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Prolonged pregnancy and the biophysical profile
PROLONGED PREGNANCYAND THE BIOPHYSICALPROFILE A Birthing Center Perspective
George J. Gilson, MD, Mary Ellen O’Brien, CNM, Robert W. Vera, MD, Mary E. Mays, CNM, David R. Smith, MD, and Cheryl Y. Ross, CNM
ABSTRACT A triage system for antepartum surveillance of postdates pregnancy is studied in a busy, indigent care service with limited resources for in-hospital delivery. One hundred seventy-eight pregnancies (13.2% of the total population) were thought to be at least 42 weeks’ gestation by clinical criteria, and 128 of these underwent at least one complete biophysical profile within seven days of delivery. We find no statistically significant difference in the incidence of meconium staining, fetal distress in labor, or low Apgar scores when either the high or low scoring groups are compared, or when compared with the 50 patients who delivered without a biophysical evaluation. Specific components of the testing schema, however, namely oligohydramnios and spontaneous decelerations on the nonstress test, are highly associated with adverse perinatal events. Of the total population thought to be postmature clinically, only 60 infants (33.9%) were actually beyond 42 weeks’ gestation by Dubowitz scoring. We conclude that a modified biophysical assessment as described is easily performed in a nontertiary care setting where a CNM-MD team approach is applied and may help to differentiate patients who require expeditious termination of pregnancy in-hospital from those who can be managed expectantly in the birthing center.
Management of postdate pregnancy is problematic for the practitioner because of the significantly greater incidence of adverse perinatal events associated with this condition.’ Routine induction of labor at 42 weeks’ gestation, however, has not been shown to improve outcomes significantly.* Antepartum fetal surveillance is therefore the mainstay of management, but is complicated by poor predictive value if fetal heart rate monitoring alone is used. Both the nonstress test (NST) and the more cumbersome contraction stress test
Address correspondence to: Mary Ellen O’Brien, Maternity Center, Brownsville Community Health Center, 2137 East 22nd Street, Brownsville, TX 78520. Journal of Nurse-Midwifery
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have high false positive rates that often prompt unnecessary intervention.3 Biochemical evaluation with estriol determinations is often logistically difficult to accomplish, even in a tertiary center, and results are often difficult to interpret. Studies4-7 have reported that real-time ultrasound evaluation of the fetus, by a CNM-MD team practice like our own, significantly increases the accuracy of identifying the at-risk fetus, especially in the presence of a nonreactive NST. Prompted by these reports, we decided to apply this methodology to the management of our own population which has a high incidence of postdate pregnancy. Our situation is complicated not only by the indigent nature of our population, but also by very
Vol. 33, No. 4,
July/August 1988
Copyright 0 1988 by the American College of Nurse-Midwives
limited resources for in-hospital delivery. To select postdate patients who would not be safe candidates for birthing center delivery, we attempted to use the biophysical score. We studied five fetal variables as previously described,’ and used the score of less than 8 to mandate hospital delivery. This study reports the impact of this method of fetal assessment on the prediction of adverse perinatal events and the incidence of truly prolonged pregnancy.
MATERIALS AND METHODS Patient
Population
The 178 patients with postdate pregnancies who comprised the study 171 0091.2182/88/$03.50
George J. Gilson, MD, FACOG, is a consulting obstetrician at the Brownsuille Community Health Center, Maternity Center. He graduated from Northwestern Uniuersify Medical School in 1970, and did residencies in both Family Practice and Obstetrics and Gynecology at the University of New Mexico. May Ellen O’Brien, CNM, MSN, isacting Director of the Maternity Center of the Brownsville Community Health Center. She received her MAN. at the University of Kentucky and had her family nurse pmctitioner and nursemidwifery training at the Frontier Nursing Service in Hyden, Kentucky. Robert W. Vera, MD, isAssociate Director of the Maternity center of the Brownsuille Community Health Center. he gmduated from the Uniuersity of Texas Southwestern Medical School in 1981 and had residency training in Obstetrics and Gynecology at Texas Tech Health Sciences Center in El Paso, Texas.
were selected from 1,344 otherwise low-risk indigent Mexican-American gravidas managed by certified nursemidwives. All were patients at the Maternity Center of the Brownsville Community Health Center (a free standing birth center) between January 1, 1984 and February 1, 1986. Two obstetricians employed by the Brownsville Community Health Center were available for consultation and comanagement of any patients who became postdates. All patients on the nurse-midwife caseload were expected to deliver in the birthing center, unless some ante- or intrapartum risk factor developed that mandated hospital delivery. All patients had completed 42 weeks’ gestation by dates determined with consistent clinical sizing (identified last menstrual period supported by appropriate fundal heights), stethoscope fetal heart tones (for more than 22 weeks), or confirmatory second trimester ultrasound evaluation.
Real-time ultrasound scanning was performed by means of an ADR Model 2130 equipped with a 3.5 MH, transducer. All the scanning was done by the two obstetricians. The components of the biophysical score were classified according to a modification of the system of Vintzileos7 (Table 1). If, after the first 15 minutes of scanning, the ultrasound examination showed a fetus presumed sleeping due to normal periodicity, a second patient was seen, and the first patient was later rescanned. In almost no case was more than 30 minutes required for any one patient. All patients had the cervix examined and a Bishop score assigned at each visit in order to determine if the cervix was favorable for stimulation or induction of labor. Some patients had more than one biophysical profile performed, but only the last test result, within seven days of delivery, was used for evaluation.
Patient Management May E. Mays, ~NM, was a midwifery intern at Brownsville Community Health Center, Maternity Center. She receiued her nursing diploma at L&-USC Medical Center School of Nursing and her family nurse practitioner and nursemidwife y training at Frontier Nursing
Seruice in Hyden, Kentucky. David R. Smith, MD, FAAP,was Medical Director of the Brownsville Community Health Center. He receiued his M.D. degree from the University of Cincinnati in 2980 and did his residency training in pediatn’cs, as well as fellowship work in neonatology at the University of Pennsylvania. Cheryl Y. Ross, CNM, was a staff midwife at the Brownsuille Community Health Center, Maternity Center. She receiued her A.A.S. in Nursing at Hudson Valley Community College in Troy, New York and receiued her nurse-midwifey training at the State Uniuersity of New York at Downstate Medical Center, Brooklyn, New York in 1979.
