Umbilical cord anomalies: antenatal ultrasound findings and postnatal correlation

Abstract

Umbilical cord anomalies are rare. The differential diagnosis for a cystic structure around the umbilical cord and its insertion include pseudocyst, omphalomesenteric duct cyst, haemangioma, omphalocele or anterior abdominal wall defects. Although cord anomalies can be detected through antenatal ultrasound scans (US), very often a definitive diagnosis cannot be made. This may affect the management of the infant at birth. In cases where antenatal US was not diagnostic, current evidence supports the use of MRI to help in making an accurate diagnosis. We report two cases of umbilical cord anomalies. The first case was diagnosed in antenatal US as an omphalocele, but was found to be an allantoic cyst with hamartoma on postnatal diagnosis. The second case was not detected on antenatal US, and was diagnosed postnatally as a small omphalocele with vitellointestinal duct remnants.

Background

The embryonic vitellointestinal duct (VID) that connects the midgut to the yolk sac becomes narrowed at the 5th week of intrauterine life.¹ VID anomalies result from failure of obliteration of the VID at 5th–9th weeks of intrauterine life.^{1 2} Remnants of VID account for a wide variety of umbilical abnormalities. Umbilical anomalies are uncommon and often arise when embryological remnants persist or fail to completely involute.³ These umbilical anomalies can be broadly classified into VID or urachal abnormalities according to the embryological remnants contained in the umbilicus.⁴ The differential diagnosis for a cystic structure around the umbilical cord and its insertion include: pseudocyst, omphalomesenteric duct cyst, haemangioma, omphalocele or anterior abdominal wall defects.⁵ Ultrasonography allows some of these anomalies to be detected prenatally. However, a definitive diagnosis cannot be made from an antenatal ultrasound scan (US). This inability to make a definitive diagnosis may affect management of the infant at birth. We present two cases of umbilical cord anomalies, both due to the failure of complete or partial obliteration of the VID.

Case presentation

Case 1

A fetal US of a multigravida mother showed an echogenic mass at the umbilicus measuring 1.4×0.7 cm. The mass protruded from the fetal abdomen into the umbilical cord at 18 weeks of gestation, and was reported to be a small omphalocele. Parents were counselled about the postnatal management plan by the neonatologist and paediatric surgeon. She delivered a baby boy at 39 weeks gestation via normal vaginal delivery. The infant weighed 3650 g and was appropriate for gestational age. The umbilical cord was remarkably oedematous, with a large cyst at its proximal part (figure 1A–D). It was associated with a firm mass at the cord insertion below the skin, measuring 3×3 cm in diameter. An US of the abdomen at birth showed a heterogeneous, rounded and tubular area at the base of the umbilical cord. There was vascularity in the wall and appeared to be continuous with the abdominal cavity. They were thought to represent bowel loops. No extension of the urinary bladder or liver was seen within this region.

Figure 1.

Clinical photograph of an umbilical cord cyst over the anterior abdomen of a baby (A–B). A segment of the cord shows cystic distension of the cord (C). Cut section of the cord reveals a central solid grey-white area (D).

On day 1 of life, the infant underwent umbilical exploration. Intraoperatively, a widened umbilical ring with fibrofatty tissue together with few vessels and a patent urachus was noted. The urachus was traced to the bladder, ligated and buried followed by umbilicoplasty. A histological examination of the specimen showed oedematous expansion of Wharton’s jelly, with collections of thin walled blood vessels in a myxoid and fibrous stroma, and occasional scattered nerves (figure 2A–C), indicating a hamartomatous lesion. In addition, there was a focal small solid nest of epithelial cells, consistent with a remnant of the allantoic duct.

Figure 2.

Vascular proliferation in close proximity to an umbilical artery (A). A small solid nest of epithelial cells (asterisk) representing an allantoic duct remnant is present adjacent to a collection of thin-walled vessels (B). Scattered nerves (asterisks) are admixed in the vascular proliferation (C).

The infant had an uneventful recovery postoperatively.

Case 2

A male infant was born at 34 weeks of gestation at home. Fetal US scans were unremarkable. Mother reported that he cried at birth and there was no meconium staining of the amniotic fluid. Paramedics were called in and they cut and clamped his cord at 10–12 min of life, before bringing him to the hospital. On examination, the infant looked well with normal vital signs. He weighed 2410 g and was appropriate for gestational age. However, his torso and umbilical cord were both stained with meconium. Intestinal loops were also seen within the umbilical cord, with two discrete areas of perforation in the bowel wall, where meconium extruded from (figure 3). He was seen by the paediatric surgeon and a clinical diagnosis of exomphalos minor with bowel perforation was made at 5 hours of life. An abdominal X-ray showed protrusion of bowel at the anterior abdominal wall.

Figure 3.

Meconium stained umbilical cord with intestinal loops and two areas of perforation. Meconium is seen coming out through one of them.

On day 1 of life, he underwent an exploratory laparotomy. Intraoperative findings showed an exomphalos minor, containing small intestine and vitellointestinal remnant. Two small perforations of the small intestine were noted with in the umbilical cord, with intestinal content visible (figure 4). Repair of the exomphalos minor was done with resection of the VID remnant, followed by primary anastomosis.

Figure 4.

Intraoperative photo showing bowel connected through the vitello intestinal duct (arrow).

