This presentation provides a detailed guide to the gross examination and sectioning protocols for placenta specimens in surgical pathology, which are typically received only when abnormalities (such as intrauterine growth restriction, preeclampsia, or multiple gestations) are noted. The speaker reviews the normal anatomy and measurements of the placental disc, umbilical cord, and membranes, contrasting them with common pathological findings. Key abnormalities discussed include placental infarcts (emphasizing the clinical significance of central and extensive involvement), types of abnormal membrane insertion (circumvallate vs. circummarginate), cord anomalies (two-vessel cord, hypercoiling, velamentous insertion), and the classification of invasive placentas (accreta, increta, percreta). The video concludes with specific, mandatory sectioning protocols for both singleton and twin placentas, along with examples of complete gross descriptions.
Gross Examination and Sectioning of Placenta Specimens
0:18 Specimen Indications: Placentas are only sent to pathology if there is an abnormality (e.g., chorioamnionitis, preeclampsia, IUGR) related to the fetus or mother, or in cases of multiple gestations.
1:28 Placental Disc Normals: A term placenta averages 22 cm diameter, 2–2.5 cm thickness, and 470 grams (trimmed). The featured specimen was smaller due to intrauterine growth restriction (IUGR).
2:39 Placental Layers: Going from the fetal surface to the maternal surface, the layers are: Amnion, Chorion, Decidua.
3:38 Succenturiate Placenta (Accessory Lobe): This involves smaller lobes connected to the primary disc by membranes or vessels, but not by placental parenchyma (tissue).
4:58 Fetal Surface Normals/Pathology: The fetal surface should be pale blue, smooth, and shiny. White plaque-like areas are typically benign subchorionic fibrin deposits (5:20).
6:00 Maternal Surface Assessment: The maternal surface should be gray-brown and rubbery. Pathologists must check for intactness; a non-intact surface may suggest retained placenta.
6:37 Placental Abruption: Adherent blood clots on the maternal surface must be measured and their involvement with the parenchyma reported, as they may represent abruption (placenta separating from the uterine wall).
7:18 Umbilical Cord Vessels: The cord typically contains one large vein (oxygenated blood to fetus) and two smaller arteries (deoxygenated blood away from fetus), all supported by Wharton’s jelly.
8:44 Velamentous Cord Insertion: The cord inserts onto the membranes rather than the disc, exposing the vessels to rupture or trauma, significantly increasing the risk of fetal morbidity/mortality.
9:21 Cord Coiling Normals: A normal cord should have 1–2 coils per five centimeters. Hypercoiling (more than 2 coils) is associated with fetal growth restriction or death.
10:44 Cord Knots: False knots (extra looping of vessels in Wharton's jelly) have no clinical significance, but true knots can lead to fetal hypoxia and demise.
11:14 Membrane Opacity and Color: Normal membranes are translucent and pale tan. Opaque membranes may indicate chorioamnionitis (11:36).
Circumvallate (Clinically Significant): Membranes insert inward on the disc and fold back onto themselves, forming a ridge (valley).
Circummarginate (Less Significant): Membranes insert inward but lie flat (do not fold back).
17:01 Placental Infarcts: Infarcts can be older (pale) or newer (hemorrhagic). Key Takeaway (17:59): Multiple infarcts occupying 30% of the disk or more, particularly if located centrally, are the most clinically significant finding.
18:53 Chorioangioma: The most common (though still rare) placental tumor; appears as a single or multiple well-circumscribed, spherical/ovoid masses.
Increta: Invades into the myometrium (correct answer to polling question).
Percreta: Perforates the serosa.
22:15 Invasive Placenta Risk Factors: Major risks include previous cesarean sections and placenta previa; chorioamnionitis is not a risk factor.
24:19 Singleton Sectioning Protocol: Requires one membrane roll (including the rupture site), two cord sections (near insertion and near fetus), and two full-thickness sections of the disc (fetal to maternal surface is recommended to preserve the amnion layer).
31:44 Twin Sectioning Protocol: Requires a T-shaped sample of the dividing membrane and standard sections (membrane roll, cord, and full-thickness disc sections) submitted separately for each twin.