Neonatology Book

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UrachusAka: Urachal Anomaly, Urachal Vestige, Patent Urachus, Urachal Cyst, Urachal Sinus, Vesicourachal Diverticulum

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  1. Physiology
    1. Urachus develops from Urogenital sinus
      1. Superior portion develops into bladder and urachus
      2. Inferior portion develops into urethra
    2. Urachus obliterates during month 4-5 of gestation
      1. Urachus left as fibrous cord remnant
      2. Cord stretches from bladder to Umbilicus
  2. Signs
    1. Persistent drainage from newborn Umbilicus
    2. Delayed separation of Umbilical Cord
    3. Omphalitis
  3. Urachal anomaly causes (Urachus not fully obliterated)
    1. Patent Urachus (50%)
      1. Results from complete lack of urachal involution
      2. Free communication from bladder to Umbilicus
    2. Urachal Cyst (30%)
      1. Cyst of desquamated epithelial cells
      2. Small and undetected in two thirds of cases
      3. Risk of urachal abscess with secondary peritonitis
    3. Urachal Sinus
      1. Communication with Umbilicus
    4. Vesicourachal Diverticulum (Bladder Diverticulum)
  4. Radiology: Urachal Anomaly Detection
    1. CT Abdomen (best evaluation)
    2. Abdominal Ultrasound
    3. Voiding Cystourethrogram (if umbilical discharge)
  5. References
    1. Hollinshead (1985) Anatomy, Harper and Row, p. 756
    2. Lotan (2002) Am Fam Physician 65(10):2067
    3. Razvi (2001) Pediatrics 108(2):493

Urachus (C0041916)

Definition (MSH)An embryonic structure originating from the ALLANTOIS. It is a canal connecting the fetal URINARY BLADDER and the UMBILICUS. It is normally converted into a fibrous cord postnatally. When the canal fails to be filled and remains open (patent urachus), urine leaks through the umbilicus.
Definition (NCI)(YOU-rah-kus) A fibrous cord that connects the urinary bladder to the umbilicus (navel). The urachus is formed as the allantoic stalk during fetal development and lasts through life. Also called the median umbilical ligament.
Definition (NCI)The urinary canal of the fetus; postnatally it is usually a fibrous cord but occasionally persists as a vesicoumbilical fistula. (MeSH)
ConceptsEmbryonic Structure (T018)
EnglishStructure of urachus, Urachus
Spanishestructura del uraco, uraco
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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