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Key Points
A variety of umbilical cord abnormalities may be sonographically detected, including short cord, lack of coiling, and cystic and vascular malformations.
Sonographic examination of the cord should include counting the number of vessels, Doppler studies, notation of coiling, and observation of the presence of cysts, masses, and vascular malformations.
Umbilical cord diameter increases with age.
The major consideration in the differential diagnosis is to determine if cord abnormality is isolated or associated with anomalies or aneuploidy.
The umbilical cord grows by tension generated by fetal movement. Short cords are associated with trisomy 21 and neuromuscular abnormalities.
Other findings associated with aneuploidy include lack of coiling, umbilical vein varix, aneurysms, and pseudocysts. Abnormal umbilical cord diameter measurements are not currently thought to be accurate markers of aneuploidy.
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A variety of umbilical cord abnormalities may be detected by prenatal sonography. These conditions include a short cord, lack of coiling, umbilical cord ulceration, a knot in the umbilical cord, umbilical artery hypoplasia, supernumerary vessels, and a variety of cystic and vascular malformations (Table 108-1) (Persutte and Hobbins, 1995). The most common abnormality, single umbilical artery, is discussed in Chapter 109.
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An absolutely short cord (<35 cm at term) occurs in 0.78% of pregnancies (Skupski et al., 1992). A relatively short cord (<54 cm at term) occurs in 16.8% of pregnancies (Skupski et al., 1992). Noncoiled umbilical vessels occur in 4.3% (38of 394 pregnancies) (Strong et al., 1993). Umbilical cord ulceration is a rare abnormality. Four umbilical vessels have been notedin 0.4% (2 of 444 pregnancies) (Aokio et al., 1997). Umbilical artery hypoplasia occurs in 1.9% of pregnancies (6 of 310 high-risk patients) (Sepulveda et al., 1992). A knot occurs in the umbilical cord in 0.3% to 2.1% of pregnancies (Sepulveda et al., 1995). Vascular malformations are rare. Tumors of the umbilical cord are extremely rare.
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Sonographic examination of the umbilical cord includes documentation of the number of vessels, Doppler velocimetry studies, and observation of coiling and looping of the cord (Figure 108-1). The umbilical cord is routinely examined ...