Sibai et al.

therapy of mild disease and in patients receiving ap­propriate magnesium sulfate therapy may require reas­sessment of current obstetric practices.

REFERENCES

I. Sibai BM, McCubbinJH, Anderson GD, Dilts PV. Eclamp­sia: treatment and referral. South MedJ 1982:75:267.

2. Zuspan FP. Problems encountered in the treatment of pregnancy-induced hypertension. AM J OBSTET GYNECOL 1978;131:591.

3. Pritchard JA, MacDonald PC, Gant NF. Williams' Ob­stetrics. 17th ed. New York: Appleton-Century-Crofts, 1984:525.

4. Sibai BM, McCubbin JH, Anderson GD, et al. Eclampsia I. Observations from 67 recent cases. Obstet Gynecol areas, 1980;55:74.

5. Gilstrap LC, Cunningham FG, Whalley PJ. Management of pregnancy induced hypertension in the nulliparous patient remote from term. Semin Perinattal 1978;2:73.

6. Sibai BM, Schneider JM, Morrison JC, et al. The late postpartum eclampsia controversy. Obstet Gynecol 1980; 55:74.

7. Oney HT, Kaulhausen H. The value of the mean arterial blood pressure in the second trimester (MAP-2 value) as a predictor of pregnancy-induced hypertension and pre­eclampsia. Clin Exp Hypertens 1983;B2:211.

March, 1986 Am.J Obstet Gynecol

8. Dubowitz LMS, Dubowitz V, Goldberg C. Clinical assess­ment of gestational age in the newborn infant. J Pediatr 1970;77: I.

9. Campbell DM, Templeton AA. Is eclampsia preventable? In: Bonnar J, MacGillivray I, Symonds EM, eds. Preg­nancy hypertension. Baltimore: University Park Press, 1980.

10. Page EW, Christianson R. The impact of mean arterial pressure in the middle trimester upon the outcome of pregnancy. AMJ OBSTET GY~ECOL 1976;125:740.

II. Phelan JP. Enhanced prediction of pregnancy-induced hypertension by combining supine pressor test with mean arterial blood pressure of middle trimester. AM J OBSTET GYNECOL 1977;129:397.

12. Gant NF, Chand S, Worley JR, et al. A clinical test useful for predicting the development of acute hypertension of pregnancy. AM J OBSTET GYNECOL 1974;120: I.

13. Kuntz WD. Supine pressor (roll-over) test: an evaluation. AMJ OBSTETGYNECOL 1980;137:764.

14. Paul RH, Koh KS, Bernstein SG. Changes in fetal heart rate uterine contraction patterns associated with eclamp­sia. AMJ OBSTET GYNECOL 1978;130:165.

15. Goodlin RC, Cotton DB, Haesslein He. Severe edema­proteinuria-hypertension gestosis. AM J OBSTET GYNECOL 1978;132:595.

16. Sibai BM, Spinnato JA, Watson DL, et al. Eclampsia. IV. Neurologic findings and future outcome. AM J OBSTET GYNECOL 1985;152:184.

Variable decelerations during nonstress tests are not a sign of fetal compromise

Paul J. Meis, M.D., John R. Ureda, Ph.D., Melissa Swain, R.N., Randall T. Kelly, M.D., Mary Penry, R.N., and Penny Sharp, M.A.

Winston-Salem, North Carolina

An examination of 908 fetal heart rate tests of 418 consecutive patients revealed brief variable

decelerations in more than 50.7% of the patients. Although an association existed with nuchal cord location found at delivery, no association existed between these variable decelerations and fetal heart rate decelerations during labor, low Apgar scores at birth, or birth weight. We find no evidence to suggest that

these brief variable decelerations are a sign of fetal compromise or an indication for obstetric intervention. (AM J OBSTET GYNECOL 1986;154:586-90.)

Key words: Fetal heart rate, deceleration, nonstress tests

In the management of women with high-risk preg­nancies, surveillance of fetal well-being by means of antepartum fetal heart rate tests has attained wide­spread use. A number of authors'·6 have found that a

From the Department of Obstetrics and Gynecology and Department of Community Medicine, Bowman Gray School of Medicine of Wake Forest University.

