Amnioinfusion during labor complicated by particulate meconium-stained amniotic fluid decreases neonatal morbidity

Intrapartum amnioinfusion reduces meconium aspiration syndrome and improves neonatal outcomes in patients with meconium-stained fluid: a systematic review and meta-analysis

OBJECTIVE

This study aimed to reassess the effect of prophylactic transcervical amnioinfusion for intrapartum meconium-stained amniotic fluid on meconium aspiration syndrome and other adverse neonatal and maternal outcomes.

DATA SOURCES

From inception to November 2021, a systematic search of the literature was performed in PubMed, Embase, Web of Science, and Scopus databases and gray literature sources.

STUDY ELIGIBILITY CRITERIA

We identified randomized controlled trials of patients with intrapartum moderate to thick meconium-stained amniotic fluid that evaluated the effect of amnioinfusion on adverse neonatal and maternal outcomes.

METHODS

Of note, 2 reviewers independently abstracted data and gauged study quality by assigning a modified Jadad score. Meconium aspiration syndrome constituted the primary outcome. The secondary outcomes were meconium below the cords, Apgar scores of <7 at 5 minutes, neonatal acidosis, cesarean delivery, cesarean delivery for fetal heart rate abnormalities, neonatal intensive care unit admission, and postpartum endometritis. This study calculated the odds ratios with 95% confidence intervals for categorical outcomes and weighted mean differences with 95% confidence intervals for continuous outcomes.

RESULTS

A total of 24 randomized studies with 5994 participants met the inclusion criteria. The overall odds of meconium aspiration syndrome was reduced by 67% in the amnioinfusion group (pooled odds ratio, 0.33; 95% confidence interval, 0.21-0.51). Except for postpartum endometritis, amnioinfusion was associated with a significant reduction in all secondary outcomes.

CONCLUSION

Our study found that the use of intrapartum amnioinfusion in the setting of meconium-stained amniotic fluid significantly reduces the odds of meconium aspiration syndrome and other adverse neonatal outcomes.

Meconium-stained amniotic fluid: a risk factor for postpartum hemorrhage

Background/aim

Clinical data with respect to the impact of meconium on the risk of maternal hemorrhage are scarce. Therefore, in this study, we aimed to determine whether meconium-stained amniotic fluid (MSAF) represents a risk factor for postpartum hemorrhage (PPH) after vaginal delivery in a large unselected population.

Patients and methods

A retrospective cohort study evaluated 78,542 consecutive women who had a vaginal delivery between 24th and 44th weeks of gestation. The women who had undergone cesarean section were excluded to avoid possible bias. Postpartum blood loss was measured with graduated blood sack. Postpartum blood loss between 1,000 and 2,000 mL and >2,000 mL were classified as moderate and severe PPH, respectively.

Results

A total of 74,144 patients were available for analysis. According to the color of amniotic fluid (AF), two groups of patients were identified: MSAF (n=10,997) and clear AF (n=63,147). The rates of severe and massive PPH were found to be significantly higher in the MSAF group than that of clear AF group (OR=1.3, 95% CI: 1.2-1.5, p<0.001 and OR=2.5, 95% CI: 1.5-4.2, p<0.001). Operative vaginal delivery rate was found to be higher in the MSAF group than that of clear AF group, but the difference was only borderline significant (OR=1.5, 95% CI: 1.0-2.2, p=0.05). There were no significant differences between the MSAF and the clear AF groups with respect to episiotomies, second- or third-degree perineal tears, vaginal-perineal thrombus, cervical lacerations, vaginal births after cesarean section, twin deliveries, and placental retention rates.

Conclusion

To the best of our knowledge, this is the first clinical study that has investigated the role of MSAF as a risk factor for PPH after vaginal delivery in an unselected population. Our results suggest that MSAF is significantly associated with higher risk of moderate and severe PPH than clear AF.

Amnioinfusion for meconium-stained liquor in labour

BACKGROUND

Amnioinfusion is thought to dilute meconium present in the amniotic fluid and so reduce the risk of meconium aspiration.

OBJECTIVES

To assess the effects of amnioinfusion for meconium-stained liquor on perinatal outcome.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 December 2013).

SELECTION CRITERIA

Randomised trials comparing amnioinfusion with no amnioinfusion for women in labour with moderate or thick meconium staining of the amniotic fluid.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed eligibility and trial quality, and extracted data.

MAIN RESULTS

Fourteen studies of variable quality (4435 women) are included.Subgroup analysis was performed for studies from settings with limited facilities to monitor the baby's condition during labour and intervene effectively, and settings with standard peripartum surveillance.Settings with standard peripartum surveillance: there was considerable heterogeneity for several outcomes. There was no significant reduction in the primary outcomes meconium aspiration syndrome, perinatal death or severe morbidity, and maternal death or severe morbidity. There was a reduction in caesarean sections (CSs) for fetal distress but not overall. Meconium below the vocal cords diagnosed by laryngoscopy was reduced, as was neonatal ventilation or neonatal intensive care unit admission, but there was no significant reduction in perinatal deaths or other morbidity. Planned sensitivity analysis excluding trials with greater risk of bias resulted in an absence of benefits for any of the outcomes studied.Settings with limited peripartum surveillance: three studies were included. In the amnioinfusion group there was a reduction in CS for fetal distress and overall; meconium aspiration syndrome (three studies, 1144 women; risk ratio (RR) 0.17, 95% confidence interval (CI) 0.05 to 0.52); perinatal mortality (three studies, 1151 women; RR 0.24, 95% CI 0.11 to 0.53) and neonatal ventilation or neonatal intensive care unit admission. In one of the studies, meconium below the vocal cords was reduced and, in the other, neonatal encephalopathy was reduced.

