Polyhydramnios

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Chapter 218 Polyhydramnios

INTRODUCTION

Description: Polyhydramnios is an abnormal increase in the amount of amniotic fluid surrounding the fetus. This diagnosis is generally reserved for volumes >2 L and amniotic fluid index >24 to 25 cm. (At term, there should be about 800 mL of amniotic fluid present.) This fluid may accumulate gradually over time (chronic hydramnios) or acutely over the course of several days (more common in early pregnancy).

Prevalence: In 0.9% to 1.6% of women, some increase in amniotic fluid is seen during pregnancy (80% mild, 5% severe).

Predominant Age: Reproductive.

Genetics: No genetic pattern.

ETIOLOGY AND PATHOGENESIS

Causes: Idiopathic (two thirds), maternal diabetes, multiple gestation, fetal anomalies (50% of patients with severe hydramnios: central nervous system, gastrointestinal tract, chromosomal).

Risk Factors: Fetal anomalies that impair swallowing or alter urine production, multiple gestation (twin–twin transfusion), maternal diabetes, erythroblastosis.

MANAGEMENT AND THERAPY

Nonpharmacologic

General Measures: Evaluation. Mild conditions may be managed expectantly. If dyspnea or abdominal pain is present, hospitalization may be required.

Specific Measures: Indomethacin therapy has been shown to be of help in some patients. Therapeutic amniocentesis may be used to transiently relieve maternal symptoms and in some cases allow prolongation of the gestation. (If performed, the rate of withdrawal should be about 500 mL/hour and limited to 1500 to 2000 mL total volume.) Bed rest, diuretics, and salt and water restrictions are ineffective.

Diet: No specific dietary changes indicated.

Activity: No restriction except for those imposed by the enlarged uterus.

Patient Education: Reassurance; American College of Obstetricians and Gynecologists Patient Education Pamphlet AP025 (Ultrasound Exams), AP098 (Special Tests for Monitoring Fetal Health).

Drug(s) of Choice

Indomethacin 1.5 to 3.0 mg/kg/day.

Contraindications: Aspirin-sensitive asthma, inflammatory bowel disease, or ulcers.

Precautions: Use of nonsteroidal anti-inflammatory agents has been associated with premature closure of the ductus arteriosus. This is generally transient and may be monitored by ultrasonography.

Alternative Drugs

FOLLOW-UP

Patient Monitoring: Normal health maintenance.

Prevention/Avoidance: None.

Possible Complications: Premature labor and delivery (40%), abruptio placenta, maternal pulmonary compromise, umbilical cord prolapse.

Expected Outcome: Mild to moderate increases in fluid are not associated with significant risk. Severe polyhydramnios is often associated with significant fetal anomalies. Perinatal mortality is as high as 25% to 30% in some studies. In general, the more severe the hydramnios, the greater the fetal risk.

MISCELLANEOUS

ICD-9-CM Codes: 657, 761.3 (Affecting the fetus).

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