Co-Relation of Non-Stress Test and Amniotic Fluid Volume in Antenatal Fetal Monitoring
                     CO-RELATION OF NON-STRESS TEST AND AMNIOTIC FLUID VOLUME 177 
s. K. PATIL • R. H. GI!REGRAT • s. s. KHADILKAR • K. K. DESHMUKH 
SUMMARY 
A total of 650 high risk pregnant patients were monitored antenatally for fetal well 
being at the Grant Medical College, J. J. Hospital, Bombay for 2 years from Jan. 90 to 
Dec. 91. The purpose of this study was to study the perinatal outcome of high risk cases 
which were monitored by N. S. T. and especially to co-relate the results of non-reactive 
NST group with amniotic fluid volume studied ultra-sonographically. 
A total of 902 recordings were made in 650 patients for various high risk indications 
like post-maturity, PIH, IUGR, BOH etc. 65% of nonreactive cases required LS CS, 20% 
were delivered with vaccum or forceps and 15% had normal vaginal delivery. The 
Incidence of meconium was 34% and fetal distress 20% in non-t·eactive cases, there were 
3 still births and 2 neonatal deaths in the non-reactive group. The incidence of neonatal 
morbidity was 44% as compared to 1.8% in the reactive group. 
Screening patients with USG, for non-reactive NST cases, decreases incidence of false 
positive tests to 7.2% and decreases perinatal morbidity and mortality. 
Obstetricians have long searched methods tion, these tests in common predict normal 
of antepartum foetal evaluation that would be outcome well, but are much less accurate in 
non-invasive and accurate and yield results predicting poor outcome. According to Schifrin 
that were immediately available. Ideally, the et al (1979), NST has low false negative rate 
test should be repeatable, incur minimal ex- (1% or less) and high false positive rate (more 
pense and inconvenience. While many bio- than 75 % ). Most current testing schemes require 
chemical and bio-physical measurements have another test, usually contraction stress test for 
been proposed for antepartum foetal evalua- confirmation ofN. S. T. According to Evertson 
eta! (1979), the C. S. T. has a somewhat higher 
Dept. ofObst. &: Gyn. GranlMe dical College, &:Hospiwl, false negative rate (2 to 3%) and a false positive 
Bombay. rate (50% to 75%). Use of C. S. T. is lengthy 
Accepted for Publication on 01.04.1993. and cumbersome. According to Manning et 
178 JOURNAL OF OBSTETRICS AND GYNAECOLOGY OF INDIA 
al (1982), an important factor in sensitivity of for 48 hours. This time was chosen because 
antenatal foetal monitoring is a combination data suggests that foetus A reactive N. S. T. 
of Acute Marker (N. S. T.) and chronic marker was repeated after 1 week. A nonreactive N. 
(Amniotic fluid volume) for foetal compro- S. T. was repeated after 24 hours. If N. S. 
mise. Amniotic fluid volume is not acutely T. continued to remain non-reactive, the foetus 
influenced by changes in central nervous system, was further evaluated by ultrasound for the 
yet was related to the outcome of pregnancy. amount of amniotic fluid volume. The criteria 
for scoring of N. S. T. and A. F. V. were 
AIMS AND OBJECTIVES modified from Vintzileous et al (1983). 
A prospective controlled study was carried 
outatthe Grant Medical College, Sir J. J. group OBSERVATIONS 
of Hospitals, Bombay from Jau 90 to Dec. 91 A total of 902 recordings were obtained 
for a period of 2 years. In the present study, from 650 patients. The earliest gestation at 
N. S. T. and amniotic fluid volume (A. F. V.) which monitoring was performed was 28 weeks 
were correlated regarding mode of delivery, and the latest was 44 weeks. The least no. of 
meconium staining, foetal distress in labour, tests in one patient was one and the greatest 
Apgar Score, perinatal morbidity and mortal- were 8 (Average 3). 
ity and neonatal outcome. 
