Bladder outlet obstruction, a type of lower urinary tract obstruction (LUTO), is a rare birth defect that occurs most often in males. It is a blockage of the flow of urine from the urethra, which is the tube that drains urine from the bladder and out of the body.
This blockage may cause the urine to back up in and enlarge the bladder while lowering levels of amniotic fluid. In severe cases, the lungs may not fully develop. The fetus may also have kidney damage or facial and extremity deformities.
Causes for LUTO usually are not known, although a genetic problem may be responsible in rare cases.
LUTO often is diagnosed by routine ultrasound in the second trimester of pregnancy. If the condition is suspected, other tests, including fetal MRI and echocardiogram, may be needed.
Treatment for this condition depends on the severity and location of the blockage. In some cases, a fetal shunt may help resolve LUTO