The gross specimen of the placenta and umbilical cord shown above demonstrates which of the following conditions?

Explanation

## Image Findings * Gross specimen of a placenta with an attached umbilical cord. * A distinct, tightly formed **true knot** is visible in the umbilical cord, where the cord is intertwined upon itself. * Prominent blood vessels are visible on the fetal surface of the placenta. * Surgical instruments and blood stains on the drape suggest a post-delivery clinical setting. ## Diagnosis **Key Point:** The image clearly demonstrates a **true knot of the umbilical cord**, characterized by the actual intertwining of the cord itself, forming a loop. A true knot forms when the fetus passes through a loop of the umbilical cord, typically during early pregnancy or labor. While often benign, a true knot can tighten, especially during fetal movements or labor, leading to compression of the umbilical vessels. This compression can restrict blood flow to the fetus, potentially causing fetal hypoxia, growth restriction, and even fetal demise. The image shows a well-formed, tight knot, which is a significant finding. ## Differential Diagnosis | Feature | True Knot of Umbilical Cord | False Knot of Umbilical Cord | Velamentous Insertion | Battledore Placenta (Marginal Insertion) | | :-------------------- | :-------------------------------------------------------- | :-------------------------------------------------------------- | :--------------------------------------------------------- | :----------------------------------------------------------- | | **Appearance** | Actual intertwining of the cord, forming a loop. | Localized dilatations of Wharton's jelly or umbilical vessels. | Umbilical vessels run unprotected in membranes before placenta. | Cord inserts at the very edge (margin) of the placental disc. | | **Pathogenesis** | Fetus passes through a cord loop. | Localized excess Wharton's jelly or tortuous vessels. | Abnormal placental development/implantation. | Abnormal placental development/implantation. | | **Clinical Significance** | Can tighten, causing fetal compromise (hypoxia, demise). | Usually benign, no fetal compromise. | Risk of vasa previa, vessel rupture, fetal hemorrhage. | Increased risk of preterm birth, growth restriction, abruption. | | **Image Finding** | **Clearly visible intertwining knot.** | Would appear as a bulge, not an actual loop. | Would show vessels diverging in membranes. | Would show cord attached at the periphery. | ## Clinical Relevance **Clinical Pearl:** True knots of the umbilical cord are relatively rare (incidence 0.3-2.1%) but are associated with increased risks of fetal distress, intrauterine growth restriction, and fetal demise due to potential occlusion of umbilical vessels. ## High-Yield for NEET PG **High-Yield:** Risk factors for true knots include long umbilical cords, polyhydramnios, small fetuses, monoamniotic twin pregnancies, and multiparity. **Key Point:** The primary concern with a true knot is the potential for tightening and subsequent **umbilical vessel compression**, leading to fetal hypoxia. ## Common Traps **Warning:** Do not confuse a true knot with a false knot. A true knot involves actual intertwining of the cord, while a false knot is merely a localized thickening or bulge due to variations in Wharton's jelly or tortuous vessels, without clinical significance. ## Reference [cite:Robbins Basic Pathology, 10th Ed, Ch 21; Williams Obstetrics, 25th Ed, Ch 27]