ULTRASOUND OF PATENT URACHUS

• Umbilical cord cystic mass closely related to the fetal anterior abdominal wall (1,2).
• Communication between the umbilical cord cyst and the bladder, although classical, is not always possible to document (3).
• Spontaneous resolution may be demonstrated on consecutive ultrasounds (2).
• May co-exist with an omphalocele (4).
• Color doppler may confirm that the cystic mass is not vascular as well as assessment of the adjacent umbilical vessels which may be compressed. Color flow may also assess the topographic relationship between the cystic mass and umbilical vessels.
• Separation of the umbilical (5) vessels by the patent urachus. Color doppler may demonstrate the umbilical vessels together on the same side of the cyst (5).

Video clip of Urachal Cyst that was initially thought to be a mesentric cyst

Intra-abdominal cyst at 15 weeks of gestation
Post-natal Cystogram Patent urachus. Mild vesico-ureteric reflux

REFERENCES

1. Persutte WH, Lenke RR, Krop K et.al. Antenatal diagnosis of fetal patent urachus. J Ultrasound Med 1988;7:399.
2. Persutte WH, Lenke RR. Disappearing umbilical cord masses. Are these findings suggestive of urachal anomalies? J Ultrasound Med 1990;9:547.
3. Frazier HA, Guerrieri JP, Thomas Rl et.al. The detection of a patent urachus and allantoic cyst of the umbilical cord on prenatal ultrasonography. J Ultrasound Med 1992;11:117-120.
4. Fink IJ, Filly RA. Omphalocele associated with umbilical cord allantoic cyst: Sonographic evaluation in utero. Radiology 1983;149:473.
5. Sepulveda W, Bower S, Dhillon HK et.al. Prenatal diagnosis of congenital patent urachus and allantoic cyst: The value of color flow imaging. J Ultrasound Med 1995;14:47-51.