Addition of Color Doppler Sonography for Detection of Amniotic Fluid Disturbances and Its Implications on Perinatal Outcomes

Historical Assessment, Practical Management, and Future Recommendations for Abnormal Amniotic Fluid Volumes

Objective: The purpose of this review is to examine the evidence that defines normal and abnormal amniotic fluid volumes (AFVs) and current recommendations on the management of abnormalities of AFV. Methods: The studies establishing normal actual AFVs and the ultrasound estimates used to identify normal and abnormal AFVs were evaluated. Recommendations from national and international organizations were reviewed for guidance on the definitions and management of abnormal AFVs. Results: A timeline of the development of the thresholds that define abnormal AFVs was created. Recommendations from 13 national and international guidelines were identified, but the definitions and management recommendations for abnormal AFVs varied considerably between groups. An algorithm for the management of oligohydramnios and polyhydramnios was developed. Knowledge gaps and the structure of future studies were examined. Conclusions: Assessment of AFV is performed multiple times per day in antenatal clinics and hospitals. Current recommendations on defining and managing abnormal AFVs differ between national and international organizations. We have proposed algorithms to assist in the management of abnormal AFVs until further studies can be undertaken.

Evidence for overdiagnosis in noncancer conditions was assessed: a metaepidemiological study using the 'Fair Umpire' framework

OBJECTIVES

To evaluate the strength of the evidence for, and the extent of, overdiagnosis in noncancer conditions.

STUDY DESIGN AND SETTING

We systematically searched for studies investigating overdiagnosis in noncancer conditions. Using the 'Fair Umpire' framework to assess the evidence that cases diagnosed by one diagnostic strategy but not by another may be overdiagnosed, two reviewers independently identified whether a Fair Umpire-a disease-specific clinical outcome, a test result or risk factor that can determine whether an additional case does or does not have disease-was present. Disease-specific clinical outcomes provide the strongest evidence for overdiagnosis, follow-up or concurrent tests provide weaker evidence, and risk factors provide only weak evidence. Studies without a Fair Umpire provide the weakest evidence of overdiagnosis.

RESULTS

Of 132 studies, 47 (36%) did not include a Fair Umpire to adjudicate additional diagnoses. When present, the most common Umpire was a single test or risk factor (32% of studies), with disease-specific clinical outcome Umpires used in only 21% of studies. Estimates of overdiagnosis included 43-45% of screen-detected acute abdominal aneurysms, 54% of cases of acute kidney injury, and 77% of cases of oligohydramnios in pregnancy.

CONCLUSION

Much of the current evidence for overdiagnosis in noncancer conditions is weak. Application of the framework can guide development of robust studies to detect and estimate overdiagnosis in noncancer conditions, ultimately informing evidence-based policies to reduce it.

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.

Moderate-to-Severe Polyhydramnios: Cutoffs for Deepest Vertical Pocket Corresponding to Amniotic Fluid Index

OBJECTIVE

Society for Maternal-fetal medicine Consult Series (#46) states "antenatal fetal surveillance is not required for mild idiopathic" polyhydramnios defined as amniotic fluid index (AFI) of 24 cm or a deepest vertical pocket (DVP) between 8 and 11 cm. The objective of this study was to determine the cutoff for DVP which correlates with AFI ≥ 30 cm.

METHODS

This retrospective study of singleton third trimester ultrasounds included a study group randomly divided into test and validation. In the test group, DVP cutoffs correlating with AFI ≥ 30 cm which was used to define moderate-severe polyhydramnios were calculated in two ways, rounded to the nearest whole number: 1) a receiver operating curve and Youden's J statistic (DVP-Youden) and 2) calculation of the DVP percentile that corresponded with AFI of 30 cm (DVP-Percentile). Using the validation group, diagnostic characteristics were DVP-Youden and DVP-Percentile for diagnosis of AFI ≥ 30 cm and were compared against SMFM cutoffs (DVP-SMFM).

RESULTS

Seventy one thousand eight hundred and ninety three ultrasound exams in the 3rd trimester had assessment of AFI and DVP. Moderate-severe polyhydramnios occurred in 286 (1.2%) in test group and 571 (1.2%) in validation group. AFI of 30 cm corresponded to the 98.9th percentile, which in turn correlated to a DVP of 10 cm (DVP-Percentile). The calculated cutoff for moderate-severe polyhydramnios was 8 cm for DVP-Youden.

CONCLUSION

Using 8.0 cm rather than 12.0 cm increased the detection of moderate-severe polyhydramnios to 100% with a false positive rate under 5%. For those utilizing DVP for amniotic fluid evaluation, identification of a DVP ≥ 8.0 cm should prompt further evaluation with complete AFI.

Evaluating the correlation between amniotic fluid volume and estimated fetal weight in healthy pregnant women

OBJECTIVES

The establishment of cut-offs for normal amniotic fluid volume (AFV) is valuable to predict perinatal outcomes. However, the most common methods to measure AFV are not accurate enough. It is important to understand factors that may be able to increase the accuracy of the calculation of AFV cut-off values. The objective of this study was to verify the correlation between AFV and estimated fetal weight (EFW).

