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1. USG - Types (first trimester, anatomy scan, Level II), key measurements (CRL, BPD, HC, AC, FL, AFI), anomaly detection rates
2. Doppler USG - Umbilical artery (AEDV/REDV in FGR), MCA-PSV (fetal anaemia), ductus venosus, uterine artery
3. CTG - Technical aspects (internal vs external), NST criteria (reactive = 2 accels ≥15 bpm), BPP scoring, ACOG 3-tier intrapartum classification
4. HSG - Indications, timing, findings for tubal patency and uterine cavity
5. Amniocentesis - Indications, timing (15-20 wks), complications (0.1-0.3% loss)
6. CVS - First trimester (10-13 wks), advantages/limitations vs amniocentesis
7. cfDNA/NIPT - Detection rates (>99% for T21), screening vs diagnostic distinction
8. Serum screening - First trimester combined, Quad screen markers
9. Cordocentesis - PUBS for fetal blood sampling and intrauterine transfusion

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PRACTICAL SKILLS IN OBSTETRICS

A Complete Clinical Reference

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SECTION 1: PELVIMETRY

Definition

"A particularly important measurement is the true conjugate of the pelvic inlet (the obstetric conjugate), which is the smallest anteroposterior dimension of the lesser pelvis. With pelvimetry, a method of measuring pelvic dimensions, potential obstructions to labor can be identified prior to delivery."

• General Anatomy and Musculoskeletal System, THIEME Atlas

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Anatomy of the Bony Pelvis

1. Pelvic Inlet (Brim) - bounded by sacral promontory posteriorly, linea terminalis laterally, pubic symphysis anteriorly
2. Mid-pelvis (Cavity) - bounded by ischial spines (narrowest part)
3. Pelvic Outlet - bounded by coccyx posteriorly, ischial tuberosities laterally, subpubic arch anteriorly

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CONJUGATE DIAMETERS - All Types

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1. TRUE CONJUGATE (Conjugata Vera Anatomica)

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2. OBSTETRIC CONJUGATE (True Conjugate / Conjugata Vera Obstetrica)

Obstetric Conjugate = Diagonal Conjugate − 1.5 cm

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3. DIAGONAL CONJUGATE

True (Obstetric) Conjugate = Diagonal Conjugate − 1.5 cm

• If DC = 12.5 cm → Obstetric Conjugate ≈ 11 cm (adequate)
• If DC < 11.5 cm → Obstetric Conjugate < 10 cm → suspect contracted pelvis

1. Patient in dorsal lithotomy position, bladder empty
2. Two fingers (index + middle) inserted into vagina, with palm facing upward
3. The middle finger reaches toward the sacral promontory
4. The examiner's other hand marks where the index finger touches the lower border of the symphysis pubis
5. The distance from the tip of the middle finger to the mark = diagonal conjugate
6. Measured with a ruler or pelvimeter
7. If the fingers cannot reach the sacral promontory - pelvis is adequate (DC >12.5 cm)
8. If sacral promontory is easily palpable - pelvis may be contracted

• THIEME Atlas of Anatomy - General Anatomy and Musculoskeletal System

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4. EXTERNAL CONJUGATE (Baudelocque's Diameter)

True Conjugate ≈ External Conjugate − 9 cm (Subtract 8-10 cm depending on soft tissue thickness)

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5. CONJUGATE OF PELVIC OUTLET

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Summary Table: All Conjugates

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Other Pelvic Diameters

Transverse Diameters

Oblique Diameters (of inlet)

External Pelvic Measurements (Obstetric Conjugate Estimation)

• A diamond-shaped area on the lower back
• Upper angle = depression below L5
• Lower angle = tip of sacrum
• Side angles = posterior superior iliac spines
• Normal dimensions: vertical ≈ 11 cm, horizontal ≈ 10 cm
• A flat, asymmetric, or malformed rhomboid suggests pelvic contraction

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Types of Pelves (Caldwell-Moloy Classification)

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Contracted Pelvis - Definitions

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SECTION 2: LEOPOLD'S MANEUVERS

