“Tight” Nuchal Cord is an uncommon but important etiology of “Idiopathic” Polyhydramnios

Abstract The primary source of elimination of amniotic fluid is through fetal swallowing. This fluid is absorbed through the fetal gastrointestinal system and is either recycled through the kidneys or is transferred to the maternal compartment through the placenta. Therefore any condition that interfere with fetal swallowing e.g. nuchal cord can cause polyhydramios. This research is done over about 1 year duration (between 2021–2022) in three obstetric hospitals in Mosul city. The participants in the research are 1000 pregnant women with polyhydramnios in the third trimester of pregnancy. A search for the cause of polyhydramnios is done including ultrasound of fetus with a screen for nuchal cord by color Doppler ultrasound study of neck of the fetus. Fetuses with nuchal cords are followed until delivery to confirm the tightness of the cord and also to exclude other potential causes of polyhydramnios.The survey of the causes of polyhydramnios reveals that 4.1% of the idiopathic cases of polyhydramnios was due to tight nuchal cord, i.e., 1.2% of the total cases; whereas loose nuchal cords which are found accidentally during the screen was actually did not cause polyhydramnios. Nuchal cord is an uncommon but significant cause of polyhydramnios that constitute at least 4% of all cases of idiopathic polyhydramnios. Therefore it should be searched for in any pregnant woman with polyhydramnios, especially in the third trimester of pregnancy.