172
Monitoring Procedures When a patient was almost at 42 weeks’ gestation, she was scheduled for biweekly nonstress testing (NST) and weekly real-time ultrasound scanning. At 43 weeks’ gestation, biweekly sonography was scheduled. The criteria used for evaluation of the NST were those of Paul,8 i.e., two accelerations 15 beats above baseline sustained for 15 seconds during a 20 minute strip. Fetal heart rate decelerations during the NST were defined according to the criteria of Druzin,g i.e., greater than 40 beats below baseline sustained for 60 seconds or more seen at any time. Contraction stress testing (CST) was not used in this protocol. All fetal heart rate monitoring was done using a Hewlett-Packard Model 8030A cardiotocograph. lntrapartum monitor strips and antepartum nonstress tests were read by either the nurse-midwife or an obstetrician.
In general, the management protocol used was that of Manning,‘j as modified and explained below. If the patient had a score of 8-10 she was submitted to another NST in three to four days and another complete biophysical profile (BPP) in seven days. If the BPP was 5-7, testing was repeated within 24 hours, and if persistently abnormal, the patient was transferred to the obstetricians for induction in-hospital. Any patient with severe oligohydramnios (AF-0), or spontaneous decelerations on the nonstress test (NST-D), or any who might have had a score of less than 4, was admitted immediately for delively irregardless of the biophysical score (Figure 1). Patients with scores of 8-10 were allowed to begin spontaneous labor. A preadmission monitor strip was done on most of these women before admitting them to the birth center. (A few women had rapid labors and were admitted at 8-10
Journal of Nurse-Midwifery
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Vol. 33, No. 4, July/August 1988
TABLE 1
Criteria for Scoring Biophysical Variables* Test
Nonstress (NST)
Score of 2
Score of 1
Five or more fetal heart rate accelerations of at least 15 bpm and at least 15 seconds duration associated with fetal movements
Two to four fetal heart rate accelerations of at least 15 bpm and at least 15 seconds duration associated with fetal movements in a 20-minute period One to two fetal movements within 30 minutes
in a 20-minute
Fetal movements
(PM)
Fetal breathing
movements (PEW
Fetal tone (FT)
Amniotic fluid volume (AF)
Placental grading (PL)
period At least three gross episodes of fetal movements (trunk and limbs) within 30 minutes (simultaneous trunk and limb movements count as 1) At least one episode of fetal breathing lasting at least 60 seconds within 30 minutes At least one episode of extension of extremities with return to position of flexion, plus one episode of extension of spine with return to position of flexion Fluid evident throughout uterine cavity; largest pocket measures 2 cm or more vertically 0. I or II
Score of 0
One or fewer fetal heart rate accelerations in a 20-minute
period
Measures of Outcome Absence of fetal movements within 30 minutes
At least one episode of fetal breathing lasting 30 to 60 seconds within 30 minutes At least one episode of extension of extremities with return to position of flexion, or one episode of extension of spine with return to position of flexion Largest pocket measures <2 cm, but >1 cm vertically
Absence of fetal breathing or breathing lasting ~30 seconds
Placenta posterior difficult to measure
III
within 30 minutes Extremities in
extension, not followed by return to flexion; Open hand
Largest pocket < 1 cm vertically; fetal small parts crowded
Maximum score, 12; minimum score, 0. * Reprinted (in adapted form) with permission from Vintzileos, AM. The fetal biophysical profile and its predictive value. Obstet Gynecol 62:273, 1983.
cm for imminent delivery) If the preadmission monitor strip indicated a reactive NST the patient was admitted by the CNM to the birth center. A questionable monitor strip was discussed with the backup obstetrician
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there was no other indication of fetal distress, the patient was allowed to deliver at the birth center. Pediatricians were available to visualize the vocal cords of the baby at delivery. If there was any indication of fetal distress or failure to progress during labor, the patient was transferred to the hospital for labor and delivery by the obstetricians.
for admitting the patient to the hospital. For those patients admitted to the birth center, the FHTs were monitored every 15-30 minutes with a doppler. If meconium was discovered during active labor, but
Vol. 33, No. 4, July/August 1988
For purposes of this report, the outcome measures studied were: 1) presence of the postmaturity syndrome, defined according to the criteria of CliffordlO (Table 2). 2) the presence of meconium in’the liquor at the time of amniotomy or spontaneous rupture of membranes; 3) fetal distress in labor [defined as: (a) repetitive late decelerations, (b) severe variable decelerations, (c) tachycardia with decreased beat to beat variability, (d) prolonged decelerations]; 4) Apgar scores less than 7 at one and five minutes; 5) abdominal delivery for fetal distress. These events were considered to have been undesirable for a patient planning to have a birthing center delivery.
Statistical Analysis To test the null hypothesis that there were no differences in outcome between the patients with a biophysical score of 8 or greater or those scoring less than 8, we compared the measures of outcome by chi-square analysis. Values of p < .05 were considered significant. The small-sized subgroups with decelerations on nonstress testing (NST-D) and oligohydramnios on sonography W-0) were not analyzed separately but were included in their overall biophysical score group.
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>
8 - Biweekly NST/weekly sono (expectant)
--___I
< 8-1 Repeat BPP 24 hrs.
BPP
FIGURE 1
Management Protocol for 42 Weeks’ persistent < 8 _+ \
deliver
Gestation Based on the Biophysical file. Adapted from Manning.(j
Pro-
BPP<4 or
NST-D or
> deliver
AF-0 BPP = Biophysical Profile NST-D = Significant spontaneous decelerations on non-stress test AF-0 = Severe oligohydramnios on ultrasound
RESULTS
One hundred seventy-eight (178) patients of a group of 1344 low risk gravidas (13.2%) were determined on clinical grounds to be 42 weeks’ gestation or beyond. Of this group, 128 patients (71.9%) underwent at least one complete biophysical profile within one week of delivery. Fifty patients (28.1%) delivered in the birthing center before biophysical scoring could be scheduled. Of the patients who were subjected to biophysical profile, 102 (80.3%) scored S-10 and 26 (20.5%) scored 5-7; no patient scored 4 or less. Of the 178 postdate patients, 60 (33.9%) TABLE 2
Clifford Stages of Postmaturityl Placental Dysfunction SyndromelO Stage I
Characteristics
desquamation, long nails, abundant hair, white skin, alert facies, loose skin (presumably due to recent
II
III
174
weight loss). changes of Stage I plus meconium stained amniotic fluid, skin, vernix, umbilical cord, and placental membranes (possibly as a result of acute anoxia). changes of Stage I and II, plus bright yellow staining of nails and skin and yellow-green staining of the umbilical cord.
