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Relationship between amniotic fluid triglyceride levels and fetal maturity
Relationship between amniotic fluid triglyceride levels and fetal maturity GEORGE
H.
NELSON,
DONALD
S.
FREEDMAN,
Augusta,
M.D
PH.r).,
B.S.
Georgia
Triglyceride determinations have been made in 100 samples of amniotic fluid, and the results have been correlated with gestational age and fetal weight. When the triglyceride level is 2.00 mg. per cent or greater, the correlation with a mature fetus is good. However, values less than 2.00 mg. per cent are associated with both mature and immature fetuses. Low values cannot be used as indicative of fetal prematurity. Levels of 2.00 mg. per cent or greater showed good correlation with amniotic fluid creatinine concentrations of 1.8 mg. per cent or greater, AO.D.,,, measurement of 0.02 or less, and orange cell counts of 10 per cent or greater. As a test for fetal maturity, amniotic fluid triglyceride determination offers no advantage over the standard amniotic fEuid analyses; however, this determination may be useful as an additional parameter upon which intelligent decisions of intervention can be made.
T H E N E E D F 0 R accurate parameters in assessment of fetal maturity is obvious. In recent years, amniotic fluid analyses have become commonplace in the evaluation of this problem. The most frequently utilized determinations include : creatinine concentration, measurements of A0.D.4so, and percentage of orange cells when stained with Nile blue sulfate. In addition, amniotic fluid osmolalityl and more recently lecithin concentration and/or lecithin/sphingomyelin ratios’ have been suggested. This latter test may be particularly pertinent since it may correlate with fetal lung maturity as well as fetal age and size. Brosens and Gordon” believe that the appearance of orange-stained cells in late gestation is related to the functional maturity of sebaceous glands. If this is true, it would seem reasonable to expect the triglyceride concentration in amniotic fluid to increase near term. In one previous report on quantitive amniotic fluid triglyceride determinations, From the Department of Obstetrics and Gynecology, Medical College Georgia.
Biezenski and associates’ found twice the level of triglyceride in samples collected after 34 weeks’ gestation than in samples obtained between 26 and 33 weeks. It is the purpose of this communication to report the relationship between amniotic fluid triglyceride levels, and fetal age and size. In addition, correlations have been made between triglyceride concentrations (2.00 mg. per cent or greater) and creatinine concenand percentage of orange tration, AO.D.tso, cells. Materials
and
methods
Amniotic fluid was collected by amniocentesis or amniotomy. All fetuses were alive at the time of sample collection. The fluids were refrigerated as soon as possible and either analyzed within 48 hr. or transferred to a deepfreeze until analysis. Samples grossly contaminated with blood or meconium were discarded. Clear specimens were extracted without however, centrifugation. Most samples, showed contamination with small quantities of vernix caseosa, debris, etc., and were cen-
of 930
Volume Number
111 7
Amniotic
fluid
triglyceride
and
.
fetal
maturity
931
. . . .
.
.
. ‘i.
6 .O-
.
.
l
4.02.0-
.
22 QT<
24
i
0.
26
2-6
:
l
3b
*:
32
Fig.
1. Relationship
between
triglyceride
1
)Jq
;
;
::’
4
k.
36
3’4
GESTATIONAL
t
*
3b
.
:
iu
40
0::
AGE (WEEKS)
concentration
and
estimated
gestational
age.
.
. mg 100
. . .
6.0
. .
6.0
*e .
FETAL
,
Fig.
2. Relationship
between
triglyceride
WEIGHT
concentration
trifuged slowly (approximately 1,500 r.p.m. for 3 to 5 min.), and an aliquot was obtained from the supernatant. Samples with any evidence of hemolysis were not used. Total lipid was extracted by the method previously reported5 except 9 ml. of amniotic fluid was used instead of 36 ml. Triglyceride concentration was determined by the method of Van Handel6 and is reported as milligrams per cent of tripalmitin equivalents. In a few instances, this procedure was modified for use of less amniotic fluid. The best estimate of gestational age was made by combining data from maternal history and physical examination of the neonate. The procedures
.
.
. .
.
i
.
..*
.. 4 .o
.
.
