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Ultrasound fetal femur length in relation to intrauterine growth retardation
FETUS, PLACENTA, AND NEWBORN
Ultrasound fetal femur length in relation to intrauterine growth retardation Part II GREGORY JOHN
D. O’BRIEN,
T.
Washington,
QUEENAN,
M.B.,
B.S.
M.D.
D. C.
With the establishment of a normal range of values for the growth of the ultrasound fetal femur length, a new approach for the study of growth-retarded fetuses is suggested. Ultrasound femur length was measured on a group of “high-risk” pregnancies, and its ability to differentiate the symmetrically small from the asymmetrically small fetus was studied. A reduced ultrasound fetal femur length correlated in all cases with a shortened crown-heel length in the neonate. By adding this ultrasound parameter to those routinely measured on the fetus, a three-dimensional profile can be constructed. (AM. J. OBSTET. GYNECOL. 144:35, 1982.)
THE ANTENATAL diagnosis of intrauterine growth retardation (IUGR) has definite benefits for the fetus. IUGR consists of a spectrum of features that range from the symmetric or low profile to the asymmetric or late flattening type.’ The type of IUGR appears to be related not only to the etiologic factors but also to the duration that these affect the fetus. Crown-heel length is one of the neonatal measurements used to detect retarded growth. This reduction in length has been reported to have an incidence as high as 60% in infants that are growth retarded.’ Crown-rump length has been measured throughout
From the Department of Obstetrics Georgetown University Hospital. Received for p-ublication Revised Accepted
February
October 2, 1981.
17, 1982.
May 3, 1982.
0002-9378/82/170035+05$00.50/0
Posiible
Patient
No.
factors for IUGR and their
Symbol
1
c3
2
0
3 4 5 6 7
0 $ A n
predisposing for IUGR
in
factors
Pregnancy-induced hypertension Twin gestation, hypertension Alcoholism, poor nutrition Congenital malformation Class C diabetes Hypertension Preeclampsia
The symbols are used in Table II and Figs. 1 to 5.
and Gynecoloa,
Reprint requests: Dr. John T. Queenan, Department Obstetrics and Gynecology, Georgetown University Hospital, 3800 Reservoir Road, N. W., Washington, D. C. 20007.
Table I. Possible predisposing the seven pregnancies studied corresponding symbols
of
@ 1982 The C. V. Mosby Co.
pregnancy.3 However, this requires a compound scanner, and with the changing position of the fetus and the curving of the fetal spine, there is a degree of limitation in its reproducibility. The ultrasound femur length adds a new easily reproducible linear or “length” measurement of the fetus that can be made throughout 35
36
O’Brien and Queenan
September 1, 1982 Am. J. Obstet. Gynecol.
25 26 27 29 29 30 31 32 33 34 35 36 37 38 39 40 41’42 GESTATIONAL AGE (WEEKS1
1. Birth devised
graph
weights of the eight neonates by Usher and McLean.5
GESTATIONAL (WEEKS)
plotted
43 44
on the lo
II
14
I
I
16
18
Id
20
22
(
II
24
26
1
28
30
I1
32
34
36
5
/
I
38
40
42
Weeks Gestation
AGE
Fig. 3. Antenatal
25262728293031323334-35363738394041424344
Patient
growth
of the ultrasound
femur
length
in
1.
Patients and methods 48 46 44 42 40 3a 36 34 32 30’
’
’
’
Fig. 2. Crown-heel the graph
lengths by Usher
devised
used
’
of the eight neonates and McLean.j
It adds an important
pregnancy. routinely
’
’
’
’
plotted
third dimension
two-dimensional
parameters
’
J
on
to the
(head
and
abdominal circumference) and, hence, may give help in identifying the pattern of growth retardation. Length of the neonate and later height of the child are important
in the
fetuses.
follow-up
Therefore,
of intrauterine “length”
growth-retarded
measurements
may
be
useful to follow, both antenatally and postnatally, for assessment of IUGR and its effects. The aim of this study was to determine the usefulness of ultrasound fetal femur length in identifying the growth-retarded fetus when studied in relationship to the normal fetus.”