were actually delivered of an infant who was 42 weeks or beyond by CNM or pediatric assessment. This gave an actual incidence of 4.5% true pronlonged pregnancy for the entire population. (Table 3) Only 21 of the 102 infants (20.6%) who had scored 8 or more on biophysical profile were truly postmature by pediatric assessment, whereas 14 (53.8%) of the 26 infants who had scored 8 or less were indeed postmature. Conversely, of the 118 infants not judged to be postmature on exam, 74 (62.7%) scored 8 or more, 10 (8.5%) scored 8 or less, and 25 (21.2%) had no biophysical assessment. Nine infants (7.6%) had no estimate of gestational age assigned as far as could be determined from a review of the pediatric records. Of the 60 infants felt to be truly beyond 42 weeks gestation, 22 (33.6%) had stigmata of the postmaturity syndrome. The majority of these were Clifford Stage I with only one severely dysmature infant. Six of these (27.3%) had biophysical scores of 8 or more, seven (31.8%) had scores of 8 or less, and nine (40.9%) were unscored. Meconium stained amniotic fluid was noted in 67 cases for an incidence of 37.8%, as compared to a 16.4% incidence in the overall population not thought to be postdate. Of the infants who scored 8 or more, 34 Journal of Nurse-Midwifery
(32.3%) had meconium, of these scoring 8 or less, 13 (50%) had meconium, and of those with no biophysical performed, 21 (42%) were stained. Only one infant, a 42$‘z infant week gestation, with a biophysical score of 5, who required emergency cesarean section for fetal distress early in labor, developed the meconium aspiration syndrome severe enough to require ventilator therapy; he survived without sequelae. Fetal distress in labor was encountered in 19 cases (10.3%). Eleven cases scored 8 or more (10.8%), four scored 8 or less (15.4%), and four (8%) had no biophysical profile done. There were four cesarean sections done for a primary indication of fetal distress (one 3 8, two 6 8, one had no score); all were greater than 42 weeks’ gestation by exam. The overall rate of abdominal delivery in this group was 16.4% (29 cases), compared to a rate of 7.5% in the overall nurse-midwife caseload. There was only one Apgar score of 7 or less at five minutes, this being in a 42 weeks’ gestation with no biophysical profile, who was delivered by cesarean section for chorioamnionitis with failure to progress. Apgars of 7 or less at one minute were recorded in 20 instances (11.3%). Of these, 12 scored 8 or more, two scored 8 or less, and six were unscored. The ma* Vol. 33, No. 4, July/August
1988
In this study, we have attempted to apply a biophysical scoring system to the management of postdate preg-
nancy in a l&ion intended to deliver in a -of-hospital birthing center. The county of residence of this population, with a census of 250,000, 36% of whom live below federal poverty guidelines, has a 43% out-of-hospital birth rate, and igent hospital. Selecin need of in-hospital care for delivery must be assessed carefully in order to husband the scarce funds available for high-risk intrapartum care. ecause we are no longer able to work under a protocol whereby the large number of patients reaching 42 weeks’ gestation were automatically transferred from nurse-midwife to obstetrician care for hospital delivery, we have attempted to assess the utility of the bioiphysical profile in dealing with our own population. Automatic induction of labor at 42 weeks’ gestation in the presence of an unripe cervix is also undesirable because it usually results in a high cesarean section rate due to failure to progress. These are cesareans that would not have been necessary had the intervention not taken place. We felt that this approach might be one readily applicable to the out-patient based nursemidwife faced with the common problem of prolonged pregnancy with its attendant risks. We attempted to use the biophysical profile as a discriminant of which fetuses were indeed postmature, not just postdate, because of the well-
TABLE 4 Highest Rated Testing Abnormalities
and Outco
iophysical Profile Scores and Outcomes Bio >8*
Bio <8t
Outcome Parameters
n
%
n
>42 weeks by exam Meconium staining Fetal distress in labor Cesarean section for severe fetal distress Apgar <7 at 1 min Apgar <7 at 5 min Decelerations on NST (NST-D) Severe oligohydramnios (AF-0) Perhatal mortaliQ
21 34 11
20.6 32.2 10.8
14 13 4
53.8 50 15.4
25 21 4
50 42 8
NS NS NS
1 11.8 0 4.9 2 0
2 2 0 3 7 0
7.7 7.8 0 11.5 26.9 0
1 6 1 -
2 12 2 -
NS NS NS -
7
;
1
1: 0 ; 0
No Bio$ %n%p
* n = 102; +n = 26; $n = 50. NST: nonstress test; NS: not significant; -: not tested.
jority of these low one-minute Apgars were in infants in whom tracheal suctioning was performed for meconium. (Table 3) A separate analysis was also made of the small but important group of patients who had significant spontaneous decelerations on nonstress testing (NST-D), and those who had marked oligohydraminos on sonography (AF-0). (Table 4) Five of the eight patients with NST-D were 42 weeks’ gestation or more by pediatric evaluation (62.5%), four had meconium stained fluid (50%), and three had fetal distress in labor (37.5%). Only one (12.5%) had an Apgar score of 7 or less at one minute; this being the only patient in this group who required cesarean delivery (for cephalopelvic disproportion). Three of these patients had biophysical scores of 8 or less, and three had AF-0 (37.5%). Of the nine patients with sonographic evidence of severe oligohydramnios (AF-0), five infants were felt to be more than 42 weeks’ gestation on exam (55.5%), six had meconium staining (66.6%), and three experienced fetal distress in labor (33.3%). There were two Apgars 7 or less at one minute (22.2%) and there were three cesareans. Two of the cesareans (22.2%) were performed for fetal distress in labor, these being the only fetal distress cases in the series seJourna?i of ~~rs~-~i~wife~
vere enough to mandate expeditions abdominal delivery for this indication. Seven of these patients had biophysical scores of 8 or less (77.7%), and four had NST-D (44.4%). One of the four patients with both AF-0 and NST-D required an emergency cesarean for fetal distress; this infant was the only one in the series with severe meconium aspiration. The other three patients delivered vaginally; all had meconium, one was dysmature and growth-retarded; none had distress nor poor Apgars, however.
