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COMPREHENSIVE OBG EXAM NOTES

Obstetrics & Gynaecology - Complete Revision

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1. ABNORMAL UTERINE BLEEDING (AUB)

Definition

Normal Menstrual Parameters (Remember: FORD)

PALM-COEIN Classification (FIGO 2011)

• P - Polyp (endometrial/cervical)
• A - Adenomyosis
• L - Leiomyoma (fibroid) - submucosal = most likely to bleed
• M - Malignancy/hyperplasia

• C - Coagulopathy (von Willebrand, thrombocytopenia)
• O - Ovulatory dysfunction (PCOS, thyroid, hyperprolactinaemia)
• E - Endometrial (primary endometrial disorder)
• I - Iatrogenic (HRT, anticoagulants, IUCDs)
• N - Not yet classified

Causes by Age Group (HIGH YIELD TABLE)

Dysfunctional Uterine Bleeding (DUB)

• Diagnosis of exclusion - no structural/systemic cause
• Most common cause: anovulation (80%) - excess unopposed oestrogen without progesterone surge
• Anovulatory DUB: irregular, painless, heavy; no temperature rise, no LH surge
• Remember: DUB = hormonal, no organic cause

Key Terminology

• Menorrhagia - heavy periods, regular cycle, >80 mL or >7 days
• Metrorrhagia - irregular intermenstrual bleeding
• Menometrorrhagia - heavy AND irregular
• Polymenorrhoea - cycles <21 days
• Oligomenorrhoea - cycles >35 days
• Amenorrhoea - no periods (primary: never had; secondary: absent >6 months)
• Postcoital bleeding - cervical pathology until proven otherwise

Investigation Approach

1. History: LMP, cycle pattern, HRT/COCP use, bleeding disorders, pregnancy
2. Examination: BMI, signs of androgen excess, pelvic exam, cervix
3. Bloods: FBC, coagulation, TSH, prolactin, FSH/LH, hCG (always in reproductive age)
4. Pelvic USS: first-line imaging - endometrial thickness (ET), fibroids, ovaries
   • Postmenopausal: ET >4 mm = needs biopsy
5. Endometrial biopsy (Pipelle): any age >45, or younger with risk factors
6. Hysteroscopy + D&C: gold standard for intrauterine pathology
7. Cervical smear/colposcopy: if postcoital bleeding

Management

• Mirena IUS (LNG-IUS) - most effective medical option (reduces blood loss by 90%)
• Tranexamic acid - antifibrinolytic, reduces blood loss ~50%
• NSAIDs (mefenamic acid) - reduces blood loss ~25%, helps dysmenorrhoea
• COCP - regulates cycle, reduces blood loss
• Oral progestogens (norethisterone) - luteal phase or continuous

• Endometrial ablation/resection - for completed family, failed medical
• Hysterectomy - definitive treatment
• Polypectomy/myomectomy - targeted for polyps/fibroids

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2. ACUTE ABDOMINAL PAIN IN YOUNG WOMEN

Think "GIFT" for gynaecological causes

• G - Gynaecological infection (PID)
• I - Intrauterine/ectopic pregnancy
• F - Fibroid (torsion/degeneration)
• T - Torsion (ovarian), Tumour, Twisted cyst

Causes to Differentiate

Ectopic Pregnancy (EMERGENCY)

• Triad: amenorrhoea + unilateral pelvic pain + vaginal bleeding
• Risk factors: PID, previous ectopic, tubal surgery, IUD, IVF
• USS: empty uterus + adnexal mass + free fluid in POD
• hCG: positive but lower than expected for dates
• Discriminatory zone: hCG >1500-2000 IU/L should show intrauterine sac on TVS
• Rx: Methotrexate (unruptured, hCG <5000, no FHB, <3.5 cm) OR Salpingectomy/salpingotomy

Pelvic Inflammatory Disease (PID)

• Ascending infection: Chlamydia (most common), Gonorrhoea, anaerobes
• Criteria (need 1 minimum + consider): lower abdominal pain + cervical motion tenderness + adnexal tenderness
• Additional criteria: fever >38.3°C, elevated CRP/ESR, mucopurulent cervical discharge, lab evidence of STI
• Complications (Fitz-Hugh-Curtis): perihepatitis - violin string adhesions
• Rx: Outpatient - Ceftriaxone IM STAT + doxycycline + metronidazole x14 days
• Inpatient if: TOA, pregnancy, failed oral, severe illness

