A simplified fetal biophysical profile

GYNECOLOGY &OBSTETRICS International Journal of Gynecology& Obstetrics61(1998)9-14 Article A simplified fetal biophysical profile 0. PetroviC”, E. Skunca, N. MatejEiC Department of Obstehicsand Gynecology Uniwrsity of Rijeka, Rijeka, Croatia Received7 July 1997;receivedin revisedform 12December1997;accepted17December1997 Abstract Objectiw: To modify the classic fetal biophysical profile @‘BP) with the aim of obtaining rapid and accurate information about actual fetal condition in non-compromised fetuses with a subsequent favorable outcome and to be suitable for a number of outclinic patients. Methoak Four-hundred and ninety-four fetuses from singleton pregnancies in two randomized groups were monitored by the modified FBP (mFBP) and 168 of them after the external vibratory acoustic stimulation WAS/mFBP). The mFBP was characterized by two main characteristics: non-stress test was excluded and the testing was finished at the moment when all of the three fetal biophysical activities became normal. The external VAS was applied only in caseswith no evidence of fetal activity at the start of the FBP. Results: Of the examined fetuses, 326 fetuses in the control group were monitored by the mFBP and there were 316 (96.9%) favorable outcomes and 10 (3.1%) adverse perinatal outcomes. The sensitivity, specificity and positive and negative predictive values of the mFBP score in predicting adverse perinatal outcome were 60, 99, 66.7 and 98.7%, respectively. In the study group of 168 fetuses there were 165 (98.2%) favorable outcomes and three (1.8%) adverse perinatal outcomes. The sensitivity, specificity and positive and negative predictive values of the VAS/mFBP were 66.7, 100, 100 and 99.4%, respectively. The efficiency of the VAS/mFBP in predicting perinatal mortality alone was even higher. After the external VAS and the first 5 min of the modified testing approximately two-fifths (41.8%) of healthy fetuses with a subsequent good outcome exhibited normal in all of the three biophysical activities and approximately two-thirds (65.5%) of them after 10 min. In the VAS/mFBP group of healthy fetuses, during the same time periods, normal breathing movements were observed in 72% and 87% of fetuses, respectively. Conclusions: According to our results the mFBP and particularly the VAS/mFBP antenatal protocol as a new and rational variant of the FBP could improve fetal assessment allowing in cases of non-compromised fetuses rapid and accurate information about actual fetal well-being. Because of its high accuracy and a reduced testing time the antepartal method with observation of fetal breathing movements after VAS is becoming acceptable as a screening of fetal well-being evaluation in outclinic conditions. 0 1998 International Federation of Gynecology and Obstetrics Keywords: Modified fetal biophysical profile; Breathing movements; Vibratory acoustic stimulation; Fetal assessment; Perinatal outcome; Outclinic patients * Correspondingauthor. 0020-7292/98/$19.00 0 1998International Federationof Gynecologyand Obstetrics PZZSOO20-7292(98)00009-5 10 0. Petrod et al. /International Journal of Gynecology & Obstetrics 61 (1998) 9-14 1. Introduction Since the fetal biophysical profile (FBP) was introduced by Manning et al. [l] it has been proven to be a very accurate antepartal method for fetal well-being assessment [2,3]. In a classic form it includes a 30-min observation period of biophysical activities using real-time ultrasound and a cardiotocographic registration of fetal heart rate for at least 20-30 min. In that way, the classic FBP is reserved for a limited number of patients, particularly clinic patients and that is against our efforts to always assessfetal condition as best as possible. Recently, several modifications of the FBP have been reported [4-71. This prospective study tried to modify and rationalize the FBP to suit outclinic patients. Besides, we wanted to find a way how to recognize easily those fetuses which are well oxygenated and in good condition with the aim of separating them as soon as possible from compromised fetuses which need careful attention. 2. Material and methods To modify the FBP to be suitable for a number of outclinic patients, a significant reduction of the time of the biophysical testing should be crucial for any of profile’s modifications. The next important condition must be a preservation of a high accuracy of the modified fetal biophysical profile (mFBP) in fetal assessment and prediction of perinatal outcome. According to the mentioned criteria modification of the FBP is characterized by two main characteristics: non-stress test was excluded and secondly, the mFBP was considered finished when all of the three fetal activities (breathing movements, body movements and tone) were observed to be normal according to the standard criteria m. The time interval from the beginning of biophysical testing to the moment at which fetal breathing movements were found to be normal and the total time of the mFBP (maximally 30 min) were measured, respectively. The scoring system of Vintzileos et al. [2] was used. Because of five variables the maximal score of the mFBP could be 10 and a normal score was 6 or greater. All biophysical tests were performed within 6 days before delivery. Two randomized groups of fetuses from singleton pregnancies (28-42 weeks of gestation) were included in the study. The patients get into the study according to the schedule of their admissions to our department. Indications for hospitalization and fetal well-being assessmentwere intrauterine growth retardation (approx. 