AUTHORS' CONCLUSIONS

Amnioinfusion is associated with substantive improvements in perinatal outcome only in settings where facilities for perinatal surveillance are limited. It is not clear whether the benefits are due to dilution of meconium or relief of oligohydramnios.In settings with standard peripartum surveillance, some non-substantive outcomes were improved in the initial analysis, but sensitivity analysis excluding trials with greater risk of bias eliminated these differences. Amnioinfusion is either ineffective in this setting, or its effects are masked by other strategies to optimise neonatal outcome.The trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion.

Amnioinfusion for meconium-stained liquor in labour

BACKGROUND

Amnioinfusion is thought to dilute meconium present in the amniotic fluid and so reduce the risk of meconium aspiration.

OBJECTIVES

To assess the effects of amnioinfusion for meconium-stained liquor on perinatal outcome.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2009).

SELECTION CRITERIA

Randomised trials comparing amnioinfusion with no amnioinfusion for women in labour with moderate or thick meconium-staining of the amniotic fluid.

DATA COLLECTION AND ANALYSIS

Two review authors assessed eligibility and trial quality, and extracted data, independently.

MAIN RESULTS

Thirteen studies of variable quality (4143 women) are included.Subgroup analysis was performed for studies from settings with limited facilities to monitor the baby's condition during labour and intervene effectively, and settings with standard peripartum surveillance.Settings with standard peripartum surveillance: there was considerable heterogeneity for several outcomes. There was no significant reduction in the primary outcomes meconium aspiration syndrome, perinatal death or severe morbidity, and maternal death or severe morbidity. There was a reduction in caesarean sections (CSs) for fetal distress but not overall. Meconium below the vocal cords diagnosed by laryngoscopy was reduced, as was neonatal ventilation or neonatal intensive care unit admission, but there was no significant reduction in perinatal deaths or other morbidity. Planned sensitivity analysis excluding trials with greater risk of bias resulted in an absence of benefits for any of the outcomes studied.Settings with limited peripartum surveillance: two studies (855 women) were included. In the amnioinfusion group there was a reduction in CS for fetal distress and overall; meconium aspiration syndrome (RR 0.25, 95% CI 0.13 to 0.47), and neonatal ventilation or neonatal intensive care unit admission; and a trend towards reduced perinatal mortality (RR 0.37, 95% CI 0.13 to 1.01). In one of the studies, meconium below the vocal cords was reduced and, in the other, neonatal encephalopathy was reduced.

AUTHORS' CONCLUSIONS

Amnioinfusion is associated with substantive improvements in perinatal outcome only in settings where facilities for perinatal surveillance are limited. It is not clear whether the benefits are due to dilution of meconium or relief of oligohydramnios.In settings with standard peripartum surveillance, some non-substantive outcomes were improved in the initial analysis, but sensitivity analysis excluding trials with greater risk of bias eliminated these differences. Amnioinfusion is either ineffective in this setting, or its effects are masked by other strategies to optimise neonatal outcome.The trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion.

Does amnioinfusion reduce caesarean section rate in meconium-stained amniotic fluid

INTRODUCTION

The purpose of our study was to evaluate the safety and efficacy of transcervical amnioinfusion during labour complicated by meconium-stained amniotic fluid, in a setting with limited peripartum facilities, to lower the incidence of caesarean section.

METHODS

A prospective study was conducted in a teaching hospital in north India, which enrolled 292 patients admitted in labour. Patients were randomly divided into two groups after taking their consent. One group received transcervical amnioinfusion, whilst in the other group amnioinfusion was not done. Caesarean sections were performed in either group if there were foetal heart rate abnormalities (bradycardia or irregularity for 10-20 min) or slow progress of labour. The outcomes studied were the incidence of caesarean sections, duration of maternal hospital stay, maternal febrile morbidity (temperature of >38 degrees C, 24 h after delivery), low Apgar score (at 1 and 5 min), respiratory death, MAS and perinatal mortality.

RESULT

There was a statistically significant reduction in the incidence of caesarean sections in the study group compared to the control group (31 vs. 61%). Amnioinfusion was associated with improved neonatal outcome as evidenced by statistically improved Apgar score at 1 min in newborns in the study group compared to the control group (10 vs. 37.2%). Amnioinfusion during labour was not associated with any significant maternal and neonatal complications. The mean hospital stay of the mother was decreased significantly in the study group patients compared to the control group.

CONCLUSION

Transcervical amnioinfusion in labour for meconium-stained amniotic fluid is a simple, safe and easy-to-perform procedure. It can be performed safely in a setup with limited peripartum facilities, especially in developing countries, to decrease intrapartum operative intervention and reduce foetomaternal morbidity and mortality.

