Ultimate Obstetrics Exam Guide

1. Lecture 11: Anemia in Pregnancy

Definitions & Physiological Adaptations
  • Physiological Dilution: Plasma volume expansion (50%) is greater than red cell mass increase (25%), causing decreased Hemoglobin (Hb) and hematocrit. This is a combined effect of hemodilution and negative iron balance.
  • Diagnostic Criteria: WHO recommends that the Hb concentration should not fall below 11 g/dL at any time. However, Hb < 10.5 g/dL in the second and third trimesters is considered anemia.
  • WHO Grading of Severity:
    • Mild: 10.0–10.9 g/dL
    • Moderate: 7.0–9.9 g/dL
    • Severe: <7.0 g/dL
  • Postpartum Anemia: Defined as Hb < 10 g/dL.
  • There should be no change in Mean Corpuscular Volume (MCV) or Mean Corpuscular Hemoglobin Concentration (MCHC) in normal pregnancy.
  • Requirements: 2-3 fold increase in Iron (Fe), 10-20 fold increase in Folate. Serum iron and ferritin decrease secondary to increased utilization and hemodilution. Total Iron-Binding Capacity (TIBC) increases.
  • Fetal Iron Transport: Occurs from maternal to fetal circulation against the gradient, unlike the non-pregnant state where it goes to the bone marrow.
  • Total Iron Demand: Marked demand of about 900 mg (450 mg for RBC expansion, 350 mg for fetus/placenta, 190 mg blood loss in delivery, and 1 mg/day for lactation).
Iron Deficiency Anemia (IDA) & Investigations
  • Prevalence: Most common cause (70–95% of cases in pregnancy). Often asymptomatic and detected on routine screening (FBC at booking and at 28 weeks).
  • Causes & Excess Demand:
    • Multiple pregnancy (2x iron demand).
    • Rapidly recurring pregnancy (< 2 years interval).
    • Teenage pregnancy (growth demand).
    • Faulty absorption (Intestinal infestations like hookworm, or use of antacids/H2 blockers/proton pump inhibitors).
  • Clinical Features: Fatigue (commonest), giddiness, palpitations, dyspnea, edema, soft systolic murmur (mitral area due to physiological mitral incompetence), and crepitations. Signs: Glossitis, stomatitis, koilonychia (spoon nails), pallor.
  • Investigations & Indices:
    • Peripheral smear (Leishman's stain): Microcytic hypochromic cells with anisopoikilocytosis (varying sizes and shapes, including pencil-shaped or elliptocytes).
    • MCHC is the most sensitive index. Serum ferritin < 30 µg/L is the confirmatory test.
    • Values indicating IDA: Hb < 10 gm%, PCV < 30%, MCHC < 30%, MCV < 75 µ³, MCH < 25 pg, Serum iron < 30 µg/100 mL, TIBC > 400 mcg/dl.
    • Routine exams: Stool (for hookworm) and Urine (for infection/bacteriuria, >10^5 colonies/mL).
Treatment of IDA & Complications
  • Complications: Intercurrent infection, Heart failure (30-32 weeks), Preterm labor, preeclampsia. During labor: uterine inertia, PPH, shock. Puerperium: Sepsis, subinvolution, poor lactation, DVT, Pulmonary embolism (PE).
  • Prophylaxis: 60 mg/day of oral iron supplementation throughout pregnancy and 3 months postpartum. Avoid frequent childbirths (min 2 years interval).
  • Dietary: Liver, meat, green leafy vegetables, legumes, nuts. Vitamin C (orange juice) increases absorption; tea/coffee (tannins) & antacids decrease it.
  • Oral Therapy: 100–200 mg elemental iron/day for minimum 3 months. Give 30 mins before meals (or with meals if GI irritation occurs). Expected Hb improvement: 1 g/dL in 2 weeks (~10g/L/wk). Reticulocytosis occurs within 7-10 days. Shift to syrups (use a straw to prevent teeth staining) if poorly tolerated.