25%), post-term pregnancies, pre-eclampsia, gestational diabetes, infections, reduction of fetal movements, Rh isoimmunization, unsure gestational age, malignant diseasesof pregnant women, etc. Out of 494 fetuses, 336 of them with apparently no fetal activity at the start of the modified biophysical profile were divided up in the study and the control group at random by means of the principle - one fetus into the study group and another one into the control group. The rest of the 158 fetuses with evident fetal activity were selected into the control group. The pregnant women were sent to us in the fetal assessment unit by a nurse. No personal knowledge of the patients or their histories was available. All 326 fetuses in the control group were monitored by the mFBP. In the study group of 168 fetuses, fetal condition was assessedby the use of mFBP after the external vibratory acoustic stimulation WAS). VAS lasting 5 s was applied only in cases of an apparent fetal inactivity at the onset of biophysical testing. Details about VAS are presented in previous articles [8,9]. Perinatal outcome was determined by Apgar score in the fifth minute after delivery and by a need for an admission to the intensive neonatal care unit. Adverse perinatal outcomes included fetal and early neonatal deaths and cases with a 5-min Apgar score less than 7 (determined by a neonatologist or independent gynecologist), fetal/neonatal acidosis (pH value of fetal scalp capillary blood or umbilical artery less than 7.20) and an admission to the intensive neonatal care unit for more than 24 h. Fetal morbidity was considered as a part of adverse perinatal outcome only in caseswhen at least two of three parameters of adverse perinatal outcome were observed. 0. PetrodC et al. /International 11 Journal of Gynecology & Obstetrics 61 (1998) 9-14 3. Results The prospective study was conducted between May 1995 and October 1996. A total of 494 mFBPs were performed by two authors (O.P. and E.S.) and 168 of them (the study group) were after VAS (VAS/mFBP). Among the examined fetuses there were 481 (97.4%) favorable outcomes and 13 (2.6%) adverse perinatal outcomes, six of them were antepartum stillbirths. In the control group there were 316 (96.9%) favorable outcomes and 10 (3.1%) adverse perinatal outcomes. Four deaths (1.2%) occurred and all of them were associated with growth retardation and prematurity (gestational agesbetween 28 and 34 weeks). In three cases ending in stillbirth the mFBP scores were abnormal and ranged from 2 to 4 and one stillbirth occurred after a normal profile score. In six cases of morbidity all fetuses were delivered within 2-6 days of the mFBP and all deliveries were by cesarean section because of fetal distress and unfavorable obstetric findings. Infants were depressed at delivery (5-min Apgar scores ranged from 3 to 6) and had an admission to the neonatal intensive care unit for more than 24 h. In four cases intrapartal cardiotocography showed that 50-100% of contractions were associated with late/variable decelerations and fetal capillary pH blood values were less than 7.20. They were also premature, growth retarded and acidotic at birth (range from 6.95 to 6.97). One infant weighing 5400 g at 39 weeks was delivered within 2 days of the mFBP score of 10 by the mother who suffered from gestational diabetes and marked polyhydramnios. A complicated fetal tachycardia could be noted intrapartally. The last infant weighing 3750 g at term was delivered 6 days after the mFBP score of 10 demonstrating deep variable decelerations lasting 90 s because of a very short umbilical cord (only 30 cm). Only half of the six mentioned cases of perinatal morbidity the mFBP scores were abnormal (less than 6). In this group of fetuses there was a total of nine abnormal mFBP scores (2.7%) and three of them (scores ranged from 4 to 5) were followed by favorable perinatal outcome, Table 1 Efficiency of the modified fetal biophysical profile (mFBP) and its combination with vibratory acoustic stimulation (VAS/mFBP) in predicting adverse perinatal outcome Sensitivity % (n/n) Specificity % (n/n) Positive predicitive value % (n/n) Negative predictive value % (n/n) mFBP VAS/mFBP 60 (6/10) 99 (313/316) 66.7 (6/9) 66.7 (2/3) 100 (165/165) 100 (2/2) 98.7 (313/317) 99.4 (165/166) n, number of cases. In the study group of 168 fetuses a fetal condition was assessedby the mFBP after VAS. There were 166 normal scores and only two abnormal scores of 4. A total of 165 (98.2%) fetuses had a favorable outcome. Two stillbirths occurred (both scores were abnormal) and one infant weighing 900 g at 33 weeks of gestation was severely depressed at delivery (a 5-min Apgar score of 4) and had an admission to the intensive care unit for more than 24 h. The efficiencies of the mFBP alone and its combination with VAS in predicting adverse perinatal outcome and perinatal mortality are presented in Table 1 and Table 2, respectively. Table 3 presents a distribution of fetuses with a good perinatal outcome in relation to the observation time (in 5-min intervals) of the mFBP and the VAS/mFBP. The time interval from the beginning of the modified biophysical testing to the moment at which fetal breathing movements became normal was measured. The results for the study and the control group of fetuses are detailed in Table 4, respectively. 