DISCUSSION
Significant decelerations on nonstress testing (NST-D)*
Severe oligohydramnios
CAF-01t
Outcome parameters
n
%
n
%
>42 weeks by exam Meconium staining Fetal distress in labor Apgar <7 at 1 min Cesarean for distress BPP ~8 AF-0 NST-D
5 4 3 1 0 z
62.5 50 37.5 12.5 0 37.5
5 6 3 2 2 7
55.5 66.6 33.3 22.2 22.2 77.7
-
4
4Y4
*
n = 8;
tn = 9.
e Vol. 33, No. 4, July/August 1988
175
known association of postmaturity and increased perinatal morbidity and mortality. We also hoped to be able to separate those fetuses who were likely to experience adverse intrapartum events, (meconium staining, fetal distress severe enough to require emergency cesarean delivery, and immediate neonatal depression) that are considered inappropriate for birth in an out-of-hospital setting. Suspecting that most of the postdate pregnancies were not truly prolonged, and wishing to avoid a large number of unnecessay, time-consuming, and stressful inductions, with their increased risk of abdominal delivery, we sought to use the biophysical scoring system. Despite being very meticulous in attempting to accurately establish true gestational age by clinical means early in pregnancy, we found that neither stethoscope heart tones nor sonographic dating was capable of predicting true gestational age within an error of plus or minus two weeks. This accounts for the much larger number of patients considered postdate compared to the actual number of postmature infants born. These latter infants comprised only onethird of the original group. As can be seen from the results, the biophysical profile did not allow us to anticipate all the adverse perinatal events we had hoped to avoid in the birthing center. As pointed out in a recent review of antepartum fetal surveillance,” for a problem such as petinatal mortality, a normal result does not necessarily reflect the precision of the test, but rather the low prevalence of the problem. A much larger sample size than that presently reported is necessary to accurately detect benefits of testing. Although the results presented did not reach statistical significance, the testing did, however, help us to identify the majority of the at-risk fetuses and deliver them in the appropriate setting. We feel it is significant that there
176
were no perinatal deaths in this highrisk subgroup, even though our overall perinatal mortality rate in the combined cm-obstetrician practice for this period was 12.8 per 1000 live births. We attribute this to the intensive biweekly surveillance of these patients. As other authors12 have pointed out, weekly nonstress testing may not be sufficiently sensitive, nor the interval between tests appropriate, to discern those postdate fetuses who are going to become jeopardized. We feel we accomplished this, moreover, without an inordinate expenditure of time per patient, something that makes this surveillance system appropriate for a busy service. Although the biophysical score fairly accurately predicted which fetuses were indeed greater than 42 weeks’ gestation (acknowledging that Dubowitz scoring is not strictly definitive for postmaturity), it was unable to predict as accurately which of these fetuses would actually suffer from significant adverse perinatal events. We found, however, that spontaneous decelerations on nonstress testing, and the occurrence of a marked reduction in amniotic fluid volume, were highly predictive of a uteroplacental unit that was functioning suboptimally or where cord compression was significant; although these were not common occurrences (of the total group tested, 6.3 and 7.1% respectively), they appeared to be highly correlated with untoward intrapartum events. Oligohydramnios (a marker of a chronically comprised fetoplacental unit) and fetal distress will always be highly correlated, depending upon the threshold for diagnosis of the latter, and the degree of “birth attendant distress” engendered by the more common occurrence of decelerations seen with diminution of fluid. Nevertheless, because of the number of adverse perinatal events we found associated with oligohydramnios, we have begun to place more emphasis on this finding, and
have begun to study the utility of a more objective four-quadrant assessment of amniotic fluid volume. Although we feel that these patients should be delivered expeditiously, they should be allowed a trial of carefully monitored labor. In our experience, two-thirds of this subgroup were able to deliver vaginally without problem despite their potentially precarious placental reserve. Nonstress testing alone, without sonographic study, would have failed to detect the significant number of fetuses with oligohydramnios who had no periodic heart rate changes, but who were nevertheless compromised. In the entire series there was only one severely dysmature infant. This infant was the only one of this high-risk group who could have been picked up by noticing failure of growth of the fundal height and lack of maternal weight gain. We feel the latter are late signs, and not appropriate for following the postdate pregnancy, because they lack the sensitivity necessary to detect the fetus at-risk. All patients over 42 weeks’ gestation by dates were instructed in keeping a fetal movement chart. There were no patients who reported fewer than 10 fetal movements in 12 hours after they had heightened their awareness of fetal movements by having been instructed. Again, while fetal “kick counts” may well be helpful in detecting the fetus at risk in intrauterine death, they were not helpful in predicting adverse perinatal events. In conclusion, we feel that the addition of the biophysical scoring system, although far from perfect, can contribute significantly to other modalities of surveillance of the postdate pregnancy. The suboptimal nature of our circumstances has necessitated our adapting the current scheme of management and we have found this triage scheme very useful for us. We feel that sonographic biophysical data on the postdate fetus is easy for the cNr+Obstettician team to accu-
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Vol. 33, No. 4. July/August 1988
mulate in the outpatient setting, where sonography is available, without an excessive investment of time. This information can then be used to decide who can be managed expectantly and delivered in the birthing center, and who should be delivered promptly in hospital. We recommend further study of a larger number of patients to see if it can be shown to be equally useful in nontertiary care settings besides our own.
REFERENCES 1. Fleishcer A, Schulman H, Farmakides G, et al: Antepartum nonstress test and the postmature pregnancy. Gynecol66:80, 1985.
Obstet
2. Gibb DMG, Cardoza LD, Studd JWW, Cooper DJ: Prolonged preg-
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nancy: is induction of labor indicated? A prospective study. Br J Obstet Gynecol 891292, 1982. 3. Evertson LR, Gauthier RJ, Schifrin BS, Paul RH. Antepartum fetal heart rate testing. I. Evolution of the nonstress test. Am J Obstet Gynecol133:29, 1979. 4. Manning FA, Platt LD, Sipos L: Antepartum fetal evaluation: development of a fetal biophysical profile. Am J Obstet Gynecol 136:787, 1980. 5. Manning FA, Baskett TF, Morrison I, Large I: Fetal biophysical profile scoring; a prospective study in 1,184 high-risk patients. Am J Obstet Gynecol 140:289, 1981. 6. Manning FA, Morrison I, Large IR, et al: Fetal assessment based upon fetal biophysical profile scoring; experience in 12,620 referred high-risk pregnancies. I. Perinatal mortality by frequency and etiology. Am J Obstet Gynecol 151:343. 1985. 7. Vintzileos AM, Campbell WA, In-
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gardia CH, Nochimson DJ: The fetal biophysical profile and its predictive value. Obstet Gynecol 62:271, 1983. 8. Paul RH: The evaluation of antepartum fetal well-being using the nonstress test. Clin Perinatal9:253, 1982. 9. Druzin ML, Gratacos J, Keegan KA, Paul RH: Antepartum fetal heart rate testing. VII. The significance of fetal bradycardia. Am J Obstet Gynecol 139: 194, 1981. 10. Clifford SH: Postmaturity placental dysfunction. J Pediatr 1954.
with 44:1,
11. Thacker SB, Berkelman RL: Assessing the diagnostic accuracy and efflcacy of selected antepattum fetal surveillance technqiues. Obstet Gynecol Surv 41:121, 1986. 12. Shime J, Gare DJ, Andrews J, et al: Prolonged pregnancy: Surveillance of the fetus and the neonate and the course of labor and delivery. Am J Obstet Gynecol 148547, 1984.
