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Question 13: Breech Presentation

Definition

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Varieties of Breech Presentation

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Etiology / Predisposing Factors

• Fetal factors: Prematurity (most common), multiple pregnancy, hydrocephalus, anencephaly, fetal neuromuscular disorders
• Uterine/placental factors: Placenta praevia, cornual/fundal placenta, uterine anomalies (bicornuate, subseptate), polyhydramnios, oligohydramnios
• Maternal factors: Grand multiparity (lax uterus), contracted pelvis

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Diagnosis

Abdominal Examination (Leopold's Maneuvers)

• Fundus: Hard, round, ballottable fetal head felt at the fundus
• Sides: Fetal back on one side; limbs on the other
• Lower pole: Soft, irregular, non-ballottable mass (breech)
• Auscultation: Fetal heart sounds best heard above the umbilicus

Vaginal Examination

• Soft, irregular presenting part; no sutures/fontanelles palpable
• Anus may be felt (distinguish from face — anus: finger meets resistance, sucks on finger; mouth: finger enters freely, bony alveolar ridges felt)
• In frank breech: anal orifice in the midline between two bony ischial tuberosities
• Meconium may stain examining finger

Investigations

• Ultrasound: Confirms presentation, type of breech, fetal size, placental location, liquor volume, fetal anomalies — gold standard
• X-ray: Rarely used; may show hyperextended head (flying fetus — contraindication to vaginal delivery)

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Mechanism of Labor in Breech Presentation

Engagement

• Bitrochanteric diameter (10 cm) engages in the oblique or transverse diameter of the pelvis

Descent and Internal Rotation of Buttocks

• Buttocks descend into the pelvis
• Anterior hip meets the pelvic floor → internal rotation occurs so that the bitrochanteric diameter comes to lie in the anteroposterior diameter of the outlet

Lateral Flexion and Delivery of Buttocks

• Anterior hip is born first by lateral flexion of the trunk
• The posterior hip sweeps over the perineum
• Restitution of the trunk occurs after delivery of buttocks

Engagement and Descent of Shoulders

• Shoulder enters the pelvis in the oblique diameter
• Internal rotation brings the bisacromial diameter into the AP diameter of the outlet
• Anterior shoulder delivers first under the symphysis pubis; posterior shoulder follows

Delivery of the Head

• Head enters the pelvis with its suboccipito-bregmatic diameter (9.5 cm) in the oblique
• Internal rotation: occiput rotates anteriorly under the symphysis pubis
• Head is born by flexion — nape of neck pivots under the symphysis; face, brow, vertex successively sweep over the perineum
• This is the most critical and dangerous phase (risk of head entrapment)

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Assisted Breech Delivery

DC Dutta: "In assisted breech delivery, the baby is allowed to deliver spontaneously up to the umbilicus; beyond that point, assistance is given."

Indications for Vaginal Breech Delivery

• Frank or complete breech at term
• Adequate pelvis (clinical pelvimetry/X-ray pelvimetry)
• Normal-sized fetus (~2.5–3.5 kg)
• No hyperextension of fetal head
• Experienced obstetrician available

Steps of Assisted Breech Delivery

• Patient in lithotomy position; episiotomy given when buttocks distend the perineum
• Do NOT pull on the baby — allow spontaneous descent to the umbilicus
• Once the umbilicus is born, gently pull down a loop of cord to reduce tension

1. Hold baby by the pelvic girdle (thumbs on sacrum, fingers on iliac crests)
2. Rotate trunk 180° so that the posterior shoulder becomes anterior
3. The posterior arm is delivered first (as it sweeps under the symphysis)
4. Rotate back 180° in the opposite direction; deliver the other arm
5. Arms are delivered by sweeping them across the chest (Pinard's maneuver for extended arm: finger splints along the humerus, brings the arm down)

1. After trunk is delivered, allow it to hang by its own weight (promotes flexion of head)
2. Grasp the ankles; swing the trunk upward in an arc over the maternal abdomen
3. Face, brow, vertex deliver over the perineum
4. Assistant applies suprapubic pressure to maintain flexion

1. Baby straddles the operator's forearm
2. Middle finger in fetal mouth / index and ring fingers on malar eminences (to flex head)
3. Other hand: index and middle fingers on the shoulders; middle finger on occiput (to promote flexion)
4. Gentle traction downward and anteriorly; head delivered by flexion
5. Never apply traction to the neck

• Used when above maneuvers fail or in controlled situations
• An assistant holds the trunk while forceps are applied to the fetal head
• Provides controlled delivery, reduces birth trauma

Important Rules

• "Hands off the breech" until umbilicus delivers
• Never allow the baby to dangle for more than 3–5 minutes after umbilicus is born
• Routine episiotomy is advisable (mediolateral)
• Pediatrician must be present at delivery

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Complications

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External Cephalic Version (ECV)

• Offered at 37 weeks (term)
• Success rate ~50–60%
• Contraindications: placenta praevia, previous uterine scar (relative), hypertension, IUGR, multiple pregnancy, ruptured membranes
• Tocolysis (terbutaline) improves success
• Anti-D prophylaxis in Rh-negative mothers

