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.
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.
Table 108-1Abnormalities of the Umbilical Cord ||Download (.pdf) Table 108-1 Abnormalities of the Umbilical Cord
|Umbilical cord |
|Abnormal length and diameter |
|Distortional abnormalities |
|Vascular malformations |
|Abnormal vessel number |
|Abnormal vascular spiralling |
|Umbilical cord varix |
|Umbilical artery aneurysm |
|Persistent right umbilical vein |
|Wharton jelly |
|Aberrations in amount |
|Mucinous degeneration |
|Allantoic duct cysts |
|Omphalomesenteric duct cysts |
|Varix of the umbilical cord |
|Urachal cyst |
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.
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 in three locations: at the insertion site in the anterior abdominal wall of the fetus, at some point along the cord to determine the number of vessels, and at the segment floating within the cavity during assessment of amniotic fluid volume (Sepulveda et al., 1995). The umbilical cord diameter can be measured. Its diameter increases with gestational age (Ghezzi et al., 2002; Rembouskos et al., 2004). An increased umbilical cord diameter was originally thought to be a marker for aneuploidy (Ghezzi et al., 2002) but this finding was disproven in a later study (Rembouskos et al., 2004).
Color Doppler velocimetry studies showing the normal coiling of the umbilical cord.
In extremely short umbilical cords, the cord appears to be stretched tautly across the uterine cavity (Skupski et al., 1992). Color Doppler has greatly enhanced the ability to visualize abnormalities in the umbilical cord (see Figure 108-1) (Jauniaux et al., 1989). Vascular abnormalities include umbilical artery aneurysm (Siddiqui et al., 1992), umbilical vein varix (Estroff and Benacerraf, 1992; Mahony et al., 1992; Rahemtullah et al., 2001), and persistent right umbilical vein (Jeanty, 1989; Hill et al., 1994; Wolman et al., 2002). The distance between spirals (helixes) in the umbilical cord can be measured. Normally, this distance is 2 to 2.5 cm. If the distance decreases to less than 2 cm between helixes, acute torsion of the cord is possible (Collins et al., 1993). Umbilical cord knots are difficult to identify prospectively; as many as 72% of cases are missed on third trimester color Doppler studies (Sepulveda et al., 1995). Umbilical cord cysts are found in 3% of pregnancies in the first trimester; most resolve spontaneously (Weissman and Drugan 2001). When found in the second or third trimester, there is a high incidence of structural or chromosome abnormalities (Smith et al., 1996).
The major consideration in the differential diagnosis is to determine if the umbilical cord abnormality is a false-positive finding and if it is associated with other sonographically detectable abnormalities. Many umbilical cord abnormalities are descriptive. Sensitivity and specificity of diagnosis is improved by the concurrent use of Doppler studies. The differential diagnosis for umbilical cord tumors includes hemangioma and teratoma. The differential diagnosis for cystic masses includes true cysts, pseudocysts, allantoic cysts, and hematomas.
ANTENATAL NATURAL HISTORY
The umbilical cord grows by tension generated by fetal movement; Naeye (1985) has measured umbilical cord lengths of 35,779 singletons and determined that a length of at least 32 cm is necessary to prevent traction on the cord during a vaginal delivery. The majority of umbilical cord growth occurs during the first and second trimesters. Walker and Pye (1960) demonstrated that the cord length of premature babies is similar to that of full-term babies. The mean length of a full-term newborn’s umbilical cord is 60 cm. There is no correlation between umbilical cord length and parity, maternal age, maternal weight or height, presence of preeclampsia, or fetal gender, weight, length, or presenting part (Walker and Pye, 1960).
Short umbilical cords are significantly associated with low IQ values and neuromuscular abnormalities, such as the fetal akinesia deformation sequence or severe infantile spinal muscular atrophy (Naeye, 1985). In infants with trisomy 21, the average cord length is 45 cm; this is almost certainly due to in utero hypotonia, which causes decreased tension to be placed on the cord (Moessinger et al., 1982). Miller et al. (1981) studied infants with a variety of pathologic conditions. They found the most dramatically shortened cords in patients with early evidence of amnion rupture. Restriction of fetal movement was thought to be the effect of tethering by amniotic bands. The lesser degree of cord shortening seen in renal agenesis is presumably due to a later decrease in intrauterine space resulting from oligohydramnios.
