Practice patterns in the management of isolated oligohydramnios: a survey of perinatologists

Amniotic Fluid Disorders: From Prenatal Management to Neonatal Outcomes

Amniotic fluid volume assessment has become standard in the surveillance of fetal well-being, especially in high-risk pregnancies. Amniotic fluid disorders are a frequent and important topic in fetal and perinatal medicine. However, although important advances have been achieved, many important and challenging questions remain unanswered to date. An abnormally low amniotic fluid volume, referred to as oligohydramnios, has been traditionally considered a possible indicator of placental insufficiency or fetal compromise and is associated with an increased rate of obstetric interventions. An excess of amniotic fluid, referred to as polyhydramnios, may be secondary to fetal or maternal conditions and has been associated with a variety of adverse pregnancy outcomes, especially when it is severe. The ultrasonographic detection of an amniotic fluid disorder should prompt a proper workup to identify the underlying etiology. Data on the association of isolated oligohydramnios or idiopathic polyhydramnios with adverse obstetric and perinatal outcomes are conflicting. While the management of secondary oligohydramnios is usually guided by the underlying condition, the management of isolated oligohydramnios is poorly defined. Similarly, the management of idiopathic and secondary polyhydramnios is not yet standardized. There is an urgent need for randomized clinical trials to provide stronger recommendations on the management of these two common conditions.

Diagnostic Accuracy of Cerebroplacental Ratio in Prediction of Postnatal Outcomes in Oligohydramnios

BACKGROUND AND AIM

The evidence on isolated oligohydramnios (IO) patients and their postnatal outcomes are inconsistent. Recent research has clarified the connection between that IO and negative outcomes in the postnatal period. Our goal was to analyze the correlation between Doppler measurements and postnatal outcomes in oligohydramnios patients, with a focus on the cerebroplacental ratio (CPR).

METHODOLOGY

A cohort study was conducted in the Radiology Department of Khan Research Laboratories (KRL) Hospital from October 2021 to July 2022. One hundred women were chosen as the sample size. For this study, we used the Raosoft sample size calculator with a 95% confidence interval and a 5% margin of error. Both the middle cerebral artery and the umbilical artery were imaged using ultrasound, and the systolic-to-diastolic ratio and peak systolic velocity are recorded. Pulsatility index (PI) and resistive index (RI) were also calculated. If the amniotic fluid index (AFI) is less than 5 cm, the condition is known as oligohydramnios. The newborn's APGAR score was taken immediately after birth as well as after 5 minutes.

RESULTS

We have determined that, on average, mothers are 35.45 weeks/248.15 days pregnant. When compared to the reference standard, CPR diagnostic features showed a sensitivity of 92% and a specificity of 77.27. Overall diagnostic accuracy is predicted to be 93.0%, with a 93.50% positive prognosis and a 73.91% negative prognosis. The effect size for the change in APGAR scores before and after the test was -2.38 1.03, with a 95% confidence interval of -2.58 to -2.17 and a significance level of 0.00.

CONCLUSION

This study concludes that CPR is an effective screening tool and that it can be used to predict postnatal outcomes in patients with oligohydramnios. Clinical prediction rules were found to be a more effective screening tool, with a sensitivity of 92%, a specificity of 77.27%, and a diagnostic accuracy of 92.3%.

Dynamic thiol/disulphide homeostasis and ischemic modified albumin levels in isolated oligohydramnios

OBJECTIVE

Oligohydramnios is defined as amniotic fluid index in ultrasonographic measurement is less than 5 percentile according to gestational age, the amniotic fluid volume is ≤ 5 cm, or if the single deepest dial is < 2 cm. The condition of oligohydramnios that not with fetal structural/chromosomal abnormalities, intrauterine growth retardation, intrauterine infection and maternal disease is described as isolated oligohydramnios (IO). The aim of this study is to examine whether oxidative stress and reactive oxygen species (ROS) have a place in the pathophysiology of IO.

MATERIALS AND METHODS

In this prospective case-control study, a total of 126 participants were included. The patient group consisted of 65 patients who were diagnosed IO, and the control group consisted of 61 healthy normal pregnants. Native thiol (-SH), total thiol (-SH + -SS), dynamic disulfide (-SS), IMA values from maternal serum were measured and compared between groups.