One hundred twenty-six “high-risk” pregnancies were studied. Six of these resulted in symmetrically small babies. In contrast to this group, one of the asymmetrically growth-retarded babies is also described here to illustrate the differences. Of this total group of seven, six were singleton pregnancies, and one was a twin gestation. The criteria for diagnosis of IUGR were: (1) weight below two standard deviations for gestational age based on the data of Usher and McLeanj; and (2) physical examination of the neonate showing the typical wasted or stunted appearance associated with the different forms of growth retardation. Menstrual history in these patients was accurate, and early physical findings were compatible with the gestational age. The Dubowitz scores also confirmed the gestational age.6 The possible causes for IUGR are presented in Table I. In Cases 1 through 6, the neonates were symmetrically small, and Case 7 represents the baby with asymmetric IUGR. An ADR linear-array, real-time scanner with a frequency of 3.5 MHz and a caliper calibration velocity of 1,540 m/set was used. The ultrasound measurements performed were biparietal diameter, head and abdominal circumference, and femur length. A subjective as-
Volume Number
Table
144
Fetal femur
1
II. Last ultrasound
Case
10 20 A B 30 4A 5@ 6A 7m
Gestational age (wks) 34
measurements
before
39 2% 36 35 40
(cm)
1.5
36 36
and IUGR.
II
37
delivery
Biparietai diameter
length
Head circumference (cm)
sessment of amniotic fluid volume was also made. The technique for assessing femur length has been described previously.7 At least two serial measurements were made in all patients, except one.
Results In Fig. 1, the weights are plotted according to gestational age on the chart devised by Usher and McLean.’ All these weights, except one, fall below the two standard deviation limits. The one neonate whose weight fell in the normal range was the unaffected baby of the twin gestation. Fig. 2 illustrates the crown-heel length of the neonates plotted against gestational age (on the charts devised by Usher and McLeanj). Two neonates were in the normal range. One was the normal twin, and the other was the neonate with asymmetric growth retardation (Patient 7) showing discordance of the length-to-weight ratios. All other cases demonstrated various degrees of symmetric growth retardation. Table II illustrates the last measurements of our routine ultrasound parameters used to detect IUGR in these fetuses. The antenatal measurements of the ultrasound fetal femur length were then studied on these patients. Patient 1 developed pregnancy-induced hypertension between 24 and 26 weeks gestational age. Serial measurements of femur length are shown in Fig. 3. Other ultrasound parameters showed an equivalent decrease in growth rate, although accurate head measurements were unobtainable on two occasions because of inaccessible positions. By the combination of ultrasound parameters, the symmetric growth retardation was readily detected. Fig. 4 illustrates the serial ultrasound femur measurements in the twin gestation of Patient 2. After an ultrasound examination in the first trimester to confirm dates of gestation, a sonogram was not repeated until 29 weeks’ gestation, when the patient was admitted to the hospital with hypertension. The normal growth of the femur can be followed on the unaffected twin, whereas the symmetrically growth-retarded twin
Headiabdomen radio
29.4
26.6
1.11
31.9
-
31 21.5 28.5 29.5 33.7
27.8 29.6 18.1 26.8 26.0 31.0
1.05 1.19 1.06 1.13 1.1
Unobtainable Unobtainable 8.3 5.6 8.2 7.9 8.8
Abdominal circumference (4
B clearly shows the persistently ahortened femur measurements. The femur length WJS especially significant in identifying the symmetric IUGR, since head measurements could not be ascertained on twin B because of its inaccessibility by ultrasound measurement as a result of its position. The growth of the fetal femurs in the other patients are shown in Fig. 5. The most severe case of symmetric IUGR was seen in Patient 4. Ultrasound parameters of biparietal diameter, head circumference. abdominal circumference, and femur len,gth were all well below the normal range for gestational age. A congenital malformation or infection was suspected as the cause, but all investigations were negative. A stillborn fetus at 29 weeks’ gestation was found to have extrahepatic biliary atresia. Patients 5 and 6 are further examples which illustrate varying degrees of symmetric growth retardation. Patient 3 may be considered to be an example of borderline false negative, since the femur length fitted in the normal range but the crown-heel length was below the fifth percentile. However, both measurements fitted close to the fifth percentile, with the femur length falling between the fifth and tenth percentile limits. Thus, the femur length was still an accurate detector of the shortened crown-heel length. In contrast, patient 7 is an example of asymmetric growth retardation. The femur length in this case fell within the normal range, as did the crown-heel length, whereas an abdominal circumference below the fifth percentile corresponded to the low birth weight. In all these cases, the antenatal measurements of the ultrasound femur length corresponded well with the neonatal crown-heel length and reflected the linear growth of the affected fetuses. In combination with the other ultrasound parameters of head and abdominal circumferences, ultrasound femur length enabled the construction of a three-dimensional profile of the fetus.