(Gms)
and
estimated
fetal
weight.
for fetal weight estimation, creatinine determination, A0.D.450 measurement, and orange cell count have been previously reported.’ Results The relationship between amniotic fluid triglyceride concentration and estimated gestational age and fetal weight are shown in Figs. 1 and 2. It is apparent that the values tend to be below 2.00 mg. per cent until near term at which time some samples show considerably higher levels, with the highest being about 12 mg. per cent. With the use of a value of 2.00 mg. per cent or greater as indicative of
932
December I, 1971 Am. J. Obstet. Gynecol.
and Freedman
Nelson
Table I. Relationship between triglyceride concentration and estimated gestational age
(weeks)
< 32 32-35 36-38 39 or
1
1 minations 13 13 29 45
>
Totals
100
<
2.00
1 2.00
or
12 13 16 - 14
1 0 13 31
55
45
Table III. Correlations between high triglyceride concentrations and other tests for fetal maturity Triglyceride concentratiofl (mg. %)
>
Creatinine concentration (mg. %) < 1.8 1.8
Accuracy of predicting maturity with value of 2.00 or > = 44/45 or 98 per cent. False positive values in premature group = l/26 or 4 per cent. False negative values in mature group = 30/74 or 41 per cent.
2.00 2.00
or
or <
2.00 2.00
or
AO.D.so > 0.02 0.02
Percentage orange <
Table II. Relationship
between triglyceride and estimated fetal weight
concentration
Fet(agI,z:;ht <
1d$zla]
1,500 1,500-2,499 2,500-3,499 3,500 or Totals
>
~~‘$o~or 11
10
:5” 16
::
loo
3 55
> 1
3: 13 45
Accuracy of predicting maturity with value of 2.00 or > = 43/45 or 96 per cent. False positive values in premature group = 2/29 or 7 per cent. False negative values in mature group = 28/71 or 39 per cent.
fetal maturity, the data are correlated with fetal age and size’in Tables I and II. In addition, in 25, 22, and 26 samples, respectively, triglyceride concentrations greater than 2.00 mg. per cent have been correlated with creatinine concentration, A0.D.450, and orange cell count, and the results are shown in Table III. Comment The 100 specimens of amniotic fluid reported in this study were obtained from 96 patients. A wide variety of diseases were noted in the patients studied. It would seem that the two conditions which would most likely influence amniotic fluid triglyceride concentrations would be diabetes mellitus and polyhydramnios. Because of the high plasma levels of triglyceride in patients with diabetes,
10 10 or
or >
>
or
>
No. of determinations
>
or > >
1
24 1
21
cells
2.00
or
>
2.00
or
>
1
25
one might legitimately wonder if this would be reflected in the amniotic fluid. Of the patients reported in this study, ten were diabetic. Of these, seven had mature fetuses at the time of fluid collection; 4 values were less than 2.00 mg. per cent and three were greater. In the three patients who had premature fetuses, all had values less than 2.00. Therefore, it would seem that amniotic fluid triglyceride levels are not apparently different in patients with diabetes. In this study, 6 women had polyhydramnios. Of these, five had mature fetuses. Four values were less than 2.00 mg. per cent, and one value was 2.86. The patient with polyhydramnios and a premature fetus had a value less than 2.00. From these small numbers, one could not comment accurately upon the effect of polyhydramnios on the amniotic fluid triglyceride levels. However, it would not seem unreasonable to expect a considerable number of false negative results in this group. Over-all, 50 samples have been run in which triglyceride concentration and orange cell percentage have been determined. In 24 samples in which the triglyceride level was < 2.00 mg. per cent, there was poor correlation between these 2 measurements. For instance, in 3 samples, the percentage of orange cells was 68, 74, and 78 per cent; however, the triglyceride concentration was low. If both
Volume
111
Number
i
amniotic fluid triglyceride concentration and percenltage of orange cells are solely dependent upon the functional maturity of fetal sebaceous glands, one would not expect to find this large discrepancy. Perhaps when the factors affecting these 2 measurements are kncown, this finding will be more easily undemmod.
REFERENCES
1. 2.
3.
Miles, P. A., and Pearson, J. W.: Obstet. Gynecol. 34: 701, 1969. Gluck, L., Kulovich, M. V., Borer, R. C., Brenner, P. H., Anderson, G. G., and Spellacy, W. N.: AM. J. OBSTET. GYNECOL. 109: 440, 1971.. Brosens, I. A., and Gordon, H.: J. Ohstet. Gynaecol. Br. Commonw. 73: 88, 1966.
Amniotic
fluid
triglyceride
and
fetal
maturity
933
The usefulness of amniotic fluid triglyceride levels as a test for fetal maturity would seem to be limited to those laboratories which perform a battery of tests for this purpose. High values are found at term; low values are of no prognostic significance.
4. 5. 6. 7.
Biezenski, J. J., Pomerance, W., and Goodman, J.: AM. J. OBSTET. GYNECOL. 102: 853, 1968. Nelson, G. H.: AM. J. OBSTET. GYNECOL. 105: 1072, 1969. Van Handel, E.: Clin. Chem. 7: 249, 1961. Nelson, G. H., Goodrich, S. M., Martin, T. R., Talledo, 0. E., and Freedman, M. A.: South. Med. J. 64: 1, 1971.
