Isolated oligohydramnios in term pregnancy as an indication for induction of labor

The association between isolated oligohydramnios at term and placental pathology in correlation with pregnancy outcomes

INTRODUCTION

Isolated term oligohydramnios (ITO) is an obstetrical complication of which the etiology, management, and clinical importance are controversial. In attempt to deepen our understanding, we aimed to study placental pathology and pregnancy outcomes in pregnancies complicated by ITO.

MATERIALS AND METHODS

- Maternal demographics, neonatal outcomes, and placental histopathology reports of all pregnancies complicated by ITO at 37^0/7 to 41^0/7 weeks were reviewed. Excluded were cases complicated by hypertensive disorders, intrauterine fetal growth restriction, placental abruption, and deliveries of undiagnosed small for gestational age neonates. Results were compared between the ITO group and a control group matched for gestational age and mode of delivery. Placental lesions were classified according to the current "Amsterdam" criteria. Composite adverse neonatal outcome was defined as one or more of the following early complications: neonatal intensive care unit admission, sepsis, blood transfusion, phototherapy, respiratory morbidity, cerebral morbidity, necrotizing enterocolitis, or death.

RESULTS

The study group included 108 patients with ITO that were compared to matched controls. Placentas from the ITO group were characterized by higher rates of placental weights <10th centile (p < 0.001), abnormal cord insertion (p < 0.001), and maternal vascular malperfusion (MVM) lesions (p < 0.001). Neonates from the ITO group had lower birth weights (p < 0.002), and worse composite adverse neonatal outcome (p = 0.028) compared to controls.

CONCLUSION

- The current study demonstrates higher rates of placental MVM lesions, and worse neonatal outcome in pregnancies complicated by ITO. These novel findings suggest that ITO should be seen as part of the "placental insufficiency" spectrum.

Maternal and perinatal outcomes of induction of labor in oligohydramnios at term-a retrospective cohort study

Objective: To evaluate the maternal and perinatal outcomes of labor induction in women at term with oligohydramnios.Methods: A retrospective cohort of women with a singleton pregnancy, who had oligohydramnios at or beyond term (37-42 weeks) and underwent induction of labor for oligohydramnios were studied. Antenatally diagnosed fetal anomalies and intrauterine fetal demise were excluded. The women were categorized into two groups: 1) women with isolated oligohydramnios (n = 166) and 2) women with oligohydramnios associated with other maternal or fetal complications (n = 43). Maternal and perinatal outcomes were collected from the records of all deliveries, data compiled, and appropriate statistical tests were applied.Results: The study included 209 women with mean gestational age of 38.76 ± 1.00 weeks and mean induction-delivery interval of 17.45 ± 8.70 hours (16.98 hours in group 1 versus 19.23 hours in group 2). Most (75%) women delivered vaginally. Only one of the neonates had an Apgar score of less than 7 at 5 min. Average neonatal ICU length of stay was 5.52 days (5.27 days in group 1 versus 6.17 days in group 2). Among all the maternal and neonatal outcomes studied, only the mean birth weights among the two groups was found to be statistically significant (p = 0.0017).Conclusions: Women with isolated oligohydramnios and their neonates were not found to suffer any additional harm due to labor induction at term than women who had oligohydramnios associated with other complications.

Delivery mode and perinatal outcomes after diagnosis of oligohydramnios at term in China

Objective: The purpose of this study is to assess the incidence of oligohydramnios at term and evaluate whether the mode of delivery in patients with oligohydramnios influences perinatal outcomes in China.Methods: A cross-sectional survey of all deliveries in 39 hospitals in China from 1 January 2011-31 December 2011 was evaluated for the mode of delivery and perinatal outcomes in women with oligohydramnios compared to those without known oligohydramnios after excluding preterm births, polyhydramnios, and oligohydramnios secondary to premature rupture of membranes.Results: Oligohydramnios complicated 3954 (4.4%) of the 89,050 pregnancies, analyzed. Pregnancy cases with oligohydramnios compared those without known oligohydramnios had a significantly higher incidence of preexisting or gestational diabetes mellitus, fetal growth restriction, nonreassuring fetal heart tracings, obesity and malpresentation (p<.001). The cesarean delivery (CD) rate was significantly higher in pregnancies with identified oligohydramnios compared to those without (84.4 versus 54.7%; p<.001). Furthermore, in 2/3 of these CD in pregnancies with oligohydramnios, the identification of oligohydramnios was the only indication for the CD. In pregnancies with oligohydramnios, vaginal delivery did not significantly increase the risks of adverse outcomes compared to vaginal delivery without oligohydramnios, except postpartum complication.Conclusion: CD is not indicated in term pregnancies with isolated oligohydramnios. Vaginal delivery of oligohydramnios is not associated with increased perinatal mortality.

