What is the difference between acute and chronic polyhydramnios?

Chronic polyhydramnios is the common form - excess fluid accumulates gradually over weeks (often idiopathic, or with diabetes/anomalies).

Acute polyhydramnios is rare - fluid accumulates rapidly over days, causing marked maternal discomfort, breathlessness and uterine distension; it is classically associated with monochorionic twins (twin-to-twin transfusion syndrome) and presents earlier (often mid-trimester).

Clinical relevance. Recognising acute polyhydramnios (rapid, symptomatic, often TTTS) prompts urgent assessment and amnioreduction.

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Acute versus chronic polyhydramnios

The rate of fluid accumulation distinguishes two forms.

Chronic polyhydramnios

• The common form - excess fluid accumulates gradually over weeks, usually in the third trimester.
• Often idiopathic, or associated with diabetes and fetal anomalies.
• Symptoms develop slowly and are often tolerated.

Acute polyhydramnios

• Rare - fluid accumulates rapidly over a few days.
• Causes marked maternal discomfort, breathlessness, abdominal pain and tense uterine distension.
• Tends to present earlier (mid-trimester) and is classically associated with monochorionic twin pregnancies (twin-to-twin transfusion syndrome).
• May require amnioreduction for symptom relief and is associated with a higher risk of preterm labour.