Placenta Placental Hormones Functions Placental Anomalies

Below is a **complete, concise-but-exhaustive** medical reference note on **Placenta, Placental Hormones & Functions, and Placental Anomalies**, formatted exactly as per your preferred exam-oriented NEET PG + clinical pattern. --- # **PLACENTA — COMPLETE DETAILED NOTE** --- # **1. Definition** The **placenta** is a **fetomaternal organ** that forms during pregnancy, composed of **fetal chorionic villi** and **maternal decidua basalis**, enabling **nutrient exchange, gas exchange, waste removal, immunologic protection, hormone synthesis, and metabolic support**. --- # **2. Development of Placenta** ### **2.1 Timeline** * **Day 6–7:** Blastocyst implantation → trophoblast differentiates into **cytotrophoblast** & **syncytiotrophoblast** * **Day 9–12:** Formation of **lacunae** in syncytiotrophoblast * **Day 12–14:** **Primary villi** form * **Day 16:** **Secondary villi** (mesoderm invasion) * **Week 3:** **Tertiary villi** (fetal vessels) * **Week 10–12:** Mature placenta formed * **Term weight:** ~500–600 g * **Surface:** * *Maternal side:* Rough, cotyledons (≈15–20) * *Fetal side:* Smooth, covered by amnion; umbilical cord attached centrally --- # **3. Structure of Placenta** ### **3.1 Maternal component** * **Decidua basalis** * **Intervillous space** filled with maternal blood ### **3.2 Fetal component** * **Chorionic plate** * **Chorionic villi** containing fetal capillaries * **Placental barrier layers:** 1. Syncytiotrophoblast 2. Cytotrophoblast (regresses by term) 3. Mesenchymal core 4. Fetal capillary endothelium --- # **4. Functions of Placenta** ### **4.1 Exchange Functions** | Function | Mechanism | | ----------------------- | ------------------------------------------------------------------------------------------ | | **Gas exchange** | Simple diffusion (O₂, CO₂) | | **Nutrient transport** | Facilitated diffusion (glucose), active transport (amino acids), pinocytosis (IgG, lipids) | | **Waste removal** | CO₂, urea, creatinine from fetus to mother | | **Electrolyte balance** | Active and passive transport | --- ### **4.2 Immunologic Functions** * Transfers **IgG only** (IgM, IgA do NOT cross) * Protects fetus from maternal immune attack * Produces **indoleamine 2,3-dioxygenase** to suppress maternal T-cells --- ### **4.3 Endocrine Functions** Placenta is a major endocrine organ (see section below). --- ### **4.4 Metabolic Functions** * Produces proteins: **hCG, hPL, hCT, GH-V, progesterone, estrogen** * Synthesizes glycogen, fatty acids, cholesterol * Detoxification via **cytochrome P450** --- # **5. Placental Hormones (Complete Table)** --- ## **5.1 Human Chorionic Gonadotropin (hCG)** **Source:** Syncytiotrophoblast **Peak:** 8–10 weeks **Functions:** * Maintains **corpus luteum** → progesterone production * Stimulates fetal testicular **Leydig cells** → testosterone * Marker for pregnancy testing **Clinical:** High in molar pregnancy, choriocarcinoma; low in ectopic pregnancy. --- ## **5.2 Progesterone** **Source:** * 1st trimester: corpus luteum * 2nd–3rd trimester: placenta **Functions:** * Maintains endometrium (decidualization) * Relaxes uterus, prevents contractions * Modulates immune tolerance * Breast gland development --- ## **5.3 Estrogen (Estriol)** **Source:** * Requires **maternal adrenal + fetal adrenal + fetal liver + placenta** (triple steroid pathway) **Functions:** * Breast development * Myometrial growth * Increase uteroplacental blood flow **Marker:** Estriol level indicates **fetoplacental well-being**. --- ## **5.4 Human Placental Lactogen (hPL) / Human Chorionic Somatomammotropin** **Source:** Syncytiotrophoblast **Functions:** * Maternal insulin resistance * Lipolysis → ↑ free fatty acids * Ensures glucose supply to fetus * Lactogenic effect **Clinical:** Excess → GDM --- ## **5.5 Placental Growth Hormone (GH-V)** * Replaces maternal pituitary GH during pregnancy * Regulates maternal glucose metabolism --- ## **5.6 Relaxin** * Softens cervix * Relaxes pelvic ligaments * Increases renal plasma flow --- ## **5.7 Human Chorionic Thyrotropin / ACTH-like substances** * Mild hyperthyroidism early pregnancy * Supports fetal adrenal development --- ## **5.8 Cytokines & Growth Factors** * VEGF, PGF, TGF-β, IGF * Control trophoblast invasion & vascularization --- # **6. Placental Circulation** ### **6.1 Uteroplacental (Maternal) circulation** * **Spiral arteries** supply maternal blood * Low-resistance system in normal pregnancy * In preeclampsia: inadequate trophoblastic invasion → **high resistance → placental ischemia** ### **6.2 Fetoplacental circulation** * Umbilical **two arteries (deoxygenated)**, **one vein (oxygenated)** * Flow regulated by