Evaluation of Maternal and Perinatal Outcomes of Induction in Borderline Oligohydramnios at Term

Introduction

Oligohydramnios is described as decreased amniotic fluid volume relative to gestational age. Semiquantitatively it is described using the Amniotic Fluid Index (AFI) which is calculated by adding the depth in centimetres of the largest vertical pocket in each of four equal uterine quadrants. AFI less than or equal to 5 cm is defined as oligohydramnios. A Borderline Oligohydramnios (BO) is defined as AFI 5.1-8 cm.

Aim

To assess the maternal and perinatal outcome of induction in borderline oligohydramnios cases at term.

Materials and Methods

This is a retrospective observational study done from December 2015 to November 2016 in Mahatma Gandhi Medical College and Research Institute, Puducherry, India. Fifty cases of BO with AFI 5.1 cm - 8 cm taken as case and another 50 cases of Normal Liquor (NL) with AFI 8.1 cm - 18 cm taken as control. Data was collected and analysed by SPSS software version 20.0 For qualitative data, the χ²-test or Fisher's-exact test were used and for continuous variables, the t-test was used.

Results

Cases and controls were matched in baseline parameters. More number of cases were found with meconium stained liquor during labour which is statistically significant (p<0.05). Otherwise there were no statistical significant difference between cases and controls in maternal and perinatal outcome.

Conclusion

Induction of labour in cases with BO cases compared to those with NL at term did not show very statistically significant difference in terms of induction to delivery interval and neonatal 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.

Perinatal outcomes with isolated oligohydramnios at term pregnancy

AIMS

To compare the outcomes of term gestations with oligohydramnios in the absence of other underlying disorders and term gestations with normal amniotic fluid.

METHODS

A retrospective analysis of obstetric outcomes in 27,708 term pregnancies. We compared three groups: labor induced because of oligohydramnios, spontaneous onset of labor with normal amniotic fluid, and labor induced because of late term pregnancy with normal amniotic fluid. We excluded pregnancies with maternal or fetal diseases or disorders potentially related with amniotic fluid alterations. The main outcome measures were mode of delivery, neonatal birth weight, umbilical artery blood pH, Apgar scores and neonatal discharge status.

RESULTS

Compared to spontaneous labor, induction of labor because of oligohydramnios was associated with a higher risk of cesarean delivery and small size of the fetus for gestational age (SGA). Compared to induction because of late term pregnancy there were no significant differences in neonatal, although neonates had a higher risk of being SGA.

CONCLUSION

The only perinatal outcome for which the risk was higher in term pregnancies with isolated oligohydramnios was SGA. The systematic induction of labor in these pregnancies should be questioned.

Isolated Oligohydramnios at Term as an Indication for Labor Induction: A Systematic Review and Meta-Analysis

OBJECTIVE

To investigate whether isolated oligohydramnios at term is associated with increased rates of perinatal morbidity and mortality and whether induction of labor in term pregnancies with isolated oligohydramnios is superior to conservative management in reducing perinatal morbidity and mortality.

STUDY DESIGN

We searched databases from inception to May 2015. We included studies that evaluated isolated oligohydramnios at term and perinatal outcome. Each outcome was analyzed separately, performing a comparative analysis between the study and control groups.

RESULTS

Twelve studies were included with 35,999 women: 2,414 (6.7%) with isolated oligohydramnios and 33,585 (93.29%) with normal amniotic fluid index. Patients with isolated oligohydramnios had significantly higher rates of labor induction [odds ratio (OR) 7.56, confidence interval (CI) 4.58-12.48] and Cesarean sections (OR 2.07, CI 1.77-2.41). There were higher rates of an Apgar score <7 at 1 and 5 min (OR 1.53, CI 1.03-2.26, and OR 2.01, CI 1.3-3.09, respectively) and admission to the neonatal intensive care unit (OR 1.47, CI 1.17-1.84). There were no significant differences in cord pH <7.1 and meconium-stained amniotic fluid. In the single randomized trial comparing induction of labor with expectant management, no differences were found in any significant maternal or neonatal outcomes.

CONCLUSION

Isolated oligohydramnios at term is associated with significantly higher rates of labor induction, Cesarean sections, and short-term neonatal morbidity.