Meconium-stained amniotic fluid in term pregnancies-a clinical view

The objective of this study was to explore details of the clinical relationship between meconium-stained amniotic fluid (MSAF) in labour, abnormal fetal heart pattern and meconium aspiration (MA). This was a prospective study carried out in Princess Badeea Teaching hospital during a 6-month period from March to September 1997. During the study period 344 (8.5%) of the deliveries had MSAF (344 women). Continuous fetal heart monitoring was routinely used and 36 women with MSAF (10.5%) needed to be delivered by caesarean section because of fetal distress (diagnosed by abnormal fetal heart pattern) in early labour, compared with 0.95% in those with clear amniotic fluid (CAF), (P <0.00001). Many infants in the MSAF group had a low Apgar score and required ventilation at birth. Nineteen infants (5.5%) developed MA, three of whom (15.8%) died. We conclude that there is an association between MSAF, abnormal fetal heart pattern in labour and a low Apgar score and that it should be considered a high risk situation. MA a problem that occurs with particulate meconium was significantly related to abnormal fetal heart pattern and longer length of labour.

WITHDRAWN: Amnioinfusion for meconium-stained liquor in labour

BACKGROUND

Amnioinfusion aims to prevent or relieve umbilical cord compression during labour by infusing a solution into the uterine cavity. It is also thought to dilute meconium when present in the amniotic fluid and so reduce the risk of meconium aspiration. However, it may be that the mechanism of effect is that it corrects oligohydramnios (reduced amniotic fluid), for which thick meconium staining is a marker.

OBJECTIVES

The objective of this review was to assess the effects of amnioinfusion for meconium-stained liquor on perinatal outcome.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register (October 2001) and the Cochrane Controlled Trials Register (Issue 3, 2001) were searched.

SELECTION CRITERIA

Randomised trials comparing amnioinfusion with no amnioinfusion for women in labour with moderate or thick meconium-staining of the amniotic fluid.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed by one reviewer.

MAIN RESULTS

Twelve studies, most involving small numbers of participants, were included. Under standard perinatal surveillance, amnioinfusion was associated with a reduction in the following: heavy meconium staining of the liquor (relative risk 0.03, 95% confidence interval 0.01 to 0.15); variable fetal heart rate deceleration (relative risk 0.65, 95% confidence interval 0.49 to 0.88); and reduced caesarean section overall (relative risk 0.82, 95% confidence interval 0.69 to 1.97). No perinatal deaths were reported. Under limited perinatal surveillance, amnioinfusion was associated with a reduction in the following: meconium aspiration syndrome (relative risk 0.24, 95% confidence interval 0.12 to 0.48); neonatal hypoxic ischaemic encephalopathy (relative risk 0.07, 95% confidence interval 0.01 to 0.56) and neonatal ventilation or intensive care unit admission (relative risk 0.56, 95% confidence interval 0.39 to 0.79); there was a trend towards reduced perinatal mortality (relative risk 0.34, 95% confidence interval 0.11 to 1.06).

AUTHORS' CONCLUSIONS

Amnioinfusion is associated with improvements in perinatal outcome, particularly in settings where facilities for perinatal surveillance are limited. The trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion.

Meconium-stained amniotic fluid and meconium aspiration syndrome: a prospective study

BACKGROUND

The incidence of meconium aspiration syndrome (MAS), associated perinatal factors, morbidity and deaths varies widely. This study aimed to assess the perinatal attributes and morbidity associated with MAS.

METHODS

Over a 2-year period, all neonates born through meconium-stained amniotic fluid (MSAF) were observed for respiratory distress (RD). Birth details, chest radiograph (CXR) and clinical course were documented. Neonates with consistent CXR findings whose RD could not otherwise be explained were defined as MAS.

RESULTS

Of 409 neonates born through MSAF, meconium was thick in 196 (47.9%). Fifty-five (13.4%) had RD and 45 (11.3%) were consistent with MAS. Six (1.5%) neonates died. Mean (SD) birthweight and gestation of MAS infants were 2721.9 (510.2) g and 38.67 (1.09) weeks, respectively. About one-third were of low birthweight and 28 were born by caesarean section. On univariate analysis, caesarean delivery, meconium in the trachea and thick meconium were the significant perinatal factors for the development of MAS. On multiple regression analysis, thick meconium was the only independent factor for MAS (OR 7.08, 95% CI 3.08-16.27, p<0.001). An Apgar score of <or=6 and blood gas abnormalities were found in 44.4% and 48.9%, respectively. Air leak syndrome was observed in 12 (26.7%), persistent pulmonary hypertension in seven and severe asphyxia and late sepsis in two each. Thirteen (28.9%) required mechanical ventilation and six (13.3%) died.

CONCLUSION

MAS occurred in 11.3% of neonates born through MSAF. Thick meconium was found to be an important causative factor. Nearly one-third of infants with MAS required mechanical ventilation and 13.3% died.

Meconium stained fluid: approach to the mother and the baby

Meconium aspiration syndrome (MAS) is a common problem that most pediatricians will encounter in the delivery room and normal newborn nursery. Approximately 13% of all live births are complicated by meconium stained amniotic fluid (MSAF). MAS is defined as respiratory distress in an infant born through MSAF whose symptoms cannot be otherwise explained. Optimal care for an infant born through MSAF involves cooperation between the obstetrician and pediatrician, each with separate but imperative roles.

