O40.2XX0 Polyhydramnios, second trimester, not applicable or unspecified

ICD-10-CM O40.2XX0: Polyhydramnios, second trimester, not applicable or unspecified

ICD-10-CM code O40.2XX0 identifies polyhydramnios, or excess amniotic fluid, during the second trimester of pregnancy. The terminology is active and classified as a pathologic function. Clinical literature notes polyhydramnios occurs in a small percentage of pregnancies, with most cases being mild and idiopathic, while a Nevada Medicaid document lists various pregnancy diagnosis codes for cesarean sections. 1 2 3

Plain-language overview

Polyhydramnios involves an excess of amniotic fluid during pregnancy, occurring in a small percentage of all pregnancies, with most cases classified as mild and frequently having no identifiable cause. 2

What this code represents

The ICD-10-CM code O40.2XX0 represents the pathologic function of polyhydramnios specifically during the second trimester, with an active record status in the 2026 version of the terminology. 1

Within the ICD-10-CM hierarchy, O40.2XX0 is a narrower concept under the parent code O40.2, which designates polyhydramnios occurring in the second trimester. 1

Documentation considerations

Clinical assessment of polyhydramnios evaluates severity and potential underlying causes, and targeted ultrasound assesses the fetus for associated conditions, including genetic abnormalities. 2

For severe polyhydramnios or identified congenital anomalies, clinical documentation may include chromosomal microarray analysis or whole genome sequencing to detect associated genetic syndromes. 2

Coverage and utilization context

A Nevada Medicaid document specifies ICD-10 diagnosis codes accepted to support medical necessity for cesarean sections, though the provided list does not explicitly include O40.2XX0. 3

What the sources add

While the terminology record defines the diagnostic code, the clinical source details disease severity distributions and management pathways, and the Medicaid source provides payer-specific operational context for procedures. 1 2 3

A research mapping resource includes the exact label for O40.2XX0 alongside related amniotic fluid and membrane disorders, distinguishing it from first, third, and unspecified trimester polyhydramnios codes. 4

Clinical context

Symptomatic severe polyhydramnios may involve uterine irritability, abdominal pain, or dyspnea, and increases the risk of postpartum hemorrhage secondary to uterine atony related to chronic uterine overdistention. 2

Sources

1. ICD-10-CM O40.2XX0 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. Bookshelf — ncbi.nlm.nih.gov; accessed 2026-07-27.
3. ICD-10 Diagnosis Codes for Cesarean Section — medicaid.nv.gov; accessed 2026-07-27.
4. Phecode 653 · ExPRSweb — csg.sph.umich.edu; accessed 2026-07-27.