Longitudinal measurement of amniotic fluid index in postterm pregnancies and its association with fetal outcome

Induction of Labor in Women with Oligohydramnios: Misoprostol Compared with Prostaglandin E2

Objective To compare perinatal outcomes in women with oligohydramnios and an unfavorable cervix undergoing labor induction with misoprostol to prostaglandin E2. Study Design We conducted a secondary analysis of women with oligohydramnios undergoing labor induction in the Consortium on Safe Labor study (2002-2008). Oligohydramnios was recorded in the medical chart. We evaluated perinatal outcomes. We limited the analysis to women with an unfavorable cervix defined by simplified Bishop score ≤ 4. Misoprostol was compared with prostaglandin E2. Women could have received oxytocin, underwent mechanical dilation, or had artificial rupture of membranes, but women who underwent induction with both misoprostol and prostaglandin E2 were excluded. We calculated adjusted odds ratios with 95% confidence intervals, controlling for maternal age, maternal body mass index (kg/m²), parity, and mechanical dilation. Results Among women with oligohydramnios and an unfavorable cervix who underwent induction of labor, 141 (39.4%) received misoprostol and 217 (60.6%) received prostaglandin E2. There were no significant differences in cesarean delivery, chorioamnionitis, postpartum hemorrhage, transfusion, neonatal intensive care unit (NICU) admission, NICU stay > 72 hours, mechanical ventilation, and neonatal sepsis. Conclusion In women with oligohydramnios and an unfavorable cervix, induction of labor with misoprostol was comparable to prostaglandin E2.

Oligohydramnios increases the risk of respiratory hospitalization in childhood: a population-based study

BACKGROUND

Pulmonary hypoplasia is associated with reduced lung function in infancy. The aim of this study was to evaluate the hypothesis that children exposed to oligohydramnios display an increased risk of hospitalization for respiratory illness by using a population-based matched-cohort design.

METHODS

We used three nationwide population-based data sets to identify 5,228 women who gave birth during 2004 to 2007 and were diagnosed with oligohydramnios during the third trimester of pregnancy. A cohort of 20,912 unaffected pregnant women was matched with these cases, according to neonatal sex and gestational age, maternal age and education, and level of prenatal care. Respiratory hospitalization and respiratory failure were defined using discharge diagnostic codes.

RESULTS

Oligohydramnios-exposed children had an 8% higher incidence rate of respiratory hospitalization and an 80% higher incidence rate of respiratory failure, compared with children without oligohydramnios exposure. This risk remained after adjusting for all potential risk factors. Cox regression analyses indicated that the adjusted hazard ratios of respiratory hospitalization and respiratory failure were 1.07 (95% confidence interval (CI): 1.01-1.15; P = 0.030) and 2.20 (95% CI: 1.26-3.84; P = 0.005), respectively.

CONCLUSION

Children exposed to oligohydramnios during the third trimester of pregnancy display an increased risk of hospitalization for respiratory illness.

Which is the safer method of labor induction for oligohydramnios women? Transcervical double balloon catheter or dinoprostone vaginal insert

OBJECTIVE

To compare the effectiveness and safety of two cervical ripening methods in term primiparous women with unfavorable cervices and oligohydramnios.

METHODS

Women (126 cases) with oligohydramnios [amniotic fluid index (AFI) ≤5 cm] and a low Bishop Score (≤6) were assigned randomly to use double balloon catheter (mechanical method group, 67 cases) or dinoprostone 10 mg controlled-release vaginal insert (pharmacological method group, 59 cases) for induction of labor. The study's primary outcome was caesarean section rate (CSR). The secondary outcome measures included maternal and neonatal morbidity, an incremental changes in Bishop Score, and intrapartum interventions.

RESULTS

There was no significant difference between the mechanical method group and the pharmacological method group in CSR and change in Bishop Score. Tacysystole, non-reassuring fetal heart patterns, and cases of newborn umbilical-cord arterial blood pH<7.1 were significantly lower with the mechanical method compared with the pharmacological method (p < 0.05). More patients needed additional intervention in the mechanical method group.

CONCLUSIONS

Both methods resulted in a similar CSR. Double balloon catheter resulted in fewer labor complications, but more frequent use of oxytocin and amniotomy. Compared with dinoprostone vaginal insert, double balloon catheter use may be less problematic in women with oligohydramnios.