Comment The ability to perform an accurate antenatal linear or “length” measurement of the fetus now allows a more
38
O’Brien
September
and Queenan
Am. J. Obstet.
1, 1982 Gynecol.
ao‘;E‘ 70.!% S : 60f s 3 50% 91 a 40 f 5
30-
20lo Ia, 1,
16
11 18 20
” 22
24
6 26
28
1 30
a 32
c 34
/ 36
38
fl 40
1 42
4. Antenatal growth of the ultrasound each twin in Patient 2.
I)
14
10 16
18
18 20 22
0 24
11 26 28
1 30
’ 32
0 34
0 36
‘1 38
40
1 42
Weeks Gestation
Weeks Gestation Fig.
lo
femur lengths in
complete profile of the fetus and adds a new dimension to the measurement of its growth. With the establishment of normal growth curves for ultrasound femur length during pregnancy, abnormal fetal growth in length can be identified. This may be of value to the present parameters measured by diagnostic ultrasound for assessing fetal growth and in defining the roles of symmetric and asymmetric growth retardation. The ultrasound femur length has two important roles in relationship to IUGR. It forms an antenatal measurement of length which can be followed through in postnatal life. Moreover, it defines another parameter for identifying symmetric IUGR, as illustrated in this series. Classically, symmetric IUGR has been detected by both head and abdominal measurements below the fifth percentile. The shortened crown-heel length is another feature of symmetric IUGR, and this
REFERENCES
1. Campbell, S.: Fetal growth, in Beard, R. N., and Nathanielsz, P. W., editors: Fetal Physiology and Medicine, Baltimore, 1976, W. B. Saunders Co., Ltd., Chap. 15, p. 293. 2. Woods, D. L.. Malon, A. F., and de V. Heese, H.: Patterns of retarded fetal growth, Early Hum. Dev. 3:257, 1979.
Fig. 5. Antenatal measurements length in Patients 3 through 7.
of the ultrasound
femur
can be successfully detected by shortened femur length. At the other end of the spectrum of IUGR, the asymmetric growth-retarded fetus has a crown-heel length in the normal range, with normal femur length and a reduced abdominal circumference. The femur length is of special importance when accurate head measurements are unobtainable; the femur length can substitute in these cases or be confirmative when head measurements are available. No one ultrasound measurement of the fetus has been shown to be totally accurate in detecting IUGR. It is believed that the ability to define IUGR should be improved with a three-dimensional image of the fetus with the use of femur length and circumference measurements. In the cases illustrated here, symmetric growth retardation was identified in all instances by shortened ultrasound femur lengths.
3. Neilson, J. P., Whitfieid, C. R., and Aitchison, T. C.: Screening for the small-for-dates fetus: A two-stage ultrasonic examination schedule, Br. Med. J. 480:1203, 1980. 4. O’Brien, G. D., and Queenan, J. T.: Growth of the ultrasound fetal femur length during normal pregnancy. Part I, AM. J. OBSTET. GYNECOL. 141:833, 1981.
Volume Number
144
1
5. Usher, R., and McLean, F.: Intrauterine growth of liveborn Caucasian infants at sea level: Standards obtained from measurements in seven dimensions of infants born between 25 and 44 weeks’ gestation, J. Pediatr. 74:901, 1969. 6. Dubowitz, L. M. S., Dubowitz, O., and Goldberg, C.: Clini-
Fetal
femur
length
and IUGR.
II
39
cal assessment of gestational age in the newborn infant, J. Pediatr. 77:1, 1970. 7. O’Brien, G. D., Queenan, J. T., and Campbell, S.: Assessment of gestational age in the second trimester by real-time ultrasound measurement of the femur length, AM. J. OBSTET. GYNECOL. 139~544, 1981.
