Doppler and B-mode ultrasonography in biophysical profile scoring

Illcntkulkrrld

GYNECOLOGY & OBSTETRICS International

Journal of Gynecology & Obstetrics 54 (1996) 231-236

Article

Doppler and B-mode ultrasonography in biophysical profile scoring T. $ener*, S. ozalp, H. Hassa, A. Ylldlrlm Department Of Obstetrics and Gynecology, Osmangari University, Eskuehrr, Turkey Received I February

1996; revised 10 April 1996; accepted 12 April 1996

Objective: Biophysical profile scoring (BPS) is a valuable antepartum test for establishing fetal well-being, although the time constraint in some clinics limits its extensive use. In this study we attempted to shorten the total test time without excluding any of the test components. Method: The trouTstresstest (NST) part of the BPS was performed using simultaneous pulsed wave Doppler and B-mode ultrasonography (duplex NST). It was possible to observeall the components of the BPS during the sameperiod (duplex BPS). Results: Fifty-four tests were performed on 40 pregnant patients. The mean test time was 14.3min. A discrepancy was shown between the ultrasonographic observation and the women’s perception of the fetal movementsin 46% of the tests. Conclusion: Duplex NST is considered a more reliable test than the classical cardiotocographic NST. Duplex BPS is proposed as an easy-to-perform, compact and timesaving modification to the classical BPS. Keywords: Biophysical profile scoring; Non-stress test; Doppler ultrasonography; B-mode ultrasonography

1. Introddon Biophysical profile scoring (BPS) is a reliable antepartum test for the determination of fetal wellbeing [l]. It is composed of five biophysical characteristics. The assessment of each component helps to diagnose the distressed fetus. While low scores are associated with very high perinatal morbidity and mortality, normal scores virtually l Corresponding author, Porsuk Bulvari, Bulvar Apt No 44-5, 26130 E-skqehn, Turkey, Fax.: +90 222 2398412.

0020-7292/96/$15.00 0 1996 International PII SOO20-7292(96)02696-3

assure an uncomplicated intrauterine survival for a period of 3 days to 1 week, especially if placenta and cord accidents are excluded [2]. Fetal breathing and fetal body movements, fetal tonus and amniotic fluid volume are evaluated by ultrasonographic examination, and the non-stress test (MT) is evaluated by cardiotocography. However, performing BPS sometimestakes too much time, especially if a fetus with diminished biophysical activities is being examined. Ultrasonographic observation can take up to 30 min and the NST needs another 20 min. Furthermore,

Federation of Gynecology and Obstetrics

232

T. Sener et al. /International

Journal of Gynecology & Obstetrics 54 (19%) 231-236

when the NST is non-reactive, the test should be extended to 40 min, or repeated later [3]. Some modifications to the test protocol have beensuggestedin order to overcome the problems related to BPS. For example, Manning et al. [3] modified their original protocol by limiting the use of the NST. They performed the ultrasonographic examination first of all aud did the NST only when one of the four ultrasonographic criteria was abnormal. Eden et al. [4] performed the NST and measured the amniotic fluid volume as the first step, and if the NST was non-reactive, they evaluated the fetal breathing and body movements later. In other protocols, the NST is either excluded from the profile [S], or only acoustic stimulation and amniotic fluid volume are assessed[6]. However, these ‘short’ protocols have aroused objections becausethe diagnostic value of the whole profile is reported to be greater than that of any combination of the components [2,7]. In this study a modified NST was performed using pulsed wave Doppler ultrasonography (duplex NST) while the classical four components of the BPS were observed using B-mode scanning at the sametime. In other words, Doppler and Bmode ultrasonography were used simultaneously

in an effort to shorten the total BPS time without excluding any of the test components. We called this test ‘duplex BPS’. Our other goal was to compare the results with those from two different NST techniques. 2. MateriaIs ad metbods Forty high-risk pregnancies were examined in order to test the applicability of the pulsed wave Doppler NST and the simultaneous ultrasonographic assessmentof the fetal biophysical variables. All examinations were performed using a real-time ultrasonograph (Toshiba SSA-250 alfa) which has a duplex phased array convex probe (PVF-375MT). A video cassetterecorder was used for recording. The patients were positioned for the ultrasonographic examination in the supine position and the right hips of the pregnant patients were elevated 15”. The routine fetal biometric measurements were obtained at the beginning of each examination. After determining the fetal position, the fetal body was scannedcontinuously in the sag&al section. The depth of the field was adjusted ‘and the fetal heart, chest and abdomen were brought into

Fig. I. Combined B-mode and pulsed wave Doppler examination. Baseline fetal heart rate is 138 beats/mitt.