4. Discussion The surveillance of fetal well-being is one of the most important tasks of all perinatologists. There is a lot of valuable antenatal methods for fetal assessment, but real-time ultrasonography takes a particular place in that obstetric field. Namely, fetal anatomy and biometry, estimation of fetal weight and amniotic fluid volume, placen- 12 0. Petrod et al. /International Journal of Gynecology & Obstetrics 61 (1998) 9-14 Table 2 Efficiency of the modified fetal biophysical profile (mFBP) and its combination with vibratory acoustic stimulation (VAS/mFBP) in predicting perinatal mortality Sensitivity % (n/n) Specificity % (n/n) Positive predictive value % (n/n) Negative predictive value % (n/n) mFBP VAS/mFBP 75 (3/4) 98.1(316/322) 33 (3/9) 100 (2/2) 100 (166/166) 100 (2/2) 99.7 (316/317) 100 (166/166) n, number of cases. tal grading, detection of intrauterine growth retardation, umbilical and fetal arteries flow measurements, as well as fetal biophysical activities are irreplaceable components of a diagnostic process of predicting fetal condition and perinatal outcome [ 10-141. The fetal biophysical profile (FBP) as a simple, non-invasive, very accurate and applicable antenatal method to all patients is particularly attractive since it provides immediate individual results, does not provoke fetal distress, is independent of accurate gestational dating and can be repeated frequently. In a classic form the FBP includes a 30-min observation period of fetal biophysical activities and a cardiotocographic registration (NST) during 20-40 min. It is possible that in this form and in selective obstetric cases the FBP can still satisfy the time limits for clinical screening. However, Table 3 Distribution of fetuses with a good perinatal outcome in relation to the observation time of the modified fetal biophysical protile (mFBP) and its combination with vibratory acoustic stimulation (VAS/mFBP) Observation period (minutes) mFBP n (%I VAS/mFBP n (%I o-5 6-10 11-15 16-20 21-25 26-30 10.5(33.2) 177 (56.0) 225 (71.2) 253 (80.1) 273 (86.4) 304 (96.2) 69 (41.8) 108 (65.5) 121 (73.3) 133 (80.6) 139 (84.2) 143 (86.7) n, cumulative number of fetuses. %, Cumulative percentage. Table 4 Distribution of fetuses with normal breathing movements and favorable outcome in relation to the observation time of the biophysical testing Observation period (minutes) mFBP n (%I VAS/mFBP n (%o) o-5 6-10 11-15 16-20 21-25 26-30 187 (59.2) 24lc76.3) 271c85.8) 28lc88.9) 289 (91.5) 293 (92.7) 119 (72.1) SS 144 (87.3) SS 148 (89.7) NS 153 (92.7) NS 155 (93.9) NS Notes: n, cumulative number of fetuses; %, cumulative percentage; SS, statistical significance (P < 0.01); NS, not significant. the mentioned conditions do not allow the performance of biophysical testing on a large number of patients, especially outclinic patients. It is unacceptable because of an additional reason: stillbirths before term represent a majority of perinatal deaths and, moreover, their causes remain unexplained very frequently [El. It seems that fetal monitoring in outclinic patients in the third trimester of pregnancy is insufficient. The aim of this prospective study was to investigate how to modify and rationalize the FBP and make it suitable for a large number of outclinic patients without reduction of its efficiency. In addition, we tried to find possibilities to obtain as quickly as possible information of a good fetal condition (and of a favorable perinatal outcome) in cases of really well oxygenated and non-compromised fetuses. In that way we could be more rational in saving time and focusing exclusively on those fetuses which really need special care, knowledge, time and equipment. In mFBP a non-stress test is excluded from the biophysical testing because it takes too much time in almost every case and has a lot of false positive results [9]. Secondly, the observation of fetal biophysical activities (after estimating the amniotic fluid volume and placental grading) was stopped at the moment when all of the three acute markers of fetal condition (breathing and body movements and tone) became normal according to the standard criteria. The presence of normal biophysical activities 0. Petrod et al. /International Journal of Gynecology& Obstetrics61 (1998)9-14 represents indirect evidence that the fetal central nervous system (CNS) is intact anatomically and functioning and therefore not hypoxemic. However, cyclic variations in the incidence of fetal breathing and body movements have been commonly observed in normal and risk pregnancies, so that it is possible even in non-compromised fetuses to have short or prolonged periods of absence of the mentioned biophysical activities [2]. Unfortunately, the absence of a given fetal activity is sometimes difficult to interpret clinically, because it may reflect either normal periodic conditions (the sleep - 1F or the rest state - 3F) or pathologic CNS depression [2,16]. With the purpose of awakening well oxygenated fetuses from either the 1F or 3F state, as suggested in a previous study [91, the mFBP was started by applying the external VAS. In that way, a probable long lasting period waiting for a spontaneous awakening of normal fetuses was avoided and consequently the time for biophysical testing could be reduced. The mFBP demonstrated a high accuracy in predicting adverse perinatal outcome with the sensitivity, specificity and positive and negative predictive values of 60, 99, 66.7 and 98.7%, respectively. The mFBP and VAS in combination had a similar efficiency with the higher positive predictive value than the mFBP alone. It could be difficult to say if the mentioned difference is of significant importance because of the relatively small number of fetuses in the study group. However, in predicting perinatal mortality the VAS/mFBP was more efficient than the mFBP alone, as it deals particularly with the sensitivity and the positive predictive value. In other words, it seems that VAS could reduce a rate of the false positive findings of the FBP if it is applied at the start of the testing. One of the purposes of this study was to investigate time periods in which non-compromised fetuses commonly manifest their normal biophysical activities. Recently, the fetal startle response is recommended as a rapid antepartum test to evaluate fetal condition [17]. By measuring the time of the mFBP in 5-min intervals it was found that one-third of healthy fetuses manifested normal biophysical activities in the first 5 min and 13 approximately half of fetuses until the end of the 10th minute of the modified biophysical testing. After the external VAS approximately two-fifths (41.8%) of fetuses with good outcome were normal in all of the three biophysical activities after 5 min and approximately two-thirds of fetuses after 10 min of testing. After the 10th minute of testing the distributions of fetuses were almost identical in both investigated groups. Only 4% of fetuses in the control group and approximately 13% of fetuses in the study group did not demonstrate all biophysical activities until the end of the modified testing. Actually, the classic FBP was performed in that small portion of cases. The presence of normal fetal breathing movements as the most sensitive component of the FBP clearly shows that the fetus is well and in good condition. Therefore breathing movements were observed with particular attention in each case. Results showed that 72% of fetuses with a favorable outcome could exhibit normal breathing movements in the first 5 min of the modified testing after VAS and only 59% of fetuses in the control group. After 10 min of the testing 87% of fetuses in the study group vs. 76% of fetuses in the control group manifested normal breathing movements. Later during testing, the mentioned difference between the examined groups of fetuses disappeared. Breathing movements were absent or reduced only in 6-7% of fetuses of both groups, probably, because of their normal periodic appearance in fetal life. According to the results it is possible in half of the cases of healthy and well oxygenated fetuses to finish the modified testing after 10 min, and if the VAS was applied at the start of the mFBP it could be in approximately two-thirds of fetuses showing that the mFBP and, particularly, the VAS/mFBP combination in relation to the classic FBP could be more rational and useful in casesof non-compromised fetuses, allowing, rapid and accurate information about their actual wellbeing. The mentioned findings suggest that the VAS/mFBP combination represents an improvement in antenatal fetal assessmentmethods facilitating the obstetric care in prenatal testing units. By using only the fetal breathing movements as the most sensitive component of the FBP in pre- 14 0. Petrod et al. /International Journal of Gynecology & Obstem’cs 61 (1998) 9-14 dieting fetal condition and perinatal outcome, testing time can be reduced. Namely, after the external VAS approximately 90% of fetuses with a subsequent favorable outcome demonstrated normal breathing movements during the first 10 min of the sonographic observation period. Because of a high accuracy and a significantly reduced time of testing this method is recommended to be suitable for screening of fetal wellbeing assessment in outclinic patients, too. Further studies are welcome. References 111 Manning FA, Platt LD, Sipos L. Antepartum fetal evalu- ation: Development of a fetal biophysical profile. Am J Obstet Gynecol 1980;136:787. Dl Vintzileos AM, Campbell WA. The biophysical profile - predictor of fetal condition at birth. Obstet Gynecol Rep 1989;1:140. [31 Petrovic 0, FrkoviC A, Rukavina B. Efficacy of the fetal biophysical profile and its individual components in predicting poor perinatal outcome. Acta Fat Med Fluminensis 1993;18:99. [41 Nageotte MP, Towers CV, Asrat T, Freeman RK, Dorchester W. 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