Single Umbilical Artery, Supernumerary Vessels, Segmental Thinning of the Umbilical Cord Vessels and Vascular Calcifications in Umbilical Vessels
Single umbilical artery (SUA) is diagnosed in approximately 0.2–2% of all pregnancies though some series quote rates of up to 5% depending on the population studied and the mode of examination (gross examination v microscopic). Absence of the left artery is more frequent than the absence of the right artery, being identified in 73% of cases of SUA. Supernumerary vessels (SNV) are extremely rare in humans, and persistence of the right umbilical vein with patency of the left appears more commonly than an extra artery. Both SUA and SNV can be discerned on examination of cross sections of the cord. Segmental thinning of umbilical vessels occurs in approx 1.5% of all pregnancies; the aetiology is unknown. Vascular calcifications in umbilical vessels are an extremely rare lesion with two distinct patterns recognised. The aetiology varies depending on the lesion. This chapter describes the embryology of these lesions, outlines the diagnostic pitfalls and briefly references related disorders.
KeywordsUmbilical cord Single umbilical artery Supernumerary vessels Persistent right umbilical vein Segmental thinning Vascular calcification
- 1.Moore KL, Persaud TVN. The placenta and fetal membranes. In: Moore KL, Persaud TVN, editors. The developing human: clinically oriented embryology. 6th ed. Philadelphia: W.B. Saunders; 1998. p. 129–62.Google Scholar