Intrapartum amnioinfusion for meconium-stained amniotic fluid: a systematic review of randomised controlled trials

BACKGROUND

Amnioinfusion (AI) is thought to dilute meconium when present in the amniotic fluid and so reduces the risk of meconium aspiration.

OBJECTIVES

To evaluate if AI reduces meconium aspiration syndrome (MAS) and other indicators of morbidity in babies born to women with meconium-stained amniotic fluid (MSAF).

SEARCH STRATEGY

PubMed, Medline, EMBASE, and the Cochrane Controlled Trials Register from January 1980 to May 30, 2005, using the keywords 'amnioinfusion' and 'meconium'.

SELECTION CRITERIA

Randomised trials comparing AI with no AI for women in labour with MSAF. Trial quality was evaluated using pre-established criteria.

DATA COLLECTION AND ANALYSIS

The following morbidity indicators were assessed: MAS, 5-minute Apgar score < 7, arterial cord pH < 7.2, and caesarean section. Studies were stratified according to the level of peripartum surveillance (standard versus limited). Typical relative risks (RRs) with their 95% confidence intervals were calculated for each outcome using a random effects model.

MAIN RESULTS

In clinical settings with standard peripartum surveillance, we found no evidence that AI reduced the risk of MAS (RR 0.59, 95% CI 0.28-1.25), 5-minute Apgar score < 7 (RR 0.90, 95% CI 0.58-1.41), or caesarean delivery (RR 0.89, 95% CI 0.73-1.10). In clinical settings with limited peripartum surveillance, AI appeared to reduce the risk of MAS (RR 0.25, 95% CI 0.13-0.47).

CONCLUSION

In clinical settings with standard peripartum surveillance, the evidence does not support the use of AI for MSAF. In settings with limited peripartum surveillance, where complications of MSAF are common, AI appears to reduce the risk of MAS. However, this finding requires confirmation by further studies.

Prise en charge précoce des enfants nés avec un liquide méconial: enquête dans les maternités françaises

The meconium aspiration syndrome is the first cause of respiratory distress in full term newborns. At birth, management includes systematical oropharyngeal suctioning, before and after shoulders delivery, followed by tracheal suction. During last 10 years, many trials were published which discuss again the value of this strategy.

AIM

To assess practices of the current management of births with a meconial amniotic liquid in the French maternities.

METHODS

Observational survey by written questionnaires sent to the 617 French maternities.

RESULTS

The rate of answers was of 54.3%. The incidence of the births presenting a meconial amniotic fluid was of 8.2%, complicated of meconium aspiration syndrome in 4.7%. In case of birth with presence of a meconial amniotic liquid, half of the maternities resorted systematically to oropharyngeal suctioning before shoulders delivery. A glottis exposition under laryngoscopy was practiced of principle for half of the newborn. Tracheal suctioning was achieved systematically in a quarter of the establishments. These techniques, with the exception of suctioning before clearing of the shoulders, were especially been achieved in a systematic way in the maternities of I and II A levels.

CONCLUSION

This survey shows the necessity of harmonization of the practices in France for the management of the births with a meconial amniotic liquid.

Amnioinfusion for the prevention of the meconium aspiration syndrome

BACKGROUND

It is uncertain whether amnioinfusion (infusion of saline into the amniotic cavity) in women who have thick meconium staining of the amniotic fluid reduces the risk of perinatal death, moderate or severe meconium aspiration syndrome, or both.

METHODS

We performed a multicenter trial in which 1998 pregnant women in labor at 36 or more weeks of gestation who had thick meconium staining of the amniotic fluid were stratified according to the presence or absence of variable decelerations in fetal heart rate and then randomly assigned to amnioinfusion or to standard care. The composite primary outcome measure was perinatal death, moderate or severe meconium aspiration syndrome, or both.

RESULTS

Perinatal death, moderate or severe meconium aspiration syndrome, or both occurred in 44 infants (4.5 percent) of women in the amnioinfusion group and 35 infants (3.5 percent) of women in the control group (relative risk, 1.26; 95 percent confidence interval, 0.82 to 1.95). Five perinatal deaths occurred in the amnioinfusion group and five in the control group. The rate of cesarean delivery was 31.8 percent in the amnioinfusion group and 29.0 percent in the control group (relative risk, 1.10; 95 percent confidence interval, 0.96 to 1.25).

CONCLUSIONS

For women in labor who have thick meconium staining of the amniotic fluid, amnioinfusion did not reduce the risk of moderate or severe meconium aspiration syndrome, perinatal death, or other major maternal or neonatal disorders.

Meconium passage in utero: mechanisms, consequences, and management

Meconium passage in newborn infants is a developmentally programmed event normally occurring within the first 24 to 48 hours after birth. Intrauterine meconium passage in near-term or term fetuses has been associated with fetomaternal stress factors and/or infection, whereas meconium passage in postterm pregnancies has been attributed to gastrointestinal maturation. Despite these clinical impressions, little information is available on the mechanism(s) underlying the normal meconium passage that occurs immediately after birth or during the intrauterine period of fetal development. Birth itself is a stressful process and it is possible that fetal stress-mediated biochemical events may regulate the meconium passage occurring either during labor or after birth. Aspiration of meconium during intrauterine life may result in or contribute to meconium aspiration syndrome (MAS), representing a continued leading cause of perinatal death. This article reviews aspects of meconium passage in utero, its consequences, and management.