RESULTS

Maternal serum -SH and -SH + -SS values were significantly lower in the IO group than in the control group (409.47 ± 55.36 μmol/L vs. 437.40 ± 48.68 μmol/L, p = 0.03 and 457.40 ± 63.01 μmol/L vs. 484.59 ± 52.75 μmol/L, p = 0.01). In the IO group when -SS/-SH and -SS/-SH + -SS ratio was found to be statistically significantly higher than control group (5.84 ± 1.1 vs 5.41 ± 0.71, p = 0.01 and 5.2 ± 0.88 vs 4.8 ± 0.58, p = 0.01), -SH/-SH + -SS ratio was significantly lower (89.56 ± 1.7 vs 90.24 ± 1.16, p = 0.01). There was no significant difference in terms of -SS value (p = 0.66). IMA value was significantly higher in the IO group than control group (0.76 ± 0.10 ABSU vs 0.68 ± 0.06, p < 0.01). It is seen as a result of ROC analysis that -SH, -SH + -SS, -SS/-SH, -SS/-SH + -SS, -SH/-SH + -SS and IMA values have a diagnostic value for IO (p < 0.05).

CONCLUSION

The thiol/disulfide balance shifted towards oxidative stress in IO compared to control group. So oxidative stress and ROS have a place in the pathophysiology of IO.

Oligohydramnios: how severe is severe?

OBJECTIVE

To investigate whether the severity of isolated oligohydramnios at term is associated with increased rates of adverse perinatal outcome.

STUDY DESIGN

A retrospective study conducted in a single medical center from 2017 to 2019. All low-risk pregnancies with incidental isolated oligohydramnios at term were included. The degree of oligohydramnios was arbitrarily classified into mild (AFI = 41-50 mm), moderate (AFI = 21-40 mm) and severe (AFI = 0-20 mm).

RESULT

A total of 610 women were included: 202 with a mild (33.1%), 287 moderate (47.0%), and 121 severe oligohydramnios (19.8%). Non-reassuring monitor requiring immediate delivery and worse composite neonatal outcome were more common among severe than mild or moderate oligohydramnios (14.0% and 6.4%, 7.3% respectively; p = .039 and 19.8%, 10.9% and 11.8%, respectively; p = .048).

CONCLUSION

Low-risk pregnancies with isolated severe oligohydramnios at term have a higher tendency toward non-reassuring fetal monitoring requiring prompt delivery and adverse neonatal outcomes, this calls for close intrapartum surveillance.

Management of isolated oligohydramnios in Korea: a questionnaire-based study of clinical practice patterns among the members of the Korean Society of Maternal Fetal Medicine

Objective

The aim of this survey was to investigate the recommendations and clinical practice patterns of the Korean Society of Maternal and Fetal Medicine (KSMFM) members, regarding management of isolated oligohydramnios (IO).

Methods

From December 2018 to February 2019, questionnaires were e-mailed to the KSMFM members at 257 institutes that are listed by the Korean Statistical Information Services (KOSIS) as suitable labor premises. Responses to the seven questions on the management of IO, from diagnosis to treatment, were evaluated.

Results

A total of 72 KSMFM members responded to this survey. Nearly all participants (90.1%) used the amniotic fluid index (AFI) as the primary method for estimating amniotic fluid volume. The majority of the participants (73.6%) believed that IO was a risk factor for adverse pregnancy outcomes, including abnormal fetal heart rate (73.6%), need for cesarean delivery (58.3%), intrauterine fetal demise (52.8%), and meconium aspiration syndrome (50%). Almost 70% of the participants believed that induction of labor might decrease perinatal morbidities, and that late-preterm to early-term period (36–38 gestational weeks) was a suitable timeframe for delivery, if the fetus was sufficiently grown and antenatal testing revealed reassuring results. Less than half of the participants (47.2%) believed that maternal oral or intravenous hydration was a useful intervention for IO management.

Conclusions

KSMFM members preferred labor induction at late-preterm to early-term, to decrease perinatal morbidity in cases of IO, although it was still uncertain whether labor induction improved the outcomes. Further prospective studies are needed regarding IO management.

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.

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.

Management of oligohydramnios in pregnancy

The finding of oligohydramnios in pregnancy is problematic. The various mechanisms that control amniotic fluid, the inability to precisely measure and quantify the amount, and the relevance of a "decreased" amount of fluid make the management of this finding unclear. Given the limited amount of data, the single deepest vertical pocket may be a better method than the amniotic fluid index to define oligohydramnios. A large prospective study is needed to develop the most optimal management recommendations, especially for idiopathic oligohydramnios at or near term.

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.