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George J. Gilson, MD, Mary Ellen O’Brien, CNM, Robert W. Vera, MD, Mary E. Mays, CNM, David R. Smith, MD, and Cheryl Y. Ross, CNM
ABSTRACT A triage system for antepartum surveillance of postdates pregnancy is studied in a busy, indigent care service with limited resources for in-hospital delivery. One hundred seventy-eight pregnancies (13.2% of the total population) were thought to be at least 42 weeks’ gestation by clinical criteria, and 128 of these underwent at least one complete biophysical profile within seven days of delivery. We find no statistically significant difference in the incidence of meconium staining, fetal distress in labor, or low Apgar scores when either the high or low scoring groups are compared, or when compared with the 50 patients who delivered without a biophysical evaluation. Specific components of the testing schema, however, namely oligohydramnios and spontaneous decelerations on the nonstress test, are highly associated with adverse perinatal events. Of the total population thought to be postmature clinically, only 60 infants (33.9%) were actually beyond 42 weeks’ gestation by Dubowitz scoring. We conclude that a modified biophysical assessment as described is easily performed in a nontertiary care setting where a CNM-MD team approach is applied and may help to differentiate patients who require expeditious termination of pregnancy in-hospital from those who can be managed expectantly in the birthing center.
Management of postdate pregnancy is problematic for the practitioner because of the significantly greater incidence of adverse perinatal events associated with this condition.’ Routine induction of labor at 42 weeks’ gestation, however, has not been shown to improve outcomes significantly.* Antepartum fetal surveillance is therefore the mainstay of management, but is complicated by poor predictive value if fetal heart rate monitoring alone is used. Both the nonstress test (NST) and the more cumbersome contraction stress test
Address correspondence to: Mary Ellen O’Brien, Maternity Center, Brownsville Community Health Center, 2137 East 22nd Street, Brownsville, TX 78520. Journal of Nurse-Midwifery
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have high false positive rates that often prompt unnecessary intervention.3 Biochemical evaluation with estriol determinations is often logistically difficult to accomplish, even in a tertiary center, and results are often difficult to interpret. Studies4-7 have reported that real-time ultrasound evaluation of the fetus, by a CNM-MD team practice like our own, significantly increases the accuracy of identifying the at-risk fetus, especially in the presence of a nonreactive NST. Prompted by these reports, we decided to apply this methodology to the management of our own population which has a high incidence of postdate pregnancy. Our situation is complicated not only by the indigent nature of our population, but also by very
Vol. 33, No. 4,
July/August 1988
Copyright 0 1988 by the American College of Nurse-Midwives
limited resources for in-hospital delivery. To select postdate patients who would not be safe candidates for birthing center delivery, we attempted to use the biophysical score. We studied five fetal variables as previously described,’ and used the score of less than 8 to mandate hospital delivery. This study reports the impact of this method of fetal assessment on the prediction of adverse perinatal events and the incidence of truly prolonged pregnancy.
MATERIALS AND METHODS Patient
Population
The 178 patients with postdate pregnancies who comprised the study 171 0091.2182/88/$03.50
George J. Gilson, MD, FACOG, is a consulting obstetrician at the Brownsuille Community Health Center, Maternity Center. He graduated from Northwestern Uniuersify Medical School in 1970, and did residencies in both Family Practice and Obstetrics and Gynecology at the University of New Mexico. May Ellen O’Brien, CNM, MSN, isacting Director of the Maternity Center of the Brownsville Community Health Center. She received her MAN. at the University of Kentucky and had her family nurse pmctitioner and nursemidwifery training at the Frontier Nursing Service in Hyden, Kentucky. Robert W. Vera, MD, isAssociate Director of the Maternity center of the Brownsuille Community Health Center. he gmduated from the Uniuersity of Texas Southwestern Medical School in 1981 and had residency training in Obstetrics and Gynecology at Texas Tech Health Sciences Center in El Paso, Texas.
were selected from 1,344 otherwise low-risk indigent Mexican-American gravidas managed by certified nursemidwives. All were patients at the Maternity Center of the Brownsville Community Health Center (a free standing birth center) between January 1, 1984 and February 1, 1986. Two obstetricians employed by the Brownsville Community Health Center were available for consultation and comanagement of any patients who became postdates. All patients on the nurse-midwife caseload were expected to deliver in the birthing center, unless some ante- or intrapartum risk factor developed that mandated hospital delivery. All patients had completed 42 weeks’ gestation by dates determined with consistent clinical sizing (identified last menstrual period supported by appropriate fundal heights), stethoscope fetal heart tones (for more than 22 weeks), or confirmatory second trimester ultrasound evaluation.
Real-time ultrasound scanning was performed by means of an ADR Model 2130 equipped with a 3.5 MH, transducer. All the scanning was done by the two obstetricians. The components of the biophysical score were classified according to a modification of the system of Vintzileos7 (Table 1). If, after the first 15 minutes of scanning, the ultrasound examination showed a fetus presumed sleeping due to normal periodicity, a second patient was seen, and the first patient was later rescanned. In almost no case was more than 30 minutes required for any one patient. All patients had the cervix examined and a Bishop score assigned at each visit in order to determine if the cervix was favorable for stimulation or induction of labor. Some patients had more than one biophysical profile performed, but only the last test result, within seven days of delivery, was used for evaluation.
Patient Management May E. Mays, ~NM, was a midwifery intern at Brownsville Community Health Center, Maternity Center. She receiued her nursing diploma at L&-USC Medical Center School of Nursing and her family nurse practitioner and nursemidwife y training at Frontier Nursing
Seruice in Hyden, Kentucky. David R. Smith, MD, FAAP,was Medical Director of the Brownsville Community Health Center. He receiued his M.D. degree from the University of Cincinnati in 2980 and did his residency training in pediatn’cs, as well as fellowship work in neonatology at the University of Pennsylvania. Cheryl Y. Ross, CNM, was a staff midwife at the Brownsuille Community Health Center, Maternity Center. She receiued her A.A.S. in Nursing at Hudson Valley Community College in Troy, New York and receiued her nurse-midwifey training at the State Uniuersity of New York at Downstate Medical Center, Brooklyn, New York in 1979.