Controversies in the treatment of meconium aspiration syndrome

MAS remains an infrequent but challenging condition confronting neonatologists. Avoidance of postterm pregnancies, improved intrapartum monitoring,and amnioinfusion have been beneficial. Studies have not demonstrated conclusively that any form of ventilation is superior to others, but strategies that recruit alveoli are desirable. Surfactant lavage or replacement may be beneficial. When hypoxic respiratory failure progresses, iNO may improve oxygenation and avoid ECMO.

Meconium stained fluid: approach to the mother and the baby

Meconium aspiration syndrome is a common problem that most pediatricians will encounter in the delivery room and normal newborn nursery. Approximately 13% of all live births are complicated by meconium-stained amniotic fluid. Like many aspects of the perinatal period, optimal care of an infant born through meconium-stained amniotic fluid involves collaboration between obstetrician and pediatrician, each with separate but important roles. As always, effective communication and advanced preparation and anticipation of potential problems form the cornerstone of this partnership. Together the health of infants may be improved.

Simultaneous use of intrapartum fetal pulse oximetry and amnioinfusion in meconium stained amniotic fluid

OBJECTIVE

Fetal pulse oximetry is a minimally invasive, simple technique which continuously helps to reflect in utero well-being. The presence of meconium in the amniotic fluid may be a clinical sign of fetal hypoxaemia. Amnioinfusion has a beneficial effect on the incidence of meconium aspiration syndrome (MAS), and the presence of meconium below the level of the vocal cords.

STUDY DESIGN

We studied the impact of amnioinfusion combined with fetal pulse oximetry on the incidence of meconium aspiration syndrome and operative delivery.

RESULTS

The retrospective analysis revealed that the presence of meconium below the level of vocal cords was significantly reduced. The frequency of cesarean section is decreased, however, it did not reach statistical significance.

CONCLUSION

Fetal pulse oximetry may be used in combination with amnioinfusion and cardiotocography (CTG) to reduce the risk of meconium aspiration syndrome and the number of instrumental deliveries and improve perinatal outcome.

The effects of amnioinfused solutions for meconium-stained amniotic fluid on neonatal plasma electrolyte concentrations and pH

OBJECTIVE

To determine if amnioinfused normal saline or lactated Ringer's solution in cases of meconium-stained amniotic fluid is associated with significant changes on neonatal plasma electrolyte concentrations or pH.

STUDY DESIGN

This was a prospective randomized study using normal saline or lactated Ringer's solution for amnioinfusion in women with thick meconium in the amniotic fluid. The control group was composed of women with clear amniotic fluid not receiving amnioinfusion. Cord blood arterial sampling was analyzed for sodium, potassium, and chloride plasma concentrations and pH. The sample sizes allowed for an alpha of 0.05 and power of 0.80.

RESULTS

We evaluated 61 cases (20 normal saline solution, 20 lactated Ringer's solution, and 21 control). No significant differences in cord blood arterial plasma concentrations of sodium (p=0.43), potassium (p=0.21), chloride (p=0.68), and pH (p=0.11) were noted.

CONCLUSION

Use of normal saline or lactated Ringer's solution for amnioinfusion in meconium-stained amniotic fluid is not associated with changes on neonatal plasma electrolyte concentrations or pH.

Amnioinfusion for meconium-stained liquor in labour

BACKGROUND

Amnioinfusion aims to prevent or relieve umbilical cord compression during labour by infusing a solution into the uterine cavity. It is also thought to dilute meconium when present in the amniotic fluid and so reduce the risk of meconium aspiration. However, it may be that the mechanism of effect is that it corrects oligohydramnios (reduced amniotic fluid), for which thick meconium staining is a marker.

OBJECTIVES

The objective of this review was to assess the effects of amnioinfusion for meconium-stained liquor on perinatal outcome.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group trials register (October 2001) and the Cochrane Controlled Trials Register (Issue 3, 2001) were searched.

SELECTION CRITERIA

Randomised trials comparing amnioinfusion with no amnioinfusion for women in labour with moderate or thick meconium-staining of the amniotic fluid.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed by one reviewer.

MAIN RESULTS

Twelve studies, most involving small numbers of participants, were included. Under standard perinatal surveillance, amnioinfusion was associated with a reduction in the following: heavy meconium staining of the liquor (relative risk 0.03, 95% confidence interval 0.01 to 0.15); variable fetal heart rate deceleration (relative risk 0.65, 95% confidence interval 0.49 to 0.88); and reduced caesarean section overall (relative risk 0.82, 95% confidence interval 0.69 to 1.97). No perinatal deaths were reported. Under limited perinatal surveillance, amnioinfusion was associated with a reduction in the following: meconium aspiration syndrome (relative risk 0.24, 95% confidence interval 0.12 to 0.48); neonatal hypoxic ischaemic encephalopathy (relative risk 0.07, 95% confidence interval 0.01 to 0.56) and neonatal ventilation or intensive care unit admission (relative risk 0.56, 95% confidence interval 0.39 to 0.79); there was a trend towards reduced perinatal mortality (relative risk 0.34, 95% confidence interval 0.11 to 1.06).

