Assessing the optimal definition of oligohydramnios associated with adverse neonatal outcomes

Universal late pregnancy ultrasound screening to predict adverse outcomes in nulliparous women: a systematic review and cost-effectiveness analysis

BACKGROUND

Currently, pregnant women are screened using ultrasound to perform gestational aging, typically at around 12 weeks' gestation, and around the middle of pregnancy. Ultrasound scans thereafter are performed for clinical indications only.

OBJECTIVES

We sought to assess the case for offering universal late pregnancy ultrasound to all nulliparous women in the UK. The main questions addressed were the diagnostic effectiveness of universal late pregnancy ultrasound to predict adverse outcomes and the cost-effectiveness of either implementing universal ultrasound or conducting further research in this area.

DESIGN

We performed diagnostic test accuracy reviews of five ultrasonic measurements in late pregnancy. We conducted cost-effectiveness and value-of-information analyses of screening for fetal presentation, screening for small for gestational age fetuses and screening for large for gestational age fetuses. Finally, we conducted a survey and a focus group to determine the willingness of women to participate in a future randomised controlled trial.

DATA SOURCES

We searched MEDLINE, EMBASE and the Cochrane Library from inception to June 2019.

REVIEW METHODS

The protocol for the review was designed a priori and registered. Eligible studies were identified using keywords, with no restrictions for language or location. The risk of bias in studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Health economic modelling employed a decision tree analysed via Monte Carlo simulation. Health outcomes were from the fetal perspective and presented as quality-adjusted life-years. Costs were from the perspective of the public sector, defined as NHS England, and the costs of special educational needs. All costs and quality-adjusted life-years were discounted by 3.5% per annum and the reference case time horizon was 20 years.

RESULTS

Umbilical artery Doppler flow velocimetry, cerebroplacental ratio, severe oligohydramnios and borderline oligohydramnios were all either non-predictive or weakly predictive of the risk of neonatal morbidity (summary positive likelihood ratios between 1 and 2) and were all weakly predictive of the risk of delivering a small for gestational age infant (summary positive likelihood ratios between 2 and 4). Suspicion of fetal macrosomia is strongly predictive of the risk of delivering a large infant, but it is only weakly, albeit statistically significantly, predictive of the risk of shoulder dystocia. Very few studies blinded the result of the ultrasound scan and most studies were rated as being at a high risk of bias as a result of treatment paradox, ascertainment bias or iatrogenic harm. Health economic analysis indicated that universal ultrasound for fetal presentation only may be both clinically and economically justified on the basis of existing evidence. Universal ultrasound including fetal biometry was of borderline cost-effectiveness and was sensitive to assumptions. Value-of-information analysis indicated that the parameter that had the largest impact on decision uncertainty was the net difference in cost between an induced delivery and expectant management.

LIMITATIONS

The primary literature on the diagnostic effectiveness of ultrasound in late pregnancy is weak. Value-of-information analysis may have underestimated the uncertainty in the literature as it was focused on the internal validity of parameters, which is quantified, whereas the greatest uncertainty may be in the external validity to the research question, which is unquantified.

CONCLUSIONS

Universal screening for presentation at term may be justified on the basis of current knowledge. The current literature does not support universal ultrasonic screening for fetal growth disorders.

FUTURE WORK

We describe proof-of-principle randomised controlled trials that could better inform the case for screening using ultrasound in late pregnancy.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017064093.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 15. See the NIHR Journals Library website for further project information.

Prenatal exposure to isolated amniotic fluid disorders and the risk for long-term cardiovascular morbidity in the offspring

Amniotic fluid (AF) abnormalities are often associated with short-term adverse pregnancy outcomes, including cardiovascular-related. We sought to assess whether in utero exposure to AF abnormalities increases the risk for long-term cardiovascular morbidity of the offspring. We examined the incidence of cardiovascular disorders in singletons exposed and non-exposed to isolated oligohydramnios or polyhydramnios. Cardiovascular morbidity was assessed up to the age of 18 years according to a predefined set of ICD-9 codes. A Kaplan-Meier survival curves were used to compare cumulative morbidity incidence. A Cox proportional hazards model was constructed to control for confounders. During the study period, 195,943 newborns met the inclusion criteria, of which 2.0% (n = 4063) were in pregnancies diagnosed with isolated oligohydramnios and 2.9% (n = 5684) in pregnancies with isolated polyhydramnios. Children exposed to isolated AF disorders had significantly higher rates of long-term cardiovascular morbidity (p=.042). Children exposed to isolated oligohydramnios had higher cumulative incidence of cardiovascular morbidity (log-rank test p=.026) compared to unexposed children, opposing to what was demonstrate when comparing polyhydramnios vs. normal AFV (log-rank test p=.749). In the Cox regression model, while controlling for confounders, isolated oligohydramnios were found to be independently associated with long-term cardiovascular morbidity of the offspring.

Prenatal renal parenchymal area as a predictor of early end-stage renal disease in children with vesicoamniotic shunting for lower urinary tract obstruction

BACKGROUND

Vesicoamniotic shunting (VAS) and other bladder drainage techniques for fetal lower urinary tract obstruction (LUTO) have been proven to ameliorate pulmonary hypoplasia and increase survival in patients with an initial poor prognosis. Currently there are limited prognostic tools available during gestation to evaluate and predict postnatal renal function.