Ovarian Torsion (EMERGENCY)

• Sudden severe unilateral pain, N+V, may be intermittent
• Risk: cyst >5 cm, pregnancy, ovarian hyperstimulation
• USS: enlarged ovary, absent Doppler flow, cyst
• Rx: Laparoscopy - detorsion (within 4-6 hours to save ovary)

Ovarian Cyst Rupture

• Sudden pain at mid-cycle (Mittelschmerz if follicle) or from corpus luteum
• Corpus luteum cyst rupture: right side more common, haemoperitoneum
• Rx: Usually conservative if haemodynamically stable

Degenerating Fibroid (Red Degeneration)

• Pregnancy-associated (typically 14-22 weeks)
• Constant pain, low-grade fever, localised tenderness over fibroid
• Rx: Conservative - analgesia (paracetamol, NSAIDs cautiously)

Endometriosis

• Cyclical pain (dysmenorrhoea, dyspareunia, dyschezia)
• Chocolate cyst (endometrioma) on USS - ground glass appearance
• "Kissing ovaries" on MRI in severe disease

Appendicitis

• Cannot be excluded! - McBurney's point, Rovsing's sign, Psoas sign
• Right-shifted in pregnancy (appendix displaced superiorly by uterus)
• Always do urine hCG in reproductive age women with acute abdomen

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3. PAP SMEAR, PIPELLE, HVS & OBG INSTRUMENTS

Pap Smear (Cervical Cytology)

Purpose

When

• Start at age 21 (or 25 in UK/some guidelines) regardless of sexual history
• Every 3 years (age 21-65); HPV co-testing every 5 years (age 30-65)

Technique

1. No intercourse, douching, or vaginal medications 48h prior
2. Best timed mid-cycle (days 10-20)
3. Patient in dorsal/lithotomy position
4. Cusco's/bivalve speculum inserted - visualise cervix
5. Ayre's spatula (wooden/plastic) - rotated 360° at transformation zone
6. Endocervical brush (cytobrush) - rotated in endocervical canal
7. Smear on glass slide immediately, fix with 95% ethanol (or liquid-based cytology - ThinPrep)
8. Label with patient details

Results (Bethesda System)

Instrument: Cusco's Speculum

• Bivalve self-retaining speculum
• Used for: Pap smear, HVS, IUCD insertion, colposcopy, cervical procedures

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Pipelle (Endometrial Sampler)

Purpose

Technique

1. Bimanual examination to determine uterine position (anteverted/retroverted)
2. Cusco's speculum inserted, cervix visualised + cleaned with antiseptic
3. Tenaculum applied to anterior lip of cervix (if needed for traction)
4. Uterine sound to measure cavity (6-8 cm normal)
5. Pipelle (flexible polypropylene suction curette, 3.1 mm diameter) inserted to fundus
6. Inner plunger withdrawn creating negative pressure - rotated and moved in-out 4 times
7. Sample expelled into formalin for histology

Sensitivity: ~80-99% for endometrial carcinoma (may miss focal lesions)

Contraindications: Pregnancy, cervical/uterine infection, cervical stenosis

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High Vaginal Swab (HVS)

Purpose

Technique

1. Cusco's speculum - visualise vaginal walls and cervix
2. Sterile cotton-tipped swab inserted into posterior fornix and vaginal walls
3. Rotated to collect discharge/secretions
4. Placed in Amies/Stuart transport medium immediately
5. Send for: microscopy, culture & sensitivity, wet prep (Trichomonas motile flagellates)

pH: Normal vaginal pH <4.5; BV = pH >4.5 (whiff test positive with 10% KOH)

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OBG Instruments - Summary Table

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4. MATERNAL PELVIS, FETAL SKULL & MECHANISM OF LABOUR

A. THE MATERNAL PELVIS

Parts of the Pelvis

1. False pelvis (pelvis major) - above pelvic brim, little obstetric significance
2. True pelvis (pelvis minor) - below pelvic brim; the "birth canal"
   • Inlet (brim)
   • Cavity
   • Outlet

Planes and Diameters

Pelvic Inlet (Brim)

Pelvic Cavity (Mid pelvis)