172
Monitoring Procedures When a patient was almost at 42 weeks’ gestation, she was scheduled for biweekly nonstress testing (NST) and weekly real-time ultrasound scanning. At 43 weeks’ gestation, biweekly sonography was scheduled. The criteria used for evaluation of the NST were those of Paul,8 i.e., two accelerations 15 beats above baseline sustained for 15 seconds during a 20 minute strip. Fetal heart rate decelerations during the NST were defined according to the criteria of Druzin,g i.e., greater than 40 beats below baseline sustained for 60 seconds or more seen at any time. Contraction stress testing (CST) was not used in this protocol. All fetal heart rate monitoring was done using a Hewlett-Packard Model 8030A cardiotocograph. lntrapartum monitor strips and antepartum nonstress tests were read by either the nurse-midwife or an obstetrician.
In general, the management protocol used was that of Manning,‘j as modified and explained below. If the patient had a score of 8-10 she was submitted to another NST in three to four days and another complete biophysical profile (BPP) in seven days. If the BPP was 5-7, testing was repeated within 24 hours, and if persistently abnormal, the patient was transferred to the obstetricians for induction in-hospital. Any patient with severe oligohydramnios (AF-0), or spontaneous decelerations on the nonstress test (NST-D), or any who might have had a score of less than 4, was admitted immediately for delively irregardless of the biophysical score (Figure 1). Patients with scores of 8-10 were allowed to begin spontaneous labor. A preadmission monitor strip was done on most of these women before admitting them to the birth center. (A few women had rapid labors and were admitted at 8-10
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Vol. 33, No. 4, July/August 1988
TABLE 1
Criteria for Scoring Biophysical Variables* Test
Nonstress (NST)
Score of 2
Score of 1
Five or more fetal heart rate accelerations of at least 15 bpm and at least 15 seconds duration associated with fetal movements
Two to four fetal heart rate accelerations of at least 15 bpm and at least 15 seconds duration associated with fetal movements in a 20-minute period One to two fetal movements within 30 minutes
in a 20-minute
Fetal movements
(PM)
Fetal breathing
movements (PEW
Fetal tone (FT)
Amniotic fluid volume (AF)
Placental grading (PL)
period At least three gross episodes of fetal movements (trunk and limbs) within 30 minutes (simultaneous trunk and limb movements count as 1) At least one episode of fetal breathing lasting at least 60 seconds within 30 minutes At least one episode of extension of extremities with return to position of flexion, plus one episode of extension of spine with return to position of flexion Fluid evident throughout uterine cavity; largest pocket measures 2 cm or more vertically 0. I or II
Score of 0
One or fewer fetal heart rate accelerations in a 20-minute
period
Measures of Outcome Absence of fetal movements within 30 minutes
At least one episode of fetal breathing lasting 30 to 60 seconds within 30 minutes At least one episode of extension of extremities with return to position of flexion, or one episode of extension of spine with return to position of flexion Largest pocket measures <2 cm, but >1 cm vertically
Absence of fetal breathing or breathing lasting ~30 seconds
Placenta posterior difficult to measure
III
within 30 minutes Extremities in
extension, not followed by return to flexion; Open hand
Largest pocket < 1 cm vertically; fetal small parts crowded
Maximum score, 12; minimum score, 0. * Reprinted (in adapted form) with permission from Vintzileos, AM. The fetal biophysical profile and its predictive value. Obstet Gynecol 62:273, 1983.
cm for imminent delivery) If the preadmission monitor strip indicated a reactive NST the patient was admitted by the CNM to the birth center. A questionable monitor strip was discussed with the backup obstetrician
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there was no other indication of fetal distress, the patient was allowed to deliver at the birth center. Pediatricians were available to visualize the vocal cords of the baby at delivery. If there was any indication of fetal distress or failure to progress during labor, the patient was transferred to the hospital for labor and delivery by the obstetricians.
for admitting the patient to the hospital. For those patients admitted to the birth center, the FHTs were monitored every 15-30 minutes with a doppler. If meconium was discovered during active labor, but
Vol. 33, No. 4, July/August 1988
For purposes of this report, the outcome measures studied were: 1) presence of the postmaturity syndrome, defined according to the criteria of CliffordlO (Table 2). 2) the presence of meconium in’the liquor at the time of amniotomy or spontaneous rupture of membranes; 3) fetal distress in labor [defined as: (a) repetitive late decelerations, (b) severe variable decelerations, (c) tachycardia with decreased beat to beat variability, (d) prolonged decelerations]; 4) Apgar scores less than 7 at one and five minutes; 5) abdominal delivery for fetal distress. These events were considered to have been undesirable for a patient planning to have a birthing center delivery.
Statistical Analysis To test the null hypothesis that there were no differences in outcome between the patients with a biophysical score of 8 or greater or those scoring less than 8, we compared the measures of outcome by chi-square analysis. Values of p < .05 were considered significant. The small-sized subgroups with decelerations on nonstress testing (NST-D) and oligohydramnios on sonography W-0) were not analyzed separately but were included in their overall biophysical score group.
173
>
8 - Biweekly NST/weekly sono (expectant)
--___I
< 8-1 Repeat BPP 24 hrs.
BPP
FIGURE 1
Management Protocol for 42 Weeks’ persistent < 8 _+ \
deliver
Gestation Based on the Biophysical file. Adapted from Manning.(j
Pro-
BPP<4 or
NST-D or
> deliver
AF-0 BPP = Biophysical Profile NST-D = Significant spontaneous decelerations on non-stress test AF-0 = Severe oligohydramnios on ultrasound
RESULTS
One hundred seventy-eight (178) patients of a group of 1344 low risk gravidas (13.2%) were determined on clinical grounds to be 42 weeks’ gestation or beyond. Of this group, 128 patients (71.9%) underwent at least one complete biophysical profile within one week of delivery. Fifty patients (28.1%) delivered in the birthing center before biophysical scoring could be scheduled. Of the patients who were subjected to biophysical profile, 102 (80.3%) scored S-10 and 26 (20.5%) scored 5-7; no patient scored 4 or less. Of the 178 postdate patients, 60 (33.9%) TABLE 2
Clifford Stages of Postmaturityl Placental Dysfunction SyndromelO Stage I
Characteristics
desquamation, long nails, abundant hair, white skin, alert facies, loose skin (presumably due to recent
II
III
174
weight loss). changes of Stage I plus meconium stained amniotic fluid, skin, vernix, umbilical cord, and placental membranes (possibly as a result of acute anoxia). changes of Stage I and II, plus bright yellow staining of nails and skin and yellow-green staining of the umbilical cord.