[Management of post-term pregnancies: the role for AFI, biophysical score and doppler]

OBJECTIVE

To evaluate the role of ultrasound and doppler assessment in the management of prolonged pregnancies and to state its modalities.

METHOD

Medline, PubMed, embase and the Cochrane library were searched using terms prolonged pregnancy, post date pregnancy amniotic fluid, ultrasound assessment, doppler, biophysical profile.

RESULTS

Single deepest vertical pool measurement is the method of choice of the assessment of amniotic fluid. Indeed, when this method was used, significantly fewer case of oligohydramnios were diagnosed and fewer women had inductions of labor. However, this method is not superior to the amniotic fluid index in the prevention of poor perinatal outcomes. There is a significant difference in the incidence of fetal distress, meconium stained fluid and caesarean section for fetal distress when the amniotic fluid is reduced as compared with normal amniotic fluid. However, sensibility and predictive positive value of oligohydramnios to predict poor perinatal outcomes is moderate. Similary, in most studies, diagnosis of an abnormal uterine, umbilical, aortic or cerebral blood flow doppler was associated with a weak prediction of a poor perinatal outcome. Therefore, we do not recommend its use in management of prolonged pregnancy. There were significantly more diagnosis of oligoamnios and more abnormal antenatal monitoring results in the modified biophysical profile group as compared with the group managed with only single deepest pool but no differences in cord blood gases, neonatal outcome, or in outcomes related to labour and delivery were noted between the two groups. Therefore, biophysical profile including AFI offers no advantage in detecting adverse outcomes and may cause more interventions.

CONCLUSION

Close monitoring of fetal condition including assessment of amniotic fluid by single deepest pool twice a week from 41 weeks of gestation is recommended in the management of prolonged pregnancy. Induction of labor could be considered when oligohydramnios is diagnosed by single deepest pool less than 2 cm.

[Fetal and neonatal complications related to prolonged pregnancy]

OBJECTIVE

To evaluate fetal and neonatal outcomes related to prolonged pregnancy.

METHODS

This study is based on Pubmed search, Cochrane library and HAS recommendations.

RESULTS

The risk of fetal complications including macrosomia (6 %), oligohydramnios (10 %-15 %), abnormal fetal heart rate pattern and meconium-stained fluid is increased in prolonged pregnancy (≥ 41(+0) weeks). The rate of stillbirth was estimated between 1.6 ‰ and 3.0 ‰ live births according to countries in post-term pregnancies (≥ 42(+0) weeks). The risk of umbilical cord pH less than 7.10, Apgar score at five minutes inferior to 7, ICU admissions and perinatal asphyxia is increased in post-term infants (≥ 42(+0) weeks) compared with term infants. The risk of neurologic complications including neonatal convulsion, hypoxic ischemic encephalopathy, cerebral palsy, developmental deviations and epilepsy in childhood is increased in post-term infants. The risk of meconium aspiration syndrome, neonatal sepsis, and birth trauma including shoulder dystocia and bone fracture is increased in post-term infants. The rate of perinatal mortality increases in post-term infants. The perinatal mortality in post-term infants could be explained by perinatal asphyxia and meconium aspiration syndrome.

CONCLUSIONS

The risk of perinatal complications and mortality are increased in prolonged pregnancy.

Postdates and antenatal testing

The standard definition of a prolonged pregnancy is 42 completed weeks of gestation. The incidence of prolonged pregnancy varies depending on the criteria used to define gestational age at birth. It is estimated that 4 to 19% of pregnancies reach or exceed 42 weeks gestation. Several studies that have used very large computerized databases of well-dated pregnancies provided insights into the incidence and nature of adverse perinatal outcome such as an increased fetal and neonatal mortality as well as increased fetal and maternal morbidity in prolonged pregnancy. Fetal surveillance may be used in an attempt to observe the prolonged pregnancy while awaiting the onset of spontaneous labor. This article reviews the different methodologies and protocols for fetal surveillance in prolonged pregnancies. On the one hand, false-positive tests commonly lead to unnecessary interventions that are potentially hazardous to the gravida. On the other hand, to date, no program of fetal testing has been shown to completely eliminate the risk of stillbirth.