Experiments on rat fetuses have confirmed that early oligohydramnios affects the cord length by limiting the intrauterine environment. Conversely, rat fetuses allowed to develop in the maternal abdomen have a cord length that is 147% greater than controls. In addition, rat fetuses with movements that are paralyzed by curare have cord lengths that are 85% of control values (Moessinger et al., 1986; Skupski et al., 1992).
Umbilical vascular coiling is established by the end of the first trimester. A sinistral (counterclockwise) rotation is present in most pregnancies (Fletcher 1993; Strong et al., 1993). The absence of the normal coiling of the umbilical cord has been identified as an antenatal risk factor for perinatal morbidity and mortality. This finding occurs in approximately 5% of fetuses (Weissman and Drugan, 2001). This so-called straight cord may be structurally weaker and more susceptible to external tension (Figure 108-2) (Strong et al., 1993). Lacro et al. (1987) noted a 10% stillbirth rate in newborns with absent umbilical coiling. In a prospective study, 38 fetuses with noncoiled umbilical vessels were identified. As compared with normal control fetuses, the noncoiled group had a significantly increased incidence of intrauterine death, preterm delivery, repetitive intrapartum fetal heart rate decelerations, operative delivery for fetal distress, meconium staining, and anatomical and karyotype abnormalities (Strong et al., 1993). Other investigators have calculated an umbilical coiling index by dividing the total number of coils observed by the length of the cord. Subjects with below the 10th percentile and above the 90th are defined as hypocoiled and hypercoiled, respectively. In one study of 635 placentas from deliveries of at least 24 weeks of gestation, Rana et al. (1995) found that subjects with hypocoiled cords had increased rates of fetal heart rate disturbances and interventional delivery. Fetuses with hypercoiled cords had a higher rate of premature delivery as compared with fetuses with normally coiled cords.
Color Doppler velocimetry studies demonstrating a straight umbilical cord. Note the lack of coiling as compared with Figure 108-1.
To our knowledge, prospective outcome studies related to a sonographic finding of umbilical cord ulceration have not yet been performed. The finding is described here because of the reported association of umbilical cord ulceration noted at birth with intestinal atresia in two infants and one stillborn fetus (Bendon et al., 1991). In two of three cases, severe in utero hemorrhage occurred from the ulcers. The intestinal atresia is the primary problem, with umbilical cord ulceration occurring as a secondary phenomenon. The following hypotheses have been proposed to account for this association: vascular reactivity, gastric reflux, and epithelial abnormalities (Bendon et al., 1991).
In one case report, an infant with four umbilical arteries and one vein was described (Beck and Naulty, 1985). The infant had multiple medical problems due to Escherichia coli sepsis, but ultimately survived with age-appropriate growth and development. There were no associated anomalies. The patient was shown to have triplication of the right umbilical artery.
Umbilical artery hypoplasia has been defined as a difference in the diameter between both umbilical arteries of >2 mm (Sepulveda et al., 1992). The umbilical arteries have discordant blood flow velocity waveforms in the absence of associated placental pathology. In one series, two of six affected fetuses with this finding had an adverse perinatal outcome (Dolkart et al., 1992). In another case report with pathologic follow-up of the umbilical cord after birth, no adverse effect was seen (Sepulveda et al., 1992).
Vascular malformations of the umbilical cord, such as umbilical vein varix and umbilical artery aneurysm, are rare. In one study, 25 cases of intra-abdominal umbilical vein varix were identified over a 10-year period (Rahemtullah et al., 2001). Follow-up information was available for 23 of 25 cases. Eleven of 23 cases (48%) had normal pregnancies, full-term deliveries, and normal neonatal outcome. Three cases (13%) had preterm deliveries, and one had Kell isoimmunization. In the remaining 8 cases (35%) structural anomalies were identified. These authors recommended that a thorough fetal survey and echocardiogram be performed if an umbilical vein varix is observed. Umbilical artery aneurysm is potentially lethal in utero because of umbilical venous compression (Siddiqui et al., 1992). One case of umbilical cord aneurysm and arteriovenous fistula has been reported in association with a case of trisomy 18 (Berg et al., 2001). Cystic dilatation of the umbilical vein has been variously associated with both an increased incidence of in utero death (Mahony et al., 1992) and a normal outcome (Estroff and Benacerraf, 1992). Umbilical cord cysts develop from the remnants of the allantois or omphalomesenteric duct (Weissman and Drugan, 2001). They are usually located near the fetal insertion end of the cord and range from 4 to 60 mm in size. Pseudocysts have no epithelial lining and represent localized edema of Wharton’s jelly (Kiran et al., 2003). Allantoic cysts originate from an extra-abdominal urachal system (Bunch et al., 2006).