Received for publication April 23 , 1985; revised September 23, 1985; accepted November 21, 1985.

Reprint requestL' Paul j. Meis, M.D., Department of Obstetrics and Gynecology, Bowman Gray School of Medicine, 300 South Haw­thorne Road, Winston-Salem, NC 27103.

586

reactive fetal heart rate pattern is predictive of a suc­cessful pregnancy outcome, whereas a nonreactive test, especially if accompanied by late decelerations of fetal heart rate, is associated with increased likelihood of fetal distress during labor, neonatal morbidity, and perinatal death. Recently several authors 7

" have di­rected attention to the significance of variable deceler­ations encountered during antepartum fetal heart rate tests and suggested that the occurrence of this pattern is a potentially ominous sign and is associated with ab­normal umbilical cord location, oligohydramnios, im­paired fetal growth, and increased risk to the fetus. We

Volume 154 Number 3

Table I. Indications for antepartum fetal heart rate testing

Indication

Preeclampsia Postdates Chronic hypertension Diabetes mellitus Suspected poor fetal growth Decreased fetal movement Poor past-pregnancy history Other Not stated

No. of patients

100 93 60 37 24 21 16 73

207

Table II. Occurrence of fetal heart rate deceleration in any of last four antepartum fetal heart rate tests before delivery (N = 428)

Deceleration

Brief, :S 15 sec (V-shaped) Longer, > 15 sec (U-shaped) Combined (V- + U)

%

45.8 14.3 50.7

performed the following study in an attempt to evaluate the significance of these variable decelerations.

Methods

To determine the occurrence rate and evaluate the clinical significance of these decelerations, we analyzed the last four antepartum fetal heart rate tests of 428 consecutive patients seen in our antenatal testing lab­oratory over an I8-month time span (March 1, 1979, to August 31, 1980). A total of 908 tests were examined, since some patients had less than four tests.

The customary protocol in our testing laboratory is to perform antepartum fetal heart rate tests twice weekly. The primary mode of evaluation is the non­stress test. A test is considered reactive with the pres­ence of two or more accelerations of 15 bpm lasting 15 seconds or more in a 20-minute time span. In general, a nonreactive test is followed by an oxytocin challenge test, and this test is considered negative if no late de­celerations are seen with a contraction frequency of at least three in 10 minutes. A test was classified as positive if there were consistent and persistent late decelerations in the absence of hyperstimulation. Tests were per­formed with the patient in the semirecumbent or lateral recumbent positions.

A variable deceleration occurring during a nonstress test was defined as a rapid drop in heart rate of ~20 bpm below the baseline rate. The decelerations were classified by duration (> 15 or ",; 15 seconds), by the maximal fall below baseline, and by the number of de­celerations in anyone test. The presence of variable decelerations was not considered in the clinical man­agement of the patients. Intrapartum fetal heart rate

Variable decelerations in nonstress tests 587

..,..-,.......,~--r-.,--,--r-..,--- -100...,.---,----

Ll I ! I I : : -1--1-+-+---1--'-1-

1 i-715~

! Ii: ~l i i

-+------'--+-t-+-,..----~. sr I I. !

--2S..:: ...... "'· .... ,H---'--

UAU

Fig. 1. Example of a V-shaped fetal heart rate occurring in association with a spontaneous contraction and fetal movement.

records were available for 315 of the 428 subjects and were evaluated with use of the criteria of Hon and Quilligan. 16

To examine the clinical significance of variable de­celerations, the occurrence and frequency of these de­celerations in the last nonstress test before delivery were compared with the occurrence and frequency of intra­partum fetal heart rate patterns, with 1- and 5-minute Apgar scores and with mode of delivery by means of X2 analysis.

Associations with birth weight and gestational age at delivery were made with use of Student's t test.

Results

The indications for the antepartum fetal heart rate test are shown in Table I. The most common reasons were acute or chronic hypertension. Of the patients, 51.6% had more than one indication.