Ultrasound fetal femur length in relation to intrauterine growth retardation Part II GREGORY JOHN
D. O’BRIEN,
T.
Washington,
QUEENAN,
M.B.,
B.S.
M.D.
D. C.
With the establishment of a normal range of values for the growth of the ultrasound fetal femur length, a new approach for the study of growth-retarded fetuses is suggested. Ultrasound femur length was measured on a group of “high-risk” pregnancies, and its ability to differentiate the symmetrically small from the asymmetrically small fetus was studied. A reduced ultrasound fetal femur length correlated in all cases with a shortened crown-heel length in the neonate. By adding this ultrasound parameter to those routinely measured on the fetus, a three-dimensional profile can be constructed. (AM. J. OBSTET. GYNECOL. 144:35, 1982.)
THE ANTENATAL diagnosis of intrauterine growth retardation (IUGR) has definite benefits for the fetus. IUGR consists of a spectrum of features that range from the symmetric or low profile to the asymmetric or late flattening type.’ The type of IUGR appears to be related not only to the etiologic factors but also to the duration that these affect the fetus. Crown-heel length is one of the neonatal measurements used to detect retarded growth. This reduction in length has been reported to have an incidence as high as 60% in infants that are growth retarded.’ Crown-rump length has been measured throughout
From the Department of Obstetrics Georgetown University Hospital. Received for p-ublication Revised Accepted
February
October 2, 1981.
17, 1982.
May 3, 1982.
0002-9378/82/170035+05$00.50/0
Posiible
Patient
No.
factors for IUGR and their
Symbol
1
c3
2
0
3 4 5 6 7
0 $ A n
predisposing for IUGR
in
factors
Pregnancy-induced hypertension Twin gestation, hypertension Alcoholism, poor nutrition Congenital malformation Class C diabetes Hypertension Preeclampsia
The symbols are used in Table II and Figs. 1 to 5.
and Gynecoloa,
Reprint requests: Dr. John T. Queenan, Department Obstetrics and Gynecology, Georgetown University Hospital, 3800 Reservoir Road, N. W., Washington, D. C. 20007.
Table I. Possible predisposing the seven pregnancies studied corresponding symbols
of
@ 1982 The C. V. Mosby Co.
pregnancy.3 However, this requires a compound scanner, and with the changing position of the fetus and the curving of the fetal spine, there is a degree of limitation in its reproducibility. The ultrasound femur length adds a new easily reproducible linear or “length” measurement of the fetus that can be made throughout 35
36
O’Brien and Queenan
September 1, 1982 Am. J. Obstet. Gynecol.
25 26 27 29 29 30 31 32 33 34 35 36 37 38 39 40 41’42 GESTATIONAL AGE (WEEKS1
1. Birth devised
graph
weights of the eight neonates by Usher and McLean.5
GESTATIONAL (WEEKS)
plotted
43 44
on the lo
II
14
I
I
16
18
Id
20
22
(
II
24
26
1
28
30
I1
32
34
36
5
/
I
38
40
42
Weeks Gestation
AGE
Fig. 3. Antenatal
25262728293031323334-35363738394041424344
Patient
growth
of the ultrasound
femur
length
in
1.
Patients and methods 48 46 44 42 40 3a 36 34 32 30’
’
’
’
Fig. 2. Crown-heel the graph
lengths by Usher
devised
used
’
of the eight neonates and McLean.j
It adds an important
pregnancy. routinely
’
’
’
’
plotted
third dimension
two-dimensional
parameters
’
J
on
to the
(head
and
abdominal circumference) and, hence, may give help in identifying the pattern of growth retardation. Length of the neonate and later height of the child are important
in the
fetuses.
follow-up
Therefore,
of intrauterine “length”
growth-retarded
measurements
may
be
useful to follow, both antenatally and postnatally, for assessment of IUGR and its effects. The aim of this study was to determine the usefulness of ultrasound fetal femur length in identifying the growth-retarded fetus when studied in relationship to the normal fetus.”