  • Parenteral Therapy (IV/IM): Indicated for oral intolerance (intractable GI upset), uncooperative patients, or severe anemia seen late (8-10 weeks before delivery).
    • Risk: Anaphylactoid reaction (Requires test dose of 0.5 mL, adrenaline/antihistamines must be ready).
    • Intravenous (IV): Older formulations (iron dextran, sucrose) take 4-9 weeks for Hb rise. Newer IVs like ferric carboxymaltose (Injectafer) give faster response (10g/L/wk) and are single dose. Contraindicated in 1st trimester due to oxidative free radical toxicity to placental membranes.
    • Intramuscular (IM): Z-track technique in the upper outer gluteal muscle (20-22 gauge needle) to prevent permanent skin staining. Painful, variable absorption.
  • Blood Transfusion: For active bleeding (PPH), severe anemia beyond 36 weeks, or refractory anemia. Use packed red blood cells (80-100 mL at a time, do not repeat within 24h to allow circulatory readjustment). Advantage: Fast improvement (after 3 days), supplies antibodies/proteins.
Megaloblastic, Sickle Cell, Thalassemia & Thrombocytopenia
  • Folate Deficiency: Incidence 5%. Increased MCV, decreased serum/red cell folate. Prophylaxis: 400 micrograms/day pre-conception. High risk (Antiepileptics, previous Neural Tube Defect (NTD), DM, BMI >35, Sickle cell) require 5 mg/day.
  • Vitamin B12 Deficiency: Seen in strict vegans, terminal ileum disease, pernicious anemia. Note: Normal B12 levels decrease in pregnancy, so interpret with caution.
  • Sickle Cell Disease: Autosomal recessive. Most common in Afro-Caribbean, Middle East. Pregnancy risks: Miscarriage, IUGR, Prematurity, Stillbirth, Avascular necrosis of bone, Acute chest syndrome, Iron overload (leading to cardiomyopathy). Management: MDT care, stop iron-chelators pre-pregnancy, 5mg folic acid, penicillin prophylaxis, oxygen, rehydration, avoid hypoxia in labor.
  • Thalassemia:
    • Alpha-Thalassemia Major (Hb Barts): No functional α-genes. Incompatible with life (Hydrops fetalis). Mothers get severe early-onset pre-eclampsia.
    • Alpha-Thalassemia Trait: Two (α0) or three (α+) normal genes. Mostly asymptomatic.
    • Beta-Thalassemia Major: Two defective genes. Transfusion-dependent, iron overload, heart failure (most common cause of death). Cured by bone marrow transplant.
    • Beta-Thalassemia Minor/Trait: One defective gene (incidence 1:10,000 in UK, 1:7 in Cyprus). Offspring have 1:4 chance if partner is also a carrier.
    • Management: Check ferritin first (give iron only if deficient), Folic acid 5mg, screen partner (electrophoresis). Note: Thalassemia has microcytic anemia with normal MCHC (unlike IDA).
  • Thrombocytopenia: Platelet count < 150 × 10⁹/L. Gestational thrombocytopenia (7-8% of pregnancies) is a diagnosis of exclusion (usually mild 100-150). Usually occurs in late pregnancy with no prior history. Bleeding is rare unless count is <50 × 10⁹/L. Epidural/spinal anesthesia avoided if platelets < 80 × 10⁹/L. Resolves spontaneously postpartum.
💡 High-Yield Hints (Lecture 11)
  • 1. Diagnostic Thresholds: Anemia in pregnancy is strictly defined as Hb < 11 g/dL in 1st trimester and < 10.5 g/dL in 2nd/3rd trimesters. Postpartum is < 10 g/dL.
  • 2. Confirmatory Test: While MCHC is the most sensitive index for IDA, Serum Ferritin < 30 µg/L is the absolute confirmatory test.
