📘 Essential for Obstetrics, Midwifery & Antenatal Assessment
Amniotic fluid is the protective fluid surrounding the fetus inside the amniotic sac during pregnancy. It is essential for fetal growth, movement, and development.
✅ “Amniotic fluid is the clear to slightly yellowish liquid that surrounds the fetus, providing cushioning, nutrients, and protection throughout pregnancy.”
| 💉 Component | 🔍 Function |
|---|---|
| Water (98–99%) | Main component, allows free movement |
| Electrolytes | Maintain fluid balance |
| Proteins, Enzymes | Support fetal growth |
| Hormones (hCG, Estrogen) | Aid in development and signaling |
| Desquamated fetal cells | Used in genetic testing (amniocentesis) |
| Urea, Creatinine | Reflect fetal kidney function |
| Surfactant | Indicates fetal lung maturity (Lecithin/Sphingomyelin) |
| 📅 Gestational Age | 💧 Average Volume |
|---|---|
| 12 weeks | ~50 mL |
| 20 weeks | ~400 mL |
| 36–38 weeks | ~800–1000 mL (peak) |
| >40 weeks | Gradually declines (~500 mL at term) |
🔹 Cushions fetus from mechanical injury
🔹 Maintains constant temperature (thermal regulation)
🔹 Allows fetal movement and muscle development
🔹 Prevents umbilical cord compression
🔹 Permits lung development (fetus breathes fluid)
🔹 Protects against infection
🔹 Aids in cervical dilation during labor
🔸 Causes:
• Premature rupture of membranes (PROM)
• Placental insufficiency
• Renal agenesis (Potter’s syndrome)
• Post-term pregnancy
🔸 Complications:
• Fetal deformities (club foot)
• Pulmonary hypoplasia
• Cord compression → fetal distress
🔸 Causes:
• Gestational diabetes mellitus (GDM)
• Neural tube defects (e.g., anencephaly)
• Multiple pregnancy
• Esophageal atresia (baby can’t swallow fluid)
🔸 Complications:
• Preterm labor
• Malpresentation
• Umbilical cord prolapse
• Postpartum hemorrhage
| 🎨 Color | 🔍 Clinical Indication |
|---|---|
| Clear / Pale Yellow | ✅ Normal; healthy fetal status |
| Green | ❌ Meconium-stained liquor → indicates fetal distress or hypoxia |
| Golden / Dark Yellow | ❌ Seen in Rh incompatibility → bilirubin from hemolysis |
| Red / Blood-stained | ❌ Could indicate placental abruption or trauma to cervix |
| Brown | ❌ Old meconium — fetal death or prolonged fetal distress |
| Milky White | ✅ May be normal near term due to vernix caseosa |
| Purulent / Foul-smelling | ❌ Suggests intrauterine infection or chorioamnionitis |
| 🧪 Test | 📌 Purpose |
|---|---|
| Amniotic Fluid Index (AFI) | Measured via ultrasound; normal = 5–24 cm |
| Lecithin/Sphingomyelin Ratio (L/S Ratio) | >2.0 = lung maturity |
| Amniocentesis | Genetic testing, infection, RH incompatibility |
| Nitrazine Test / Fern Test | Confirm rupture of membranes (AF is alkaline) |
🟩 Assessment:
🔹 Monitor for fluid leakage (PROM, PPROM)
🔹 Document color, odor, and amount during labor (clear, green, meconium-stained)
🟨 During Antenatal Care:
🔹 Assist with ultrasound & AFI measurement
🔹 Counsel mother on hydration (helps increase AFI)
🔹 Monitor GDM or anomalies in polyhydramnios
🟥 During Labor:
🔹 Observe amniotic fluid during rupture of membranes (ROM)
🔹 Watch for signs of cord prolapse, especially in polyhydramnios
🔹 Ensure sterile technique during amniotomy or amniocentesis
🟡 Amniotic fluid peaks at ~1000 mL at 36–38 weeks
🟡 AFI <5 cm = Oligohydramnios; >24 cm = Polyhydramnios
🟡 Lecithin/Sphingomyelin ratio >2 indicates lung maturity
🟡 Polyhydramnios is common in GDM; Oligohydramnios in PROM
🟡 Meconium-stained fluid may indicate fetal distress
Q1. Which of the following is NOT a function of amniotic fluid?
🅰️ Protects fetus from trauma
🅱️ Maintains temperature
✅ 🅲️ Provides oxygen
🅳️ Allows fetal movement
Correct Answer: 🅲️ Provides oxygen
Q2. Normal range of Amniotic Fluid Index (AFI) is:
🅰️ 3–10 cm
🅱️ 5–10 cm
✅ 🅲️ 5–24 cm
🅳️ 8–32 cm
Correct Answer: 🅲️ 5–24 cm
Q3. Oligohydramnios is commonly associated with:
🅰️ Multiple pregnancy
🅱️ Diabetes
🅲️ Neural tube defects
✅ 🅳️ Premature rupture of membranes
Correct Answer: 🅳️ Premature rupture of membranes
Q4. Which test confirms rupture of membranes by detecting alkaline pH?
🅰️ Fern test
✅ 🅱️ Nitrazine test
🅲️ Coombs test
🅳️ VDRL
Correct Answer: 🅱️ Nitrazine test
Q5. Lecithin/Sphingomyelin ratio >2 indicates:
🅰️ Fetal distress
🅱️ Kidney maturity
✅ 🅲️ Lung maturity
🅳️ Genetic defect
Correct Answer: 🅲️ Lung maturity