Postterm delivery and risk for epilepsy in childhood

OBJECTIVE

Postterm delivery is a risk factor for perinatal complications, some of which increase risk for neurologic morbidity. We aimed to examine the association between postterm delivery and risk for epilepsy in childhood.

METHODS

We conducted a cohort study of singleton children who were born in 3 Danish counties from 1980 to 2001. Birth registry data were linked with hospital records to identify cases of epilepsy in the first 12 years of life. We included children who were born at > or = 39 gestational weeks and computed crude, age-specific, and birth weight standardized incidence rates of epilepsy. We estimated adjusted incidence rate ratios according to mode of delivery by Poisson regression.

RESULTS

Among the 277,435 nonpreterm births, 32,557 were at > or = 42 weeks, including 3396 at > or = 43 weeks. Nearly one fourth of the 2805 epilepsy cases occurred in the first year of life. In that period, birth weight standardized incidence rate ratios for epilepsy were 1.3 for birth at 42 weeks and 2.0 for birth at > or = 43 weeks, compared with birth at 39 to 41 weeks. Among children who were delivered by cesarean section, incidence rate ratios adjusted for birth weight, presentation, malformations, and county were 1.4 for birth at 42 completed weeks and 4.9 for birth at > or = 43 weeks, compared with term vaginal births. There was a similar tendency among children who were delivered with the assistance of instruments. We found no evidence for the association between postterm delivery and risk for epilepsy beyond the first year of life.

CONCLUSIONS

Prolonged gestation is a risk factor for early epilepsy; the added increase in risk for instrument-assisted and cesarean deliveries could be attributable to factors that are related to both birth complications and epilepsy.

Misoprostol for Cervical Ripening and Labor Induction in Pregnancies with Oligohydramnios

The efficacy and safety of misoprostol for cervical ripening and labor induction in patients with oligohydramnios was investigated. 57 pregnancies with oligohydramnios and 58 cases with a normal amniotic fluid volume (controls) were enrolled in this prospective trial. All patients received 50 microg of intravaginal misoprostol every 5 h. Primary outcomes were: cesarean section rate; induction to delivery time; oxytocin augmentation; uterine hyperstimulation; meconium passage; fetal heart rate (FHR) changes; fetal distress requiring delivery, and Apgar scores. There were no differences in the mean time to delivery, cesarean section rate, oxytocin augmentation or Apgar scores. The mean induction to delivery time in oligohydramnios and control groups were, 11 h 43 min and 11 h 18 min, respectively (p > 0.05). FHR changes were observed in 26.3% of oligohydramnios group and 32.7% of control group (p > 0.05). There was no statistically significant difference in the cesarean section rate and the uterine hyperstimulation between the 2 groups. These data suggest that misoprostol can be used as an effective agent for cervical ripening and labor induction in pregnancies with oligohydramnios without increasing the risk for perinatal outcome, compared to those with normal amniotic fluid volumes.

Cesarean delivery for fetal distress: rate and risk factors

The objective of this article was to review the recent English language literature on cesarean delivery for fetal distress to determine its incidence, diagnostic tests, and the contributing factors to this obstetric complications. A PubMed search (1990-2000) with items of "cesarean, fetal distress," "cesarean, non-reassuring fetal heart rate," "cesarean, neonatal acidosis," and "cesarean, umbilical arterial pH," was undertaken. Reports, letters to the editor, focus on anomalous fetuses, and papers not specifically focused on this topic were excluded. Of the 392 articles that the search yielded, 169 met the inclusion criteria. Based on 37 reports with more than 1,000 patients each, the overall risk of prompt cesarean delivery for fetal concern was 3.1% (43,340 of 13,989,74). The risk exceeded 20% in patients with moderate/severe asthma, severe hypothyroidism, severe preeclampsia, and postterm or fetal growth restricted fetuses with abnormal Doppler studies. Use of likelihood ratios suggests that Doppler of the umbilical artery is a superior diagnostic test to amniotic fluid index in identifying parturients at risk for cesarean for non-reassuring fetal heart rate tracing. Although several risk factors increase the need for cesarean delivery for fetal distress, in general, most are unpreventable.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to estimate the incidence of cesarean delivery for non-reassuring fetal heart rate tracing, outline potential diagnostic tests that are useful for the detection of fetal distress, and summarize medical and obstetric conditions that place patients at risk for cesarean delivery for fetal distress.

