From the Guidelines
The combination of intrauterine growth restriction (IUGR) and polyhydramnios is most commonly caused by chromosomal abnormalities, congenital infections, structural fetal anomalies, and twin-twin transfusion syndrome, which can affect both fetal growth and amniotic fluid regulation. This combination is relatively uncommon as these conditions typically have opposing pathophysiologies. The causes of combined IUGR and polyhydramnios can be broken down into several categories, including:
- Chromosomal abnormalities, particularly trisomy 18 and trisomy 13, which can affect both fetal growth and amniotic fluid regulation 1
- Congenital infections such as cytomegalovirus, toxoplasmosis, and syphilis, which can cause placental insufficiency while simultaneously affecting fetal swallowing or urination 1
- Certain structural fetal anomalies, particularly those affecting the gastrointestinal tract like esophageal atresia or duodenal atresia, which can cause polyhydramnios due to impaired fetal swallowing while a concurrent placental issue leads to IUGR 1
- Twin-twin transfusion syndrome in monochorionic twin pregnancies, which can present with IUGR in the donor twin and polyhydramnios in the recipient twin's sac 1
- Rare genetic syndromes and metabolic disorders, which can also manifest with this combination 1 When encountering this combination, a comprehensive evaluation including detailed ultrasound, amniocentesis for karyotyping and infection screening, and fetal echocardiography is essential for diagnosis and management planning, as stated in the American College of Radiology guidelines 1.
From the Research
Causes of Combined Intrauterine Growth Restriction (IUGR) and Polyhydramnios
- The combination of polyhydramnios and intrauterine growth restriction is often associated with major anomalies or chromosome abnormalities, or both, even when other sonographic abnormalities are absent 2.
- Fetal etiologies of IUGR include genetic diseases, congenital malformations, infections, multiple gestations, and placental/cord abnormalities, which can indirectly lead to placental insufficiency 3.
- Maternal etiologies of IUGR are categorized into decreased uteroplacental blood flow, reduced blood volume, decreased oxygen carrying capacity, nutrition status, teratogens, and miscellaneous causes such as short interpregnancy intervals, race, maternal age, and low socioeconomic status 3.
- Gestational diabetes is also a risk factor for IUGR, and women with gestational diabetes are at an increased risk of developing IUGR 4.
- Placental insufficiency is the most relevant clinically, as outcome could be altered by appropriate diagnosis and timely delivery, and a diagnostic approach that aims to separate IUGR resulting from placental disease from constitutionally small fetuses and those with other underlying etiologies is necessary 5.
- Five etiological groups have been identified in prenatally detected fetal growth restriction combined with polyhydramnios: chromosomal anomalies, complex malformation syndromes, isolated malformations, musculoskeletal disorders, and prenatal non-anomalous fetuses, showing significant disparities in prenatal and postnatal outcome 6.