  • 3. IV Iron Contraindication: Intravenous iron (like Injectafer) is strictly contraindicated in the first trimester due to oxidative free radical damage to the placenta.
  • 4. Thalassemia Differentiation: Thalassemia presents as microcytic anemia but with a normal MCHC, distinguishing it from Iron Deficiency Anemia (low MCHC). Give iron to thalassemia patients ONLY if ferritin is proven low.
  • 5. Folic Acid Dosing: Standard prophylaxis is 400 mcg/day, but high-risk patients (epilepsy, DM, BMI>35, sickle cell, previous NTD) absolutely require 5 mg/day.
  • 6. Transfusion Rule: Blood transfusion for severe anemia is usually reserved for patients beyond 36 weeks to prepare them for the blood loss and strain of labor.

2. Lecture 12: Fetal Malpresentation

Abnormal Fetal Lie
  • Fetal Lie: Relationship of the longitudinal axis of the fetus to the maternal long axis.
  • Types:
    • Longitudinal (99.5%): Fetal head or breech palpable over pelvic inlet.
    • Transverse: Perpendicular to maternal axis (results in shoulder presentation).
    • Oblique: Crosses at a 45° angle.
    • Unstable Lie: Constantly changing lie, multiple times a day.
  • Causes: Multiparity (> para 2) with lax uterus, Polyhydramnios, uterine fibroids, placenta previa, pelvic tumors, fetal anomalies (anencephaly, hydrocephaly), multiple pregnancy.
  • Complications: Cord prolapse (at membrane rupture), prolapse of hand/shoulder/foot, uterine rupture, difficulty delivering at CS.
  • Management (Unstable Lie): Admission to hospital from 37 weeks. If it doesn't stabilize, CS is usually performed at 41 weeks. If stable but not longitudinal, CS at 39 weeks. Stabilizing induction (turn to cephalic + immediate amniotomy) requires high expertise.
Breech Presentation
  • Definition & Incidence: Buttocks present over pelvis. Head is at fundus. Incidence: 20% at 30 weeks, dropping to 3-4% at term. Most common malpresentation. Commonly undiagnosed before labor (30%).
  • Types:
    • Frank (extended) Breech: Hips flexed, knees extended (Most common).
    • Complete (flexed) Breech: Hips & knees flexed.
    • Incomplete (footling) Breech: Hips extended, one or both feet presenting. Highest risk of cord prolapse (5-10%).
  • External Cephalic Version (ECV): Done at or after 37 weeks. Woman laid flat with left lateral tilt. Procedure lasts max 10 mins. Must check FHR before/after and give Anti-D if Rh-negative. Success improved with tocolytics (e.g., nifedipine).
    • Contraindications: Fetal anomaly (hydrocephalus), placenta previa, bleeding/APH, previous CS scar, multiple gestation, pre-eclampsia, oligo/polyhydramnios.
  • Vaginal Breech Delivery Pre-requisites: Fetus not compromised, Frank/Complete breech, Estimated Fetal Weight (EFW) < 3.5 kg to 4kg, spontaneous labor, no hyperextension of fetal neck, adequate pelvis.
  • Maneuvers:
    • Mauriceau-Smellie-Veit: Flexing aftercoming head using index & middle finger applied over maxillae (back anterior).
    • Burn Marshall maneuver.
    • Prague Maneuver: For back posterior, 2 fingers grasping shoulders.
    • Piper's Forceps: Specifically designed for the aftercoming head.
Face, Brow, Shoulder, & Cord Presentations
  • Face Presentation: Complete extension of the head (1 in 500 labors). Attributed to excessive extensor muscle tone or fetal thyroid tumor. Presenting diameter: Submento-bregmatic (9.5 cm). Vaginal delivery possible if Mento-anterior (delivery by flexion). If Mento-posterior -> CS. Fetal risks: facial edema, lacerations (feeding difficulties).