Amniotic fluid index in low-risk pregnancy as an admission test to the labor ward

BACKGROUND

Oligohydramnios has been shown to be a predictor of intrapartal fetal distress. In a selected group of low-risk pregnancies, however, it has not yet been established that oligohydramnios contributes to intrapartal fetal distress.

METHODS

Ultrasonically estimated four-quadrant amniotic fluid index as a test for admission to the labor ward was evaluated as a predictive factor for fetal distress during labor in a prospective "blind" study comprising 600 low-risk pregnancies. Oligohydramnios was defined as an amniotic fluid index < or = 50 mm. The parturients were divided into two groups according to the status of the fetal membranes. The amniotic fluid index results were correlated to fetal outcome: Apgar score at 1 and 5 min, pH of blood in umbilical artery and vein, operative delivery because of fetal distress, cesarean delivery because of fetal distress, and number of babies referred to the neonatal intensive care unit.

RESULTS

Two-hundred and sixty-seven women had ruptured membranes. Among these a significant increase in operative delivery because of fetal distress was seen in cases of oligohydramnios compared with the normal amount of amniotic fluid (odds ratio 3.86, confidence interval = 1.25-11.9). No significant differences were seen regarding other variables of perinatal outcome. The group with intact membranes comprised 333 parturients. Among these, no significant differences in perinatal outcome could be seen in relationship to the amniotic fluid index, although a 50% increase in emergency operations for fetal distress was seen in women with oligohydramnios. A significant correlation might have been evident even in that group if a larger sample had been studied.

CONCLUSION

The results indicate that measurement of the amniotic fluid index in low-risk pregnant women admitted for labor might identify parturients with an increased risk of intrapartal fetal distress.

Low amniotic fluid index as a predictor of adverse perinatal outcome

OBJECTIVE

To determine whether an antepartum amniotic fluid index (AFI) of 5.0 cm or less is a predictor of adverse perinatal outcome.

STUDY DESIGN

The antepartum testing records of 779 women seen over a 12-month period were reviewed. Data, including the reasons for testing, the testing results, and pregnancy outcome were abstracted from these records. Inclusion criteria included a nonanomalous fetus and delivery within 7 days of the last antepartum surveillance test (modified biophysical profile). Chi-square analysis, Fisher's exact test, t tests and receiver-operator curves (ROCs) were used for analysis.

RESULTS

An AFI of 5.0 cm or less was significantly associated with an abnormal antepartum fetal heart rate (FHR) tracing but not with cesarean delivery, meconium-stained fluid, Apgars less than 7, or NICU admission. Subjects with an AFI of 5.0 cm or less had a higher rate of cesarean for fetal distress, but this did not reach statistical significance. ROCs produced no diagnostic cutoff values for AFI or largest pocket and prediction of any of the chosen parameters.

CONCLUSIONS

Antepartum oligohydramnios is associated with an increased risk of fetal heart rate abnormalities. Although in our population it is not predictive of adverse perinatal outcome as measured by low Apgars and NICU admissions, this may be reflective of the aggressive antepartum and intrapartum management that these patients received.

Relationship between meconium staining and amniotic fluid volume in term pregnancies

OBJECTIVE

Our purpose was to evaluate the relationship between meconium-stained amniotic fluid (MEC-AF) and amniotic fluid volume (AFV) and their impact on the risk of cesarean delivery for fetal indications in term pregnancies.

METHODS

1,655 live-born singleton gestations delivering at > or = 37 weeks within 7 days of sonographic assessment of the amniotic fluid index (AFI) were studied. AFI was categorized as: oligohydramnios (< or = 5.0 cm); decreased (5.1-8.0 cm); normal (8.1-18.0 cm); increased (18.1-23.9 cm), and polyhydramnios (> or = 24.0 cm). Frequencies of MEC-AF for each AFV category were stratified by gestational age (GA) and rates of cesarean delivery for fetal indications compared between patients with clear amniotic fluid and those with MEC-AF. Stepwise logistic regression analyses were performed for determinants of MEC-AF and the need for cesarean delivery for fetal indications.