• Nearly round
• AP and transverse both ~12 cm
• Interspinous diameter (transverse): 10.5 cm (NARROWEST PART OF PELVIS - important!)
• Ischial spines project into cavity here - station 0 reference point

Pelvic Outlet

Types of Pelvis (Caldwell-Moloy)

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B. FETAL SKULL

Bones of the Fetal Skull

• 2 Frontal bones
• 2 Parietal bones (largest)
• 2 Temporal bones
• 1 Occipital bone
• 1 Sphenoid, 1 Ethmoid

Sutures (Membranous connections)

• Sagittal - between 2 parietal bones (anteroposterior)
• Coronal - frontals + parietals
• Lambdoid - parietals + occipital
• Frontal (metopic) - between 2 frontal bones
• Squamous - temporal + parietal

Fontanelles

Regions of Fetal Skull

• Vertex - area bounded by anterior fontanelle (bregma), posterior fontanelle (lambda), and parietal eminences
• Brow - between bregma and orbital ridges
• Face - below orbital ridges
• Occiput - behind lambda fontanelle

Fetal Skull Diameters (HIGH YIELD)

Moulding

• Overlapping of skull bones at sutures during labour
• Reduces biparietal diameter by up to 0.5 cm
• Grading: 0 = bones separate; + = touching; ++ = overlapping reducible; +++ = fixed (pathological - obstructed labour)

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C. PRESENTING PART, DENOMINATOR & ENGAGING DIAMETER

• In vertex: biparietal diameter (9.5 cm) passes through brim
• Head is 2/5 or less palpable abdominally (3/5 or more in pelvis)
• On VE: presenting part at or below ischial spines (station 0)

• -3 to 0: floating/engaged above spines
• 0: at spines
• +1 to +3: descent below spines
• Some systems use cm (-5 to +5)

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5. MECHANISM OF LABOUR

Cardinal Movements (Remember: EDFERE-E or D.E.F.R.E.E.)

1. ENGAGEMENT

• Biparietal diameter enters pelvic inlet
• Fetal head enters pelvis in transverse or oblique diameter
• In primigravidas: usually occurs weeks before labour
• In multigravidas: may occur in early labour

2. DESCENT

• Progressive descent through birth canal throughout labour
• Aided by: uterine contractions, maternal pushing, amniotic fluid pressure, straightening of fetal body
• Continuous process accompanying all other movements

3. FLEXION

• As head descends and meets pelvic floor resistance, chin flexes onto chest
• Diameter changes from occipitofrontal (11.5 cm) to suboccipitobregmatic (9.5 cm)
• Why it matters: 2 cm reduction - critical for successful vaginal delivery

4. INTERNAL ROTATION

• Occiput rotates from transverse/oblique to AP position (usually OA)
• Occurs as head reaches level of ischial spines (mid-pelvis)
• Due to: shape of pelvic floor (levator ani muscle gutter), pelvic cavity narrowing
• LOA/ROA: occiput rotates anteriorly 45° → OA
• LOP/ROP: occiput rotates posteriorly or anteriorly 135°

5. EXTENSION

• Head reaches pelvic outlet - occiput under pubic arch (subpubic angle)
• Uterine pressure pushes occiput forward; perineum pushes chin upward
• Head born by extension: brow → bregma → vertex → occiput sweeps over perineum
• Suboccipital region (nape of neck) pivots under pubic arch (hypomochlion)

6. RESTITUTION

• After birth of head, it rotates back 45° to align with fetal shoulders
• Corrects the twist from internal rotation
• Head returns to its natural relationship with shoulders
• Visible external rotation of head

7. EXTERNAL ROTATION (SHOULDER ROTATION)

• Shoulders rotate from oblique to AP diameter of outlet
• Anterior shoulder descends under pubic arch first
• Head rotates a further 45° as shoulders rotate to AP
• Now both head and shoulders align with mother's transverse axis

8. EXPULSION (Birth of Body)

• Anterior shoulder born first (under pubic arch)
• Posterior shoulder born over perineum
• Body born by lateral flexion

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Cardinal Movements - Clinical Implications

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Mechanism of Labour: LOA (Left Occipito-Anterior)