  • Brow Presentation: Midway between vertex and face (1 in 2,000 labors). Diagnosed in advanced labor (head does not descend below ischial spines). Frontal sutures, orbital ridges palpable. Presenting diameter: Mento-vertical (13.5 cm). Incompatible with vaginal delivery; watch and wait to see if it flexes to vertex or extends to face. If it persists -> CS.
  • Shoulder Presentation: Result of transverse/oblique lie (1 in 300 pregnancies at term). High risk of cord prolapse and uterine rupture. Delivery MUST be by Cesarean Section.
  • Cord Presentation: Loops of cord lie below presenting part with intact membranes. Associated with high head, abnormal lie. Artificial Rupture of Membranes (ARM) is strictly contraindicated to prevent cord prolapse (which is a catastrophic obstetric emergency). Suspect if persistent variable FHR decelerations occur early in labor.
💡 High-Yield Hints (Lecture 12)
  • 1. The Most Dangerous Breech: Footling (incomplete) breech carries the absolute highest risk of cord prolapse (5-10%) among breech types.
  • 2. Brow Presentation Diameter: The mento-vertical diameter (13.5 cm) is the largest presenting diameter and makes vaginal delivery anatomically impossible if the head does not flex or extend further.
  • 3. Face Presentation Positioning: Mento-anterior can deliver vaginally (via flexion), whereas mento-posterior almost always requires a C-section.
  • 4. ECV Timing & Safety: External Cephalic Version is never attempted before 37 weeks. Anti-D immunoglobulin must be administered to Rh-negative mothers afterward.
  • 5. Unstable Lie Protocol: Mothers with an unstable lie must be admitted to the hospital at 37 weeks to immediately manage potential cord prolapse if membranes rupture.
  • 6. Cord Presentation vs Prolapse: Cord presentation occurs with INTACT membranes. ARM is strictly forbidden as it directly causes cord prolapse.

3. Lecture 13: Cesarean Section (CD/CS)

Overview, Preparation & Anesthesia
  • Incidence: Dramatically increased (globally ~32%). Maternal request accounts for 7% (tokophobia = irrational fear of childbirth).
  • Pre-operative Prep: Informed consent, Foley catheter (kept perioperatively), Antacids/H2 blockers (to prevent Mendelson syndrome - aspiration pneumonia), Antiemetics.
  • Anesthesia: Regional anesthesia (spinal/epidural) is preferred over General Anesthesia (GA). For GA, preoxygenation and rapid sequence induction are required.
  • Preventing Hypotension: IV ephedrine or phenylephrine infusion, volume preloading (crystalloid/colloid), and 15-degree left lateral tilt (prevents aortocaval compression and maintains placental perfusion).
Indications, VBAC & Categories of CD
  • VBAC (Vaginal Birth After Cesarean): Uterine rupture risk is 50:10,000 (spontaneous) vs 1:10,000 for repeat CD. Induction highly increases rupture risk: 8:1000 with oxytocin, 24:1000 with prostaglandins. Continuous Electronic Fetal Monitoring (CEFM) is mandatory as FHR changes are the earliest signs of scar rupture.
  • Category 1 (Immediate/Crash): Immediate threat to life. Delivery within 30 mins. Examples: Placental abruption, cord prolapse, scar rupture, prolonged bradycardia, Scalp pH < 7.20.
  • Category 2 (Urgent): Maternal/fetal compromise, NOT immediately life-threatening. Examples: Pathological CTG in 1st stage, failure to progress with poor pain control.
  • Category 3 (Scheduled): Early delivery needed, no immediate compromise. Examples: Severe pre-eclampsia, FGR with abnormal Doppler but normal HR, failed IOL.
  • Category 4 (Elective): Timed to suit staff/mother. Delayed until 39 weeks to prevent transient tachypnea of the newborn. Examples: Placenta previa, maternal HIV, term breech, primary genital herpes in 3rd trimester.
