Current Indications for Sending a Placenta to Pathology
Placentas should be sent to pathology when there are maternal comorbidities, pregnancy complications, fetal/neonatal abnormalities, or gross placental abnormalities that could provide clinically relevant information for current or future maternal-infant care. 1
Maternal Indications
Maternal conditions warranting placental examination include:
- Preeclampsia with severe features - placental pathology helps identify maternal vascular malperfusion patterns and informs recurrence risk 1
- Suspected placental abruption - confirms diagnosis and identifies underlying vascular pathology 1
- Clinical suspicion of placenta accreta spectrum (PAS) - particularly with placenta previa overlying a cesarean scar, retained placenta requiring manual removal, or maternal surface disruption 2, 3
- Maternal infection or fever during labor or delivery - identifies infectious/inflammatory processes 1
- Maternal comorbidities such as diabetes, autoimmune disease, or chronic hypertension where placental findings inform management 1, 4
Fetal and Neonatal Indications
Fetal/neonatal conditions requiring placental examination include:
- Fetal growth restriction - placental pathology identifies maternal vascular malperfusion, chronic inflammation, or other growth-limiting processes 1
- Preterm birth (particularly <34 weeks) - determines etiology such as infection, inflammation, or vascular compromise 1
- Nonreassuring fetal heart rate patterns requiring urgent delivery - identifies acute hypoxic-ischemic events 1
- Neonatal multiorgan system failure or neurologic compromise - correlates placental findings with neonatal outcomes 1
- Pregnancy loss at any gestational age - provides diagnostic and prognostic information 1
- Multiple gestation with discordant growth, demise, or twin-twin transfusion - characterizes placental sharing and vascular anastomoses 4
Placental Indications
Gross placental abnormalities mandating pathologic examination include:
- Any placenta that appears abnormal on focused gross examination at delivery - abnormal size, color, consistency, cord insertion, or maternal surface disruption 1
- Retained placenta or placental fragments - particularly when manual removal is required or there is no plane of separation 3
- Suspected placental masses or tumors - requires histologic characterization 4
- Abnormal cord characteristics - single umbilical artery, short cord, true knots, or abnormal insertion 4
Special Considerations for Placenta Accreta Spectrum
The presence of basal plate myometrial fibers (BPMF) in delivered placentas represents a distinct category from true PAS. 2 When a delivered placenta shows maternal surface disruption with missing parenchyma or loss of smooth contour, directed sampling at the junction between intact and disrupted areas increases detection of BPMF 2. These findings may indicate focal adherence and increased risk for PAS in subsequent pregnancies 2.
Practical Implementation
A focused gross examination should be performed on ALL placentas at delivery by the provider or attendant. 1 This examination identifies abnormalities that warrant complete pathologic evaluation even when standard clinical indications are absent 1.
The sensitivity of placental examination following established guidelines is approximately 63%, with specificity of 92%. 5 This means that adherence to submission criteria captures the majority of clinically significant pathology while avoiding unnecessary examinations 5.
Common Pitfalls
Avoid assuming that absence of clinical complications means the placenta is normal - gross examination may reveal unexpected findings with implications for future pregnancies 1. Do not attempt forced removal of a retained placenta when PAS is suspected, as this causes catastrophic hemorrhage; the placenta should be left in situ 3. Ensure meaningful communication between obstetricians, neonatologists, and pathologists to maximize the clinical utility of placental examination 5, 6.