RESULTS

The frequency of MEC-AF at birth in term pregnancies was not related to AFV: oligohydramnios (16.7%); decreased (16.7%); normal (20.1%); increased (24.4%), and polyhydramnios (22.1%). The only factor associated with the occurrence of MEC-AF was increasing GA at delivery (p < 0.01). Both MEC-AF (p < 0.02) and decreasing neonatal ponderal index (p < 0.02) were independently associated with cesarean delivery for fetal distress.

CONCLUSIONS

MEC-AF does not appear to be related to AFV in term pregnancies, and its presence increases the risk of cesarean delivery for fetal distress independent of AFV and neonatal ponderal index.

Use of prostaglandin E2 for cervical ripening in pregnancies with oligohydramnios

The effectiveness of intracervical prostaglandin E2 (PGE2) was studied in 96 primigravidas with unfavorable cervix and need for induction of labor. Group A consisted of 49 oligohydramnios and group B of 47 cases with normal amniotic fluid volume (controls). A single dose of 0.5 mg PGE2 gel was applied intracervically and several parameters were recorded during the next hours. The mean number of uterine contractions increased during the first 2 h in both groups, decreased during the next one and did not change significantly afterwards. The mean fetal heart rate (FHR) in group A decreased during the first 2 h and then increased, staying always within normal limits. The mean FHR in group B increased for 2 h, decreased during the next hour and did not change significantly afterwards. No significant differences were found between the two groups regarding mode of delivery, Apgar score and neonatal acidosis. Intracervical PGE2 appeared to effectively stimulate cervical ripening and labor induction in oligohydramnios, without causing side effects to the uterus and fetus.

Pregnancy outcomes after antepartum diagnosis of oligohydramnios at or beyond 34 weeks' gestation

OBJECTIVE

Our purpose was to assess whether antepartum oligohydramnios is associated with adverse perinatal outcomes.

STUDY DESIGN

Women delivered between July 1, 1991, and September 30, 1996, who underwent ultrasonography at >/=34 weeks' gestation were analyzed. Oligohydramnios was defined as an amniotic fluid index </=50 mm. Perinatal outcomes in pregnancies with oligohydramnios were compared with those with an amniotic fluid index of >50 mm.

RESULTS

In our analysis of 6423 pregnancies, 147 (2.3%) were complicated by oligohydramnios. This complication was associated with increased labor induction (42% vs 18%; P <.001), stillbirth (1. 4% vs 0.3%; P <.03), nonreassuring fetal heart rate (48% vs 39%; P <. 03), admission to the neonatal intensive care nursery (7% vs 2%; P <. 001), meconium aspiration syndrome (1% vs 0.1%; P <.001), and neonatal death (5% vs 0.3%; P <.001).

CONCLUSION

Antepartum oligohydramnios is associated with increased perinatal morbidity and mortality.

A randomised comparison between amniotic fluid index and maximum pool depth in the monitoring of post-term pregnancy

OBJECTIVE

To compare the impact of two different ultrasound methods for assessing amniotic fluid volume on the incidence of obstetric interventions in post-term pregnancies.

DESIGN

A prospective randomised controlled trial.

SETTING

Liverpool Women's Hospital.

PARTICIPANTS

Five hundred women with singleton, uncomplicated pregnancies with gestational age > or = 290 days.

INTERVENTIONS

Random allocation to fetal monitoring by either: 1. amniotic fluid index and computerised cardiotocography, or 2. maximum pool depth and computerised cardiotocography.

MAIN OUTCOME MEASURES

Primary: caesarean section. Secondary: the number of abnormal monitoring tests, induction of labour, intrapartum management and neonatal outcome.

RESULTS

The number of abnormal amniotic fluid indices was significantly higher than the number of abnormal maximum pool depths (10% vs 2.4%; OR 4.51, 95% CI 1.82-11.21; P = 0.0008) which resulted in more inductions for abnormal post-term monitoring in the amniotic fluid index group (14.8% vs 8.4%; OR 1.89; 95% CI 1.07-3.33; P = 0.0362) and more intrapartum electronic fetal monitoring (94.4% vs 88.4%; OR 2.21; 95% CI 1.13-4.29; P = 0.0255). There were no other statistically significant differences in outcomes related to labour and delivery, but there was a trend towards more caesarean sections in the amniotic fluid index group (18.8% vs 13.2%), in particular caesarean sections for fetal distress (8% vs 4%). There were no perinatal deaths and no statistically significant differences in perinatal outcome between the two groups.

