Severe Variable Decelerations Research Articles

Transcervical intrapartum amnioinfusion: a simple and effective technique

Objective: To test a simple method of intrapartum amnioinfusion to replace amniotic fluid during labor in cases of prolonged labor and severe variable fetal heart rate decelerations or thick meconium. Study design: We conducted a prospective study of intrapartum amnioinfusion in sixteen consecutive patients. A simple transcervically placed Foley bladder catheter was used for intrauterine infusion of saline solution, while monitoring was performed by external cardiotocography. Results: In twelve patients, catheter placement was easily performed; the remaining four required stabilization by a mandrel for insertion. Amnioinfusion was effective in ten out of thirteen patients for relief of fetal heart rate anomalies. No complications were observed; all had good neonatal outcome. Conclusions: In our small, uncontrolled study, this amnioinfusion method proved to be a simple, inexpensive, effective and safe technique for the relief of severe heart rate anomalies in prolonged labor.

Fetal heart rate decelerations precede a decrease in fetal oxygen content.

To determine the relationship between abnormal fetal heart rate (FHR) patterns, fetal oxygen content by reflectance pulse oximetry, and the effects of maternal oxygen administration, 158 intrapartum women consisting of 120 women with normal FHR patterns, and 38 women with varying degrees of variable FHR decelerations were examined. A new reflectance pulse oximetry probe was attached to the fetal forehead to continuously monitor fetal oxygen saturation (SpO2) during labor. Oxygen was administered for 30 min at 5 liters/min by nasal canula in 32 women. No significant change in fetal SpO2 was seen in women with normal FHR patterns, but a significant decline in SpO2 was observed shortly before births. FHR decelerations less than 90 bpm occurred prior to the decline in fetal SpO2. Maternal oxygen administration was effective in increasing fetal SpO2 in fetuses with decreased SpO2 (SpO2 < 50%), but not in fetuses with high SpO2 (SpO2 > 60%). It is concluded that fetal SpO2 exhibits no change during normal labor but significantly declines shortly before birth, that relatively severe variable decelerations (<90 bpm) can decrease fetal SpO2, and that maternal oxygen treatment at 5 liters/min is effective in augmenting fetal oxygen tension in fetuses with decreased oxygen tension.

Characterization and prognostic significance of severe variable decelerations in the second stage of labor

Characterization and prognostic significance of severe variable decelerations in the second stage of labor

Amniotic fluid index predicts the relief of variable decelerations after amnioinfusion bolus

OBJECTIVE: Our purpose was to determine whether intrapartum amniotic fluid index before amnioinfusion can be used to predict response to therapeutic amnioinfusion. STUDY DESIGN: Intrapartum patients (n = 85) with repetitive variable decelerations in fetal heart rate that necessitated amnioinfusion (10 ml/min for 60 minutes) underwent determination of amniotic fluid index before and after bolus amnioinfusion. The fetal heart tracing was scored (scorer blinded to amniotic fluid index values) for number and characteristics of variable decelerations before and 1 hour after initiation of amnioinfusion. The amnioinfusion was considered successful if it resulted in a decrease of ≥50% in total number of variable decelerations or a decrease of ≥50% in the rate of atypical or severe variable decelerations after administration of the bolus. Spontaneous vaginal births before completion of administration of the bolus (n = 18) were excluded from analysis. The probability of success of amnioinfusion in relation to amniotic fluid index was analyzed with the χ2 test for progressive sequence. RESULTS: The mean amniotic fluid index before amnioinfusion was 6.2 ± 3.3 cm. An amniotic fluid index of ≤5 cm was present in 40% of patients (27/67), and an amniotic fluid index of ≤8 cm was present in 72% of patients (48/67). The probability of success of amnioinfusion decreased with increasing amniotic fluid index before amnioinfusion (76% [16/21] when initial amniotic fluid index was 0 to 4 cm, 63% [17/27] when initial amniotic fluid index was 4 to 8 cm, 44% [7/16] when initial amniotic fluid index was 8 to 12 cm, and 33% [1/3] when initial amniotic fluid index was >12 cm, p = 0.03). The incidence of nuchal cords or true umbilical cord knots increased in relation to amniotic fluid index before amnioinfusion. CONCLUSIONS: Amniotic fluid index before amnioinfusion can be used to predict the success of amnioinfusion for relief of variable decelerations in fetal heart rate. Failure of amnioinfusion at a high amniotic fluid index before amnioinfusion may be explained by the increased prevalence of nuchal cords or true knots in the umbilical cord. (Am J Obstet Gynecol 1996;175:1066-70.)