Amniotic fluid as a vital sign for fetal wellbeing

Introduction: Amniotic fluid, once thought to merely provide protection and room for necessary movement and growth for the fetus, is now understood to be a highly complex and dynamic system that is studied as a data point to interpret fetal wellbeing. Methods: Assessment of amniotic fluid volume is now routine when performing a sonographic evaluation of fetal status and is an important consideration in the assessment and management of perinatal morbidity and mortality.1,2 In this review, we will cover the dynamics that affect amniotic fluid volume, review methods for measurement and quantification of volume, review definitions for normative data as related to neonatal outcomes, and provide evidence based guidance on the workup and management options for oligoydramnios and polyhydramnios in singleton and twin pregnancies. Conclusions: When abnormalities of fluid exist, appropriate workup to uncover the underlying etiology should be initiated as adverse fetal outcomes are sometimes associated with these variations from normalcy.

"Early rupture of membranes" during induced labor as a risk factor for cesarean delivery in term nulliparas

Objective

To determine if “early rupture of membranes” (early ROM) during induction of labor is associated with an increased risk of cesarean section in term nulliparas.

Study Design

The rate of cesarean section and the timing of ROM during the course of labor were examined in term singleton nulliparas whose labor was induced. Cases were divided into 2 groups according the timing of ROM: 1)“early ROM”, defined as ROM at a cervical dilatation<4 cm during labor; and 2) “late ROM”, ROM at a cervical dilatation≥4 cm during labor. Nonparametric techniques were used for statistical analysis.

Results

1) In a total of 500 cases of study population, “early ROM” occurred in 43% and the overall cesarean section rate was 15.8%; 2) patients with “early ROM” had a higher rate of cesarean section and cesarean section due to failure to progress than did those with “late ROM” (overall cesarean section rate: 24%[51/215] vs. 10%[28/285], p<0.01; cesarean section rate due to failure to progress: 18%[38/215] vs. 8%[22/285], p<0.01 for each) and this difference remained significant after adjusting for confounding variables.

Conclusion

“Early ROM” during the course of induced labor is a risk factor for cesarean section in term singleton nulliparas.

Determining a threshold for amniotic fluid as a predictor of perinatal outcome at term

OBJECTIVE

To determine a threshold level of amniotic fluid in low-risk term pregnancies predictive of adverse perinatal outcome.

METHODS

Prospective cohort study of low-risk patients at term undergoing amniotic fluid volume measurement. Amniotic fluid index (AFI) remained blinded unless ≤ 1 cm or ≥ 25 cm. Primary outcome was a positive fetal vulnerability index (FVI). The last AFI was evaluated as predictor of a +FVI. We estimated that we needed to perform ultrasounds on 620 women.

RESULTS

Patients were enrolled through 2004-2008. There were 24 (7.8%) patients delivering a neonate with +FVI. An AFI < 8 cm increased the risk of a +FVI (risk ratio 2.70 [95% CI 1.2, 6.0]; p = 0.01); however, the area under the receiver operating characteristics curve was 0.60. Enrollment was stopped at 308 patients due to enrollment challenges.

CONCLUSIONS

An AFI cutoff <8 cm was associated with an increase in FVI outcomes but had a low positive predictive value for a +FVI. Isolated incidentally found low fluid in uncomplicated pregnancies may not be an indication for immediate intervention.

Perinatal outcome in pregnancies complicated by isolated oligohydramnios diagnosed before 37 weeks of gestation

OBJECTIVE

To analyze pregnancy outcome in cases of isolated oligohydramnios at preterm.

METHODS

A retrospective cohort study of singleton pregnancies diagnosed with isolated oligohydramnios at preterm (n = 108). Pregnancy outcome was compared with a matched control group of low-risk preterm pregnancies with normal levels of amniotic fluid in a 3:1 ratio (n = 324).

RESULTS

Pregnancies complicated by isolated oligohydramnios were characterized by a higher rate of preterm deliveries (26.9% vs 12.3%, P < .001), most of which were iatrogenic, and a higher rate of labor induction and cesarean delivery. Neonates with isolated oligohydramnios were characterized by a lower birthweight and a higher rate of neonatal morbidity. These differences were eliminated when the analysis was limited to the subgroup of pregnancies with isolated oligohydramnios that were managed expectantly and delivered spontaneously at term.

CONCLUSION

Adverse pregnancy outcome in cases of isolated oligohydramnios diagnosed at <37 weeks appears to be related to a considerable degree to iatrogenic prematurity.

Maternal-fetal fluid balance and aquaporins: from molecule to physiology

Maternal-fetal fluid balance is critical during pregnancy, and amniotic fluid is essential for fetal growth and development. The placenta plays a key role in a successful pregnancy as the interface between the mother and her fetus. Aquaporins (AQPs) form specific water channels that allow the rapid transcellular movement of water in response to osmotic/hydrostatic pressure gradients. AQPs expression in the placenta and fetal membranes may play important roles in the maternal-fetal fluid balance.