Prevalence, Morphology, Embryogenesis, and Diagnostic Utility of Umbilical Cord Vitelline Vascular Remnants

Abstract

The objective of this study is to better understand embryonic vitelline vascular remnants in the umbilical cord, to assess their prevalence, to categorize their morphology, and then finally to describe and assess inflammation arising from these structures. During routine placental sign out, the author noted the presence or absence of vitelline vessel remnants for 1 year; when present, he assessed their histologic patterns and noted whether there were neutrophils marginating from the remnants and into the adjacent Wharton's jelly and whether there was any other evidence of amniotic fluid infection in sections of placental disc, membranes, or cord. All cord sections with vitelline vessel remnants were immunostained for CD15 to document any infiltrates, to highlight patterns of infiltration, and to evaluate whether mild cases of umbilical phlebitis were associated with these lesions and were at risk of being missed. Vitelline vessel remnants were present in 4.2% of placentas examined. There were 5 vitelline vessel remnant histologic patterns identified providing insight into the vitelline vessel circulation. Funisitis, primarily neutrophilic, arising from vitelline vessel remnants was present in 70.3% of the 37 cords with vitelline vessel remnants. The presence of vitelline vessel remnant funisitis documents continued active circulation in these vascular structures, and vitelline vessel remnant funisitis was associated with the presence of other placental histological evidence of amniotic fluid infection in 53.8% of cases. The author also reviews normal embryology and the pathology of vitelline vessel remnants.

Vitelline Vessel Remnant-Derived Funisitis Is a Sensitive and Specific Predictor of Histological Evidence of Amniotic Fluid Infection

“…VVR-derived funisitis was subdivided into low stage/grade (defined as neutrophils in Wharton's jelly near VVRs) or high stage/ grade (defined as neutrophils appearing in Wharton's jelly near both VVRs and cord surface amnion). 2 This classification system is a simplification of a system used in our previous study. 2 While the previous stage/grading system, which was partially dependent upon CD15-staining, was useful to prove the existence of VVR-derived funisitis, it was both impractical and unnecessary, as the presence of significant numbers of neutrophils in Wharton's jelly is readily identified with HE-staining.…”

“…2 This classification system is a simplification of a system used in our previous study. 2 While the previous stage/grading system, which was partially dependent upon CD15-staining, was useful to prove the existence of VVR-derived funisitis, it was both impractical and unnecessary, as the presence of significant numbers of neutrophils in Wharton's jelly is readily identified with HE-staining. 2 Furthermore, CD15 is overly sensitive as it also stains CD68þ macrophages, which often exist in small numbers near VVRs.…”

“…One of these paired vessels is derived from the embryonic vitelline artery, a branch of the embryonic superior mesenteric artery, and the other, which represents the embryonic vitelline vein, communicates with the embryonic portal venous system. 2 Surprisingly, JRW observed CD15þ inflammatory responses arising from the VVRs in 70.3% of these 37 cords. In all of these cords, neutrophils were found in Wharton's jelly surrounding the paired VVRs; however, some infiltrates also extended to the nearest cord amniotic surface.…”

“…However, the presence of an inflammatory response arising from VVRs was offered as proof of active fetal circulation in paired VVRs. 2…”

Dissecting the Vitelline Vessel Remnant

“…Consistent with the utility of immunohistochemistry, the authors formerly used a three-grade evaluation system with combined CD15 immunostaining and H&E staining for VVR-related inflammatory lesions. 5 Although this grading scheme includes Grade 1, which may overestimate neutrophils with CD15-positive cells, this problematic group is a relatively minor population, accounting for 7.7% of VVR cases. (2/26).…”