were actually delivered of an infant who was 42 weeks or beyond by CNM or pediatric assessment. This gave an actual incidence of 4.5% true pronlonged pregnancy for the entire population. (Table 3) Only 21 of the 102 infants (20.6%) who had scored 8 or more on biophysical profile were truly postmature by pediatric assessment, whereas 14 (53.8%) of the 26 infants who had scored 8 or less were indeed postmature. Conversely, of the 118 infants not judged to be postmature on exam, 74 (62.7%) scored 8 or more, 10 (8.5%) scored 8 or less, and 25 (21.2%) had no biophysical assessment. Nine infants (7.6%) had no estimate of gestational age assigned as far as could be determined from a review of the pediatric records. Of the 60 infants felt to be truly beyond 42 weeks gestation, 22 (33.6%) had stigmata of the postmaturity syndrome. The majority of these were Clifford Stage I with only one severely dysmature infant. Six of these (27.3%) had biophysical scores of 8 or more, seven (31.8%) had scores of 8 or less, and nine (40.9%) were unscored. Meconium stained amniotic fluid was noted in 67 cases for an incidence of 37.8%, as compared to a 16.4% incidence in the overall population not thought to be postdate. Of the infants who scored 8 or more, 34 Journal of Nurse-Midwifery
(32.3%) had meconium, of these scoring 8 or less, 13 (50%) had meconium, and of those with no biophysical performed, 21 (42%) were stained. Only one infant, a 42$‘z infant week gestation, with a biophysical score of 5, who required emergency cesarean section for fetal distress early in labor, developed the meconium aspiration syndrome severe enough to require ventilator therapy; he survived without sequelae. Fetal distress in labor was encountered in 19 cases (10.3%). Eleven cases scored 8 or more (10.8%), four scored 8 or less (15.4%), and four (8%) had no biophysical profile done. There were four cesarean sections done for a primary indication of fetal distress (one 3 8, two 6 8, one had no score); all were greater than 42 weeks’ gestation by exam. The overall rate of abdominal delivery in this group was 16.4% (29 cases), compared to a rate of 7.5% in the overall nurse-midwife caseload. There was only one Apgar score of 7 or less at five minutes, this being in a 42 weeks’ gestation with no biophysical profile, who was delivered by cesarean section for chorioamnionitis with failure to progress. Apgars of 7 or less at one minute were recorded in 20 instances (11.3%). Of these, 12 scored 8 or more, two scored 8 or less, and six were unscored. The ma* Vol. 33, No. 4, July/August
1988
In this study, we have attempted to apply a biophysical scoring system to the management of postdate preg-
nancy in a l&ion intended to deliver in a -of-hospital birthing center. The county of residence of this population, with a census of 250,000, 36% of whom live below federal poverty guidelines, has a 43% out-of-hospital birth rate, and igent hospital. Selecin need of in-hospital care for delivery must be assessed carefully in order to husband the scarce funds available for high-risk intrapartum care. ecause we are no longer able to work under a protocol whereby the large number of patients reaching 42 weeks’ gestation were automatically transferred from nurse-midwife to obstetrician care for hospital delivery, we have attempted to assess the utility of the bioiphysical profile in dealing with our own population. Automatic induction of labor at 42 weeks’ gestation in the presence of an unripe cervix is also undesirable because it usually results in a high cesarean section rate due to failure to progress. These are cesareans that would not have been necessary had the intervention not taken place. We felt that this approach might be one readily applicable to the out-patient based nursemidwife faced with the common problem of prolonged pregnancy with its attendant risks. We attempted to use the biophysical profile as a discriminant of which fetuses were indeed postmature, not just postdate, because of the well-
TABLE 4 Highest Rated Testing Abnormalities
and Outco
iophysical Profile Scores and Outcomes Bio >8*
Bio <8t
Outcome Parameters
n
%
n
>42 weeks by exam Meconium staining Fetal distress in labor Cesarean section for severe fetal distress Apgar <7 at 1 min Apgar <7 at 5 min Decelerations on NST (NST-D) Severe oligohydramnios (AF-0) Perhatal mortaliQ
21 34 11
20.6 32.2 10.8
14 13 4
53.8 50 15.4
25 21 4
50 42 8
NS NS NS
1 11.8 0 4.9 2 0
2 2 0 3 7 0
7.7 7.8 0 11.5 26.9 0
1 6 1 -
2 12 2 -
NS NS NS -
7
;
1
1: 0 ; 0
No Bio$ %n%p
* n = 102; +n = 26; $n = 50. NST: nonstress test; NS: not significant; -: not tested.
jority of these low one-minute Apgars were in infants in whom tracheal suctioning was performed for meconium. (Table 3) A separate analysis was also made of the small but important group of patients who had significant spontaneous decelerations on nonstress testing (NST-D), and those who had marked oligohydraminos on sonography (AF-0). (Table 4) Five of the eight patients with NST-D were 42 weeks’ gestation or more by pediatric evaluation (62.5%), four had meconium stained fluid (50%), and three had fetal distress in labor (37.5%). Only one (12.5%) had an Apgar score of 7 or less at one minute; this being the only patient in this group who required cesarean delivery (for cephalopelvic disproportion). Three of these patients had biophysical scores of 8 or less, and three had AF-0 (37.5%). Of the nine patients with sonographic evidence of severe oligohydramnios (AF-0), five infants were felt to be more than 42 weeks’ gestation on exam (55.5%), six had meconium staining (66.6%), and three experienced fetal distress in labor (33.3%). There were two Apgars 7 or less at one minute (22.2%) and there were three cesareans. Two of the cesareans (22.2%) were performed for fetal distress in labor, these being the only fetal distress cases in the series seJourna?i of ~~rs~-~i~wife~
vere enough to mandate expeditions abdominal delivery for this indication. Seven of these patients had biophysical scores of 8 or less (77.7%), and four had NST-D (44.4%). One of the four patients with both AF-0 and NST-D required an emergency cesarean for fetal distress; this infant was the only one in the series with severe meconium aspiration. The other three patients delivered vaginally; all had meconium, one was dysmature and growth-retarded; none had distress nor poor Apgars, however.