OBJECTIVE

The aim was to describe the prenatal growth of the renal parenchymal area (RPA) in patients with LUTO and determine its application as a predictor of renal function at one year of life.

STUDY DESIGN

The study population comprised a retrospective cohort of all infants who survived the fetal VAS to birth. Renal growth and size were measured using imageJ software to calculate the RPA in sequential prenatal ultrasounds. The parenchymal area was measured from the image of each kidney with the greatest longitudinal length. These measurements were further correlated and analyzed as a predictor of end-stage renal disease (ESRD) within the first year of life.

RESULTS

Etiologies of LUTO in the 15 male fetuses included eight posterior urethral valves, four Eagle-Barrett/prune belly syndrome, two urethral atresia, and one megacystis microcolon intestinal hypoperistalsis syndrome. All patients had patent shunts, in place, at birth. Furthermore, ultrasonographic parameters such as oligohydramnios, keyhole sign, and bladder wall thickness showed no statistical difference between groups. Renal parenchymal growth correlated with postnatal renal function in both the ESRD (r = 0.409, p = 0.018) and the non-ESRD (r = 0.657, p < 0.001) groups. Most notably, RPA during the 3rd trimester predicted ESRD with the best cut-off point determined to be 8 cm² (sensitivity, 0.714; specificity, 0.882; and positive likelihood ratio, 6.071) (Table).

DISCUSSION

Despite definitive VAS for LUTO, postnatal morbidity and mortality remain high, emphasizing the role of renal dysplasia in postnatal renal failure, in spite of urinary diversion. Renal growth statistically differs between groups in the 3rd trimester of gestation; RPA development appears stagnant in patients that developed ESRD within the first year of life. In contrast, patients that did not develop ESRD continued to have renal parenchymal growth in a linear fashion. This suggests that prenatal RPA may be predictive of postnatal ESRD.

CONCLUSIONS

RPA measurement during the prenatal period could play an important role as a non-invasive tool to predict postnatal renal function and to anticipate postnatal clinical interventions.

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.

Pregnancy Outcomes in Isolated Oligohydramnios during Second Trimester: A Case Series

Oligohydramnios is associated with increased maternal and foetal morbidities. However, some of the recent studies have shown no adverse effect of isolated oligohydramnios on perinatal outcome and recommends continuation of pregnancy. Pregnancies between 18-28 weeks with isolated Oligohydramnios were included. History and physical examination was recorded in a pre-designed proforma. All the cases received care as per the protocol. A total of seven patients were recruited of which one was a twin pregnancy with Oligohydramnios in both sacs. The mean age at presentation was 30 years. Three patients went into spontaneous explusion at an average gestational age of 22-24 weeks. One patient with twins delivered vaginally at 32 weeks. Rest were delivered by caesarean section between 34-35 weeks (indication in majority of the cases was foetal distress and cord compression). None of the babies suffered any complication and were discharged in good condition. Isolated oligohydramnios during second trimester does not increase adverse perinatal outcome significantly (but increases the caesarean section rate) and therefore, should not be an indication for termination of pregnancy.

Usefulness of fetal urine production measurement for prediction of perinatal outcomes in uteroplacental insufficiency

OBJECTIVES

To evaluate whether fetal urine production measurement is useful for predicting adverse outcomes in patients with uteroplacental insufficiency.

METHODS

We enrolled patients with uteroplacental insufficiency at 24 to 40 weeks' gestation and normal pregnancies matched for gestational age and divided them into 3 groups according to perinatal outcomes: group 1 (n = 141), a control group of normal pregnancies; group 2 (n = 29), uteroplacental insufficiency without adverse outcomes; and group 3 (n = 18), uteroplacental insufficiency with adverse outcomes. An adverse outcome was defined as 1 or more of the following: (1) cesarean delivery because of fetal distress; (2) admission to the neonatal intensive care unit; (3) cord arterial pH less than 7.15 at birth; and (4) low 5-minute Apgar score (<7). The fetal urine production rate was obtained by serial bladder volume measurement using virtual organ computer-aided analysis. For bladder volume determination, we scanned the bladder in the 3-dimensional mode and defined the bladder surface contour in the reference plane, repeating the rotation of the reference plane with an angle of 30° and determining the surface contour on each plane. Statistical methods, including the Mann-Whitney U test, Fisher exact test, χ(2) test, and Kruskal-Wallis analysis of variance, were used.

RESULTS

Group 3 had a lower mean fetal urine production rate than groups 1 and 2, whereas the urine production rate was not different between groups 1 and 2 (group 1, 49.0 mL/h; group 2, 59.4 mL/h; group 3, 20.7 mL/h; P < .001 between groups 1 and 3 and between groups 2 and 3). This difference between groups 2 and 3 remained significant after adjusting for the amniotic fluid index, umbilical artery Doppler pulsatility index, and presence of fetal growth restriction.

CONCLUSIONS

Uteroplacental insufficiency cases with adverse perinatal outcomes had a lower fetal urine production rate than those without adverse outcomes. This difference might be used to predict adverse perinatal outcomes in uteroplacental insufficiency.

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.