H.
NELSON,
DONALD
S.
FREEDMAN,
Augusta,
M.D
PH.r).,
B.S.
Georgia
Triglyceride determinations have been made in 100 samples of amniotic fluid, and the results have been correlated with gestational age and fetal weight. When the triglyceride level is 2.00 mg. per cent or greater, the correlation with a mature fetus is good. However, values less than 2.00 mg. per cent are associated with both mature and immature fetuses. Low values cannot be used as indicative of fetal prematurity. Levels of 2.00 mg. per cent or greater showed good correlation with amniotic fluid creatinine concentrations of 1.8 mg. per cent or greater, AO.D.,,, measurement of 0.02 or less, and orange cell counts of 10 per cent or greater. As a test for fetal maturity, amniotic fluid triglyceride determination offers no advantage over the standard amniotic fEuid analyses; however, this determination may be useful as an additional parameter upon which intelligent decisions of intervention can be made.
T H E N E E D F 0 R accurate parameters in assessment of fetal maturity is obvious. In recent years, amniotic fluid analyses have become commonplace in the evaluation of this problem. The most frequently utilized determinations include : creatinine concentration, measurements of A0.D.4so, and percentage of orange cells when stained with Nile blue sulfate. In addition, amniotic fluid osmolalityl and more recently lecithin concentration and/or lecithin/sphingomyelin ratios’ have been suggested. This latter test may be particularly pertinent since it may correlate with fetal lung maturity as well as fetal age and size. Brosens and Gordon” believe that the appearance of orange-stained cells in late gestation is related to the functional maturity of sebaceous glands. If this is true, it would seem reasonable to expect the triglyceride concentration in amniotic fluid to increase near term. In one previous report on quantitive amniotic fluid triglyceride determinations, From the Department of Obstetrics and Gynecology, Medical College Georgia.
Biezenski and associates’ found twice the level of triglyceride in samples collected after 34 weeks’ gestation than in samples obtained between 26 and 33 weeks. It is the purpose of this communication to report the relationship between amniotic fluid triglyceride levels, and fetal age and size. In addition, correlations have been made between triglyceride concentrations (2.00 mg. per cent or greater) and creatinine concenand percentage of orange tration, AO.D.tso, cells. Materials
and
methods
Amniotic fluid was collected by amniocentesis or amniotomy. All fetuses were alive at the time of sample collection. The fluids were refrigerated as soon as possible and either analyzed within 48 hr. or transferred to a deepfreeze until analysis. Samples grossly contaminated with blood or meconium were discarded. Clear specimens were extracted without however, centrifugation. Most samples, showed contamination with small quantities of vernix caseosa, debris, etc., and were cen-
of 930
Volume Number
111 7
Amniotic
fluid
triglyceride
and
.
fetal
maturity
931
. . . .
.
.
. ‘i.
6 .O-
.
.
l
4.02.0-
.
22 QT<
24
i
0.
26
2-6
:
l
3b
*:
32
Fig.
1. Relationship
between
triglyceride
1
)Jq
;
;
::’
4
k.
36
3’4
GESTATIONAL
t
*
3b
.
:
iu
40
0::
AGE (WEEKS)
concentration
and
estimated
gestational
age.
.
. mg 100
. . .
6.0
. .
6.0
*e .
FETAL
,
Fig.
2. Relationship
between
triglyceride
WEIGHT
concentration
trifuged slowly (approximately 1,500 r.p.m. for 3 to 5 min.), and an aliquot was obtained from the supernatant. Samples with any evidence of hemolysis were not used. Total lipid was extracted by the method previously reported5 except 9 ml. of amniotic fluid was used instead of 36 ml. Triglyceride concentration was determined by the method of Van Handel6 and is reported as milligrams per cent of tripalmitin equivalents. In a few instances, this procedure was modified for use of less amniotic fluid. The best estimate of gestational age was made by combining data from maternal history and physical examination of the neonate. The procedures
.
.
. .
.
i
.
..*
.. 4 .o
.
.