T. Setter et al. /International JOWMI of Gynecology di Obstetrics 54 (1996) 231-236

233

Fig. 2. Fetal heart rate measurementduring fetal movement. Fetal heart rate is 156 beat&in.

the samesection. Pulsed wave Doppler was activated and the Doppler sampling marker was positioned with its widest range over the fetal heart image (Fig. 1). The location of the marker on the fetal heart was carefully selectedto get the optimal waveform and fetal heart tone. When a clear Dop pler waveform was seen on the screen, the image was frozen. The fetal heart rate was determined using the calipers, then the image was released.If the fetus was in a non-moving state, this sequence was repeatedthree times during the first minute. If the fetus was moving, we waited for a silent period. The average of these three measurementswas accepted as the baseline fetal heart rate. When a new fetal movement was observed on the B-mode screen,the image was frozen and the heart rate was measured. Then the image was released and immediately refrozen and the heart rate was measuredagain. If the first and second measured heart rates were at least 15 beats/mm over the baseline, it was acceptedas an acceleration lasting at least 15 s (one measuring sequence takes approximately 15 s) and considered a positive acceleration (Fig. 2). The NST was acceptedas reactive

if accelerations had occurred during at least two separatefetal movements.The fetal heart rate was also monitored when a deceleration or acceleration in the heart rhythm which was not related to the fetal movements was detected. As another study parameter, the patients were asked to declare any fetal movements which they felt during the test period. Fetal movements detected by ultrasonography or perceived by the patient were noted for later comparison. Fetal breathing movements were observed and noted during the same observation period. This was easily accomplished becausethe fetal thorax, diaphragm and abdominal wall were all on the sameplane as the fetal heart during the whole test period. Fetal tone was also evaluated during or at the end of the ultrasonographic evaluation. The examination was completed by an assessmentof the amniotic fluid volume. The test was completed in less than 30 min if all of the expectedmovements(i.e. three separatefetal body movements, fetal respiration lasting at least 30 s, and one extension-flexion movement of the fetal body or hands) had occurred.

234

T. Sener et al. /International

JOWMI

of Gynecology & Obstetrics 54 (19%) 231-236

All examinations were recorded on video tape for documentation. The measurements were repeated later on the video tape, when necessary. Classical NST was performed in the routine way after the completion of each ultrasonographic examination and the results were compared with duplex NST. 3.Redts Fifty-four tests were performed in 40 high-risk pregnant patients. Intrauterine growth retardation (IUGR), preeclampsia, rhesus factor (Rh) incompatibility, polyhydramnios, absenceof fetal movements, post-term pregnancy and diabetes mellitus were the main indications for duplex BPS (Table 1). Thirty-five tests out of 54 (64.8%) were completed in 15min. The mean test time was 14.3min. The shortest test was 4 min (Table 2). Duplex NST was reactive in 46 examinations and non-reactive in 10 examinations. Reactivity could easily be assessedin all of the patients during the test period. Half @/lo) of the non-reactive tests were due to the absenceof fetal movements. In 46% (25/54) of the tests, the patients declared fetal movement at some time during the test period, even though no fetal movement was evident on the monitor. Conversely, women could

Table 1 Indications for BPS Diagnosis

IUGR Preeclampsia Rh incompatibility Polyhydmmnios Absence of fetal movements Diabetes mellitus Severematernal anemia Recurrent intrauterine fetal death post-term pregnancy PWWlll

p~tUl-2

of membranes

NptUlE

No. of patients (n=40)

No. of tests (n=54)

.6 5 4 4 4 4 3 4

9 I I 4 5 6 4 4

4 2

6 2

Table 2 The number of tests completed at S-mitt intervals Test time (tin)

No. of tests (n=54)

l-5 6-10 11-15 16-20 21-25 26-30

6 14 15 5 6 8

not feel fetal movementsin 5.6% (3/54) of the tests, although they were observed on the monitor. Fetal heart rate decelerations were detected in three preeclamptic patients who also had oligohydramnios. In those casesfetal heart rate suddenly deceleratedwith no obvious reason and returned to baseline within seconds. There was a discrepancy between duplex and classical NST (Table 3). In 70.4% (38/54) of cases both tests were reactive and in 11.1% (6154)both were non-reactive. However, 18.5%(10/54) of the test results were not concordant. 4. Dlscussloo Up to the present, some attempts have been made to modify the original BPS test protocol. In these studies, some components have been changed or excluded from the original protocol of Manning et al. 111. The main goal of these modifications has been to shorten the total test time without decreasingits diagnostic value. VintTable 3 Discrepancy between duplex NST and classical NST Test result

No. of cases (n=54)

Reactive duplex NSTkeactive classical NST Reactive duplex NST/non-reactive classical NST Non-Reactive duplex NSTkeactive classical NST Non-Reactive duplex NST/non-reactive classical NST