Surgical Approaches & Complications
  • Lower Uterine Segment Transverse Incision: Used in >95%. Advantages: Less blood loss, less adhesion, lower risk of rupture in future, cosmetic value. Disadvantages: Takes longer, unsuitable for very premature infants. Closed in two layers.
  • Classical (Vertical Upper Segment) Incision: High risk of future rupture. Indications: Dense adhesions, transverse lie with ruptured membranes/anomaly, preterm breech with poorly formed lower segment, carcinoma of cervix, big fibroid in lower segment, anterior placenta previa with engorged vessels, repair of vesicovaginal fistula.
  • Second Stage CS: Deeply impacted head requires push (from below) or pull (reverse breech extraction) techniques, or a Fetal Pillow. High risk of uterine incision extension.
  • Complications:
    • Intra-op: Extension of incision into uterine vessels (broad ligament hematoma), bladder/bowel/ureter injury, Hemorrhage. Morbidly adherent placenta (Placenta Accreta/Increta/Percreta) commonly seen with previa and prior CS, may need total hysterectomy.
    • Immediate post-op: PPH, Shock, Mendelson syndrome (aspiration pneumonia), Endomyometritis, Peritonitis.
    • Late post-op: Incisional hernia, adhesions causing intestinal obstruction, future scar rupture.
💡 High-Yield Hints (Lecture 13)
  • 1. Aortocaval Compression: Always use a 15-degree left lateral tilt during a C-section to prevent hypotension caused by the uterus compressing the inferior vena cava.
  • 2. Mendelson Syndrome: Prophylactic antacids and H2 blockers are given strictly to prevent aspiration pneumonitis (Mendelson syndrome) during anesthesia.
  • 3. Elective CS Timing: Elective (Category 4) CS is strategically delayed until 39 weeks specifically to reduce the incidence of transient tachypnea of the newborn (TTN).
  • 4. VBAC Risk Factors: Induction of labor with prostaglandins in a VBAC patient carries the highest risk of uterine rupture (24:1000) and is extremely dangerous compared to spontaneous labor.
  • 5. Classical CS Indicator: A classical (vertical) incision is rarely used today but is mandatory if there is a transverse lie with ruptured membranes or an anterior placenta previa with heavily engorged vessels.

4. Lecture 14: Intrapartum Fetal Monitoring

Methods of Monitoring
  • Intermittent Auscultation: Recommended for low-risk women in spontaneous labor. Use handheld Doppler or Pinard stethoscope. Auscultate every 15 minutes for at least 1 minute after a contraction during the 1st stage.
  • Continuous Electronic Fetal Monitoring (CEFM/CTG): Indicated for high-risk pregnancies: Pre-eclampsia, DM, IUGR, Multiple pregnancy, breech, previous CS, significant meconium staining, induction/augmentation, prolonged ROM (>24h), oligohydramnios, post-term. Risk can change during labor (e.g., onset of bleeding, fever >38°C).
  • Note: Admission CTG for uncomplicated low-risk pregnancies is not recommended (increases unnecessary interventions like FBS and CS).
  • Maternal Monitoring (1st Stage): 4-hourly temp/BP, hourly pulse, half-hourly contraction frequency tracking, vaginal exam every 4 hours.
Cardiotocography (CTG) Features
  • Normal Baseline: 110–160 beats per minute (bpm) (at term).
    • Tachycardia >160: Associated with maternal/fetal infection (chorioamnionitis, fever), acute fetal hypoxia, fetal anemia, or drugs (ritodrine).
    • Bradycardia <110: Prolonged indicates severe hypoxia/cord compression.
  • Baseline Variability: Normal is 5 to 25 bpm. Reflects neuro-autonomic health. Reduced variability (<5 bpm for >90 mins) is an ominous sign of severe fetal hypoxemia/CNS depression, sleep states, prematurity, or drugs (epidural).
