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Isolated Polyhydramnios: diagnosis should be made based on both elevated AFI and elevated MVP
Alessandro Petrecca1, Vivian Nguyen2, Lauren Bracken2
1Department of Woman and Child Health and Public Health Sciences, Fondazione Policlinico A. Gemelli IRCSS, Rome, Italy (Petrecca, Ghi).
Objective:
To evaluate which of the different sonographic definitions of isolated polyhydramnios (elevated amniotic fluid index [AFI] alone, elevated maximum vertical pocket [MVP] alone, or both elevated AFI and MVP) is best associated with adverse perinatal outcomes.
Study Design:
This retrospective case-control study included singleton pregnancies undergoing sonographic surveillance at a tertiary referral center between February 2021 and January 2026. Cases of isolated polyhydramnios identified during this time-period were compared with pregnancies with normal amniotic fluid volume from 2024. Polyhydramnios was categorized as elevated AFI only (AFI ≥24 cm), elevated MVP only (MVP ≥8 cm), or both elevated AFI and elevated MVP. Pregnancies complicated by multiple gestations, diabetes mellitus (gestational or pregestational), oligohydramnios, or fetal structural anomalies were excluded. The primary outcome was a composite adverse perinatal outcome (CAPO) including intrauterine fetal death (IUFD), neonatal intensive care unit (NICU) admission, neonatal and perinatal death. Secondary outcomes comprised each individual component of CAPO, as well as a composite adverse maternal outcome (CAMO) and multiple maternal/obstetric outcomes. Multivariable logistic regression analysis was performed to estimate adjusted odds ratios (aORs) for perinatal outcomes. Statistical significance was defined as P<.05.
Results:
A total of 1860 pregnancies were included, comprising 958 cases of isolated polyhydramnios and 902 controls. Compared with controls, pregnancies with isolated polyhydramnios had higher rates of cesarean delivery (42.2% vs 27.1%, P<.001), large-for-gestational-age neonates (18.8% vs 8.0%, P<.001), and macrosomia (11.7% vs 5.5%, P<.001). Among patients undergoing cesarean delivery, parity distribution and indications for CD were similar between groups. In multivariable analysis, only pregnancies meeting both diagnostic criteria (elevated AFI and elevated MVP) were independently associated with CAPO (aOR 1.73, 95% CI 1.14-2.60), NICU admission (aOR 1.71, 95% CI 1.13-2.60) and perinatal death (aOR 7.56, 95 % CI 1.02-56.4). In addition, isolated polyhydramnios was independently associated with higher odds of composite adverse maternal outcome (CAMO) across all diagnostic groups, including AFI-only (aOR 1.71, 95% CI 1.28-2.27, P<.001), MVP-only (aOR 1.29, 95% CI 1.03-1.62, P=.027), and both AFI and MVP (aOR 2.02, 95% CI 1.49-2.74, P<.001). Similarly, cesarean delivery remained significantly associated with polyhydramnios diagnosed by AFI only (aOR 1.98, 95% CI 1.25-3.14, P=.003), MVP only (aOR 1.43, 95% CI 1.16-1.77, P<.001), and both AFI and MVP (aOR 1.97, 95% CI 1.44-2.69, P<.001).
Conclusion:
Among pregnancies complicated by isolated polyhydramnios, adverse perinatal outcomes-perinatal death and NICU admission in particular-were increased only when both diagnostic criteria-elevated AFI and elevated MVP-were present. In contrast, regardless of the type of measurement used, polyhydramnios was independently associated with adverse maternal outcomes, driven by an increase in cesarean delivery. El resumen está disponible en Español al final del artículo.