1. Engagement: Head enters brim in left oblique diameter; occiput pointing left-anterior; BPD in right oblique diameter
2. Descent: Head descends with slight flexion
3. Flexion: Complete flexion as head meets pelvic floor; SOB diameter presents (9.5 cm)
4. Internal Rotation: Occiput rotates 45° from LOA → OA (directly anterior); rotation along right pelvic wall; head in AP diameter of outlet
5. Extension: Head born - occiput pivots under pubic arch; brow, face, chin delivered over perineum sequentially
6. Restitution: Head rotates 45° back to LOA; sagittal suture in left oblique diameter
7. External Rotation: Shoulders rotate from right oblique → AP; head turns further to face left thigh; occiput now pointing to left
8. Expulsion: Anterior (right) shoulder under pubic arch, posterior (left) shoulder over perineum; body born

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Mechanism of Labour: ROP (Right Occipito-Posterior)

1. Engagement: Head enters brim in right oblique diameter; occiput pointing right-posterior; BPD in left oblique
2. Descent: With some deflexion initially; occipitofrontal (11.5 cm) or larger diameter often presenting
3. Flexion: May be incomplete - OP positions often present with deflexion
4. Internal Rotation:
   • Long rotation (135°): Occiput rotates anteriorly from ROP → OA (preferred, 65-75% of OP cases) - labour longer but vaginal delivery likely
   • Short rotation (45°): Occiput rotates posteriorly from ROP → OP (direct OP) - persistent OP = face-to-pubes delivery possible but difficult
5. Extension (if long rotation occurs): Normal as in OA
6. Extension (if persistent OP):
   • Head delivered face-to-pubes
   • Occiput in sacral hollow; brow emerges under pubic arch; head born by flexion (not extension)
   • Sinciput, vertex, occiput born over perineum
7. Restitution + External Rotation: Head rotates to align with shoulders
8. Expulsion: As above

• Prolonged labour (deflexion, larger diameter)
• Backache ("posterior labour pain")
• Early urge to push (pressure on sacrum)
• Higher risk of: operative delivery, perineal tears (3rd/4th degree), PPH
• Diagnosis: VE - sagittal suture in AP or right oblique; posterior fontanelle posterior; face palpable anteriorly

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6. PARTOGRAM

Definition

Components

1. Fetal Condition

• Fetal heart rate (FHR): recorded every 30 min (normal 110-160 bpm)
• Liquor: colour (clear=C, blood-stained=B, meconium=M1/M2/M3)
• Moulding: 0, +, ++, +++ (excessive = obstructed labour)

2. Progress of Labour

• Cervical dilation (cm) - plotted on cm axis; most important parameter
• Descent of head (fifths palpable abdominally)
• Contractions: frequency, duration, strength per 10 minutes
  • Mild: <20 sec; Moderate: 20-40 sec; Strong: >40 sec

3. Maternal Condition

• Urine (volume, protein, acetone)
• Blood pressure + pulse (every 30 min in active labour)
• Temperature (4-hourly)
• Drugs/IV fluids/oxytocin

Alert and Action Lines

• Alert line: starts at 4 cm dilation, line of progress at 1 cm/hour
• Action line: 4 hours to the right of alert line (WHO) or 2 hours (some guidelines)
• Cervical curve crossing alert line = increased surveillance
• Crossing action line = INTERVENTION required (assess for CPD, augmentation or C/S)

Normal Progress of Labour

• Latent phase: 0-4 cm; up to 8 hours (primipara), 6 hours (multipara) - variable
• Active phase: 4-10 cm; minimum 0.5 cm/hr (WHO 2018 - was 1 cm/hr); most dilate 1-2 cm/hr
• Second stage:
  • Primipara: passive up to 2 hours, active pushing up to 1 hour (total ≤3 hours)
  • Multipara: up to 1 hour total
• Third stage: up to 30 minutes (active management) to 60 minutes

Clinical Use of Partogram

• Identifies prolonged labour early
• Guides decision for augmentation (amniotomy, oxytocin)
• Reduces operative delivery and neonatal morbidity (especially in resource-limited settings)
• WHO recommends use in all labouring women

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7. CTG (CARDIOTOCOGRAPHY)

Purpose

Two Components

1. Cardio (FHR) - via Doppler US or fetal scalp electrode (FSE)
2. Toco (uterine contractions) - external tocodynamometer or IUPC

CTG Parameters (FIGO/NICE Classification)