  • Accelerations: Increase of ≥15 bpm lasting ≥15 seconds. Two or more in 20-30 mins = reactive trace. Indicates pH > 7.25 (positive sign of fetal health). Can be provoked by vibroacoustic or scalp stimulation.
Decelerations & Categorization
  • Early Decelerations: Mirrors the contraction (nadir aligns with peak of contraction). Caused by head compression (vagal nerve stimulation). Benign, not associated with hypoxia.
  • Variable Decelerations: Variable in shape and timing. Most common (1 in 8 traces). Caused by umbilical cord compression or head compression.
    • Typical Variable: Initial acceleration -> rapid drop -> rapid return -> secondary acceleration.
    • Atypical variables: Unfavorable. Show slow return to baseline, loss of variability, loss of accelerations, overshoot, or continuation at a lower baseline. Indicative of hypoxia.
  • Late Decelerations: Nadir occurs after the peak of contraction. Caused by placental insufficiency / fetal hypoxia. Always significant and concerning.
  • Classification (RCOG/ACOG):
    • Reassuring: 110-160 bpm, variability ≥5, no decelerations, accelerations present.
    • Non-reassuring: 100-109 or 161-180 bpm, variability <5 for 40-90 mins, typical variables >90 mins, absent accelerations.
    • Pathological: <100 or >180 bpm, sinusoidal pattern ≥10 mins, variability <5 for >90 mins, atypical variables or late decelerations >30 mins, single prolonged deceleration >3 mins.
Secondary Tests & Management
  • Fetal Blood Sampling (FBS): Gold standard secondary test. Checks fetal scalp pH or lactate.
    • Normal: pH ≥ 7.25.
    • Borderline: pH 7.21 - 7.24 (repeat in 30 mins).
    • Abnormal: pH < 7.20 (Indicates immediate urgent delivery).
  • Management of Suspected Compromise:
    • Improve placental blood supply: Correct maternal hypotension/hypovolemia (IV fluids), positioning (avoid aorto-caval compression), use ephedrine if epidural-induced vasodilation.
    • Diminish uterine activity: Stop oxytocin, remove prostaglandins (lavage if gels used), give bolus tocolytics (e.g., Terbutaline 0.25 mg).
    • Improve maternal oxygenation: Only short term, prolonged use may be detrimental.
    • Improve umbilical blood flow: Amnioinfusion (reduces cord compression, 500 mL Hartmann's over 20-30 mins gravity fed).
    • If no response -> Category 1 or 2 CS.
💡 High-Yield Hints (Lecture 14)
  • 1. Auscultation Protocol: In low-risk pregnancies, you must auscultate the fetal heart rate every 15 minutes for at least 1 full minute immediately following a contraction.
  • 2. Ominous Variability: Baseline variability less than 5 bpm for greater than 90 minutes is one of the most critical markers of severe fetal hypoxia and CNS depression.
  • 3. Deceleration Triggers: Memorize the triad: Early = Head Compression, Variable = Cord Compression, Late = Placental Insufficiency.
  • 4. Admission CTG Rule: Do NOT perform a routine admission CTG on a low-risk, uncomplicated pregnancy, as it falsely elevates the rate of unnecessary C-sections.
  • 5. FBS Action Thresholds: Fetal scalp blood pH < 7.20 mandates immediate delivery. A borderline pH (7.21-7.24) requires repeating the test in exactly 30 minutes.

5. Lecture 15: Multiple Pregnancy

Epidemiology & Classification
  • Incidence: Twins 15:1000 (1 in 34 births), Triplets 1:5000, Quadruplets 1:360,000. Risk factors: Assisted reproduction (IVF, IUI, Clomifene 10%), increased maternal age (>35 yrs = 22:1000, >45 yrs = 57:1000), increased parity, family history, ethnicity (Nigeria 40:1000). HFEA recommends max 2 embryos per IVF cycle.
  • Dizygotic (Fraternal, 70%): Two eggs, two sperm. Always Dichorionic Diamniotic (DC/DA).