REVIEWER'S CONCLUSIONS

Amnioinfusion is associated with improvements in perinatal outcome, particularly in settings where facilities for perinatal surveillance are limited. The trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion.

Randomised trial of amnioinfusion during labour with meconium stained amniotic fluid

OBJECTIVE

To assess the effect of amnioinfusion during labour with meconium stained amniotic fluid on caesarean section rate and perinatal outcome.

DESIGN

Prospective randomised controlled study.

SETTING

A tertiary care teaching hospital in India.

POPULATION

Women in labour at term with meconium stained amniotic fluid.

METHODS

Two hundred women in labour with > or = 37 weeks gestation, single cephalic presentation with moderate or thick meconium were randomised to control and amnioinfusion groups at a 1:1 ratio. Amnioinfusion was performed using 500 mL of normal saline over a period of 30 minutes in a study group. The control group received routine care. Both groups had intermittent auscultation of fetal heart rate during labour.

MAIN OUTCOME MEASURES

The primary outcome measure was caesarean section rate. Secondary outcome measures were meconium aspiration syndrome, 1 minute and 5 minute apgar < 7, hypoxic ischaemic encephalopathy, neonatal intensive care unit admission, meconium at the level of vocal cords.

RESULTS

The caesarean section rate in the amnioinfusion group was less than the control group (RR 0.47; 95% CI 0.24-0.93). Amnioinfusion was associated with a significant decrease in the incidence of meconium at the vocal cords (P = 0.001); improvement in 1 minute apgar scores (P < 0.05), respiratory distress (P = 0.002) and fewer admissions to nursery compared with the controls. This sample size was inadequate to study the impact on meconium aspiration syndrome.

CONCLUSION

Amnioinfusion in an under resourced labour ward decreases caesarean section rates and fetal morbidity.

Meconium-stained amniotic fluid in labor: a randomized trial of prophylactic amniofusion

OBJECTIVES

To investigate the effect of amnioinfusion in women with meconium-stained amniotic fluid on the rate of cesarian sections and on neonatal morbidity.

STUDY DESIGN

A randomized controlled trial. A total of 206 women with meconium-stained amniotic fluid were assigned to receive amnioinfusion via two-way catheter or no amnioinfusion (control group). The catheter was inserted and other treatment was the same in both groups.

RESULTS

Amnioinfusion decreased the rate of cesarian sections for fetal distress (RR 0.23, 95% CI 0.07-0.79) and increased mean pH at birth (7.24+/-0.1 versus 7.21+/-0.1, P<0.05). It also decreased the frequency of variable fetal heart rate decelerations (RR 0.74, 95% CI 0.59-0.92), and of meconium below the vocal cords in neonates (RR 0.37, 95% CI 0.19-0.69).

CONCLUSIONS

Amnioinfusion improves the neonatal outcome and reduces the frequency of cesarian sections.

Risk factors for meconium aspiration syndrome in infants born through thick meconium

OBJECTIVE

To determine risk factors for meconium aspiration syndrome (MAS).

METHOD

A cohort study was conducted of 70 consecutive singleton pregnancies complicated with thick meconium-stained amniotic fluid delivered at > or = 37 weeks' gestation. Cases were randomized either for elective abdominal delivery or spontaneous vaginal delivery after 20 min of external fetal heart rate (FHR) monitoring. Risk estimation analysis for MAS was performed calculating relative risks (RR) and odds ratios (OR).

RESULTS

The presence of meconium below the vocal cords (RR=7.3, 95% CI=2.6-20.3), non-reassuring FHR tracings (RR=3.0, 95% CI=1.2-7.5), Apgar score < or = 6 at 5 min (RR=3.8, 95% CI=1.7-8.4) and an umbilical cord plasma erythropoietin (UCPer) level > 50 mlU/ml (RR=5.0, 95% CI=2.1-12.0) were found to be significant risk factors for MAS. The presence of meconium below the vocal cords (OR=33.4, 95% CI=3.6-303.7) and non-reassuring FHR tracings (OR=12.2, 95% CI=1.3-111.7) remained as significant risk factors at the end of the multivariate analysis.

CONCLUSION

Non-reassuring FHR tracings and the presence of meconium below vocal cords are associated with an increased risk for MAS in infants born through thick meconium.

Amnioinfusion for meconium-stained liquor

Amnioinfusion reduces the risk of meconium aspiration by the infants of women with thick meconium staining of the amniotic fluid. The benefits are clear in facilities with high baseline rates of meconium aspiration, and are therefore likely to outweigh the risk of uncommon but serious maternal side-effects. Larger randomized trials are needed to determine more precisely the relative risks and benefits in facilities with low baseline rates of meconium aspiration. The addition of antibiotics to the infusate has not been shown to reduce the risk of sepsis related to meconium.

Prophylactic cefazolin in amnioinfusions administered for meconium-stained amniotic fluid

OBJECTIVE

To determine if amnioinfusion with an antibiotic solution decreased the rate of clinical chorioamnionitis and puerperal endometritis in patients with meconium-stained amniotic fluid.

METHODS

Patients in labor at 36 weeks of gestation or greater with singleton pregnancies and meconium-stained amniotic fluid were randomized to receive either cefazolin, 1 g/1,000 mL, of normal saline (n = 90) or normal saline (n = 93) amnioinfusion. Rates of clinically diagnosed chorioamnionitis and endometritis and of suspected and culture-proven neonatal infection were determined.