Doppler study of the fetal cardiac function in prolonged pregnancies

To evaluate the association between fetal cardiac function and amniotic fluid index (AFI) in postterm fetuses, and to determine if changes in fetal cardiac function precede the occurrence of nonreassuring intrapartum fetal heart rate (FHR) patterns. Forty-five otherwise low-risk pregnant women between 41 and 43 weeks' gestation were studied longitudinally. Gestational age was confirmed in all patients by ultrasound before 20 weeks' gestation. Each subject had two or three tests performed every 3-4 days, including a non-stress test, a biophysical profile, and Doppler studies of the aortic and pulmonic outflow tracts. Aortic and pulmonic artery flow velocity waveforms were recorded slightly distal to the valves. Peak velocity, velocity time integral, and heart rate were calculated from the flow velocity waveforms we obtained. The change in AFI and aortic and pulmonic peak velocity and [velocity time integral] x [heart rate] were calculated for each fetus. Labor was induced at 42 weeks' gestation in 20 patients, and 17 entered labor spontaneously. Changes in AFI, observed during the follow-up period, correlated significantly with changes in aortic peak velocity (r = 0.54, P < .01) and with aortic outflow [velocity time integral] x [heart rate] (r = 0.60, P < .001) but not with pulmonic peak velocity and [velocity time integral] x [heart rate]. The decrease in aortic peak velocity and aortic and pulmonic [velocity time integral] x [heart rate] was significantly higher (P < .01) in eight fetuses that developed a nonreassuring intrapartum FHR (reduced FHR variability, late decelerations, and severe variable decelerations) than in those who had an uneventful labor. In prolonged pregnancies, cardiac function deteriorates in fetuses that develop a nonreassuring intrapartum FHR, and the changes in the left cardiac function correlate with changes in AFI.

Cesarean delivery for intrapartum fetal heart rate abnormalities: Incorporating survey data into clinical judgment

To identify the descriptive clinical practice of maternal-fetal medicine specialists when faced with severe intrapartum fetal heart rate (FHR) abnormalities (as determined by continuous electronic fetal monitoring). All regular members of the Society of Perinatal Obstetricians (maternal-fetal medicine specialists) were sent a survey questionnaire on the topic of cesarean delivery for intrapartum FHR abnormalities. The time from observation of FHR abnormalities to making the decision to proceed to cesarean delivery was the main outcome measure. Time was allowed for intrauterine resuscitative maneuvers to alleviate the abnormal pattern. Legislative definitions of consensus and strong consensus were applied to the data. Analysis of covariance was performed to determine the effect of physician demographic factors on the times reported. Four hundred thirty-one of 704 (61.2%) questionnaires were returned. Consensus was identified for deciding on cesarean delivery (after intrauterine resuscitation) 1) after 30 minutes for cases of repetitive late and severe variable decelerations, 2) after 10 minutes in cases of fetal bradycardia, and 3) in all scenarios with decreased beat-to-beat variability of the FHR. Consensus was identified for deciding on cesarean delivery in five of eight intrapartum FHR pattern abnormalities. The descriptive clinical practice of maternal-fetal medicine specialists demonstrated in this study should be considered in prudential clinical judgment.

Umbilical plasma concentration of endothelin-1 in intrapartum fetal stress: effect of fetal heart rate abnormalities

