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OB
CMECNE

Polyhydramnios – Possible Causes and Next Steps

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Learning Objectives and CME/Disclosure Information

This activity is intended for healthcare providers delivering care to women and their families.

After completing this activity, the participant should be better able to:

1. List the causes of polyhydramnios
2. Define polyhydramnios

Estimated time to complete activity: 0.25 hours

Faculty:

Susan J. Gross, MD, FRCSC, FACOG, FACMG
President and CEO, The ObG Project

Disclosure of Conflicts of Interest

Postgraduate Institute for Medicine (PIM) requires faculty, planners, and others in control of educational content to disclose all their financial relationships with ineligible companies. All identified conflicts of interest (COI) are thoroughly vetted and mitigated according to PIM policy. PIM is committed to providing its learners with high quality accredited continuing education activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of an ineligible company.

The PIM planners and others have nothing to disclose. The OBG Project planners and others have nothing to disclose.

Faculty: Susan J. Gross, MD, receives consulting fees from Cradle Genomics, and has financial interest in The ObG Project, Inc.

Planners and Managers: The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.

Method of Participation and Request for Credit

Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from Dec 31 2017 through Jan 25 2023, participants must read the learning objectives and faculty disclosures and study the educational activity.

If you wish to receive acknowledgment for completing this activity, please complete the test and evaluation. Upon registering and successfully completing the test with a score of 100% and the activity evaluation, your certificate will be made available immediately.

Joint Accreditation Statement

In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Physician Continuing Medical Education

Postgraduate Institute for Medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Continuing Nursing Education

The maximum number of hours awarded for this Continuing Nursing Education activity is 0.2 contact hours.

Read Disclaimer & Fine Print

WHAT IS IT?

The term polyhydramnios, also known as hydramnios, refers to an excessive amount of amniotic fluid. The primary sources of amniotic fluid are fetal urine production, fetal lung fluid and fetal oral and nasal secretions. The main routes of amniotic fluid removal are fetal swallowing and absorption via the intramembranous pathway.

Incidence and Causes

  • The overall incidence is 0.2-2.0 % of pregnancies
    • More common in twins, likely due to complications of monochorionic placentation
  • Idiopathic polyhydramnios will occur in approximately 1% of pregnancies
  • Causes of polyhydramnios are many and account for varying percentages of cases:
    • Idiopathic polyhydramnios (50-60%)
    • Congenital anomalies and genetic disorders (8-45%)
    • Maternal diabetes (5-26%)
    • Multiple gestation (8-10%)
    • Fetal anemia (1-11%)

Measurement

  • Two commonly used sonographic measurements that suggest an increased volume of amniotic fluid include (Grade 2C)
    • Amniotic fluid index (AFI) of ≥24 cm based on a total measurement of 4 different quadrants

OR

    • A single deepest pocket (SDP) of ≥8 cm, measured by holding the ultrasound transducer perpendicular to the floor in the sagittal plane
  • SMFM states in the consult series (see ‘Learn More – Best Practices’ below) that polyhydramnios can be defined by either AFI or SDP using the above parameters, but also recommends use of SDP in the 3rd trimester (see ‘Related ObG Topics’ below)
  • ACOG states that “best available evidence supports using the deepest vertical pocket method of measurement because it leads to fewer interventions with no increase in poor perinatal outcomes compared with use of the AFI”
  • Severity
    • Mild AFI: 24.0-29.9 cm or SDP 8-11 cm
    • Moderate AFI: 30.0-34.0 cm or SDP 12-15 cm
    • Severe AFI: ≥35 cm or SDP ≥16 cm
  • Recommended AFI technique
    •  Amniotic fluid pocket must be ≥1 cm wide
    • Measured pocket(s) should not contain fetal parts or loops of umbilical cord
      • Color Doppler can be used to identify cord
  • Increasing severity of polyhydramnios correlates with an increased risk of perinatal mortality and congenital abnormalities

KEY POINTS:

  • Idiopathic polyhydramnios is a diagnosis of exclusion
    • At diagnosis, refer for anatomic survey and work up to rule out alloimmunization, congenital infection, diabetes and other causes
    • Alert patient that even with a full and thorough ‘negative’ work-up, and underlying cause may be identified following delivery
  • Assess fetal growth
    • Association between macrosomia and polyhydramnios
    • IUGR may be related to single gene or chromosomal anomaly such trisomy 13 or 18
  • Rescreening for diabetes (data limited)
    • Consider if polyhydramnios identified in the 3rd trimester or more than 1 month since diabetes screen
  • Severe polyhydramnios
    • Especially if early in pregnancy, should be considered concerning and generate a referral to high-risk and genetic specialists
      • Detailed medical and family history is required
    • SMFM recommends delivery at a specialized, tertiary care unit (GRADE 1C)