RESULTS

Between the study and control groups, the incidences of clinical chorioamnionitis (7.8% vs. 8.6%), endometritis (2.4% vs. 3.5%), aggregate intrauterine infection (10.0% vs. 11.8%), suspected neonatal infection (17.8% vs. 21.5%), and proven neonatal infection (0.0% vs. 2.2%) were not significantly different.

CONCLUSIONS

Prophylactic use of cefazolin in amnioinfusions did not significantly reduce rates of maternal or neonatal infection in patients with meconium-stained amniotic fluid.

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.

Prophylactic intrapartum amnioinfusion: a controlled retrospective study of 135 cases

OBJECTIVE

To show that intrapartum prophylactic amnioinfusion (AI) in case of oligohydramnios or particulate meconium-stained amniotic fluid could be beneficial.

STUDY DESIGN

From the first March 1993 until the 30th June 1995, 4031 women were delivered at the University Hospital of Poitiers. Patients presenting with oligohydramnios (G1) (71 patients with an amniotic fluid index below 5 cm) or a particulate meconium-stained amniotic fluid (G2) (64 patients) were included. Each group was compared to an historical control group constituted retrospectively according to the following criteria: oligohydramnios (CG1), particulate meconium-stained amniotic fluid (CG2), age, parity, gestational age and duration of labor. Statistical analysis was performed using the Student's t-test and the Fisher's exact test when appropriate with a level of significance of P less than 0.05.

RESULTS

The mean infused volume was 893 ml in G1 and 734 ml in G2. A significant difference was found in terms of cesarean section between G1 and CG1 (11.3 vs. 24.5%; P < 0.05) and of assisted deliveries for fetal distress between G2 and CG2 (12.5 vs. 23.43%; P < 0.05). No other significant difference was found between the study groups and their control for all other studied criteria. When considering more specifically the presence of meconium below the vocal cords we also could not find any significant difference between G2 and CG2 (1.6 vs. 9.4%; P = 0.05). No neonatal or maternal adverse effect happened in this short study.

COMMENT

AI is easy to perform during labour in case of oligohydramnios or particulate meconium-stained amniotic fluid. In case of oligohydramnios, a decreased rate of cesarean sections has been observed in the infused group. Considering patients with particulate meconium-stained amniotic fluid, less interventions for fetal distress and neonates with meconium below the vocal cords has been found in the infused group. Further prospective evaluation is needed to confirm these results in case of particulate meconium-stained amniotic fluid and to compare the advantage of prophylactic versus therapeutic AI performed in case of oligohydramnios and abnormal fetal heart rate.

A prospective randomized trial of two solutions for intrapartum amnioinfusion: effects on fetal electrolytes, osmolality, and acid-base status

OBJECTIVE

Our purpose was to compare the effects of intrapartum amnioinfusion with normal saline solution versus lactated Ringer's solution plus physiologic glucose on neonatal electrolytes and acid-base balance.

STUDY DESIGN

Patients undergoing amnioinfusion for obstetric indications were randomized to receive normal saline solution or lactated Ringer's solution plus physiologic glucose at standardized amnioinfusion rates. Data were collected prospectively on maternal demographics, course of labor, and maternal and neonatal outcome. Arterial cord blood was obtained for analysis of electrolytes, glucose, osmolality, lactic acid, and blood gases. Control subjects with normal fetal heart rate patterns, and clear amniotic fluid not receiving amnioinfusion were studied concurrently.

RESULTS

Data were collected on 59 patients (21 normal saline solution, 18 lactated Ringer's solution plus physiologic glucose, and 20 controls). Maternal demographics, course of labor, and neonatal outcome were similar in all three groups. Cesarean sections were performed more often in the amnioinfusion groups (33.3% for normal saline solution, 38.9% for lactated Ringer's solution plus physiologic glucose) than in the control group (5.0%), p < 0.05. Cord arterial electrolytes, glucose, osmolality, lactic acid, and blood gases were not altered by amnioinfusion with either solution.

CONCLUSION

Intrapartum amnioinfusion with normal saline solution or lactated Ringer's solution plus physiologic glucose has no effect on neonatal electrolytes or acid-base balance.

Transabdominal amnioinfusion in oligohydramnios at term before induction of labor with intact membranes: a randomized clinical trial

OBJECTIVE

Our purpose was to determine the effectiveness of transabdominal amnioinfusion before induction of labor in reducing the incidence of fetal distress in pregnancies with oligohydramnios at term.

STUDY DESIGN

Between June 1991 and September 1994 primiparous women with ultrasonographic evidence of oligohydramnios at term, intact membranes, and unripe cervix (Bishop score < or = 6), candidates for induction of labor with cervical or vaginal prostaglandin E2 gel, were randomly selected to receive transabdominal amnioinfusion (amnioinfused group, n = 39) or to proceed with direct labor induction (control group, n = 40). Inclusion criteria were (1) singleton gestation, (2) vertex presentation, (3) ultrasonographic estimation of fetal weight > or = 2500 gm, and (4) reactive nonstress test. Fetoneonatal outcome variables were compared between the two groups. Statistical analysis used contingency tables, Student t test, or Wilcoxon rank-sum tests, where applicable.