To measure the umbilical plasma concentration of endothelin (ET)-1 in the presence of labor, fetal heart rate (FHR) abnormalities, and fetal hypoxia. Umbilical and maternal plasma concentrations of ET-1 were measured in 100 pregnant women at full-term deliveries (60 with vaginal delivery without induction and 40 with elective cesarean delivery without labor). We assessed the FHR pattern, measured umbilical blood gases and plasma concentration of vasopressin, and investigated the relationships between the umbilical vein-artery ET-1 concentration difference and these variables. The concentration of ET-1 in the umbilical vein was higher than in the umbilical artery and the maternal vein in all cases. The umbilical vein-artery ET-1 concentration difference (mean +/- standard error of the mean) was significantly greater in the vaginal delivery group (4.5 +/- 2.0 pmol/L) than in those delivered by elective cesarean (1.7 +/- 1.5 pmol/L) (P < .05). The umbilical vein-artery ET-1 concentration difference was significantly greater when more than three episodes of severe variable decelerations occurred during the 30-minute period before delivery (7.0 +/- 2.0 pmol/L) than in the absence of any decelerations (1.6 +/- 1.5 pmol/L) (P < .05). The umbilical vein-artery ET-1 concentration difference correlated positively with the umbilical arterial concentration of vasopressin (r = 0.45, P < .05) and negatively with the umbilical arterial oxygen pressure (r = -0.47, P < .05). In cases of vaginal delivery with FHR abnormalities and with fetal hypoxia, the fetoplacental concentration of ET-1 was increased.

Early versus late amniotomy for labor induction: A randomized trial

OBJECTIVE: Our purpose was to determine the impact of early and late amniotomy on labor induction with continuous oxytocin infusion at term. STUDY DESIGN: A total of 209 women admitted for labor induction were randomized to early or late amniotomy. The early amniotomy group ( n = 106) had membranes ruptured as soon as it was deemed safe and feasible. The late amniotomy group ( n = 103) had membrane rupture performed at ≥5 cm dilatation. The first 103 women received a continuous oxytocin infusion with incremental adjustments at 60-minute intervals as required. The next 106 women had adjustments every 30 minutes as required. Statistical analysis was confined to concurrent groups. RESULTS: Early amniotomy was associated with shorter labor (13.3 vs 17.8 hours, p = 0.001), chorioamnionitis (22.6% vs 6.8%, p = 0.002), and significant fetal umbilical cord compression (12.3% vs 2.9%, p = 0.017). The benefit regarding shortening of labor was limited to women having oxytocin increments every 30 minutes as required (13.3 vs 17.8 hours, p = 0.001). Alternatively, the increase in chorioamnionitis was confined to the 60-minute group (39% vs 11%, p < 0.001), which also demonstrated a trend toward increased moderate and severe variable decelerations (19.6% vs 6.4%, p = 0.08). CONCLUSIONS: When a protocol of 60-minute inrements in oxytocin infusion rate is desired, amniotomy should be performed late in labor to reduce chorioamnionitis and significant umbilical cord compression. Alternatively, if early amniotomy is necessary, oxytocin should be adjusted every 30 minutes as tolerated.

Daily antenatal testing in women with severe preeclampsia

OBJECTIVE: Our purpose was to determine whether daily antenatal testing in the expectant management of severe preeclampsia remote from term prevents stillbirth or neonatal compromise at birth. STUDY DESIGN: We reviewed the medical records of 68 women with severe preeclampsia remote from term who underwent expectant management with daily fetal testing until delivery. On admission each patient had reassuring nonstress testing (absence of persistent severe variable or late decelerations), biophysical profile (≥6), and amniotic fluid volume (≥2 cm maximal vertical pocket before 32 weeks or amniotic fluid index ≥5 after 32 weeks). RESULTS: There were no stillbirths. Twenty-one patients (31%) had nonreassuring testing necessitating delivery. Two neonatal deaths occurred as a result of complications of prematurity. There were no statistical differences in the cord arterial pH ( p = 0.93) or in the 1- and 5-minute Apgar scores ( p = 0.18 and p = 0.88, respectively) between those with normal and abnormal antenatal testing. CONCLUSIONS: Because optimizing neonatal outcome is the only reason to prolong pregnancy in women with severe preeclampsia, confirmation of fetal well-being is mandatory. Because neither stillbirths nor fetal compromise at birth occurred in patients undergoing daily antenatal testing, we recommend daily testing in patients with severe preeclampsia managed expectantly.

Changes in Blood Velocities of Fetal Circulation in Association with Fetal Heart Rate Abnormalities: Effect of Sublingual Administration of Nifedipine

Nifedipine has been used to treat hypertension in pregnancy, and does not influence fetal or uteroplacental circulations in patients with preeclampsia. A 29-year-old multi-gravid woman presented at 32 weeks' gestation with significant elevation of her blood pressure. After sublingual administration of nifedipine, the blood pressure decreased from 208/122 to 136/96 mm Hg at 30 minutes. In her growth-retarded fetus with abnormal flow velocity waveforms, pulsatility index values for middle cerebral artery and umbilical artery did not change; however, peak systolic velocities, end-diastolic velocities, and time-averaged mean peak velocities for these arteries became significantly elevated. Simultaneously, severe variable decelerations and late decelerations occurred. The adverse effect of nifedipine on fetal circulation might occur in a growth-retarded fetus with abnormal flow velocity waveforms.