CONCLUSIONS

Published reference ranges for amniotic fluid index overestimate the number of abnormal results in post-term pregnancies. Their use, when compared with maximum pool depth, is likely to increase the number of obstetric interventions with, as yet, an uncertain impact on perinatal mortality and morbidity. It is possible that antepartum fetal assessment in pregnancies where the risk of adverse perinatal outcome is very low may cause, rather than prevent morbidity.

Serial amniotic fluid index in severe preeclampsia: a poor predictor of adverse outcome

OBJECTIVE

The purpose of the study was to determine the relationship between low amniotic fluid index and intrauterine growth restriction and nonreassuring fetal testing in patients with severe preeclampsia.

STUDY DESIGN

We reviewed the medical records of 136 women with severe preeclampsia managed conservatively for at least 48 hours. Patients were followed up with a daily nonstress test and amniotic fluid index. We evaluated amniotic fluid index < or = 5 cm and < or = 7 cm, measured on admission or just before delivery (i.e., final), and attempted to correlate these findings with the incidence of nonreassuring fetal testing necessitating cesarean section or the incidence of intrauterine growth restriction (birth weight < or = 10th percentile).

RESULTS

One hundred seven patients had a cesarean section, but only 42 (39%) of these were for a nonreassuring fetal heart rate tracing or a persistent biophysical profile of < or = 4, and 38 (36%) of the pregnancies resulted in infants with intrauterine growth restriction. During expectant management, the amniotic fluid index worsened for 61 (45%) patients and improved or remained the same for 75 (55%). For those with an amniotic fluid index of < or = 5 cm both on admission and at delivery, there was a significantly higher incidence of intrauterine growth restriction compared with those with an amniotic fluid index > 5 cm (p = 0.007 and p = 0.029, respectively). However, there was no association between intrauterine growth restriction and an amniotic fluid index < or = 7 cm. Moreover, there was no difference in the frequency of nonreassuring fetal heart rate testing on the basis of amniotic fluid volume (p = 0.59) or intrauterine growth restriction (p = 0.4).

CONCLUSIONS

For women with severe preeclampsia remote from term, an amniotic fluid index < or = 5 cm is predictive of intrauterine growth restriction but lacks sensitivity. There is no association between the amniotic fluid index status and frequency of cesarean section for fetal distress or nonreassuring fetal testing.

Effects of intracervical prostaglandin E2 on fetal heart rate and uterine activity patterns in the presence of oligohydramnios

OBJECTIVE

Our purpose was to compare fetal heart rate patterns and uterine activity before and after preinduction prostaglandin E2 administration in the presence or absence of oligohydramnios.

STUDY DESIGN

In a retrospective case-controlled review we examined cases in which prostaglandin E2 (Prepidil) was inserted intracervically for gravid women requiring an induction of labor in the presence of either oligohydramnios (amniotic fluid index < or = 5.0) or adequate fluid (amniotic fluid index 5.1 to 23.9). Uterine activity and fetal heart rate tracings that were begun 1 hour before and continued for 6 hours after dosing were interpreted without knowledge of amniotic fluid volume.

RESULTS

Cases in the oligohydramnios (n = 51) and adequate fluid (n = 49) groups were the same for maternal age, race, parity, gestational age, and predose Bishop score. Patients with oligohydramnios had more high-amplitude contractions in the first hour after dosing (9.0 +/- 1.2 vs 6.1 +/- 0.9, p < 0.05), but there were no significant differences in the frequency or duration of contractions during the subsequent 5 hours. Uterine hyperstimulation was not seen, and there were no differences in the frequency of variable or late fetal heart rate decelerations.

CONCLUSION

For pregnancies undergoing preinduction cervical ripening with intracervical prostaglandin E2, the presence of oligohydramnios was not associated with a greater risk of fetal heart rate decelerations, although contractions were more common during the first hour after dosing.