  • Monozygotic (Identical, 30%): One egg, splits later.
    • Split < 3 days: Dichorionic Diamniotic (DC/DA).
    • Split 4-7 days: Monochorionic Diamniotic (MC/DA).
    • Split 8-12 days: Monochorionic Monoamniotic (MC/MA).
    • Split > 13 days: Conjoined twins.
  • Ultrasound Diagnosis (Chorionicity): Crucial in 1st trimester.
    • Lambda (λ) sign: Thick septum, indicates Dichorionic (DC).
    • T-sign (absence of Lambda sign before 14wks): Thin septum, indicates Monochorionic (MC).
    • Fetuses of different sexes are definitively DC (dizygotic).
Complications of Multiple Pregnancy
  • Maternal Risks: Hyperemesis, Anemia, Pre-eclampsia (5x greater risk), GDM, Polyhydramnios, APH, PPH (due to uterine atony), increased CS rates.
  • General Fetal Risks: Preterm labor (40% <37wks, 10% <32wks - main cause of morbidity/mortality), FGR (up to 25%), increased risk of miscarriage and congenital anomalies (only in MC). Cerebral Palsy risk is increased (7:1000 for DC twins).
  • Vanishing Twin Syndrome: Up to 25% of twins suffer early demise/reabsorption in the 1st trimester.
Unique Monochorionic Complications
  • Twin-to-Twin Transfusion Syndrome (TTTS): Affects 5-25% of MC twins. 80% mortality if untreated. Unbalanced vascular anastomoses shift blood: 'Recipient' gets hypervolemic/polyuria/polyhydramnios/heart failure/hydrops, 'Donor' gets hypovolemic/oliguria/oligohydramnios ('stuck twin').
    • Quintero Staging: I (oligo/poly sequence, bladder visible), II (bladder invisible), III (abnormal Doppler, AREDF), IV (Hydrops), V (Death).
    • Requires serial USS every 2 weeks. Treatment: Fetoscopic laser ablation (80% survival of at least one), amnioreduction, selective feticide.
  • Twin Anemia Polycythemia Sequence (TAPS): Marked Hb difference between MC twins without fluid differences. Caused by tiny AV anastomoses. Often post-laser for TTTS.
  • Twin Reversed Arterial Perfusion (TRAP): 1% of monozygotic twins. One twin is structurally highly abnormal (acardiac/rudimentary heart) and receives reverse blood flow from the 'pump' twin via arterial anastomoses. Heart failure risk for the pump twin. Requires radiofrequency ablation.
  • Selective Fetal Growth Restriction: Growth discordance >20% or one twin < 10th centile. Absent/Reversed End-Diastolic Flow (AREDF) indicates high risk of sudden demise.
  • Monochorionic Monoamniotic (MCMA) Risks: Extremely high risk of Cord Entanglement (>50% mortality). Needs intense surveillance and CS delivery around 32-34 weeks.
Antenatal Care & Delivery
  • Care must be consultant-led. Give 150mg aspirin OD if pre-eclampsia risk factors exist. Iron/folate supplements.
  • Serial scans: Every 2 weeks for MC twins (16 weeks onwards). 28, 32, 36 weeks for DC twins.
  • Delivery: DC twins offered delivery at 37 weeks. Leading twin delivered as singleton; stabilize 2nd twin immediately. Ensure adequate monitoring of 2nd twin. Internal podalic version / breech extraction for the 2nd twin only by an experienced obstetrician. Use Syntometrine/oxytocin prophylactically to prevent PPH from uterine atony.
💡 High-Yield Hints (Lecture 15)
  • 1. Twin Splitting Timeline: Splitting at <3 days = DC/DA. 4-7 days = MC/DA. 8-12 days = MC/MA. >13 days = Conjoined.
  • 2. Crucial Ultrasound Signs: The Lambda (λ) sign strictly diagnoses Dichorionic twins, whereas the T-sign diagnoses Monochorionic twins (must be checked < 14 weeks).