Effect of intravenous magnesium sulfate on the biophysical profile of the healthy preterm fetus

OBJECTIVE: The null hypothesis is that intravenous magnesium sulfate does not affect the biophysical profile of the healthy preterm fetus. STUDY DESIGN: Thirty-one fetuses of 25 patients between the gestational ages of 24 and 35 weeks, median 31.4 and mean (± SD) 30.4 (± 2.9), who required tocolysis for uterine contractions were prospectively studied. After normal fetal biophysical assessment was documented, intravenous magnesium sulfate was started as a 4 or 6 gm loading dose and then infused at 2 to 3.5 gm/hr to achieve tocolysis. Blood was drawn for measurement of maternal serum magnesium levels immediately before intravenous magnesium sulfate was administered and at 2 and 12 hours after the loading dose. Biophysical profiles, consisting of a possible 12 points, were performed at the same time as blood was drawn. Serum magnesium levels were compared with one-way analysis of variance for repeated measures and biophysical profile scores with Friedman's test. Statistical significance was considered p < 0.05. RESULTS: Mean (± SD) serum magnesium levels were 1.7 (± 0.1) mg/dl before infusion, 4.3 (± 0.6) mg/dl at 2 hours, and 5.2 (± 0.7) mg/dl at 12 hours (p < 0.001). Six fetuses did not have a 12-hour biophysical profile; three were delivered for severe variable decelerations, two progressed in labor, and in one tocolysis was discontinued. The median biophysical profile score was 11 before intravenous magnesium sulfate, at 2 hours, and at 12 hours after the loading dose. The biophysical parameters present and the percentage of fetuses with each parameter were as follows: breathing (>30 seconds), 88% (22/25) before magnesium sulfate, 84% (21/25) at 2 hours, and 92% (23/25) at 12 hours; nonstress test (reactive), 84% (21/25) before magnesium sulfate, 68% (17/25) at 2 hours, and 80% (20/25) at 12 hours; movement (normal), 100% (25/25) before magnesium sulfate, 100% (25/25), at 2 hours, and 96% (24/25) at 12 hours; tone (normal), 100% (25/25) before magnesium sulfate, 100% (25/25) at 2 hours, and 96% (24/25) at 12 hours. CONCLUSION: Intravenous magnesium sulfate did not significantly alter the biophysical profile in the 25 fetuses evaluated by three biophysical profiles in spite of the significant increase in maternal serum magnesium levels. (AM J OBSTET GYNECOL 1994;170:1131-5.)

The umbilical coiling index

Our purpose was to objectively quantitate umbilical vascular coiling. In this prospective study the umbilical cords and delivery records of 100 consecutive liveborn neonates were studied. The umbilical coiling index of each cord was determined by dividing the total number of complete umbilical vascular coils by the umbilical cord length (in centimeters). The obstetric history, intrapartum fetal heart rate tracing, and pregnancy outcome of each fetus were evaluated without knowledge of the umbilical coiling index. The mean umbilical coiling index was 0.21 +/- 0.07 (SD) coils per centimeter. The 100 values were normally distributed. Among those whose umbilical coiling index values fell < or = 10th percentile, there was a significantly greater incidence of karyotypic abnormalities (p = 0.04), meconium staining (p = 0.03), and operative intervention for fetal distress (p = 0.03). There was a significantly greater incidence of moderate or severe variable fetal heart rate decelerations for those whose umbilical coiling index value was either < or = 10th percentile (0.1 coils per centimeter) or > 90th percentile (0.3 coils per centimeter) (p = 0.03). The umbilical coiling index may have utility for objectively describing the degree of umbilical vascular coiling.