The occurrence of variable decelerations in the last four antepartum fetal heart rate tests before delivery is indicated in Table II. These decelerations were clas­sified according to their duration into brief (V-shaped) with a duration of",; 15 seconds as shown in Fig. 1, and longer (U-shaped) with a duration of> 15 seconds, as shown in Fig. 2. Most of the U-shaped variable decelera­tions had a duration of 16 to 30 seconds, and variable decelerations of extended duration (>30 seconds) were rarely seen. In the total group of subjects, > 50% of the patients had one or more variable decelerations in one of the last four antepartum fetal heart rate tests before

588 Meis et al.

i I 240 . , 1

i 11fi-m 210 I I I' ,. I 1 , 1 1 .

l'iO ~ : : I i 11·litM

120 1 I 1 I . i I I I I , 1 I I' . 90 1 1

1 "I 1 1 60 I I

I I : : 30

~""l -r-,--~500 ..100"""'1--'"-'--'--'

I ! 1;1 ! I I : ! I i +-... i -+-+-r, 375-+ . ......J.--I.-r-r-r-+--+-----r-+-75,-,.-;--l--+

I ! I' Iii I I I I ' ! I i

-'I'""' _i~._""-:. 250! I 1 Ii: I : 50: I 1.1 II ,

I ! ! : I; :: ,;1 i I I I, I I I 125' ~ ., 2 ---

I : I I

i I ____ ~~_ - __ L-L-__ ~~~ __ --I.~O ____ ~~_

UA

Fig. 2. Example of a U-shaped deceleration associated with fetal movement and a V-shaped deceleration not associated with fetal movement.

delivery. In the last antepartum fetal heart rate test before delivery, as shown in Table III, 31 % of the pa­tients had one or more V-shaped decelerations, and 9% had one or more U-shaped decelerations.

In evaluating possible associations of variable decel­erations with perinatal events, no difference in signif­icance was found when comparing duration of deceler­ation (V-shaped versus U-shaped) or in comparing ex­tent of fall in fetal heart rate from baseline. Therefore the presence and number of any variable deceleration in the last antepartum fetal heart rate test before de­livery was examined for associations with intrapartum fetal heart rate patterns, Apgar scores, and other peri­natal events.

The incidence of periodic fetal heart rate patterns during intrapartum fetal heart rate monitoring is shown in Table IV. No association existed between the occurrence of variable decelerations in antepartum fe­tal heart rate tests and the presence or number of in­trapartum variable, early, or late fetal heart rate de­celerations. The data relating to severe variable deceler­ations and late decelerations are shown in Table V. Likewise, no association was present between the oc­currence of these antepartum variable decelerations and the occurrence of low Apgar scores at 1 or 5 min­utes after birth, as shown in Table V.

The subset of patients who were ;;;.42 weeks in ges­tational age were examined for the same associations. Again, no association existed between occurrence of variable decelerations and intrapartum fetal heart rate patterns or Apgar scores.

March,1986 Am J Obstet Gynecol

Table III. Incidence of fetal heart rate deceleration in last antepartum fetal heart rate test before delivery (N = 428)

Brief Longer (V-shaped) (V-shaped)

No. of decelerations decelerations decelerations (%) (%)

0 68.9 90.9 1 13.8 4.4 2 6.6 2.3 3 4.2 l.4

4 or more 6.5 l.0 Total 100 100

Table IV. Incidence of intrapartum fetal heart rate patterns

Pattern

Mild variable decelerations Severe variable decelerations Early decelerations Late decelerations Accelerations

Incidence (%)

77.7 5.1

13.6 18.6 69.2

The group of patients who exhibited a nonreactive antepartum fetal heart rate test (24% of the group) was considered, and once again, no association existed be­tween variable decelerations and intrapartum fetal heart rate patterns or Apgar scores.

Neither V-shaped nor U-shaped decelerations showed any association with birth weight (as shown in Table VI) or gestational age when patients who exhib­ited these signs were compared by means of Student's t test with patients who did not exhibit them.

An association was found between variable deceler­ations and umbilical cord abnormalities found at the time of delivery, as shown in Table VII. These abnor­malities consisted of 67 patients with a nuchal cord location and one patient with a true knot of the cord. Although a statistically significant association was pres­ent, the sensitivity and specificity were only 38% and 70%, respectively.

