Prenatal causes of an allantoic cyst with a patent urachus

Prenatal diagnosis of an allantoic cyst with a patent urachus is rare. A urological etiology can sometimes be associated with it. We report 4 cases of allantoic cyst with a patent urachus and reviewed the literature to investigate for any etiology using the keywords “allantoic cyst” and “patent urachus”. Diagnosis of an allantoic cyst with a patent urachus was established during the first or second trimester of pregnancy. In two cases, rupture of prenatal cysts occurred and in one case, we described a prenatal vesicourethral abnormality. Surgery was performed with good results and no complications. A literature review collected 12 studies (15 fetuses) with a sex ratio of 3 boys/1 girl. The cysts ruptured in 2/3 of the cases, and in half of the cases, urinary abnormalities were found before birth (enlarged bladder, bladder prolapse). At birth, one boy had posterior urethral valve (PUV) and 4 boys had a bladder prolapse. The postoperative course was uneventful. We present our series with one case showing the etiology of a patent urachus during prenatal life. Cystoscopy seems to be valuable in the post-natal diagnosis. In the literature, we found one case of PUV. Surgery was performed with good results and no complications