Antepartum Management

  • Amniocentesis
    • No data to support amniocentesis specifically for isolated polyhydramnios
    • However, additional findings such as altered growth or movement may involve offering invasive testing to determine underlying cause
    • Note: ACOG/SMFM guidelines state that invasive testing should be made available to all women
  • Amnioreduction
    • SMFM recommends against amnioreduction except in the presence of severe polyhydramnios and (GRADE 1C)
      • Severe maternal discomfort and/or
      • Dyspnea
  • Indomethacin
    • Not recommended for the sole purpose of decreasing amniotic fluid (GRADE 1B)
    • Increased neonatal risks including
      • Decreased neonatal (preterm) urine output and elevated
        serum creatinine
      • Intraventricular hemorrhage | Periventricular leukomalacia | Necrotizing enterocolitis
  • Serial growth scans
    • SMFM suggests that “antenatal fetal surveillance is not required for the sole indication of mild idiopathic polyhydramnios” (GRADE 2C)
  • Induction vs Spontaneous Labor (GRADE 1C)
    • SMFM recommends that labor be allowed to occur spontaneously in the case of mild idiopathic polyhydramnios
    • Do not induce <39 weeks gestation without indication
    • Mode of delivery based on obstetrical indications
  • Timing of delivery (mild, idiopathic)
    • 39w0d – 40w6d

Intrapartum Management

  • Data to support higher risk for dysfunctional labor and cesarean section
  • Determine fetal presenting part on admission to L&D
    • Clinical or ultrasound
    • External cephalic version for nonvertex presentation may be considered if patient meets criteria and no contraindications
  • Amniotomy
    • “Controlled” amniotomy for moderate or severe polyhdramnios has been suggested, to be performed in the OR using spinal or pudendal block
    • Note: No evidence that this approach is advantageous
  • PPH
    • Increased risk for PPH
    • Uterotonics should be available in the delivery room
  • Risk of structural anomalies/genetic syndromes
    • Even if no antenatal diagnosis available, pediatric support should be available for any degree of polyhydramnios

Learn More – Primary Sources:

SMFM Consult Series #46 : Evaluation and Management of Polyhydramnios

ACOG/SMFM Committee Opinion 831: Medically Indicated Late-Preterm and Early-Term Deliveries

ACOG Practice Bulletin No. 175: Ultrasonography in Pregnancy

Single Deepest Vertical Pocket or Amniotic Fluid Index as Evaluation Test for Predicting Adverse Pregnancy Outcome (SAFE Trial): A Multicenter, Open-label, Randomized Controlled Trial

Locate a genetic counselor or genetics services:

Genetic Services Locator-ACMG

Genetic Services Locator-NSGC

Genetic Services Locator-CAGC

Locate a Maternal Fetal Medicine Specialist

Maternal Fetal Medicine Specialist Locator-SMFM

Take a post-test and get CME credits

TAKE THE POST TEST

2nd Trimester Ultrasound Reference Library, Now Available on Your Phone with ObGFirst

Learn More  »

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Related ObG Topics:

Practical obstetrics info for your women's healthcare practice
Duodenal Atresia – When the “Double Bubble” is Observed on Fetal Ultrasound
Outcomes of Normal oGCT with Polyhydramnios and/or Increased Fetal Growth
SMFM and Choosing Wisely: Practices That Doctors and Patients Should Question
Practical obstetrics info for your women's healthcare practice

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OBG Project CME requires a modern web browser (Internet Explorer 10+, Mozilla Firefox, Apple Safari, Google Chrome, Microsoft Edge). Certain educational activities may require additional software to view multimedia, presentation, or printable versions of their content. These activities will be marked as such and will provide links to the required software. That software may be: Adobe Flash, Apple QuickTime, Adobe Acrobat, Microsoft PowerPoint, Windows Media Player, or Real Networks Real One Player.

Disclosure of Unlabeled Use

This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. The planners of this activity do not recommend the use of any agent outside of the labeled indications.

The opinions expressed in the educational activity are those of the faculty and do not necessarily represent the views of the planners. Please refer to the official prescribing information for each product for discussion of approved indications, contraindications, and warnings.

Disclaimer

Participants have an implied responsibility to use the newly acquired information to enhance patient outcomes and their own professional development. The information
presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patient’s conditions and possible contraindications and/or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities.

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