Lower urinary tract obstruction (LUTO)

LUTO can lead to prenatal enlargement of the urinary bladder and obstructive uropathy affecting both kidneys. The damage to the renal parenchyma can lead to kidney failure. The impaired production or excretion of urine leads to oligohydramnios in pregnancy, which can result in impaired lung development in the fetus (lung hypoplasia). Both damage to the kidneys and lung hypoplasia are responsible for the high mortality rate of fetuses and newborns with LUTO. Postnatally, complications can include frequent urinary tract infections, micturition disorders, bladder enlargement, and secondary failure to thrive. In many cases, terminal renal failure requiring dialysis may develop.

LUTO is a rare congenital malformation with an estimated prevalence ranging from 1:5,000 to 1:8,000. It mainly affects boys. The incidence during pregnancy has been estimated at approximately 1:5,000 to 1:25,000.

LUTO represents a heterogeneous group of congenital urinary tract malformations. The most frequent causes are posterior urethral valves (PUV) or urethral atresia. In both conditions, narrowing or complete obstruction of the urethra leads to urinary outflow obstruction and accumulation of urine.

LUTO can occur as an isolated malformation or as part of a syndrome in combination with other congenital anomalies.

Prenatal findings include enlargement of the urinary bladder, bilateral obstructive uropathy, and oligohydramnios. Renal and urinary tract involvement can be detected before birth due to urinary retention and secondary organ damage.

LUTO must be differentiated from other congenital urinary tract malformations that may occur either in isolation or as part of syndromic conditions involving additional anomalies.

LUTO can be detected prenatally based on characteristic findings such as an enlarged urinary bladder, obstructive uropathy, and oligohydramnios.