Acute severe polyhydramnios developing in the third trimester or at term is a rare condition. Although there are many possible fetal or maternal causes for this phenomenon, in the majority of cases a specific etiology cannot be found. We describe our imaging findings and management of a case of severe acute polyhydramnios developing at the 40 th gestational week.A 24-year-old healthy mother of two children was referred to our obstetrics department at 41+2 gestational weeks of her third pregnancy owing to very recent distention of her uterus. Her pregnancy had been uneventful, including a 22-week sonographic anomaly scan. No other screening tests were performed during pregnancy. During a visit for a routine check-up 1 week earlier, a sonogram revealed normal amniotic fluid volume and adequate gross body and breathing movements. Current sonography at admission revealed severe polyhydramnios, reaching an amniotic fluid index of 40 cm. A Doppler examination of the umbilical cord discovered multiple cord loops wrapped around the fetal neck ( Figure 1). A healthy baby was delivered by Cesarean section. The estimated amniotic fluid volume was approximately 2.5 L. The umbilical cord was tightly wrapped three times around the fetal neck, forming a bulk which limited the free movement of the neck, but no strangulation marks were evident around the baby's neck.Third-trimester or term pregnancy acute onset polyhydramnios is rare, usually mild, and not associated with structural defects 1 . However, in the severe polyhydramnios state, in 75% of cases significant fetal abnormalities are found that predominantly involve the central nervous system, gastrointestinal tract, heart and genitourinary tract 2 . Esophageal atresia often leads to polyhydramnios, usually early in the third trimester 3 . We found some circumstantial evidence in the literature that impediment to swallowing by goiters 4 , cervical teratomas 5 -7 or skin abnormalities 8 is associated with polyhydramnios. In our case, the lack of any of these abnormalities in the newborn makes it tempting to postulate that the bulky accumulation of cord loops around its neck may have limited the in-utero ability to swallow amniotic fluid. This in turn could have led to accelerated, late-onset polyhydramnios. We propose that in any case of such sudden and late development of polyhydramnios, the fetal neck area should be scanned by ultrasonography, and the presence of nuchal cord loops should be considered as a possible cause of the polyhydramnios.
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