38 6 4 6

T. Sener et al. /International Journal of Gynecology & Obstetrics 54 (19%) 231-236

xileos et al. [7] declared that the NST is not only a sensitive indicator of fetal condition, but that it can also select fetuses(i.e. those with variable decelerations) who are candidates for a cord accident [7]. These authors stated that the NST should be an integral part of fetal biophysical monitoring. Furthermore, the diagnostic accuracy of the complete profile score has been declared to be greater than that of the score of any combination of the components [2]. Devoe [8] also stated that the NST should be better integrated into the various management schemes that incorporate other assessmenttechniques. In this study we have tried to demonstrate that it may be possible to shorten the BPS test time without abandoning any of the test components. A modified NST was integrated into the ultrasonographic part of the BPS. This modification spared the extra time that would be required for the cardiotocographic NST. With duplex BPS, the score is determined at the end of the ultrasonographic examination. The physician can proceed to deliver or alternatively observe the patient depending on the test result. In this study the whole test was completed within 4-30 min (mean 14.3 min). If we had not performed the tests simultaneously, we would probably have spent much more time completing the BPS. There is another advantage to the duplex BPS. Duplex NST is a direct NST method with real-time observation of the fetus. This method assuresthe physician that fetal movement is occurring. One can seethe fetal movement, rather than depend on the perception of the patient. Although accordance between the patient’s perception and the ultrasonographic visualization of fetal movement is reported to be high [9], we could not obtain similar findings. We showed that in 46% (25/54) of the teststhe women declared there was fetal movement even though no fetal movement could be seen on the monitor. The absence of fetal heart rate acceleration during the false fetal movement in classical NST can tempt the obstetrician to intervene and deliver the fetus, instead of waiting and repeating the test when the fetus is in an active state. We think that this discrepancy is an important cause of the false-positive (false non-reactive)

235

NST results. Although we have not yet studied this issue,we believe that the high rate of false-positive NST results could be diminished by duplex BPS. Similarly, some discrepancies between the test components can be seenin classical BPS. A reactive NST with no fetal body movements on ultrasonographic examination is a good example. The fetus can be asleepafter an active NST period. The reversecan also occur: the fetus may get two points for fetal body movements, but no movement may be felt at the NST. In duplex BPS, simultaneous testing for the fetal heart rate and fetal body movements obviates such confusing situations. With duplex BPS, decelerations can also be identified, as with the classical NST. One can easily note the decreasingfetal heart rate by the audio signal and Doppler waves on the monitor, freeze the frame and obtain the heart rate and observe the duration of the deceleration. This brings an advantage to the test over the other modified BPS protocols which exclude the NST. Another important advantageof the duplex BPS is its compactness.It is performed and evaluated by the same person during the same time period. A more clearly defined prediction of the fetal prognosis can be obtained at the end of the test. The value of the duplex BPS in predicting fetal wellbeing and prognosis will be the subject of future study at our clinic. In conclusion, we suggestthat duplex BPS is a reliable, practical, compact and time-saving method of fetal monitoring. It has many of the inherent advantagesof classical BPS, and has been relined from the weakness of the other modified BPS methods. We also think that this integration is a very feasible solution for some clinics with a limited number of technicians and nurses. References [l] [2]

Manning FA, Platt LD, Sipos L. Antepartum fetal evaluation: development of a fetal biophysical score. Am J Obstet Gynecol 1980; 136: 787. Manning FA, Harman CR, Morrison I, Menticoglou SM, Lange IR, Johnson JM. Fetal assessmentbased on fetal biophysical scoring. IV. An analysis of perinatal morbidity and mortality. Am J Obstet Gynecol 1990, 162: 703.

236 [3]

T. Setter et al. /International Journal of Gynecology & Obstetrics 54 (19%) 231-236

Manning FA, Morrison I, Lange I, Harman CR, Chamberlain PFC. Fetal biophysical profile scoring: selective use of the non-stress test. Am J Obstet Ciynecol 1987; 156: 709. [4] Eden RDF, Seifert LS, Kodack LD, Trofatter KF, Kyllam AP, Gall SA. A modified biophysical profde for antenatal fetal surveillance. Obstet Gynecol 1988; 71: 365. 151 Shah DM, Brown JE, Salyer SL, Fleischer AC, Boehm FH. A modified schemefor biophysical profile scoring. Am J Obstet Ciynecol 1989; 160: 586.

[6]

[7l [8] [9]

Clark SL, Sabey P, Jolley K. Non-stress testing with acoustic stimulation and amniotic fluid assessment:5973 tests without unexpected fetal death. Am J Obstet Gynecol 1989, 160: 694. Vintxileos AM, Campbell WA, Nochimson DJ, Weinbaum PJ. The useand misuseof the fetal biophysical profile. Am J Obstet Gynecol 1987; 156: 527. Dcvoe LD. The nonstress test. Obstet Gynecol Clin North Am 1990; 17(l): 111. Rayburn WF. Monitoring fetal body movement. Clin Obstet Gynecol 1987; 3(4): 899.