**5. Patent urachus**

Pseudocysts are more common than true cysts and can be located anywhere along the cord; they have no epithelial lining and represent localized edema and liquefaction of Wharton's jelly (known as Wharton jelly cysts). It is rarely possible to differentiate between true cysts and pseudocysts on ultrasound imaging [50]. But differentiation between the two entities is not very important because both are associated with anomalies. Pseudocysts are more common than true cysts and they are strongly associated with chromosomal defects and other congenital anomalies, especially omphalocele, hydrops, and trisomy 18 [51]. Usually, ultrasonography monitoring is sufficient, invasive tests not being typically needed. A higher risk of fetal anomalies is associated with the following: detection of cysts in the second or third trimester, persistence after the first trimester, large size, and location near fetal or placental end. Also, trisomy 18, 13, and 21 are known to be associated, in such cases, chromosomal analysis may be warranted [52]. They might be associated with omphalocele, Meckel's diverticulum, patent urachus, and hydronephrosis. False cysts are most commonly found at the fetal end of the cord, do not have an epithelial lining and might be associated with omphalocele, patent urachus, and chromosomal anomalies [53]. Twenty percent of cord cysts, no matter what type they are, are associ-

When the umbilical cyst is detected antenatally, especially in second or third trimesters, it is recommended a detailed ultrasonographic examination of the fetus, and it should be carefully looked for any associated defects. In case of any suspicion should be done the karyotyping analysis.

They are rare benign lesions, only 12 cases reported in the literature, which may lead to adverse fetal outcomes. These tumors are the only true neoplasms of the umbilical cord which

ated with structural or chromosomal anomalies [54].

**Figure 8.** Large umbilical cyst in the second trimester.

354 Congenital Anomalies - From the Embryo to the Neonate

**4.5. Umbilical cord teratomas**

Urachus represents a vestigial structure formed by the bladder dome and the obliterated umbilical arteries. Patent urachus represents 10–15% of all urachal anomalies in the literature [58] and may lead to urination through umbilicus and infections. It is a rare condition because urachal lumen typically closes at week 17 post-conception [59]. Alterations in the morphology of the umbilical cord should extend the investigation, since there are associations with chromosomal anomalies. It has been associated with bladder exstrophy and anterior abdominal wall defects.