One hundred twenty-six “high-risk” pregnancies were studied. Six of these resulted in symmetrically small babies. In contrast to this group, one of the asymmetrically growth-retarded babies is also described here to illustrate the differences. Of this total group of seven, six were singleton pregnancies, and one was a twin gestation. The criteria for diagnosis of IUGR were: (1) weight below two standard deviations for gestational age based on the data of Usher and McLeanj; and (2) physical examination of the neonate showing the typical wasted or stunted appearance associated with the different forms of growth retardation. Menstrual history in these patients was accurate, and early physical findings were compatible with the gestational age. The Dubowitz scores also confirmed the gestational age.6 The possible causes for IUGR are presented in Table I. In Cases 1 through 6, the neonates were symmetrically small, and Case 7 represents the baby with asymmetric IUGR. An ADR linear-array, real-time scanner with a frequency of 3.5 MHz and a caliper calibration velocity of 1,540 m/set was used. The ultrasound measurements performed were biparietal diameter, head and abdominal circumference, and femur length. A subjective as-
Volume Number
Table
144
Fetal femur
1
II. Last ultrasound
Case
10 20 A B 30 4A 5@ 6A 7m
Gestational age (wks) 34
measurements
before
39 2% 36 35 40
(cm)
1.5
36 36
and IUGR.
II
37
delivery
Biparietai diameter
length
Head circumference (cm)
sessment of amniotic fluid volume was also made. The technique for assessing femur length has been described previously.7 At least two serial measurements were made in all patients, except one.
Results In Fig. 1, the weights are plotted according to gestational age on the chart devised by Usher and McLean.’ All these weights, except one, fall below the two standard deviation limits. The one neonate whose weight fell in the normal range was the unaffected baby of the twin gestation. Fig. 2 illustrates the crown-heel length of the neonates plotted against gestational age (on the charts devised by Usher and McLeanj). Two neonates were in the normal range. One was the normal twin, and the other was the neonate with asymmetric growth retardation (Patient 7) showing discordance of the length-to-weight ratios. All other cases demonstrated various degrees of symmetric growth retardation. Table II illustrates the last measurements of our routine ultrasound parameters used to detect IUGR in these fetuses. The antenatal measurements of the ultrasound fetal femur length were then studied on these patients. Patient 1 developed pregnancy-induced hypertension between 24 and 26 weeks gestational age. Serial measurements of femur length are shown in Fig. 3. Other ultrasound parameters showed an equivalent decrease in growth rate, although accurate head measurements were unobtainable on two occasions because of inaccessible positions. By the combination of ultrasound parameters, the symmetric growth retardation was readily detected. Fig. 4 illustrates the serial ultrasound femur measurements in the twin gestation of Patient 2. After an ultrasound examination in the first trimester to confirm dates of gestation, a sonogram was not repeated until 29 weeks’ gestation, when the patient was admitted to the hospital with hypertension. The normal growth of the femur can be followed on the unaffected twin, whereas the symmetrically growth-retarded twin
Headiabdomen radio
29.4
26.6
1.11
31.9
-
31 21.5 28.5 29.5 33.7
27.8 29.6 18.1 26.8 26.0 31.0
1.05 1.19 1.06 1.13 1.1
Unobtainable Unobtainable 8.3 5.6 8.2 7.9 8.8
Abdominal circumference (4
B clearly shows the persistently ahortened femur measurements. The femur length WJS especially significant in identifying the symmetric IUGR, since head measurements could not be ascertained on twin B because of its inaccessibility by ultrasound measurement as a result of its position. The growth of the fetal femurs in the other patients are shown in Fig. 5. The most severe case of symmetric IUGR was seen in Patient 4. Ultrasound parameters of biparietal diameter, head circumference. abdominal circumference, and femur len,gth were all well below the normal range for gestational age. A congenital malformation or infection was suspected as the cause, but all investigations were negative. A stillborn fetus at 29 weeks’ gestation was found to have extrahepatic biliary atresia. Patients 5 and 6 are further examples which illustrate varying degrees of symmetric growth retardation. Patient 3 may be considered to be an example of borderline false negative, since the femur length fitted in the normal range but the crown-heel length was below the fifth percentile. However, both measurements fitted close to the fifth percentile, with the femur length falling between the fifth and tenth percentile limits. Thus, the femur length was still an accurate detector of the shortened crown-heel length. In contrast, patient 7 is an example of asymmetric growth retardation. The femur length in this case fell within the normal range, as did the crown-heel length, whereas an abdominal circumference below the fifth percentile corresponded to the low birth weight. In all these cases, the antenatal measurements of the ultrasound femur length corresponded well with the neonatal crown-heel length and reflected the linear growth of the affected fetuses. In combination with the other ultrasound parameters of head and abdominal circumferences, ultrasound femur length enabled the construction of a three-dimensional profile of the fetus.