RESULTS

Amnioinfusion was successfully performed in 100% of the patients randomized for the procedure. The incidence of severely abnormal fetal heart rate tracings was significantly higher in the control than in the amnioinfused group (42% [17/33] vs 5% [2/37], relative risk 12.9, 95% confidence interval 2.4 to 56.4). The rate of cesarean sections performed for fetal distress was fivefold higher in the control group (25% [10/40] vs 5% [2/39], relative risk 4.9, 95% confidence interval 1.1 to 32.4). No bleeding complications or fetomaternal infectious morbidity were noticed.

CONCLUSION

Transabdominal amnioinfusion is a safe, effective option for the prevention of fetal distress in pregnancies with oligohydramnios at term with intact membranes and unripe cervix.

Clinical role of amnio-infusion

Amnio-infusion is a simple, yet beneficial, technique for improving pregnancy outcome. Antepartum amnio-infusion has been shown to be beneficial as an aid to enhancing ultrasonographic fetal imaging and may have a role in the administration of antibiotic therapy or the prevention of pulmonary hypoplasia. There are considerable data to support the intrapartum use of amnio-infusion in the presence of oligohydramnios, variable decelerations or meconium. Numerous prospective clinical trials have shown a significant benefit of amnio-infusion in reducing the rate of emergency caesarean section for fetal distress and complications related to meconium when used for these indications. Additional research is needed to clarify further its intrapartum role in patients with premature rupture of membranes or chorio-amnionitis.

Amnioinfusion

Abnormal amniotic fluid volume may be both the result and the cause of complications at various stages of pregnancy. This review focuses on evidence from randomised trials of the effectiveness of amnioinfusion. Attempts to prevent the development of pulmonary hypoplasia by means of transabdominal amnioinfusion to correct severe oligohydramnios in the middle trimester of pregnancy have not been evaluated by randomised trials. Long-term transcervical amnioinfusion for prelabour rupture of the membranes has shown promising results in prospective studies, but has also not been subjected to randomised evaluation. Transcervical amnioinfusion during labour is a relatively simple procedure. Normal saline is infused through an intrauterine catheter, preferably one with a catheter-tip pressure transducer. Once an adequate volume of amniotic fluid has been achieved, it is maintained by means of a slow continuous infusion or repeated bolus infusions. Amnioinfusion has been used to prevent or treat fetal heart rate (FHR) decelerations thought to be due to oligohydramnios. In several rather small randomised trials, amnioinfusion has been associated with a reduction in FHR decelerations, caesarean sections, low Apgar scores, low umbilical arterial pH values and postpartum endometritis. Amnioinfusion has also been used to dilute thick meconium-staining of the amniotic fluid. In trials for this indication, amnioinfusion has been associated with similar benefits, and in addition a reduction in meconium presence below the vocal cords, meconium aspiration syndrome and the need for neonatal ventilation. Larger trials are needed to determine whether amnioinfusion is associated with an effect on perinatal mortality, and whether complications such as umbilical cord prolapse are increased.

Classifying meconium-stained liquor: is it feasible?

Four samples each of clear and lightly (thin), moderately, and heavily (thick) meconium-stained amniotic fluid were divided in two portions and submitted twice for assessment to 20 midwives (a total of 320 case assessments). None of the midwives completely agreed with the standard assessment for more than 85 percent of the cases. When disregarding clear samples, for which there was good agreement, each of the midwives classified on average only 35.8 percent of the meconium-stained samples in the same category on each of the four occasions that they were presented to them. Calculation of kappa statistics, which express proportional agreement corrected for chance, indicated that none of the midwives showed very good agreement (kappa > 0.81) with the standard and that fewer than 10 percent showed very good agreement with themselves. The data indicate that grading the severity of meconium staining by visual assessment has such poor accuracy and precision that it cannot provide a valid basis for assigning different care policies to different degrees of meconium staining.

Amnioinfusion and the intrauterine prevention of meconium aspiration

OBJECTIVE

We evaluated the published literature on the effectiveness of amnioinfusion in reducing meconium below the vocal cords and meconium aspiration syndrome among infants born to women presenting with more than trace meconium-stained fluid.

STUDY DESIGN

A literature search was conducted to evaluate clinical trials of amnioinfusion and meconium aspiration. Trials meeting certain basic design criteria (n = 5), which included a prospective study design and blinded assessment of newborn outcome, were selected for statistical analyses estimating the average effect's size and direction. In total, 247 women with meconium-stained fluid receiving amnioinfusion and 260 women with meconium-stained fluid not receiving amnioinfusion were represented by these trials.

RESULTS

Infants born to women with meconium-stained fluid receiving amnioinfusion were less likely to have meconium below the vocal cords (odds ratio 0.13, 95% confidence interval 0.08 to 0.20) and were less likely to have meconium aspiration syndrome (odds ratio 0.20, 95% confidence interval 0.08 to 0.48) than were infants born to women with meconium-stained fluid not receiving amnioinfusion.

DISCUSSION

Amnioinfusion appears to be an effective intrauterine intervention for the prevention of meconium aspiration. Clinicians should consider implementing amnioinfusion in women presenting with thick meconium to prevent intrapartal meconium aspiration in newborns.