Two fetal deaths and five neonatal deaths occurred in this series of high-risk patients, for a perinatal mor­tality of 16.4 per 1000 live births. One fetal death was in a twin gestation before 30 weeks with a positive oxy­tocin challenge test and brief variable decelerations, in which the other twin showed no sign of fetal compro­mise and intervention was withheld. The other fetal death occurred in a postdates patient after a nonreac­tive antepartum fetal heart rate test, which was read as a negative oxytocin challenge test but which in retro­spect showed small but clearly present late decelera­tions. No variable decelerations were present in the fetal heart rate tracing. One neonatal death was that of

Volume 154 Number 3

Variable decelerations in nonstress tests 589

Table V. Comparison of occurrence and frequency of variable decelerations in last antepartum fetal heart rate test with fetal heart rate patterns in labor and Apgar scores at birth

Severe variable decelerations during Late decelerations during Apgar score at Apgar score at

{abor* {abort 1 minute:f: 5 minutes§

Present Present 0-6 0-6 No. of

decelerations

o I

2 or more

Total

Absent (n)

186 41 71

298

*x2 = 0.28; P = NS. tX2 = 2.21; P = NS. *X2 = 0.79; p = NS. §X2 = 2.21; P = NS.

n

II 2 3

16

I %

5.6 4.7 4.1

Absent (n)

164 36 56

256

Table VI. Comparison of occurrence of variable decelerations in last antepartum fetal heart rate test with birth weight

Decelerations

Present Absent

t = 0.49; P = NS.

Birth weight (gm)

Mean

2954 2994

SD

890 766

n

33 7

18

58

an infant with trisomy 13, three were those of infants weight ~660 gm, and one involved an 1100 gm infant who suffered perinatal asphyxia and showed severe hyaline membrane disease at postmortem examination. During this same time frame, the perinatal mortality at this hospital for nonreferral patients (residents of Forsyth County) was 17.5 per 1000 live births.

Comment

Previously published studies"" have found occur­rences of variable decelerations in antepartum fetal heart rate tests varying from 1.6%" to 56.8%.' An association with abnormal umbilical cord anatomy or location ranges from 45.6% to 92%." This wide vari­ation between studies may be due to differences in the definition of these phenomena, since only three studiesll. I". 13 offered a precise definition of these de­

celerations. With use of a definition of variable deceler­ation as a drop of ;;.20 bpm below baseline rate, we find an occurrence of these patterns in 50.7% of our patients. Of those patients exhibiting these patterns, 24.3% had a nuchal cord location at birth.

The results of this study indicate that these variable decelerations or V- and U-shaped dips in fetal heart rate were frequently encountered in antepartum fetal heart rate tests, with over half of all patients undergoing these tests exhibiting these patterns in one of the last

I %

16.8 16.3 23.6

n

80 14 29

123

I %

29.4 24.1 30.5

7-10 (n)

192 44 66

302

n

20 2

10

32

T %

7.4 3.4

10.5

Table VII. Comparison of occurrence and frequency of variable decelerations in last antepartum fetal heart rate test with nuchal cord found at delivery

Nuchal cord No. of

I decelerations Absent Present

0 252 42 I 53 6

2 or more 54 20

Total 359 68

7-10 (n)

252 56 85

393

%

14.3 13.8 27.0

X2 = 8.86, P = 0.012, sensitivity = 38.2%, specificity = 70.2%.

four tests before delivery. Although an association ex­isted between these variable decelerations and nuchal cord location at delivery, no association existed between these fetal heart rate patterns and any measurement of intrapartum or neonatal morbidity in the entire group of patients studied, in the group over 42 weeks' ges­tation, or in the group with a nonreactive antepartum fetal heart rate test. These patterns were not associated with low birth weight infants.

Some authors7. II. I. have suggested that variable de­

celerations occurring during antepartum fetal heart rate tests are a sign of oligohydramnios and should be considered ominous, since the diminished amniotic fluid volume may represent a compromised fetus or may lead to a cord accident. Although we did not per­form ultrasound scans routinely in this series of pa­tients, < 10% of these patients showed any clinical sign of oligohydramnios or impaired fetal growth, while > 50% of the patients exhibited these fetal heart rate patterns. It seems highly unlikely that oligohydramnios was present in >50% of all patients routinely screened in the Antenatal Testing Laboratory.