Comment The ability to perform an accurate antenatal linear or “length” measurement of the fetus now allows a more
38
O’Brien
September
and Queenan
Am. J. Obstet.
1, 1982 Gynecol.
ao‘;E‘ 70.!% S : 60f s 3 50% 91 a 40 f 5
30-
20lo Ia, 1,
16
11 18 20
” 22
24
6 26
28
1 30
a 32
c 34
/ 36
38
fl 40
1 42
4. Antenatal growth of the ultrasound each twin in Patient 2.
I)
14
10 16
18
18 20 22
0 24
11 26 28
1 30
’ 32
0 34
0 36
‘1 38
40
1 42
Weeks Gestation
Weeks Gestation Fig.
lo
femur lengths in
complete profile of the fetus and adds a new dimension to the measurement of its growth. With the establishment of normal growth curves for ultrasound femur length during pregnancy, abnormal fetal growth in length can be identified. This may be of value to the present parameters measured by diagnostic ultrasound for assessing fetal growth and in defining the roles of symmetric and asymmetric growth retardation. The ultrasound femur length has two important roles in relationship to IUGR. It forms an antenatal measurement of length which can be followed through in postnatal life. Moreover, it defines another parameter for identifying symmetric IUGR, as illustrated in this series. Classically, symmetric IUGR has been detected by both head and abdominal measurements below the fifth percentile. The shortened crown-heel length is another feature of symmetric IUGR, and this
REFERENCES
1. Campbell, S.: Fetal growth, in Beard, R. N., and Nathanielsz, P. W., editors: Fetal Physiology and Medicine, Baltimore, 1976, W. B. Saunders Co., Ltd., Chap. 15, p. 293. 2. Woods, D. L.. Malon, A. F., and de V. Heese, H.: Patterns of retarded fetal growth, Early Hum. Dev. 3:257, 1979.
Fig. 5. Antenatal measurements length in Patients 3 through 7.
of the ultrasound
femur
can be successfully detected by shortened femur length. At the other end of the spectrum of IUGR, the asymmetric growth-retarded fetus has a crown-heel length in the normal range, with normal femur length and a reduced abdominal circumference. The femur length is of special importance when accurate head measurements are unobtainable; the femur length can substitute in these cases or be confirmative when head measurements are available. No one ultrasound measurement of the fetus has been shown to be totally accurate in detecting IUGR. It is believed that the ability to define IUGR should be improved with a three-dimensional image of the fetus with the use of femur length and circumference measurements. In the cases illustrated here, symmetric growth retardation was identified in all instances by shortened ultrasound femur lengths.
3. Neilson, J. P., Whitfieid, C. R., and Aitchison, T. C.: Screening for the small-for-dates fetus: A two-stage ultrasonic examination schedule, Br. Med. J. 480:1203, 1980. 4. O’Brien, G. D., and Queenan, J. T.: Growth of the ultrasound fetal femur length during normal pregnancy. Part I, AM. J. OBSTET. GYNECOL. 141:833, 1981.
Volume Number
144
1
5. Usher, R., and McLean, F.: Intrauterine growth of liveborn Caucasian infants at sea level: Standards obtained from measurements in seven dimensions of infants born between 25 and 44 weeks’ gestation, J. Pediatr. 74:901, 1969. 6. Dubowitz, L. M. S., Dubowitz, O., and Goldberg, C.: Clini-
Fetal
femur
length
and IUGR.
II
39
cal assessment of gestational age in the newborn infant, J. Pediatr. 77:1, 1970. 7. O’Brien, G. D., Queenan, J. T., and Campbell, S.: Assessment of gestational age in the second trimester by real-time ultrasound measurement of the femur length, AM. J. OBSTET. GYNECOL. 139~544, 1981.