When a short cord is diagnosed, detailed level II sonography is indicated to look for evidence of oligohydramnios, amniotic bands, body wall defects, neuromuscular abnormalities, and arthrogryposis. A short cord in the setting of abnormalities such as increased nuchal translucency measurement and a decreased ratio of femur to foot length may suggest trisomy 21. Fetuses with noncoiled umbilical cords may also be at increased risk for aneuploidy. In one study of 48 consecutive liveborn neonates with noncoiled umbilical vessels, four cases of trisomy (8.3%) and one case of mosaic trisomy (2.1%) were identified (Strong, 1995). However, all of these fetuses had additional anomalies detected with sonography. It is therefore unclear at present whether amniocentesis is indicated for an isolated noncoiled cord. Umbilical cord pseudocysts, if detected with other sonographic abnormalities, are strongly associated with aneuploidy and, in particular, trisomy 18 (Sepulveda et al., 1999). A good general principle is that cord abnormalities, when found with other malformations, are an indication for fetal karyotyping.
Fetuses with noncoiled umbilical cords are at increased risk for perinatal mortality; antepartum testing and early documentation of fetal lung maturity should be considered. Fetuses with evidence of bowel atresia should be monitored for sonographic findings consistent with umbilical cord ulceration and resulting hemorrhage.
Fetuses with vascular malformations such as umbilical artery aneurysm may need to be delivered as soon as lung maturity is present (Siddiqui et al., 1992). Fetuses with true knots of the umbilical cord ascertained prenatally may need to be delivered by cesarean section. In one report, a fetus with umbilical cord cysts underwent magnetic resonance imaging (MRI). The MRI suggested that the diagnosis was actually an allantoic cyst (Bunch et al., 2006).
There are no fetal interventions for umbilical cord abnormalities.
For all of the conditions discussed here, a thorough physical examination of the newborn and the umbilical cord is indicated. Umbilical cord hemangioma is associated with a high (40%) incidence of vascular birthmarks, such as port wine stains (Daniel-Spiegel et al., 2005).
In the setting of the short cord, observation of newborn movements, with particular emphasis on the neurologic examination, is important. Tables of normal values exist for the measurement of periumbilical skin length in the newborn. These standards are useful in the neonatal diagnosis of syndromes that include umbilical dysmorphology (O’Marcaigh et al., 1992).
There is no surgical treatment indicated for most umbilical cord abnormalities. Allantoic cyst is the prenatal presentation of patent urachus (Van der Bilt et al., 2003; Bunch et al., 2006). These umbilical cords are often grossly edematous from reflux of urine via the patent urachus. The cord is usually clamped well away from the edematous segment of cord. In the newborn period, the urachus can be surgically closed and cord remnants debrided away. Postnatally, the patent urachus needs to be resected.
The isolated umbilical cord findings do not need follow-up. Follow-up is indicated for associated abnormalities.
GENETICS AND RECURRENCE RISK
None of the conditions discussed, when present as an isolated finding, have implications for familial recurrence.
M Antenatal diagnosis of aberrant umbilical vessels. Gynecol Obstet Invest. 1997;43:232-–235.
CM A human umbilical cord with four arteries. Clin Pediatr (Phila). 1985;24:118-–119.
M Umbilical cord ulceration and intestinal atresia: a new association? Am J Obstet Gynecol. 1991;164:582-–586.
U Prenatal diagnosis of umbilical cord aneurysm in a fetus with trisomy 18. Ultrasound Obstet Gynecol. 2001;17:79-–81.