(Gms)
and
estimated
fetal
weight.
for fetal weight estimation, creatinine determination, A0.D.450 measurement, and orange cell count have been previously reported.’ Results The relationship between amniotic fluid triglyceride concentration and estimated gestational age and fetal weight are shown in Figs. 1 and 2. It is apparent that the values tend to be below 2.00 mg. per cent until near term at which time some samples show considerably higher levels, with the highest being about 12 mg. per cent. With the use of a value of 2.00 mg. per cent or greater as indicative of
932
December I, 1971 Am. J. Obstet. Gynecol.
and Freedman
Nelson
Table I. Relationship between triglyceride concentration and estimated gestational age
(weeks)
< 32 32-35 36-38 39 or
1
1 minations 13 13 29 45
>
Totals
100
<
2.00
1 2.00
or
12 13 16 - 14
1 0 13 31
55
45
Table III. Correlations between high triglyceride concentrations and other tests for fetal maturity Triglyceride concentratiofl (mg. %)
>
Creatinine concentration (mg. %) < 1.8 1.8
Accuracy of predicting maturity with value of 2.00 or > = 44/45 or 98 per cent. False positive values in premature group = l/26 or 4 per cent. False negative values in mature group = 30/74 or 41 per cent.
2.00 2.00
or
or <
2.00 2.00
or
AO.D.so > 0.02 0.02
Percentage orange <
Table II. Relationship
between triglyceride and estimated fetal weight
concentration
Fet(agI,z:;ht <
1d$zla]
1,500 1,500-2,499 2,500-3,499 3,500 or Totals
>
~~‘$o~or 11
10
:5” 16
::
loo
3 55
> 1
3: 13 45
Accuracy of predicting maturity with value of 2.00 or > = 43/45 or 96 per cent. False positive values in premature group = 2/29 or 7 per cent. False negative values in mature group = 28/71 or 39 per cent.
fetal maturity, the data are correlated with fetal age and size’in Tables I and II. In addition, in 25, 22, and 26 samples, respectively, triglyceride concentrations greater than 2.00 mg. per cent have been correlated with creatinine concentration, A0.D.450, and orange cell count, and the results are shown in Table III. Comment The 100 specimens of amniotic fluid reported in this study were obtained from 96 patients. A wide variety of diseases were noted in the patients studied. It would seem that the two conditions which would most likely influence amniotic fluid triglyceride concentrations would be diabetes mellitus and polyhydramnios. Because of the high plasma levels of triglyceride in patients with diabetes,
10 10 or
or >
>
or
>
No. of determinations
>
or > >
1
24 1
21
cells
2.00
or
>
2.00
or
>
1
25
one might legitimately wonder if this would be reflected in the amniotic fluid. Of the patients reported in this study, ten were diabetic. Of these, seven had mature fetuses at the time of fluid collection; 4 values were less than 2.00 mg. per cent and three were greater. In the three patients who had premature fetuses, all had values less than 2.00. Therefore, it would seem that amniotic fluid triglyceride levels are not apparently different in patients with diabetes. In this study, 6 women had polyhydramnios. Of these, five had mature fetuses. Four values were less than 2.00 mg. per cent, and one value was 2.86. The patient with polyhydramnios and a premature fetus had a value less than 2.00. From these small numbers, one could not comment accurately upon the effect of polyhydramnios on the amniotic fluid triglyceride levels. However, it would not seem unreasonable to expect a considerable number of false negative results in this group. Over-all, 50 samples have been run in which triglyceride concentration and orange cell percentage have been determined. In 24 samples in which the triglyceride level was < 2.00 mg. per cent, there was poor correlation between these 2 measurements. For instance, in 3 samples, the percentage of orange cells was 68, 74, and 78 per cent; however, the triglyceride concentration was low. If both
Volume
111
Number
i
amniotic fluid triglyceride concentration and percenltage of orange cells are solely dependent upon the functional maturity of fetal sebaceous glands, one would not expect to find this large discrepancy. Perhaps when the factors affecting these 2 measurements are kncown, this finding will be more easily undemmod.
REFERENCES
1. 2.
3.
Miles, P. A., and Pearson, J. W.: Obstet. Gynecol. 34: 701, 1969. Gluck, L., Kulovich, M. V., Borer, R. C., Brenner, P. H., Anderson, G. G., and Spellacy, W. N.: AM. J. OBSTET. GYNECOL. 109: 440, 1971.. Brosens, I. A., and Gordon, H.: J. Ohstet. Gynaecol. Br. Commonw. 73: 88, 1966.
Amniotic
fluid
triglyceride
and
fetal
maturity
933
The usefulness of amniotic fluid triglyceride levels as a test for fetal maturity would seem to be limited to those laboratories which perform a battery of tests for this purpose. High values are found at term; low values are of no prognostic significance.
4. 5. 6. 7.
Biezenski, J. J., Pomerance, W., and Goodman, J.: AM. J. OBSTET. GYNECOL. 102: 853, 1968. Nelson, G. H.: AM. J. OBSTET. GYNECOL. 105: 1072, 1969. Van Handel, E.: Clin. Chem. 7: 249, 1961. Nelson, G. H., Goodrich, S. M., Martin, T. R., Talledo, 0. E., and Freedman, M. A.: South. Med. J. 64: 1, 1971.