1. Baseline FHR

• Normal: 110-160 bpm
• Tachycardia: >160 bpm (infection, maternal fever, drugs, fetal hypoxia late sign, prematurity)
• Bradycardia: <110 bpm (cord compression, placental abruption, cord prolapse, terminal event)

2. Baseline Variability

• Normal: 5-25 bpm (assessed over 10-minute windows)
• Reduced variability (<5 bpm for >40 min): fetal sleep, prematurity, drugs (morphine, MgSO4), hypoxia
• Increased/saltatory variability (>25 bpm): cord compression (acute)
• Sinusoidal pattern: fetal anaemia, Rh isoimmunisation (smooth, regular sine wave) - EMERGENCY

3. Accelerations

• Increase of ≥15 bpm lasting ≥15 seconds
• Normal: ≥2 accelerations in 20-minute window = reactive CTG
• Absence of accelerations alone: not necessarily abnormal but needs context
• Good sign of fetal wellbeing

4. Decelerations

CTG Classification (NICE/FIGO)

Fetal Blood Sampling (FBS) - pH interpretation

• pH >7.25: Normal - labour can continue
• pH 7.21-7.24: Borderline - repeat in 30 min
• pH ≤7.20: Fetal acidosis - IMMEDIATE DELIVERY

ALSO/NLS Mnemonic for CTG: DR C BRAVADO

• Define Risk, Rhythm, Contractions, Baseline Rate, Reactivity (accelerations), Acceleration, Variability, Anormalities (decelerations), Decelerations, Overall assessment

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8. HORMONAL & EMERGENCY CONTRACEPTION

Hormonal Contraception Methods

Combined Oral Contraceptive Pill (COCP)

• Contains: Ethinyloestradiol (EE) + progestogen
• Mechanism: Suppress LH surge → inhibit ovulation; thicken cervical mucus; thin endometrium
• Failure rate: 0.3% perfect use, 7-9% typical use
• Contraindications (WHO MEC 4 - absolute):
  • VTE/thrombophilia, migraine with aura
  • Smoker >35 years, HTN (SBP >160)
  • Current breast cancer, liver disease
  • History of stroke/IHD
• Benefits: Regulate cycle, reduce dysmenorrhoea, reduced endometrial/ovarian cancer risk, treat acne/PCOS

Progestogen-Only Pill (POP/Mini-pill)

• Contains: Norethisterone OR Desogestrel (75 mcg - also inhibits ovulation)
• Traditional POP: strict 3-hour window; Desogestrel: 12-hour window
• Mechanism: Mainly thicken cervical mucus; some suppress ovulation (desogestrel ~95%)
• Side effects: Irregular bleeding, amenorrhoea
• When to use: Breastfeeding, contraindication to oestrogen, >35 and smoker

Injectable Contraception

• Depo-Provera (DMPA - depot medroxyprogesterone acetate): 150 mg IM every 12 weeks
• Mechanism: Suppress ovulation, thicken cervical mucus, thin endometrium
• Side effects: Irregular bleeding, amenorrhoea, weight gain, delay in fertility return (6-12 months)
• Can use in breastfeeding

Subdermal Implant (Nexplanon)

• Etonogestrel rod; 40 mm × 2 mm; last 3 years
• Inserted subdermally in inner upper arm
• Failure rate: 0.05% (most effective)
• Side effects: Irregular/unpredictable bleeding

Hormonal IUD/IUS (Mirena)

• Levonorgestrel 52 mg; releases 20 mcg/day
• Mechanism: Primarily local - thicken cervical mucus, thin endometrium; minimal ovulation suppression
• Duration: 5-8 years (licensed 8 years for Mirena in some guidelines now)
• Benefits: Reduce heavy bleeding (90%), treat dysmenorrhoea, HRT adjunct
• Side effects: Initial irregular spotting, eventual amenorrhoea (in many)

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Emergency Contraception (EC)

3 Options Available

1. Levonorgestrel (LNG) - Plan B, Norlevo, Postinor

• 1.5 mg single dose (or 750 mcg × 2, 12 hours apart)
• Effective up to 72 hours after unprotected intercourse (UPSI) - efficacy declines with time
• Mechanism: Delay/inhibit ovulation; does NOT prevent implantation (if ovulation already occurred, less effective)
• Efficacy: 85% (within 72 h); lower if BMI >75 kg (consider double dose or Ella)
• No significant effect on established pregnancy (not abortifacient)
• OTC available

