Megabladder in the first trimester of pregnancy is defined by a size of this organ >7 mm between 11 and 13 + 6 weeks of gestation; in fetuses with bladder size >12.5 mm, the rate of hydronephrosis and oligohydramnios at this stage is higher, indicating possible abnormalities in other systems.Objective: To report the case of a female fetus that presented a corresponding clinical case with megabladder. Materials and Methods:A case of a female fetus of 14.3 weeks with a megabladder with a diameter of 40 mm is described. Results:The finding of the anomaly constitutes a negative and incompatible prognostic factor with intrauterine and postnatal life, it was also evidenced ascent of the diaphragm and thoracic content with an hydramnios. Conclusion:It is shown that it is a case of urethral atresia, for which the voluntary interruption of pregnancy is advised.