A case of a four-vessel umbilical cord: don’t stop counting at three!

Introduction

During the first full physical investigation of any neonate, close inspection of the umbilical cord is of paramount importance. This examination should include the presence of meconium staining, which can indicate the severity and duration of intrauterine fetal distress, the degree of coiling and fragility of the cord, the number of umbilical vessels present, hematomas, and the quantity of Wharton’s jelly, aberrations in either of which may give rise to a suspicion of further (congenital) pathology. The single umbilical artery is the best known numerical vessel abnormality [2, 12]. Therefore, most investigators are inclined to stop counting once three have been identified.

We present a case in which a four-vessel umbilical cord was found, which appeared to contain two arteries and two veins. Although a literature search demonstrated that this is not a rare event (1:526) [17], it appears to be little known among both obstetricians/sonographers and pediatricians.

Case report

A 26-year-old primigravida was referred to our hospital by her primary caregiver at 41 weeks and 3 days because of decreased fetal movements and oligohydramnios. Labor was induced, and she had a spontaneous vaginal delivery. Even though the labor was complicated by meconium-stained amniotic fluid, a baby boy was born in good condition: Apgar scores 8 and 9 after 1 and 5 min, respectively, birth weight of 4420 g, and umbilical cord blood gas with a pH 7.13 and base excess of −12.5 mmol/L. The presence of meconium-stained amniotic fluid constitutes, in our hospital, a reason for postnatal examination by the pediatric faculty. The examination showed no dysmorphic signs or other abnormalities during cardiopulmonary auscultation. However, the umbilical cord seemed to contain four vessels, two of which were obviously arteries and two appeared to be veins (Figure 1). The routine 20-week ultrasound scan had revealed no abnormalities. However, our guidelines state a screening for two arteries and one vein, in which case an extra vein can be overlooked. This finding was consequently reported during handover the next morning, but elicited a certain amount of surprise and disbelief. Apparently, our pediatric faculty (including neonatal specialists) was unfamiliar with this entity. We conducted a review of the literature on the subject. This yielded a substantial number of publications in which we found that some of the defects associated with a four-vessel umbilical cord can be of a potentially serious nature. Therefore, we decided to recall the infant, who had already been discharged, to our neonatal outpatient department for further evaluation on day 4 of postnatal life.

Figure 1

Umbilical cord (reproduced with permission of the parents).

Apart from age-appropriate weight loss and minor jaundice, the neonate had been well. Physical examination again showed no abnormalities. Special attention was paid to the existence of a cardiac murmur suggestive of congenital defects. In addition, a screening ultrasound examination was performed to rule out congenital defects of the heart, liver, and kidneys. At that time, intra-abdominal umbilical vessels were not seen, probably because umbilical vessels were obliterated in the transitional phase of the circulation, so a differentiation between the intrahepatic and extrahepatic variant could not be made. The child was discharged from specialist care and referred back to the primary health-care provider.

Discussion

The 5-week embryo has a right and a left umbilical vein as well as two umbilical arteries. Between the gestational ages of 6 and 7 weeks, the right umbilical vein normally becomes obliterated [15] and the left vein and both arteries remain to form the umbilical cord [16]. In some cases, this obliteration does not take place and both left and right umbilical veins persist, leading to a four-vessel umbilical cord. A persistent right umbilical vein (PRUV) is believed to be associated with first-trimester folic acid deficiency, specific teratogens such as retinoic acid, and early obstruction of the left umbilical vein from external pressure or occlusion [9].

In 1826, Mende reported a case of an abnormal route of the umbilical vein entering the right atrium, suggestive for what we now know as extrahepatic PRUV [10, 11]. Initial reports mention a high prevalence of associated abnormalities [5, 9, 13]; however, in recent years, a less serious picture has emerged [16]. Prenatal diagnosis is possible and of importance, as PRUV is associated in the literature with a wide range of congenital defects of varying severity [1, 3, 6, 8, 14, 16, 17] (Table 1), some of which could cause significant morbidity and even mortality if not discovered and treated in a timely fashion.

When more than the usual three vessels are found to be present on either ultrasound or postnatal examination, the extra lumen can be a vein (PRUV), an artery, or a remnant of the omphalomesenteric or allantoic duct [3]. Of these, PRUV is the most prevalent.

On prenatal ultrasound, two types of PRUV can be distinguished: the intrahepatic and the extrahepatic type. The intrahepatic type (75–95%) is the most common variant [6, 8] and is not usually associated with other abnormalities [1, 17]. In this variant, the aberrant right umbilical vein connects to the right portal branch and from there to the ductus venosus. There are two sonographic clues that point in this direction: the portal vein curves toward the stomach in a transverse section of the abdomen, and the fetal gallbladder is located medially to the umbilical vein [14, 17]. In the extrahepatic type, the right umbilical vein drains directly into the systemic circulation. This type is associated with absence of the ductus venosus or the left umbilical vein (in which case only three umbilical vessels are present) and can be associated with a variety of other congenital abnormalities [1].

Postnatal diagnosis is usually made during cannulation of the umbilical cord for the purpose of neonatal treatment, in which case the catheter intended for an umbilical artery ends up in the extra umbilical vein [6].

Our search of the literature yielded several studies describing an incidence for PRUV of 0.2–0.4% [4, 7]. The largest of these prospectively evaluated 8950 low-risk patients who were seen for routine second-trimester ultrasound [17]. The sonographers were specifically instructed and trained to screen for PRUV. They found an incidence of 1:526, whereby 23% of these fetuses were found to have additional malformations. Another study retrospectively analyzed 39 neonates with PRUV and found that in 7.9% of the cases where other malformations were present, karyotyping showed aneuploidy [16].

Conclusion

A four-vessel cord, most often caused by a persistent right umbilical vein, is not an extremely rare occurrence but is often overlooked during routine ultrasound because the sonographer is unaware of this possibility. Furthermore, physical examination of the neonate by midwives or medical doctors is frequently limited to searching for three umbilical vessels. The extrahepatic variant of PRUV can be associated with numerous, sometimes serious, congenital abnormalities and, if found, warrants careful further evaluation. This could include karyotyping.

When, as in our case, the diagnosis of PRUV is made postnatally, a systematic physical examination should be performed by qualified staff with extra attention being paid to the possibility of congenital heart defects.

In conclusion, regarding the umbilical cord, we recommend both antenatally and postnatally, don’t stop counting at three!