Definition

• Bladder empty
• Patient supine, knees slightly flexed (semi-recumbent)
• Examiner stands to the patient's right side (for maneuvers 1-3), then facing feet (maneuver 4)
• Warm hands; palpate gently

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MANEUVER 1 - Fundal Grip (Fundal Palpation)

• Examiner faces the patient's head
• Both hands placed on the fundus, fingers pointing downward and inward
• Palpate the mass in the fundus

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MANEUVER 2 - Lateral (Umbilical) Grip (Lateral Palpation)

• Examiner faces the patient's head
• Both hands placed on the lateral sides of the uterus at umbilical level
• One hand steadies the uterus; the other palpates the opposite side, then vice versa

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MANEUVER 3 - Pawlik's Grip (Lower Pole Palpation)

• Examiner faces the patient's head
• One hand only - right hand
• Thumb and fingers grasp the lower uterine segment just above the symphysis pubis
• Gently move the presenting part side to side

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MANEUVER 4 - Pelvic (Bi-manual) Grip

• Examiner turns and faces the patient's feet
• Both hands placed on the lower abdomen, fingers pointing downward toward the pelvic inlet
• Fingers slide down toward the pelvic brim on both sides of the presenting part
• Press inward and downward

• On the same side as the back → head extended (face/brow presentation)
• On the opposite side from the back → head flexed (normal vertex - occiput is cephalic prominence)

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Engagement Assessment (Fifths Rule)

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Determining Fetal Lie, Presentation, Position

• Longitudinal (99%)
• Transverse
• Oblique

• Vertex (cephalic - occiput leading): most common (95%)
• Face, Brow (cephalic - deflexed)
• Breech (frank, complete, footling)
• Shoulder (transverse lie)

• LOA (Left Occiput Anterior) - most common
• ROA (Right Occiput Anterior)
• LOT, ROT (transverse)
• LOP, ROP (posterior)
• OA (direct anterior), OP (direct posterior)

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SECTION 3: AUSCULTATION OF FETAL HEART SOUNDS

Instruments

1. Pinard fetoscope (wooden/metal stethoscope) - from 20-24 weeks
2. Sonicaid / handheld Doppler (CTG) - from 12-14 weeks
3. Electronic CTG monitor - from 28 weeks

Technique with Pinard Fetoscope

1. Patient supine, abdomen exposed
2. Identify fetal back (from Leopold's maneuver 2)
3. Place Pinard fetoscope over the fetal back - sounds are transmitted through fetal chest wall
4. Apply ear (not hand-held stethoscope style) firmly to the fetoscope opening - use head contact, not holding
5. Listen for 1 full minute

Normal Fetal Heart Rate

110-160 beats per minute

• Tachycardia: >160 bpm (sustained) - may indicate fetal distress, maternal fever, drugs
• Bradycardia: <110 bpm - may indicate cord compression, fetal hypoxia

Point of Maximum Intensity (PMI) of Fetal Heart

Differentiating from Maternal Pulse

• Simultaneously palpate maternal radial pulse
• If rate same as auscultated rate → maternal aortic pulsation (not fetal)
• True FHR differs from maternal pulse

Souffle (Murmurs)

• Uterine souffle (funic souffle): Soft blowing sound, synchronous with FHR - from umbilical arteries
• Placental souffle: Soft blowing sound, synchronous with maternal pulse - from uteroplacental vessels

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SECTION 4: ESTIMATION OF FETAL WEIGHT

A. Clinical Estimation (Abdominal Palpation)

EFW (grams) = (Fundal Height in cm − n) × 155

• n = 12 if presenting part is above the ischial spines (not engaged)
• n = 11 if presenting part is at or below the ischial spines (engaged)

• Fundal height = 36 cm, head not engaged
• EFW = (36 - 12) × 155 = 24 × 155 = 3720 g

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B. Dawson's / McDonald's Rule (Fundal Height for Gestational Age)

Gestational age (weeks) ≈ SFH (cm) in cm measured from symphysis pubis to uterine fundus

"Measurement of the symphysis-fundal height is helpful in screening for abnormal fetal growth and documenting continued growth if performed repeatedly by the same observer." - Creasy & Resnik's Maternal-Fetal Medicine