The umbilical coiling index

OBJECTIVE: Our purpose was to objectively quantitate umbilical vascular coiling. STUDY DESIGN: In this prospective study the umbilical cords and delivery records of 100 consecutive liveborn neonates were studied. The umbilical coiling index of each cord was determined by dividing the total number of complete umbilical vascular coils by the umbilical cord length (in centimeters). The obstetric history, intrapartum fetal heart rate tracing, and pregnancy outcome of each fetus were evaluated without knowledge of the umbilical coiling index. RESULTS: The mean umbilical coiling index was 0.21 ± 0.07 (SD) coils per centimeter. The 100 values were normally distributed. Among those whose umbilical coiling index values fell ≤10th percentile, there was a significantly greater incidence of karyotypic abnormalities (p = 0.04), meconium staining (p = 0.03), and operative intervention for fetal distress (p = 0.03). There was a significantly greater incidence of moderate or severe variable fetal heart rate decelerations for those whose umbilical coiling index value was either ≤10th percentile (0.1 coils per centimeter) or >90th percentile (0.3 coils per centimeter) (p = 0.03). CONCLUSION: The umbilical coiling index may have utility for objectively describing the degree of umbilical vascular coiling. (AM J OBSTET GYNECOL 1994;170:29-32.)

A non-hemorrhagic manifestation of vasa previa: A clinicopathologic case report

The rare entity of vasa previa occurs when fetal vessels lying between the amniotic and chorionic membranes cross the cervical os. This report presents a case that was associated with vessel compression and concomitant adverse effects on fetal hemodynamics. A 23-year-old nulliparous woman at 36 weeks' gestation developed persistent, progressive severe variable decelerations several hours after spontaneous rupture of the membranes, resulting in a decision to perform a cesarean. At delivery, fetal vessels were noted in the membranes near the cervical os, leading into a marginally inserted cord. The decelerations were attributed to compression of the unprotected umbilical arteries by the fetal head. Vasa previa often results in fetal death and may be associated with fetal hemorrhage, but lack of bleeding does not exclude the existence of vasa previa. Altered fetal hemodynamics from varying degrees of vessel compression by the presenting part during labor may result in hypoxia and acidosis. A high index of suspicion is necessary to make the diagnosis and institute proper, timely management.

The predictive value of fetal heart rate monitoring: a retrospective analysis of 2165 high-risk pregnancies

The predictive value of fetal heart-rate monitoring on fetal well-being was studied in 2165 high-risk pregnancies. 1883 reactive nonstress test (NST) patterns and 278 nonreactive NST patterns and 4 cases of sinusoidal pattern were obtained. Oxytocin challenge test (OCT) was applied to 263 nonreactive cases. OCT was not applied to 15 cases out of 278 nonreactive NST cases, because of placenta previa, abruptio placenta and previous cesarean section. There were 155 cases with negative OCT, 84 cases with positive OCT and 24 cases with equivocal, prolonged or severe variable decelerations. Sensitivity and specificity were for NST 50 and 88% and for OCT 60 and 67%. The positive and negative predictive values were 11 and 98% for NST and 18 and 93% for OCT. It is concluded that the reactive nonstress test is a reliable test for good outcome but a positive oxytocin challenge test is not a reliable test for poor outcome. Additional procedures are necessary such as assessment of fetal growth, doppler velocity waveforms and fetal biophysical profile to avoid unnecessary obstetric interventions and to reach good fetal outcome.

Sonographic Verification of a Nuchal Cord Following a Vibratory Acoustic Stimulation-Induced Severe Variable Fetal Heart Rate Deceleration with Expedient Abdominal Delivery

A case is presented in which external vibratory acoustic stimulation performed following a nonreactive nonstress test produced a severe variable deceleration of the fetal heart rate. A clinically suspected nuchal cord was confirmed by ultrasound. This rapid precise antepartum diagnosis of cord compression prevented untimely delay and led to immediate abdominal delivery of a nonacidotic, yet hypoxic, infant. This report suggests care be taken when fetal vibratory acoustic stimulation is applied in cases of oligohydramnios and a known existing nuchal cord.