2. Ulipristal Acetate (UPA) - EllaOne

• 30 mg single dose
• Effective up to 120 hours (5 days) after UPSI - more effective than LNG at 72-120 hours
• Mechanism: Selective progesterone receptor modulator; delays ovulation even near LH surge
• Better for women with BMI >75 kg
• Contraindicated: Asthma requiring oral steroids (theoretical)
• Avoid breastfeeding for 1 week after use

3. Copper IUD (IUCD) - Most Effective

• Effective up to 120 hours (5 days) after UPSI or up to 5 days after calculated ovulation
• Efficacy: >99% (risk reduction 99.2%)
• Mechanism: Spermicidal (copper ions toxic to sperm); prevents fertilisation; hostile endometrium
• Advantage: Can remain as ongoing contraception (up to 10 years)
• Requires healthcare professional insertion
• Contraindicated: Pregnancy, unexplained AUB, copper allergy, Wilson's disease, current STI

EC Comparison Table

After EC - Advise:

• Barrier method until next period
• Pregnancy test if period >7 days late
• LNG and UPA may interact with enzyme-inducing drugs (rifampicin, anticonvulsants) - double dose LNG or use Cu-IUD

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9. ULTRASOUND IN OBG

Ultrasound Basics in OBG

• Transabdominal USS (TAS): requires full bladder in 1st trimester; good for overview
• Transvaginal USS (TVS): better resolution; empty bladder; superior for early pregnancy, endometrium, ovaries

1st Trimester USS Findings

Findings in Pregnancy Complications

2nd & 3rd Trimester USS

Anatomy Scan (18-20 weeks)

• Head (BPD, HC, ventricles, cerebellum, corpus callosum)
• Face (lip, palate - limited)
• Heart (4-chamber view, LVOT, RVOT)
• Abdomen (AC, stomach, kidneys, bladder, abdominal wall)
• Spine, limbs, cord insertion
• Placenta location + umbilical cord (3 vessels: 2 arteries, 1 vein)

Biometry for Gestational Age

Key Disease - USS Finding Table (HIGH YIELD)

Doppler in OBG

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10. ANTIBIOTICS, ANTIVIRALS, CHEMOTHERAPEUTICS & DRUGS IN OBG

Antibiotics in Obstetrics & Gynaecology

SAFETY CLASSIFICATION IN PREGNANCY

• SAFE: Penicillins, cephalosporins, azithromycin, erythromycin, nitrofurantoin (avoid near term)
• AVOID: Tetracyclines (teeth/bone), fluoroquinolones (cartilage), aminoglycosides (ototoxicity), chloramphenicol (grey baby), metronidazole (caution 1st trimester), trimethoprim (folate antagonist - 1st trimester)
• SAFE in pregnancy: Clindamycin, vancomycin

Common OBG Conditions & Antibiotic Treatment

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Antivirals in OBG

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P-Drugs (Priority Drugs) in OBG

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Chemotherapeutic Agents in OBG

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11. NORMAL LABOUR & INDUCTION OF LABOUR

Normal Labour

Definition

Onset of Labour - Mechanism

• PGE2 and PGF2α rise → initiate contractions
• Fetal cortisol surge (maturation signal)
• Oestrogen/progesterone ratio shifts (progesterone withdrawal)
• Oxytocin receptor upregulation in myometrium

Stages of Labour

Signs of 3rd Stage Placental Separation

• Calkin's sign: uterus becomes globular and firm
• Cord lengthening (Strassmann sign)
• Gush of blood
• Uterine fundus rises (placenta descends into lower segment)

Active Management of 3rd Stage (AMTSL)

1. Uterotonic - Oxytocin 10 IU IM (within 1 minute of birth)
2. Controlled cord traction (CCT) - after uterus contracted, apply counter-pressure above pubic symphysis
3. Uterine massage (optional post-delivery)

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Induction of Labour (IOL)

Definition

Indications

Contraindications

• Placenta praevia/vasa praevia
• Transverse lie
• Active genital herpes
• Previous classical uterine scar (2 previous CS is relative)
• Cord prolapse

Prerequisites (Bishop Score)

• Score ≥8: Favourable cervix - direct IOL with oxytocin/ARM
• Score <6: Unfavourable - cervical ripening needed first

Methods of IOL

Cervical Ripening (unfavourable cervix)