DISCUSSION
Significant decelerations on nonstress testing (NST-D)*
Severe oligohydramnios
CAF-01t
Outcome parameters
n
%
n
%
>42 weeks by exam Meconium staining Fetal distress in labor Apgar <7 at 1 min Cesarean for distress BPP ~8 AF-0 NST-D
5 4 3 1 0 z
62.5 50 37.5 12.5 0 37.5
5 6 3 2 2 7
55.5 66.6 33.3 22.2 22.2 77.7
-
4
4Y4
*
n = 8;
tn = 9.
e Vol. 33, No. 4, July/August 1988
175
known association of postmaturity and increased perinatal morbidity and mortality. We also hoped to be able to separate those fetuses who were likely to experience adverse intrapartum events, (meconium staining, fetal distress severe enough to require emergency cesarean delivery, and immediate neonatal depression) that are considered inappropriate for birth in an out-of-hospital setting. Suspecting that most of the postdate pregnancies were not truly prolonged, and wishing to avoid a large number of unnecessay, time-consuming, and stressful inductions, with their increased risk of abdominal delivery, we sought to use the biophysical scoring system. Despite being very meticulous in attempting to accurately establish true gestational age by clinical means early in pregnancy, we found that neither stethoscope heart tones nor sonographic dating was capable of predicting true gestational age within an error of plus or minus two weeks. This accounts for the much larger number of patients considered postdate compared to the actual number of postmature infants born. These latter infants comprised only onethird of the original group. As can be seen from the results, the biophysical profile did not allow us to anticipate all the adverse perinatal events we had hoped to avoid in the birthing center. As pointed out in a recent review of antepartum fetal surveillance,” for a problem such as petinatal mortality, a normal result does not necessarily reflect the precision of the test, but rather the low prevalence of the problem. A much larger sample size than that presently reported is necessary to accurately detect benefits of testing. Although the results presented did not reach statistical significance, the testing did, however, help us to identify the majority of the at-risk fetuses and deliver them in the appropriate setting. We feel it is significant that there
176
were no perinatal deaths in this highrisk subgroup, even though our overall perinatal mortality rate in the combined cm-obstetrician practice for this period was 12.8 per 1000 live births. We attribute this to the intensive biweekly surveillance of these patients. As other authors12 have pointed out, weekly nonstress testing may not be sufficiently sensitive, nor the interval between tests appropriate, to discern those postdate fetuses who are going to become jeopardized. We feel we accomplished this, moreover, without an inordinate expenditure of time per patient, something that makes this surveillance system appropriate for a busy service. Although the biophysical score fairly accurately predicted which fetuses were indeed greater than 42 weeks’ gestation (acknowledging that Dubowitz scoring is not strictly definitive for postmaturity), it was unable to predict as accurately which of these fetuses would actually suffer from significant adverse perinatal events. We found, however, that spontaneous decelerations on nonstress testing, and the occurrence of a marked reduction in amniotic fluid volume, were highly predictive of a uteroplacental unit that was functioning suboptimally or where cord compression was significant; although these were not common occurrences (of the total group tested, 6.3 and 7.1% respectively), they appeared to be highly correlated with untoward intrapartum events. Oligohydramnios (a marker of a chronically comprised fetoplacental unit) and fetal distress will always be highly correlated, depending upon the threshold for diagnosis of the latter, and the degree of “birth attendant distress” engendered by the more common occurrence of decelerations seen with diminution of fluid. Nevertheless, because of the number of adverse perinatal events we found associated with oligohydramnios, we have begun to place more emphasis on this finding, and
have begun to study the utility of a more objective four-quadrant assessment of amniotic fluid volume. Although we feel that these patients should be delivered expeditiously, they should be allowed a trial of carefully monitored labor. In our experience, two-thirds of this subgroup were able to deliver vaginally without problem despite their potentially precarious placental reserve. Nonstress testing alone, without sonographic study, would have failed to detect the significant number of fetuses with oligohydramnios who had no periodic heart rate changes, but who were nevertheless compromised. In the entire series there was only one severely dysmature infant. This infant was the only one of this high-risk group who could have been picked up by noticing failure of growth of the fundal height and lack of maternal weight gain. We feel the latter are late signs, and not appropriate for following the postdate pregnancy, because they lack the sensitivity necessary to detect the fetus at-risk. All patients over 42 weeks’ gestation by dates were instructed in keeping a fetal movement chart. There were no patients who reported fewer than 10 fetal movements in 12 hours after they had heightened their awareness of fetal movements by having been instructed. Again, while fetal “kick counts” may well be helpful in detecting the fetus at risk in intrauterine death, they were not helpful in predicting adverse perinatal events. In conclusion, we feel that the addition of the biophysical scoring system, although far from perfect, can contribute significantly to other modalities of surveillance of the postdate pregnancy. The suboptimal nature of our circumstances has necessitated our adapting the current scheme of management and we have found this triage scheme very useful for us. We feel that sonographic biophysical data on the postdate fetus is easy for the cNr+Obstettician team to accu-
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Vol. 33, No. 4. July/August 1988
mulate in the outpatient setting, where sonography is available, without an excessive investment of time. This information can then be used to decide who can be managed expectantly and delivered in the birthing center, and who should be delivered promptly in hospital. We recommend further study of a larger number of patients to see if it can be shown to be equally useful in nontertiary care settings besides our own.
REFERENCES 1. Fleishcer A, Schulman H, Farmakides G, et al: Antepartum nonstress test and the postmature pregnancy. Gynecol66:80, 1985.
Obstet
2. Gibb DMG, Cardoza LD, Studd JWW, Cooper DJ: Prolonged preg-
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nancy: is induction of labor indicated? A prospective study. Br J Obstet Gynecol 891292, 1982. 3. Evertson LR, Gauthier RJ, Schifrin BS, Paul RH. Antepartum fetal heart rate testing. I. Evolution of the nonstress test. Am J Obstet Gynecol133:29, 1979. 4. Manning FA, Platt LD, Sipos L: Antepartum fetal evaluation: development of a fetal biophysical profile. Am J Obstet Gynecol 136:787, 1980. 5. Manning FA, Baskett TF, Morrison I, Large I: Fetal biophysical profile scoring; a prospective study in 1,184 high-risk patients. Am J Obstet Gynecol 140:289, 1981. 6. Manning FA, Morrison I, Large IR, et al: Fetal assessment based upon fetal biophysical profile scoring; experience in 12,620 referred high-risk pregnancies. I. Perinatal mortality by frequency and etiology. Am J Obstet Gynecol 151:343. 1985. 7. Vintzileos AM, Campbell WA, In-
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gardia CH, Nochimson DJ: The fetal biophysical profile and its predictive value. Obstet Gynecol 62:271, 1983. 8. Paul RH: The evaluation of antepartum fetal well-being using the nonstress test. Clin Perinatal9:253, 1982. 9. Druzin ML, Gratacos J, Keegan KA, Paul RH: Antepartum fetal heart rate testing. VII. The significance of fetal bradycardia. Am J Obstet Gynecol 139: 194, 1981. 10. Clifford SH: Postmaturity placental dysfunction. J Pediatr 1954.
with 44:1,
11. Thacker SB, Berkelman RL: Assessing the diagnostic accuracy and efflcacy of selected antepattum fetal surveillance technqiues. Obstet Gynecol Surv 41:121, 1986. 12. Shime J, Gare DJ, Andrews J, et al: Prolonged pregnancy: Surveillance of the fetus and the neonate and the course of labor and delivery. Am J Obstet Gynecol 148547, 1984.
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