Atlas
 

Pathology of the umbilical cord



3  Atlas of fetal pathology

3.6  Pathology of the umbilical cord

Introduction:

Histology:

3 umbilical vessels  —  2 arteries and 1 vein in loose myxoid tissue (Whartons jelly). Ensheathed by amnion.

Pictures

False knot:
False umbilical knot, Macro, autopsy (73229)

3.6.1  Abnormal length

Introduction:

Cord length is determined by mechanical stretching of the cord by fetal movements. The cord grows in 1st and 2nd trimestr in particular and approaches most of its ultimate length by 28 weeks.

3.6.1.1  Short cord

Introduction:

Umbilical cord is shorter than 35 cm at term.

Etiology:

Congenital neuromuscular disorders, skeletal disorders, multiple malformations and similar conditions characterized by decreased fetal movements in utero.

Clinical signs:

  • perinatal asphyxia
  • fetal malpresentation (transverse, oblique)

Extremely short or absent umbilical cord is found in limb body wall complex. It is a severe malformation complex with large abdominal/thoracic wall defect, limb anomalies, severe scoliosis and internal anomalies. Limb body wall complex is uniformly lethal.

3.6.1.2  Long cord

Introduction:

Cord longer than 70 – 80 cm at term

Clinical signs:

Increased risk of cord prolapse, entanglement, knotting or torsion.

3.6.2  Insertion abnormalities

Clinical signs:

Velamentous (membranous) insertion: Occurs in 1% of singletons and in almost 15% of twins. The cord inserts into the membranes far away from the placental margin. Umbilical vessels run unprotected by Whartons jelly and are vulnerable to injury. Velamentous vessels run over the internal os are called vasa previa. These vessels are at risk of rupture during delivery. The mortality of vasa previa hemorrhage is very high, the fetus exsanguinates within minutes. Velamentous insertion can be detected before the delivery using color Doppler ultrasound. The fetus is delivered by elective cesarean section.

Marginal insertion: Insertion at the placental margin (battledore placenta) occurs in 5 – 7% pregnancies.

3.6.3  Abnormal coiling

Clinical signs:

Hypocoiled umbilical cord, achirality (absence of coiling) has adverse fetal outcome (intrauterine distress, intrauterine demise).

Hypercoiled cord, torsion Umbilical cord torsion (hypercoiling) is a freqent cause of abortion in the 2nd trimestr. Characteristic findings include long hypercoiled cord, stricture of the cord usually at the fetal end (focal depletion of Whartons jelly) or multiple strictures. The fetus is macerated.

3.6.4  Umbilical vessels pathology

Introduction:

SUA — single umbilical artery.

Clinical signs:

  • about 1% of singletons at term, up to 10 % of twins
  • common association with some malformations e.g. sirenomely, trisomy 18, 13, VACTERL
  • occult malformations (renal in particular) should be searched for in an otherwise healthy infant with SUA
  • association between low birth weight and SUA is controversial

3.6.5  Umbilical cord accidents which compromise the blood flow

Classification:

  • true knot
  • nuchal cord, cord entanglements
  • strangulation by amniotic bands
  • cord prolapse — cord presents in front of the fetal presenting part

Clinical signs:

The incidence of true knots is 0,5% – 1%. Nuchal cord with one loop is found in 20% of deliveries, two or three loops in 2.5% and 0.5% respectively. Cord prolapse is estimated to occur in 0.4% of deliveries.

Blood flow is compromised if the knot or nuchal cord tightens. The tightening occurs most often during delivery. Decreased venous return from the placenta leads to asphyxia. Cord compression may cause neurologic damage, intrauterine or intrapartum death. Perinatal mortality is approximately 10% in the presence of prolapsed cord or true knot.

Strangulation by amniotic bands causes fetal demise.

3.6.6  Thrombosis of umbilical blood vessels

Etiology:

  • umbilical cord compression and stasis in true knots, amniotic band constriction, torsion, velamentous insertion etc.
  • maternal of fetal thrombophilia
  • funisitis
  • unknown reason often

Clinical signs:

Venous thrombi are more common than arterial thrombi. Fetal outcome is poor.

3.6.7  Umbilical cord inflammation

3.6.7.1  Acute funisitis

Etiology:

  • accompanies acute chorioamnionitis
  • inflammatory cells are of fetal origin and constitute the fetal inflammatory response

Macroscopic appearance:

The umbilical cord looks normal. White, tan or yellow plaques are seen with Candida infection.

Histology:

Inflammatory cells migrate from the umbilical vessels towards the amniotic surface.

3.6.7.2  Subacute necrotizing funisitis

Introduction:

Subacute or chronic inflammation of the umbilical cord associated with high perinatal mortality.

Etiology:

Treponema pallidum, herpes simplex virus, other organisms with low virulence such as Mycoplasma are also suspected.

Macroscopic appearance:

Thickened whitish umbilical vessels resembling macaroni.

Histology:

Necrotizing basophilic exudate accumulates in concentric perivascular rings or crescents. The exudate may become calcified.

3.6.8  Miscellaneous rare cord lesions

Classification:

  • Cysts: develops from embryonic remnants (allantois, ductus omphaloentericus)
  • Tumors: hemangioma is the most common
  • Hematomas: invasive prenatal prodedures, rupture of a varix
  • Rupture of the umbilical cord: very rare, described as either complete or more often partial with local hematoma


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