Decelerations of the fetal heart rate lasting >60

590 Meis et al.

seconds occurring during antepartum fetal heart rate tests may be of more worrisome significance. Two authors" 11 report an association of these prolonged decelerations with fetal distress in labor. In both of these studies the occurrence rate of these decelerations was 1.6% of patients receiving antepartum fetal heart rate tests. These prolonged decelerations were not identified in the antepartum fetal heart rate tests of patients in this study, and variable deceleration of >30 seconds were rarely encountered.

We conclude that if one examines antepartum fetal heart rate tests in a rigorous manner, brief variable deceleration will frequently be seen. These brief vari­able decelerations should not be confused with the much less common but potentially ominous prolonged variable deceleration (>60 seconds) which may be as­sociated with severe oligohydramnios and fetal com­promise. Variable decelerations that are of <30 seconds duration are not a sign of a compromised fetus nor are they an indication for immediate delivery.

REFERENCES

I. Rochard F, Schifrin BS, Goupil F, Legrand H, Blottiere j, Sureayu C. Nonstressed fetal heart rate monitoring in the antepartum period. A~l J OBSTET GY:\ECOL 1976; 126:699.

2. Fox HE, Steinbrecher M, Ripton B. Antepartum fetal heart rate and uterine activity studies. A~I J OBSTET Gy­:\ECOL 1976; 126:61.

3. Visser GHA, Huisjes HJ. Diagnostic value of the un­stressed antepartum cardiotocogram. BrJ Obstet Gynecol 1977;84:321.

Bound volumes available to subscribers

March, 1986 Am J Obstet Gynecol

4. Nochimson Dj, TurbevilleJS, TerryJE, Petrie RH, Lundy LE. The nonstress test. Obstet Gynecol 1978;51 :419.

5. Evertson LR, Gauthier Rj, Schifrin BS, Paul RH. Ante­partum fetal heart rate testing. I. Evolution of the non­stress test. A:I1 j OBSTET GY1'ECOL 1979; 133:29.

6. Keegan KAjr, Paul RH. Antepartum fetal heart rate test­ing. IV. The nonstress test as a primary approach. AM j OBSTET GY:\ECOL 1980;136:75.

7. Baskett TF, Sandy EA. The oxytocin challenge test: an ominous pattern associated with severe fetal growth re­tardation. Obstet Gvnecol 1979;54:365.

8. Bruce SL, Petrie RH, Davison J. Prediction of abnormal umbilical cord position and intrapartum cord problems from the nonstress test. Diagn Gynecol Obstet 1980;2:47.

9. O'Leary JA, Andrinopoulos GC, Giordano Pc. Variable decelerations and the nonstress test: an indication of cord compromise. A~1 j OBSTET GY:\ECOL 1980; 137:704.

10. PhelanjP, Lewis PEjr. Fetal heart rate decelerations dur­ing a nonstress test. Obstet Gynecol 1981 ;57:228.

11. Druzin ML, Gratacos j, Keegan KA, Paul RH. Antepar­tum fetal heart rate testing. VII. The significance of fetal bradycardia. A~I j OBSTET GY:\ECOL 1981; 139: 194.

12. Freeman RK, Garite TJ, Modanlou H, Dorchester W, Rommal C, Devaney M. Postdate pregnancy: utilization of contraction stress testing for primary fetal surveillance. A:I1 J OBSTET GY:\ECOL 1981; 140: 128.

13. Pazos R, Vuolo K, Aladjem S, Lueck J, Anderson C. As­sociation of spontaneous fetal heart rate decelerations during antepartum nonstress testing and intrauterine growth retardation. A~IJ OBSTET GY:\ECOL 1982; 144:574.

14. Eden R, Gergely RZ, Schifrin BS, Wade ME. Comparison of antepartum testing schemes for the management of the postdate pregnancy. AM J OBSTET GY:\ECOL 1982; 144:683.

15. Bourgeois FJ, Thiagarajah S, Harbert GM. The signifi­cance of fetal heart rate decelerations during nonstress testing. A~1 J OBSTET (;Y:\EC01. 1984; 150:213.

16. Hon EH, Quilligan EJ. The classification of fetal heart rate. II. A revised working classification. Conn Med 1967;31 :779.

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