pelvis diameter
MEASUREMENTS
Up to 20 weeks of gestation: < 4 mm is normal.
≥ 4 mm is suggestive of mild renal pyelectasis.
At 32 weeks of gestation. < 7 mm is normal.
Obstruction is more likely if calyceal or ureteral dilatation is also pres-
ent.
FURTHER READING
Grignon A, Filion R, Filiatrault D, Robitaille P, Homsy Y, Boutin H,
Leblond R. Urinary tract dilatation in utero: Classication and
clinical application. Radiology. 1986;160:645–647.
Mandell J, Blyth RR, Peters CA, Retik AB, Estroff JA, Benacerraf
BR. Structural genitourinary defects detected in utero.
Radiology. 1991 178:193–196.
Reddy UM, Abuhamad AZ, Levine D. Fetal imaging: Executive
summary of a joint Eunice Kennedy Shriver National Institute
of Child Health and Human Development, Society for
Maternal-Fetal Medicine, American Institute of Ultrasound
in Medicine, American College of Obstetricians and
Gynecologists, American College of Radiology, Society for
Pediatric Radiology, and Society of Radiologists in Ultrasound,
Fetal Imaging Workshop. Obstet Gynecol. 2014;123:070 –1082 .
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