First trimester megacystis caused by a homozygous variant in MYL9

The finding of a distended urinary bladder (megacystis) is not uncommon in early pregnancy since first trimester ultrasound has become a fundamental element of screening policy. Fetal megacystis detected in the first trimester of pregnancy can be obstructive or non-obstructive [1] and each can be isolated or associated with other abnormalities. Determining the etiology is crucial for counselling the parents regarding the prognosis and recurrence risk and providing them with options for their future reproductive plans.