1. PGE2 (Dinoprostone): Vaginal gel (Prostin) 1-2 mg or slow-release pessary (Cervidil) 10 mg; Contraindicated: previous CS (↑ uterine rupture risk), asthma
2. Mechanical methods: Balloon catheter (Foley), hygroscopic dilators (laminaria) - lower hyperstimulation risk; safe for VBAC
3. Misoprostol (PGE1): 25 mcg vaginal 4-6 hourly or 25-50 mcg sublingual; highly effective but requires careful monitoring; off-label but widely used

Active IOL (favourable cervix)

1. Artificial Rupture of Membranes (ARM/Amniotomy): Amniohook or Kocher's forceps; increases prostaglandin release; used before/with oxytocin
2. Oxytocin infusion: Start 1-2 mU/min, increase by 1-2 mU/min every 30 minutes; continuously monitor FHR (CTG mandatory); risk of hyperstimulation, fetal distress

Complications of IOL

• Failed induction (→ C/S)
• Uterine hyperstimulation (>5 contractions in 10 min or contraction >2 min) → stop oxytocin; tocolysis with terbutaline
• Fetal distress
• Cord prolapse (after ARM)
• Uterine rupture (especially VBAC)
• PPH

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12. PPH MANAGEMENT

Definition

• Primary PPH: ≥500 mL blood loss within 24 hours of vaginal delivery (≥1000 mL after C/S)
• Secondary PPH: Abnormal/excessive uterine bleeding 24 hours to 12 weeks postpartum
• Severe PPH: ≥1000 mL or any loss causing haemodynamic compromise

Incidence: ~5% of all deliveries; major cause of maternal mortality worldwide

The 4 T's (Causes)

Management - Stepwise (HAEMOSTASIS Mnemonic)

Uterotonic Drugs in PPH

Bakri Balloon

• Intrauterine tamponade balloon; fill with 300-500 mL saline
• "Tamponade test": if bleeding stops = may avoid surgery
• Used for: uterine atony, low-lying placenta, post-CS bleeding

B-Lynch Suture

• Compression brace suture over uterus
• Bilateral vertical sutures compress uterine cavity
• Alternative: Hayman (vertical), Cho (square), Pereira

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13. ISOIMMUNISATION (Rh Incompatibility)

Pathophysiology

1. Rh-negative mother carries Rh-positive fetus (Rh antigen from father)
2. Sensitising events: delivery, miscarriage, ectopic, amniocentesis, CVS, APH, ECV, trauma
3. Maternal IgG anti-D antibodies produced
4. In SUBSEQUENT pregnancy: IgG (small enough to cross placenta) → binds fetal RBCs → haemolysis
5. → Fetal anaemia → erythroblastosis fetalis → hydrops fetalis (if severe)

Rh Antigens

• Main clinically significant: D, c, E, Kell, Duffy
• Anti-D = most important

Prevention - Anti-D Immunoglobulin

Routine Antenatal Prophylaxis

• 28 weeks (and 34 weeks in some protocols): Anti-D 500-1500 IU IM to ALL Rh-negative pregnant women (NICE: 1500 IU at 28 weeks)

After Sensitising Events (within 72 hours)

Kleihauer-Betke Test

• Quantifies fetal red cells in maternal blood
• 1% fetal cells = ~50 mL fetal blood = needs extra anti-D doses
• Used to calculate dose after large fetomaternal haemorrhage

Monitoring in Sensitised Pregnancy

1. Maternal antibody titres: Anti-D antibody level; critical titre = 1:16 (referral to specialist)
2. Middle Cerebral Artery Doppler (MCA-PSV):
   • PSV >1.5 MoM = fetal anaemia (most sensitive non-invasive test)
   • Replaced amniocentesis (ΔOD450) as standard
3. Cordocentesis (PUBS): fetal blood sampling; used for diagnosis and intrauterine transfusion (IUT)

Intrauterine Transfusion (IUT)

• Indicated: MCA-PSV >1.5 MoM, fetal Hb <2 SD below mean
• Technique: Cordocentesis at umbilical vein at cord insertion; transfuse O-negative, CMV-negative, irradiated blood
• Target Hct 40-45%
• Repeat every 2-3 weeks
• Delivery when fetal lung mature (34-37 weeks)

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14. MULTIFETAL PREGNANCY (TWINS/TRIPLETS)