His karyotype was normal; there were no associated malformations. His postoperative period was uneventful. Histopathology showed a three-vessel umbilical cord and VID remnant with focal transmural defects consistent with perforation.

On day 4, feeds were started and he tolerated well. He recovered well and was discharged home on postoperative day 12.

Outcome and follow-up

Case 1: This infant was reviewed in the neonatal follow-up clinic at 1 year of age. His growth and development are appropriate for age.

Case 2: He had moderate to severe gastro-oesophageal reflux disease at 2 months of age, needing antireflux medications and modified formula milk. He had his medical check-up at 5 months of age. His growth and development are progressing well.

Discussion

VID anomalies occur in 2% of the newborn population.⁶ Such anomalies include: an omphalomesenteric fistula, an enterocyst, an umbilical sinus, a fibrous band connecting the intestine to the umbilicus, a patent VID (PVID) and a Meckel’s diverticulum⁷ Of these, the most common is Meckel’s diverticulum; whereas PVID is the most symptomatic anomaly.⁸

Accumulation of mucus in a portion of the VID results in the formation of an umbilical cyst. About 0.4%–3.4% of umbilical cord cysts are detected by US in the first trimester, and are classified as either true cysts or pseudocysts.⁹ True cysts usually have an epithelial lining, and include allantoic cysts and omphalomesenteric duct cysts. True cysts are less common and they are located towards the anterior abdominal wall of the fetus. If true cysts are present in the second and third trimesters, they are associated with an omphalocele or patent urachus. Pseudocysts are more common than true cysts, and are usually smaller. They may also be located anywhere along the length of the umbilical cord.^{10 11} It is difficult to differentiate them antenatally as prenatal US of cystic masses in the umbilical cord show them as similar. Therefore, a detailed morphology scan is recommended, as both types of umbilical cysts may be associated with omphalocele or other fetal anomalies.^{5 12} As umbilical cord cysts have increased association with chromosomal abnormalities like trisomy 18, karyotype analysis is warranted to rule out this lethal anomaly.¹⁰

There is paucity of data on the use of prenatal US in diagnosing VID anomalies. VID anomalies can be complicated with intestinal obstruction.¹³ Although sonographic features of intestinal obstruction such as dilated bowel loops can be visualised on the prenatal US, it is difficult to distinguish the aetiology of intestinal obstruction based on the scan.¹⁴

It has been shown that in cases of suspected fetal or umbilical cord abnormalities, Doppler evaluation of the umbilical cord blood flow pattern is crucial as a supplementary tool to assess for and diagnose vascular cord abnormalities.¹⁵ Recent studies have also suggested the use of three or four-dimensional Doppler US of the umbilical cord and associated abdominal vasculature for greater comprehensive evaluation of the cord to improve accuracy of diagnosis.¹⁶ This will help to provide important information for prognostication antenatally.¹⁷

Though relatively inexpensive and easy to apply, there is lack of specificity of ultrasonography in diagnosing fetal anomalies.¹⁸ In cases where US was not specific, prenatal MRI scan was used to aid in making the diagnosis and to define the relationship to surrounding structures, thus enhancing anatomic evaluation, facilitating perinatal management and parental counselling.^{18 19} MRI also plays a role in the assessment of bowel obstruction as it is able to provide better anatomic detail and added diagnostic specificity in evaluation of the cause of bowel obstruction.²⁰

PVID though rare, is well known to present itself in the neonatal period.²¹ PVID may present clinically due to the anomaly itself, with continuous or intermittent umbilical discharge, or with complications like skin infection, excoriation, bleeding and rupture or bowel prolapse.⁸ A prolapsed PVID can be associated with complications of intestinal obstruction, strangulation or ischaemic changes of the prolapsed bowel loop, thus, timely surgical intervention is essential.²² In neonates presenting with a prolapsed PVID, care must be taken in placing the cord clamp judiciously to prevent perforation or injury to the prolapsed bowel.

An early precise diagnosis of an umbilical anomaly can be made in the immediate newborn period with a thorough history and physical examination and appropriate imaging to support clinical suspicion. These include US of the abdomen, water-soluble contrast studies or scintigraphy. The choice of which diagnostic tools to use depends on the clinical presentation.^{21 23}

Umbilical cord cysts and bowel prolapse through a PVID occur infrequently in newborn infants. Nonetheless, more research is needed to identify an accurate antenatal diagnostic tool. Early recognition of these conditions is paramount because of both the unnecessary anxiety and concern to families when these conditions are undiagnosed and the threats posed by their associated complications. Prompt management of the umbilical defect is also associated with good prognosis. A multidisciplinary approach involving the neonatologist, paediatric surgeon, geneticist and radiologist would also be helpful in managing these cases for a favourable outcome.

Learning points.

• Umbilical cord anomalies, which result from failure of obliteration of the vitellointestinal duct, though rare, are associated with complications in newborn infants.

• Some of these anomalies can be detected on prenatal ultrasound scan, but very often a definitive diagnosis cannot be made through a prenatal scan.

• It is important for the neonatologist to perform a thorough history and physical examination postdelivery, for an early diagnosis of an umbilical cord anomaly. A multidisciplinary team approach including the surgeon and geneticist to decide on appropriate investigations to delineate the lesion will be rewarding.

• Prompt surgical management of an umbilical cord anomaly is associated with good prognosis.