Predictive value of the nonreactive nonstress test in evaluating neonatal outcome.

A Bhide, MS Bhattacharya 
 Department of Obstetrics and Gynaecology, Seth G. S. Medical College, Bombay, Maharashtra.

Correspondence Address:
A Bhide
Department of Obstetrics and Gynaecology, Seth G. S. Medical College, Bombay, Maharashtra.

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::   Introduction

Electronic foetal monitoring is a relatively recent development in the field of perinatology. While the implications of a reactive non-stress test are will known, the same cannot be said about a non-reactive non-stress test. The following study was carried out in a high-risk pregnant population to gain an insight into the problem. A non-reactive non-stress test was a sign of bad omen in a fair proportion of cases.

::   Material and method

Hundred and forty-three high-risk cases were followed up with the non-stress testing. Corometrics-112 machine was used. The test was done for 20 minutes; extendable upto 40 minutes to call it non-reactive. Criteria described by Evertson et al[1] were used to classify the strip as non-reactive. The neonatal outcome was assessed using three criteria-a) neonatal survival, b) Apgar scores at 5 minutes and c) incidence of caesarean sections done for foetal distress. The test results in the preceding 7 days of delivery were considered. The largest high-risk group was pregnancy induced hypertension.

::   Results

A total of 287 tests were carried out in 143 cases. The last test was reactive in 95, and non-reactive in 48 cases.

a) Perinatal outcome: The results are shown in [Table:1]. A total of 13 mortalities occurred, out of which 8 were from the non-reactive group.

b) Apgar scores: Five minute Apgar scores of less than 7 were taken as abnormal [2]. A total of 17 babies were found to be depressed at birth, of which 13 were from the non-reactive group. The results are shown in

c) Caesarean section for foetal distress: As shown in [Table:3], of caesarean sections done for foetal distress 10 were from the non-reactive group. Ninety-four patients underwent vaginal delivery and remaining 34 underwent caesarian sections for causes other than foetal distress.

::   Discussion

Non-stress test is an accepted method of monitoring high risk pregnancies. One of the objections to the test is that it has a high false positive rate; in other words, it cannot predict adverse foetal outcome. In our series, the mean false positive rate was 76.87% with 23.13% of abnormal results correctly predicted, and these figures closely approximate to those quoted in the literature.3 In our opinion this is an asset of the test since if the false positive rate is very low, majority of the cases will have an abnormal outcome. Thus the test would have failed us in intervening early enough to avoid a poor outcome. In our view, a non-reactive non-stress test is a bad omen, signifying a higher incidence of foetal distress, depressed neonates and a higher perinatal mortality.

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