Comparative efficacy of umbilical arterial Doppler indices for predicting adverse perinatal outcome

A variety of descriptor indices for the umbilical arterial Doppler waveform are currently in use for predicting perinatal outcome. However, there is a paucity of data regarding the relative diagnostic merits of these indices. We addressed this issue in a prospective, blind study in which the diagnostic efficacy of the following Doppler indices was compared: resistance index, systolic/diastolic ratio, pulsatility index, and diastolic average ratio. The analytic technique consisted of the receiver operating characteristic method, which evaluates a test's ability to discriminate a diseased from a healthy population. The patient population consisted of 350 pregnant patients with gestational ages of 34 to 36 weeks. A continuous-wave Doppler device with a 4 MHz transducer was used to investigate the umbilical vessels. The test was performed only once in each patient. The abnormal outcome parameters included small for gestational age (less than 10th percentile), Apgar score less than 7 at 5 minutes, fetal distress (late and severe variable decelerations, absent variability, fetal scalp pH less than 7.20), umbilical cord arterial pH less than 7.10, presence of thick meconium, and admission to neonatal intensive care unit (greater than 48 hours). The results showed that the resistance index had the best discriminatory ability when compared with other Doppler indices: the systolic/diastolic ratio (p less than 0.05), the pulsatility index (p less than 0.001), and the diastolic/average ratio (p less than 0.05). It is concluded that of the various Doppler indices assessed in this investigation, the resistance index offers the best diagnostic efficacy in predicting perinatal compromise.

Prophylactic intrapartum amnioinfusion: A randomized clinical trial

Amnioinfusion was performed in a prospective, randomized trial of 60 women in the latent phase of labor with oligohydramnios, as defined by an amniotic fluid index ≤5.0 cm. All fetuses were at least 37 weeks' gestational age, had normal baseline fetal heart rate variability, and no clinically significant fetal heart rate decelerations at the outset. Subjects in the amnioinfusion group ( n = 30) were titrated to and maintained at an amniotic fluid index level ≥8.0 cm throughout labor. In the group receiving amnioinfusion, significantly lower rates of meconium passage ( p = 0.04), severe variable decelerations ( p = 0.04), end-stage bradycardia ( p = 0.05), and operative delivery for fetal distress ( p = 0.002) occurred. Significantly higher umbilical arterial blood pH values were also noted in the infusion group ( p = 0.02). We conclude that prophylactic intrapartum amnioinfusion is an important technique for the reduction of intrapartum morbidity.

Prophylactic intrapartum amnioinfusion: A randomized clinical trial

Amnioinfusion was performed in a prospective, randomized trial of 60 women in the latent phase of labor with oligohydramnios, as defined by an amniotic fluid index less than or equal to 5.0 cm. All fetuses were at least 37 weeks' gestational age, had normal baseline fetal heart rate variability, and no clinically significant fetal heart rate decelerations at the outset. Subjects in the amnioinfusion group (n = 30) were titrated to and maintained at an amniotic fluid index level greater than or equal to 8.0 cm throughout labor. In the group receiving amnioinfusion, significantly lower rates of meconium passage (p = 0.04), severe variable decelerations (p = 0.04), end-stage bradycardia (p = 0.05), and operative delivery for fetal distress (p = 0.002) occurred. Significantly higher umbilical arterial blood pH values were also noted in the infusion group (p = 0.02). We conclude that prophylactic intrapartum amnioinfusion is an important technique for the reduction of intrapartum morbidity.

Usefulness of Continuous Fetal Heart Rate Monitoring During Cesarean Section

Cesarean section performed for fetal distress usually leaves the fetus unmonitored peri- and intraoperatively. Two cases are presented in which continuous fetal heart rate monitoring during cesarean section modified the obstetric management. In case one, emergency section was undertaken because of severe variable decelerations and a scalp pH of 7.20. The mother had had a previous abdominal delivery but attempted vaginal birth. Internal FHR monitoring was continued during surgery. Following endotracheal intubation, the FHR returned to normal. This permitted the surgeons to dissect multiple adhesions between loops of small bowel, omentum and uterus meticulously and without haste. The infant was born in good condition with Apgar scores of 8 and 9, respectively, and a venous cord pH of 7.28. There were 2 loops of umbilical cord around the fetal neck. In case 2, cesarean section was performed because of late decelerations, diminished beat-to-beat variability, and scalp pH of 7.18 at 3 cm dilation of the cervix. The FHR improved during general anesthesia but, after the myometrial incision, dropped abruptly without tendency to recover. Expeditious delivery of the fetus was undertaken by the senior operator. The neonate was born with mild hypoxia.