  • 3. Pre-eclampsia Risk: Mothers carrying multiples face a massive 5x increased risk of developing pre-eclampsia compared to singleton pregnancies.
  • 4. TTTS Pathophysiology: In TTTS, the "Recipient" twin is actually at higher risk of death due to cardiac volume overload and hydrops, despite receiving more blood.
  • 5. Cord Entanglement: Monochorionic Monoamniotic (MCMA) twins share one sac and face an extreme risk of lethal cord entanglement, mandating C-section around 32-34 weeks.

6. Top 5 High-Yield Comparisons

1. Types of Breech Presentations
Type of Breech Leg & Hip Position Prevalence Cord Prolapse Risk
Frank (Extended) Hips flexed, knees extended (legs straight up) Most common Low (Good fit in pelvis)
Complete (Flexed) Hips flexed, knees flexed (tailor sitting) Less common Moderate
Footling (Incomplete) Hips extended, one or both feet presenting Least common Highest risk (5-10%)
2. Types of Fetal Heart Rate (FHR) Decelerations
Deceleration Type Timing vs Contraction Pathophysiology (Cause) Clinical Significance
Early Mirrors contraction (Nadir aligns with Peak) Head compression (Vagal nerve stimulation) Benign. Rarely associated with fetal compromise.
Variable Unpredictable, variable shape (V or W) Umbilical cord compression Most common. Atypical variables suggest hypoxia.
Late Starts after contraction onset, Nadir after Peak Placental insufficiency / Fetal hypoxia Pathological/Ominous. Demands urgent intervention.
3. Monochorionic vs. Dichorionic Twins
Feature Dichorionic (DC) Monochorionic (MC)
Zygosity All Dizygotic + 30% of Monozygotic 70% of Monozygotic (split 4-12 days)
Ultrasound Sign (<14wks) Lambda (λ) sign (thick septum) T-sign (thin septum)
Specific Complications Pre-eclampsia, FGR, Preterm birth TTTS, TAPS, TRAP, Congenital anomalies
Surveillance & Delivery Scans at 28, 32, 36 wks. Deliver ~37 wks. Intense 2-weekly scans (from 16 wks). Deliver earlier.
4. Alpha (α) vs. Beta (β) Thalassemia
Feature Alpha (α) Thalassemia Beta (β) Thalassemia
Genetic Defect Defect in 1-4 of the α-globin genes Defect in 1-2 of the β-globin genes
Demographics Most common in South-East Asia Most common in Cyprus, Asia, Middle East
Major Form Severity Hb Barts: Incompatible with life (Hydrops fetalis, maternal pre-eclampsia) Transfusion-dependent, Iron overload, Heart failure (Can be cured by BM transplant)
Trait / Minor Form Usually asymptomatic, may become anemic in pregnancy Asymptomatic but anemic in pregnancy. 1:4 risk to offspring if partner is carrier.
5. Categories of Cesarean Section Timing
Category Urgency Definition Time Target Classic Examples
Category 1 (Crash) Immediate threat to life of woman or fetus Within 30 minutes Placental abruption, Cord prolapse, Uterine rupture, Scalp pH < 7.20
Category 2 (Urgent) Maternal/fetal compromise, NOT immediately life-threatening As soon as possible Pathological CTG in 1st stage, Failure to progress with poor pain control
Category 3 (Scheduled) No immediate compromise, but early delivery needed Planned timing Severe pre-eclampsia, FGR with abnormal Doppler but normal FHR
Category 4 (Elective) Timed to suit woman and staff Delayed to 39 wks Maternal HIV, Placenta previa, Elective breech, Previous Classical CS
Theme 🌙
L11: Anemia L12: Malpresentation L13: Cesarean Section L14: Fetal Monitoring L15: Multiple Pregnancy ⭐ Comparisons
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