MATERIALS AND METHODS Table ll 
Heart rate and uterine activity patterns 'were 
studied with an ultrasound transducer and a Results of non-stress test 
tocodyanometercombined in Cerometrics model 
140. N. S. T. was done in left lateral position Reactive (R) 435 66.93% 
for 20 minutes to avoid supine hypotension 
Borderline Reactive (BR) 124 19.07% 
syndrome. In non-reactive cases the test was 
continued for another 20 minutes period with Non-reactive (NR) 91 14% 
manual stimulation. NO' sedatives were given 
Table I 
Indications for NST 
i) Post-maturity (more than 42 weeks) 128 19.7% 
ii) Pregnancy-induced hypertension 125 19.2% 
iii) Suspected IUGR 120 18.4% 
iv) Bad Obstetrics History 115 17.6% 
v) Decreased foetal movements 110 16.9% 
vi) Premature rupture of membranes 14 2.1% 
vii) Antepartum haemorrhage 13 2% 
viii) Diabetes mellitus 13 2% 
ix) Rh !so-immunisation 12 1.8% l 
Total 650 
CO-RELATION OF NON-STRESS TEST AND AMNIOTIC FLUID VOLUME 179 
Table III 
Mode of Delivery 
Test N Normal Vag. Delivery Forceps/Ve LSCS 
Reactive 435 317 (73%) 65 (15%) 52 (12%) 
B. R. 124 80 (65%) 21 (17%) 22 (18%) 
NR 91 13 (15%) 18 (20%) 60 (65%) 
Table IV 
Incidence of Meconium Staining, Foetal Distress And Apgar Score 
Test N Meconium Foetal Apgar 
Staining distress 7 at 1 min 7 at 5 min 
R 435 30 (7%) 21 (5%) 375 (86%) 409 (94%) 
BR 124 14 (11%) 11 (9%) 99 (80%) 112 (91%) 
NR 91 31 (34%) 25 (28%) 69 (76%) 77 (85%) 
According to incidence of foetal distress, false negative rate was 5% and false positive rate 
was 72%. The incidence of LSCS for foetal distress in monitored group was 15.4% and 
unmonitored group was 2.9%. 
Table V ity, absence of acceleration to stimulated 
movements and late declaration with sponta-
·Perinatal Mortality neous contraction. Resting heart rate are usually 
in normal range. This was observed in 8.1% 
Test N Still births Neonatal Deaths of our non-reactive cases. Schifrin et al (1975) 
suggested that when acceleration with good 
R 435 0(0%) 1 (0.2%) variability were present, no foetus developed 
NR 124 1 (0.8%) 1 (0.8%) late declaration during stress-induced contrac-
tion. Lee et al (1975) have concluded that 
BR 91 3 (3.2%) 2 (2.1 %) 
acceleration with foetal movement is a reliable 
sign of foetal well-being. The loss of beat -
to- beat variability appears to represent blunt-
COMMENTS ing of homeostatic mechanism for control of 
In normal foetus, there may be periods of heart rate. There is an increased likelihood 
decreased variability which usually lasts less of late deceleration during spontaneous con-
than30 minutes. These represents foetal sleep- traction in these foetuses. This was observed 
wake pattern or rest-activity cycles and does in 6.5% of our non-reactive cases. 
not signify foetal compromise. Compromised Reactive heart rate pattern in ante-partum 
foetus shows persistently decreased variabil- period reflect foetal well-being. Out of 435 
180 JOURNAL OF OBSTETRICS AND GYNAECOLOGY OF INDIA 
Table VI 
Neonatal Morbidity 
Neonatal morbidity R BR NR 
i) Meconium aspiration 2 3 7 
syndrome 
ii) IUGR 5 11 23 
iii) Anaemia 1 5 
iv) Prematurity and RDS 1 2 5 
v) Congenital anomalies 
8 (1.8%) 17 (13.7%) 40 (43.9%) 
Table VII high risk foetuses with reactive pattern in 1.8% 
required prolonged neonatal stay and 1 died 
Results of Amniotic l