Chorionicity - KEY DISTINCTION

Determining Chorionicity by USS

• Twin peak sign (lambda sign): triangular wedge of placental tissue between membranes = DCDA (dichorionic)
• T-sign: Thin membrane meets placenta at right angle = MCDA (monochorionic)
• Best assessed at 11-14 weeks

Complications of Multiple Pregnancy

Maternal Complications

• Pre-eclampsia (3× increased risk)
• GDM, anaemia, PPH (overdistension)
• Preterm labour/delivery (50% of twins deliver <37 weeks)
• C/S rate higher

Fetal Complications Specific to Monochorionic Twins

1. TTTS (Twin-to-Twin Transfusion Syndrome) - 10-15% MCDA
   • Vascular anastomoses → net blood transfusion donor → recipient
   • Donor: small, oligohydramnios, "stuck twin", anaemia
   • Recipient: large, polyhydramnios, hypervolaemia, hydrops
   • Staging (Quintero): Stage I-V
   • Treatment: Fetoscopic laser ablation of anastomoses (before 26 weeks); amnioreduction; expectant
2. TAPS (Twin Anaemia Polycythaemia Sequence)
   • Slow net transfer of RBCs; donor anaemic (MCA-PSV >1.5 MoM), recipient polycythaemic
3. sIUGR (Selective IUGR): one twin growth restricted with normal other; discordance >25%
4. TRAP (Twin Reversed Arterial Perfusion): acardiac/acephalic parasitic twin
5. Conjoined twins: failure of complete separation; rare; 1:50,000

Management of Multifetal Pregnancy

Delivery in Twins

• 1st twin: vaginal delivery if cephalic
• 2nd twin: deliver immediately after 1st (continuous CTG)
• Options for 2nd non-cephalic: ECV, breech extraction, or C/S
• 3rd stage: high PPH risk - oxytocin infusion, active management

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15. DRUGS USED IN LABOUR THEATRE

Anaesthesia/Analgesia

Uterotonics

Antihypertensives (in Labour)

Tocolytics

Anticoagulation in Labour

• LMWH (enoxaparin/tinzaparin): stop 24h before planned delivery; restart 4h post-vaginal/24h post-CS
• Heparin infusion: easier reversal; used in high-risk (mechanical valves)
• Protamine sulphate: reverses heparin

Other Common Drugs in Labour Theatre

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16. MASS PER ABDOMEN (MPA) IN GYNAECOLOGY

Systematic Approach

History

• Duration, rate of growth
• Menstrual history (LMP, AUB)
• Pain (sudden = torsion/rupture; chronic = endometriosis/malignancy)
• Urinary/bowel symptoms (pressure effects)
• Weight loss, anorexia (malignancy)
• Fertility desire
• Family history (BRCA1/2 - ovarian/breast cancer)

Examination

• Site, size, shape, surface
• Consistency (cystic/solid/mixed)
• Mobility (fixed = malignancy/endometriosis)
• Tenderness
• Relationship to uterus (bimanual - separate from uterus or not)
• Ascites (shifting dullness, fluid thrill) - malignancy
• Lymphadenopathy, pleural effusion (Meigs' syndrome)

Differential Diagnosis of MPA in Women

Tumour Markers (Key)

ROMA Score (Risk of Ovarian Malignancy Algorithm)

• Combines CA-125 + HE4 + menopausal status
• High ROMA = high risk; refer MDT

Risk of Malignancy Index (RMI)

• RMI = U × M × CA-125
  • U = USS score (1 or 3)
  • M = menopausal (1 = pre; 3 = post)
  • CA-125 (IU/mL)
• RMI >250 = HIGH risk → refer to gynaecological oncologist

Ovarian Cyst Management (by Risk)

Pre-menopausal

• Simple <5 cm: USS follow-up at 6-12 months; most resolve
• Dermoid cyst: elective cystectomy (preserve ovary)
• Symptomatic/>7 cm/complex features: surgical review
• Suspicious/solid: MDT - laparoscopic/open cystectomy or salpingo-oophorectomy + staging

Post-menopausal

• Any ovarian mass requires investigation
• Simple unilocular cyst <1 cm: follow-up with serial USS + CA-125
• Complex/solid/CA-125 elevated: surgical staging

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QUICK VIVA REVISION CARDS

"Must Know" Numbers in OBG

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