Wharton’s jelly protection + fetal heart --- # **7. Placental Anomalies — COMPLETE LIST + CLINICAL NOTES** --- # **A. Abnormal Shape of Placenta** ### **1. Bilobed Placenta** * Two equal-sized lobes * Risk: vasa previa, retained placenta ### **2. Succenturiate Lobe** * Accessory lobe * Risks: postpartum hemorrhage (retained lobe), vasa previa ### **3. Circumvallate Placenta** * Folded membranes with thick peripheral ring * Risks: IUGR, abruption, oligohydramnios, PTL ### **4. Placenta Membranacea (Diffuse Placenta)** * Entire chorion covered with villi * Massive PPH risk ### **5. Ring-shaped Placenta** * Rare * Associated with fetal growth restriction --- # **B. Abnormal Position (Placenta Previa)** ### **Types:** * Type I: Low-lying * Type II: Marginal * Type III: Partial * Type IV: Complete **Presentation:** Painless antepartum hemorrhage **Management:** No PV exam; C-section for major degrees --- # **C. Abnormal Invasion (Placenta Accreta Spectrum — PAS)** ### **Types:** 1. **Accreta** – attaches to myometrium 2. **Increta** – invades myometrium 3. **Percreta** – penetrates serosa ± bladder **Risk factors:** * Previous C-section + placenta previa (highest risk) * Multiparity * Curettage **Management:** * Planned cesarean hysterectomy at 34–36 wks * Avoid manual removal --- # **D. Abnormal Cord Insertion** ### **1. Central / Eccentric** (normal variants) ### **2. Marginal (Battledore)** * Cord inserted at placental edge * Mild FGR risk ### **3. Velamentous Insertion** * Cord inserts into membranes * Risks: vasa previa, fetal exsanguination --- # **E. Vasa Previa** * Fetal vessels run in membranes over internal os * **Type I:** Velamentous cord * **Type II:** Between lobes of bilobed or succenturiate placenta **Presentation:** Bleeding + fetal bradycardia **Management:** Emergency C-section --- # **F. Placental Abruption** * Premature separation of placenta * Painful bleeding * Types: concealed, revealed * Risks: hypertension, trauma, cocaine * Management: stabilize, expedite delivery --- # **G. Placental Infarcts** * Common at term * Large infarcts → IUGR * Common in preeclampsia --- # **H. Chorioangioma** * Benign vascular tumor * Large tumors → polyhydramnios, fetal anemia, hydrops * Diagnosis: Doppler, ultrasound --- # **I. Chronic Villitis / Infections** * TORCH infections * Leads to FGR --- # **J. Placental Cysts** * Usually benign * Large cysts → FGR --- # **K. Twin Placenta Anomalies** ### **Types:** * Dichorionic Diamniotic * Monochorionic Diamniotic * Monochorionic Monoamniotic **Complications:** * Twin-Twin Transfusion Syndrome * TRAP sequence * Cord entanglement (MCMA) --- # **Exam Important Points** * **IgG only crosses placenta** * **Estriol (E3) level indicates fetoplacental well-being** * **Placenta previa = painless bleeding** * **Abruption = painful bleeding** * **Most common cause of PAS = previous C-section** * **Velamentous + bilobed = vasa previa risk** --- # **Tags** Placenta, Placental Hormones, hCG, Estriol, hPL, Placental Anomalies, Placenta Previa, PAS, Accreta, Abruption, Velamentous Insertion, Vasa Previa, Succenturiate Lobe, Obstetrics Notes, NEET PG Obstetrics --- If you want, I can also generate **35 case scenarios**, **15 MCQs**, **HTML-CSS-JS MCQs**, or a **placenta anomalies table for your JSON-based notes**. Below are **15 high-yield placenta-related case scenarios** with **complete management + counselling advice**, designed in **NEET PG / Clinical exam** style — concise but fully comprehensive. --- # **15 Placenta Case Scenarios (With Complete Management & Advice)** --- # **Case 1 — Placenta Previa (Painless APH at 32 Weeks)** **Scenario:** A 29-year-old G2P1 at 32 weeks presents with sudden **painless vaginal bleeding**. USG shows **complete placenta previa**. ### **Management** * NO PV exam * Admit + IV line + crossmatch * Corticosteroids (betamethasone) * Avoid tocolysis if bleeding heavy * Expectant management if stable * **Elective C-section at 36–37 weeks** ### **Advice** * Strict pelvic rest * Avoid travel, intercourse * Report immediately if bleeding recurs --- # **Case 2 — Placental Abruption (Painful Bleeding + HTN)** **Scenario:** 35-year-old with chronic hypertension presents with **painful bleeding** + rigid uterus. FHR absent. ### **Management** * ABC stabilization * IV fluids, blood transfusion * Immediate delivery — vaginal if no fetal distress + labor progressing; C-section rarely needed if fetal demise * Treat DIC if present ### **Advice** * Optimal BP control in future * Avoid smoking, cocaine * Early ANC in next pregnancy --- # **Case 3 — PAS (Placenta Accreta in Previous C-Section Scar)** **Scenario:** A 32-year-old G3P2 with 2 prior CS, USG shows **loss of clear zone** and **placental lacunae**. ### **Management** * Plan **cesarean hysterectomy at 34–36 weeks** * Multidisciplinary team (OB, anesthesia, urology) * Massive transfusion protocol ready * Do NOT attempt placental removal ### **Advice** * Delivery only at tertiary center * High recurrence risk in future pregnancies --- # **Case 4 — Velamentous Cord Insertion** **Scenario:** A 26-year-old primigravida, USG shows **cord vessels entering membranes**. ### **Management** * Detailed Doppler * Rule out **vasa previa** * Serial growth scans * Elective C-section at 37 weeks ### **Advice** * Avoid vaginal delivery if vasa previa * Close fetal monitoring --- # **Case 5 — Vasa Previa With Fetal Bradycardia** **Scenario:** 30-year-old in labor with sudden bleeding + fetal heart 80 bpm. Known velamentous insertion. ### **Management** * **Emergency C-section immediately** * Avoid vaginal exam / labor continuation * Neonatal resuscitation ### **Advice** * Risk of recurrence low * Early USG in future pregnancy --- # **Case 6 — Circumvallate Placenta** **Scenario:** USG at 28 weeks shows thick ring-like placenta. ### **Management** * Serial growth scans * Monitor AFI * Risk of PTL → consider tocolysis if contractions * Antenatal steroids ### **Advice** * Report decreased fetal movements * Higher risk of preterm birth → seek early care --- # **Case 7 — Succenturiate Lobe** **Scenario:** After normal vaginal delivery, placenta delivered but membranes show torn vessels; USG suggests retained lobe. ### **Management** * Manual removal OR suction curettage * Prophylactic antibiotics * Monitor for PPH ### **Advice** * Next pregnancy: Doppler to rule out vasa previa --- # **Case 8 — Bilobed Placenta** **Scenario:** USG detects two equal placental lobes at 20 weeks. ### **Management** * Look for connecting vessels (risk vasa previa) * Plan delivery in hospital setting * Active management of 3rd stage to prevent retention ### **Advice** * Increased PPH risk—seek medical help immediately after delivery if heavy bleeding --- # **Case 9 — Placental Chorioangioma (Large >4 cm)** **Scenario:** Anomaly scan shows 5 cm placental tumor. Fetal anemia suspected. ### **Management** * Serial Doppler (MCA PSV) * Fetal echocardiography * Treat hydrops if present * Intrauterine transfusion if severe anemia * Early delivery at 34–36 weeks ### **Advice** * Regular follow-ups necessary * Most small chorioangiomas benign --- # **Case 10 — Placental Infarction in Preeclampsia** **Scenario:** A 30-year-old with severe preeclampsia, USG shows **multiple infarcts** + IUGR. ### **Management** * BP control (labetalol/hydralazine) * Magnesium sulfate prophylaxis * Deliver at 34 weeks or earlier if complications * Corticosteroids if <34 weeks ### **Advice** * Future risk of HTN disorders ↑ * Preconception counseling --- # **Case 11 — Placenta Membranacea** **Scenario:** Placenta covers entire gestational sac. ### **Management** * Prepare for **massive PPH** * Delivery in tertiary center * Postpartum curettage if retained tissue ### **Advice** * High recurrence risk * Antenatal USG important --- # **Case 12 — Twin Pregnancy With Monochorionic Diamniotic Placenta** **Scenario:** MCDA twins at 20 weeks; Doppler mismatch suggests **early TTTS**. ### **Management** * Stage using Quintero system * Laser ablation of placental vascular anastomoses (Stage II+) * Weekly Dopplers * Deliver at 34–36 weeks ### **Advice** * Educate signs of TTTS (rapid distension) * More frequent USG needed --- # **Case 13 — Abnormal Placental Attachment After IVF Pregnancy** **Scenario:** Primigravida via IVF; USG shows placenta previa + accreta suspicion. ### **Management** * MRI confirmation * Planned CS-hysterectomy * Avoid trial of labor * Blood bank preparation ### **Advice** * IVF pregnancies have higher PAS risk * Counselling on future fertility options --- # **Case 14 — Low-Lying Placenta Migrating Upward** **Scenario:** At 20 weeks, placenta is 1.2 cm from os; at 32 weeks now 3 cm away. ### **Management** * Reassurance—normal “placental migration” * Plan vaginal delivery * Routine care ### **Advice** * Avoid unnecessary restrictions * Report any bleeding --- # **Case 15 — Fetal Growth Restriction due to Placental Insufficiency** **Scenario:** 28-year-old, fundal height lag; Doppler shows **high umbilical artery resistance**. ### **Management** * Growth scan every 2 weeks * NSTs, BPP * If absent EDF—deliver at 34 weeks * If reversed EDF—deliver immediately * Steroids before 34 weeks ### **Advice** * Avoid smoking, alcohol * Adequate nutrition * Daily fetal movement counts --- # **If you want next:** ✅ **10 hard MCQs on placenta** ✅ **HTML-CSS-JS MCQ interactive file** ✅ **Tags & JSON-format structured notes** Just tell me!