LF Allantoic cyst: a prenatal clue to patent urachus. Pediatr Radiol. 2006;36:1090-–1095.
CL Prenatal observation of umbilical cord abnormalities: a triple knot and torsion of the umbilical cord. Am J Obstet Gynecol. 1993;169:102-–104.
E The association of umbilical cord hemangioma with fetal vascular birthmarks. Prenat Diagn. 2005;25:300-–303.
CA Discordant umbilical arteries: ultrasonographic and Doppler analysis. Obstet Gynecol. 1992;79:59-–63.
BR Umbilical vein varix: sonographic appearance and postnatal outcome. J Ultrasound Med. 1992;11:69-–73.
H First-trimester umbilical cord diameter: a novel marker of fetal aneuploidy. Ultrasound Obstet Gynecol. 2002;19:235-–239.
D Persistent right umbilical vein: sonographic detection and subsequent neonatal outcome. Obstet Gynecol. 1994;84:923-–925.
S The use of color Doppler imaging for prenatal diagnosis of umbilical cord anomalies: report of three cases. Am J Obstet Gynecol. 1989;161:1195-–1197.
P Fetal and funicular vascular anomalies: identification with prenatal US. Radiology. 1989;173:367-–370.
Y Pseudocyst of the umbilical cord with mucoid degeneration of Wharton’s jelly. Eur J Obstet Gynecol Reprod Biol. 2003;111:91-–93.
K The umbilical cord twist: origin, direction, and relevance. Am J Obstet Gynecol. 1987;157:833-–838.
DP Varix of the fetal intra-abdominal umbilical vein: comparison with normal. J Ultrasound Med. 1992;11:73-–76.
DW Short umbilical cord: its origin and relevance. Pediatrics. 1981;67:618-–621.
DC Umbilical cordlength as an index of fetal activity: experimental study and clinical implications. Pediatr Res. 1982;16:109-–112.
et al. Umbilical cord length in Down syndrome. Am J Dis Child. 1986;140:1276-–1277.
VV Umbilical morphology: normal values for neonatal periumbilical skin length. Pediatrics. 1992;90:47-–49.
J Single umbilical artery: a clinical enigma in modern prenatal diagnosis. Ultrasound Obstet Gynecol. 1995;6:216-–229.
ME Outcome of pregnancy after prenatal diagnosis of umbilical vein varix. J Ultrasound Med. 2001;20:135-–139.
KA Adverse perinatal outcome in patients with an abnormal umbilical coiling index. Obstet Gynecol. 1995;85:573-–577.
KH Umbilical cord diameter at 11–14 weeks of gestation: relation to chromosomal defects. Ultrasound Obstet Gynecol. 2004;23:237-–239.
F Umbilical artery hypoplasia. Fetus. 1992;3:9-–12.
C Pseudocyst of the umbilical cord: prenatal sonographic appearance and clinical significance. Obstet Gynecol. 1999;93:377-–381.
NM True knot of the umbilical cord: a difficult prenatal ultrasonographic diagnosis. Ultrasound Obstet Gynecol. 1995;5:106-–108.
M Umbilical artery aneurysm: prenatal diagnosis and management. Obstet Gynecol. 1992;80:530-–533.
F Umbilical cord, short. Fetus. 1992;2:1-–2.
K The sonographic finding of persistent umbilical cord cystic masses is associated with lethal aneuploidy and/or congenital anomalies. Prenat Diagn. 1996;16:1141-–1147.
TH Trisomy among fetuses with noncoiled umbilical blood vessels. J Reprod Med. 1995;40:789-–790.
TG Non-coiled umbilical blood vessels: a new marker for the fetus at risk. Obstet Gynecol. 1993;81:409-–411.
Van Der Bilt
JD, Van Zalen
DC Prenatally diagnosed ruptured vesico-allantoic cyst presenting as a patent urachus at birth. J Urol. 2003;196:1478-–1479.CrossRef
A Sonographic findings of the umbilical cord: implications for the risk of fetal chromosomal anomalies. Ultrasound Obstet Gynecol. 2001;17:536-–541.
et al. Persistent right umbilical vein: incidence and significance. Ultrasound Obstet Gynecol. 2002;19:562-–564.