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C. Ultrasound Fetal Weight Estimation

Log10(EFW) = 1.326 - 0.00326(AC × FL) + 0.0107(HC) + 0.0438(AC) + 0.158(FL)

Log10(EFW) = 1.304 + 0.05281(AC) + 0.1938(FL) - 0.004(AC × FL)

Log10(EFW) = -1.7492 + 0.166(BPD) + 0.046(AC) - 2.646(AC × BPD)/1000

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D. Additional Clinical Estimation Methods

EFW (grams) = Fundal height (cm) × Abdominal girth (cm)

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SECTION 5: EXPECTED DATE OF DELIVERY (EDD)

Naegele's Rule (Standard Method)

EDD = LMP + 9 months + 7 days OR equivalently: EDD = LMP − 3 months + 7 days + 1 year

1. Take the first day of the Last Menstrual Period (LMP)
2. Add 9 calendar months (or subtract 3 months)
3. Add 7 days

• LMP: 1st May 2025
• Add 9 months → 1st February 2026
• Add 7 days → EDD: 8th February 2026

• LMP: 1st May 2025
• Subtract 3 months → 1st February 2025
• Add 7 days + 1 year → 8th February 2026 ✓

• Regular 28-day cycle
• Ovulation on day 14
• Normal duration of pregnancy = 280 days (40 weeks) from LMP = 266 days from conception

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Adjustments to EDD

Adjusted EDD = Naegele's EDD ± (actual cycle length − 28 days)

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Other Methods to Estimate Gestational Age

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SECTION 6: STRESS TESTS

A. NON-STRESS TEST (NST)

• Post-dates pregnancy
• Gestational diabetes
• Hypertensive disorders
• FGR, decreased fetal movements
• IUGR, multiple pregnancy
• Oligohydramnios

1. Patient semi-recumbent, left lateral tilt preferred
2. External CTG applied: Doppler transducer (FHR) + tocodynamometer (uterine activity)
3. Monitor for minimum 20-30 minutes
4. Patient presses button when fetal movement felt (event marker)
5. If non-reactive at 20 min: extend to 40-60 min, use vibroacoustic stimulation (VAS)

REACTIVE (Normal) NST:

• ≥2 accelerations in 20-30 minutes
• Each acceleration: peaks ≥15 bpm above baseline and lasts ≥15 seconds
• For <32 weeks gestation: ≥10 bpm rise lasting ≥10 seconds (modified criteria)

NON-REACTIVE NST:

• Does not meet above criteria within 40-60 minutes

• Creasy & Resnik's Maternal-Fetal Medicine

• Fetal sleep (most common; 20-40 min sleep cycles)
• Prematurity (<32 weeks)
• FGR / fetal hypoxia
• Maternal sedatives, narcotics, magnesium sulfate
• Neurological anomaly

• Apply acoustic stimulator (artificial larynx) to maternal abdomen over fetal head for 1-3 seconds
• Should produce FHR acceleration
• If reactive after VAS → reactive NST

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B. CONTRACTION STRESS TEST (CST) / OXYTOCIN CHALLENGE TEST (OCT)

"The CST uses spontaneously occurring contractions or contractions induced by maternal nipple stimulation. The OCT uses intravenous oxytocin to cause repetitive uterine activity." - Creasy & Resnik's Maternal-Fetal Medicine

• Placenta praevia
• Previous classical (vertical) caesarean scar
• Preterm labour or risk of preterm labour
• Incompetent cervix
• Premature rupture of membranes
• Multiple pregnancy (relative)

1. IV oxytocin by infusion pump: start at 0.5-1 mU/min, increase every 15-20 min
2. Goal: 3 contractions of ≥40 seconds duration in 10 minutes
3. Monitor FHR and uterine activity throughout
4. Perform in hospital with emergency backup

1. Patient stimulates nipple through clothing intermittently
2. Releases endogenous oxytocin
3. Same FHR assessment applied