METHODS

Records from almost 7,000 patients between 2012 and 2017 were accessed through hospital databases. The AFV measurements included in our analysis were obtained using the maximum vertical pocket technique.

RESULTS

AFV was positively correlated with EFW in the overall, male and female samples; however, the magnitude of the association was small (0.1

CONCLUSIONS

The incorporation of EFW together with other factors (e.g., gestational age, fetus sex) may increase the accuracy of the AFV cut-offs calculation and, ultimately, reduce morbidity.

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Key Words

• amniotic fluid
• estimated fetal weight
• maximum vertical pocket
• pregnancy complications

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MESH Headings

• Amniotic Fluid/diagnostic imaging
• Female
• Fetal Weight
• Gestational Age
• Humans
• Male
• Pregnancy
• Pregnant Women
• Prenatal Care
• Ultrasonography, Prenatal

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Affiliation(s)

Sara C S Souza OMNI Research Group, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
Katherine Kim OMNI Research Group, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
Alysha L J Dingwall-Harvey OMNI Research Group, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
Romina Fakhraei OMNI Research Group, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada
Yan Liao OMNI Research Group, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
Laura M Gaudet OMNI Research Group, Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada Department of Obstetrics and Gynecology, Kingston Health Sciences Center, Kingston, Canada Department of Obstetrics and Gynecology, Queen's University, Kingston, Canada

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Semiquantitative Assessment of Amniotic Fluid Among Individuals With and Without Diabetes Mellitus

OBJECTIVE

To compare the rate and severity of abnormal amniotic fluid volumes (oligohydramnios or polyhydramnios), as well as the distribution of amniotic fluid levels, in pregnancies with and without diabetes.

METHODS

We performed a retrospective cohort study of singleton nonanomalous pregnancies receiving an ultrasound examination (USE) in the third trimester. Pregnancies were categorized into those with and without diabetes and subcategorized by diabetes type. The primary outcomes were oligohydramnios or polyhydramnios. Polyhydramnios was also examined by severity. The association between maternal diabetes status and oligohydramnios or polyhydramnios was assessed using logistic regression. In addition, we computed gestational age-specific amniotic fluid index (AFI) and deepest vertical pocket (DVP) centiles for pregnancies with and without diabetes.

RESULTS

There were 60,226 USEs from 26,651 pregnancies that met inclusion criteria. There were 3992 (15.0%) pregnancies with diabetes and 22,659 (85.0%) without diabetes. Using AFI, the rate of polyhydramnios was 10.5 versus 3.8% (odds ratio [OR] 2.95; 95% confidence interval [CI] 2.62-3.32) for pregnancies with versus without diabetes, respectively; using DVP, the rate of polyhydramnios was 13.9 versus 5.4% (OR 2.84; 95% CI 2.56-3.15). Rates of oligohydramnios were also increased in pregnancies with diabetes (3.3 versus 2.6%; OR 1.26; 95% CI 1.04-1.52). The AFI and DVP were significantly higher in the cohort with diabetes between 28 and 36 weeks.

CONCLUSION

Within our study population, pregnancies with diabetes had increased rates of oligohydramnios and polyhydramnios as well as increased gestational age-specific amniotic fluid volumes between 28 and 36 weeks. A higher prevalence of polyhydramnios was observed using DVP as compared to AFI; nevertheless, associations were similar using either method.

SMFM Consult Series #46: Evaluation and management of polyhydramnios

Polyhydramnios, or hydramnios, is an abnormal increase in the volume of amniotic fluid. Identification of polyhydramnios should prompt a search for an underlying etiology. Although most cases of mild polyhydramnios are idiopathic, the 2 most common pathologic causes are maternal diabetes mellitus and fetal anomalies, some of which are associated with genetic syndromes. Other causes of polyhydramnios include congenital infection and alloimmunization. The purpose of this document is to provide guidance on the evaluation and management of polyhydramnios. The following are Society for Maternal-Fetal Medicine recommendations: (1) we suggest that polyhydramnios in singleton pregnancies be defined as either a deepest vertical pocket of ≥8 cm or an amniotic fluid index of ≥24 cm (GRADE 2C); (2) we recommend that amnioreduction be considered only for the indication of severe maternal discomfort, dyspnea, or both in the setting of severe polyhydramnios (GRADE 1C); (3) we recommend that indomethacin should not be used for the sole purpose of decreasing amniotic fluid in the setting of polyhydramnios (GRADE 1B); (4) we suggest that antenatal fetal surveillance is not required for the sole indication of mild idiopathic polyhydramnios (GRADE 2C); (5) we recommend that labor should be allowed to occur spontaneously at term for women with mild idiopathic polyhydramnios; that induction, if planned, should not occur at <39 weeks of gestation in the absence of other indications; and that mode of delivery should be determined based on usual obstetric indications (GRADE 1C); and (6) we recommend that women with severe polyhydramnios deliver at a tertiary center due to the significant possibility that fetal anomalies may be present (GRADE 1C).