"Although these test results are good indicators of fetal well-being when negative (negative predictive values exceeding 99.8%), a positive test result alone is not sufficiently predictive to form the basis for clinical action." - Creasy & Resnik's Maternal-Fetal Medicine

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C. BIOPHYSICAL PROFILE (BPP)

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D. VIBROACOUSTIC STIMULATION TEST (VAST)

• Fetal acoustic stimulation using an artificial larynx (EAL) at 82-95 dB placed on maternal abdomen
• Applied for 1-3 seconds
• Normal response: FHR acceleration ≥15 bpm for ≥15 seconds within 15 seconds of stimulus
• Can convert non-reactive NST to reactive
• Considered part of routine NST protocol

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SECTION 7: VAGINAL EXAMINATION IN LABOUR (Internal Examination)

Findings to Assess

• Dilatation (0-10 cm): measured as finger-breadths (1 finger = ~2 cm) or in cm with both fingers spread
• Effacement (%): shortening/thinning of cervical canal; 0% = 3-4 cm long; 100% = completely thinned
• Consistency: firm (unripe), medium, soft/ripe
• Position: posterior, mid, anterior
• Bishop Score combines all above + station (see below)

• Nature (vertex, breech, face)
• Station (level relative to ischial spines)
  • -3 to +3 scale (ACOG) or -5 to +5 (older)
  • 0 = at level of ischial spines (= engaged in ACOG scale)
  • Negative = above spines; positive = below spines

• Intact / ruptured
• If intact: can feel membranes bulging through cervix
• Confirm rupture: pooling in posterior fornix, ferning on glass slide, Amnisure (AFP/IGFBP-1 test)

• Diagonal conjugate (if not done)
• Ischial spines prominence (prominent = narrowed mid-pelvis)
• Subpubic angle (normal >90° in females)
• Sacral curve
• Convergence/divergence of side walls

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Bishop Score

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SECTION 8: PARTOGRAPH (Labour Monitoring Tool)

• FHR (every 30 min)
• Membranes and liquor (colour)
• Moulding of fetal skull

• Cervicograph (cervical dilatation plotted over time)
  • Alert line: Starts at 4 cm dilatation, progresses at 1 cm/hour
  • Action line: 4 hours to the right of alert line
• Descent of presenting part (in fifths palpable abdominally)
• Uterine contractions (frequency, duration, strength per 10 min)

• BP, pulse, temperature
• Urine (volume, protein, acetone)
• Drugs / IV fluids

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QUICK REFERENCE FORMULA SHEET

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• Creasy & Resnik's Maternal-Fetal Medicine: Principles and Practice - CST/OCT, NST, BPP, Doppler, Fundal height
• THIEME Atlas of Anatomy - General Anatomy and Musculoskeletal System - Pelvimetry, conjugate diameters
• Berek & Novak's Gynecology - Pelvic anatomy, ischial spines, pelvic articulations
• Park's Textbook of Preventive and Social Medicine - ANC, fundal height landmarks, clinical examination
• Williams Obstetrics and DC Dutta standard knowledge (Leopold's maneuvers, Johnson's formula, Naegele's rule, Bishop score)

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• Ectopic pregnancy - classic triad, discriminatory zone, methotrexate criteria, surgical options
• Ruptured ovarian cyst - corpus luteum (most common), dermoid/endometrioma (chemical peritonitis), conservative vs surgical management
• Adnexal torsion - "follicular ring sign," whirlpool sign, Doppler flow can be present despite torsion, detorsion preferred over oophorectomy
• PID / TOA - CDC criteria, Fitz-Hugh-Curtis syndrome, ESR/CRP cutoffs for TOA, ruptured TOA as life-threatening emergency

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• Primary amenorrhoea: Turner syndrome, Swyer syndrome, Kallmann (anosmia), MRKH, Complete AIS (AIS vs MRKH differentiating table), imperforate hymen - all with diagnostic algorithms
• Secondary amenorrhoea: WHO 4-group classification, systematic causes (hypothalamic FHA, Sheehan syndrome, prolactinoma, Asherman syndrome, POI with FMR1/autoimmune causes), progestogen withdrawal test interpretation, full investigation protocol