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DC Dutta Key Points

• Cesarean section is now the preferred mode of delivery for breech at term in most centers
• Vaginal breech delivery is reserved for experienced centers with appropriate case selection
• Frank breech is most favorable for vaginal delivery
• Footling breech → high risk of cord prolapse → cesarean preferred

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Question 14: Multiple Pregnancy

Definition

• Twins: ~1 in 80–90 pregnancies (natural)
• Triplets: ~1 in 80²
• Hellin's Law: Twins 1:80; Triplets 1:80²; Quadruplets 1:80³

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Etiology

Dizygotic (DZ) Twins — "Fraternal" (more common, ~70%)

• Race: Highest in Black Africans (Yoruba tribe ~1:22); lowest in Asians; intermediate in Caucasians
• Heredity: Maternal family history (DZ twinning is inherited through mother)
• Increasing maternal age (peak 35–39 years)
• High parity (grand multiparity)
• Nutritional factors: Tall, well-nourished women; high dietary intake of yams
• Ovulation induction (clomiphene, gonadotrophins) — most important iatrogenic cause
• Assisted Reproductive Technologies (ART) — IVF, ICSI

Monozygotic (MZ) Twins — "Identical" (~30%)

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Varieties / Classification

By Zygosity

• Monozygotic (identical) — same sex, same genetic material
• Dizygotic (fraternal) — may be same or different sex

By Chorionicity (clinically more important)

• Dichorionic Diamniotic (DCDA): Two placentas, two chorionic sacs, two amniotic sacs — lowest risk
• Monochorionic Diamniotic (MCDA): One placenta, one chorion, two amnions — risk of Twin-to-Twin Transfusion Syndrome (TTTS)
• Monochorionic Monoamniotic (MCMA): One placenta, one sac — highest risk (cord entanglement)

Membrane Thickness on Ultrasound

• DCDA: Lambda (λ) sign or "twin peak sign" — triangular projection of placental tissue into the base of the inter-twin membrane
• MCDA: T-sign — thin membrane meets the placenta at right angles
• Best determined at 11–14 weeks

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Diagnosis

Symptoms

• Uterus larger than dates
• Excessive nausea and vomiting (high hCG)
• Exaggerated pregnancy symptoms
• Early fetal movements

Abdominal Examination

• Uterus disproportionately large for dates
• Multiple fetal parts palpable
• Two fetal heads palpable
• Three fetal poles felt (two heads + one breech or vice versa)
• Auscultation: two distinct fetal heart sounds in different areas, >10 beats/min difference, separated by a silent zone

Investigations

• Ultrasound (gold standard): Number of fetuses, chorionicity/amnionicity, fetal biometry, lie and presentation, placental location, liquor volume, Doppler
• Serum hCG/AFP: Elevated in twins (not diagnostic alone)
• X-ray: Rarely used today

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Antenatal Management

Increased Antenatal Visits

• Every 2 weeks up to 28 weeks, then weekly until delivery (DC Dutta)
• More frequent for MCDA/MCMA twins

Nutrition

• Additional 300 kcal/day over singleton requirements
• Iron: 60–100 mg elemental iron/day
• Folic acid: 5 mg/day
• Increased calcium, protein intake

Monitoring

• Serial growth scans every 2–4 weeks from 20 weeks
• Cervical length assessment (risk of preterm labor)
• Doppler velocimetry — umbilical artery, MCA (for TTTS)
• Amniocentesis/CVS if indicated (higher risk of chromosomal anomalies)

Prevention/Management of Complications

• Early diagnosis and management of anaemia, preeclampsia, preterm labor
• Cervical cerclage in selected cases of cervical incompetence
• Antenatal corticosteroids (betamethasone) if preterm delivery anticipated
• Hospitalization from 28–30 weeks in some units (especially MCDA/MCMA)

TTTS Monitoring (MCDA twins)

• Ultrasound every 2 weeks from 16 weeks
• Staging: Quintero staging (I–V)
• Treatment: Fetoscopic laser photocoagulation of placental anastomoses (preferred), amnioreduction

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Management During Labor

Pre-labor

• Mode of delivery depends on:
  • Presentation of twin 1
  • Chorionicity
  • Gestational age and fetal weight
  • Availability of experienced obstetrician

Timing of Delivery

• DCDA: 38 weeks
• MCDA: 36–37 weeks
• MCMA: 32–34 weeks (due to cord entanglement risk)

Route of Delivery

• Twin 1 is non-cephalic (breech, transverse)
• MCMA twins
• Conjoined twins
• Triplets and higher order multiples
• Fetal distress
• Placenta praevia, severe preeclampsia

• Twin 1 is cephalic (regardless of twin 2 presentation)
• No other obstetric contraindications
• Experienced obstetrician present
• CTG monitoring available

Labor Management

• IV access, cross-match blood
• Continuous CTG monitoring of both twins
• IV oxytocin if uterine inertia develops
• Epidural analgesia preferred (allows manipulation of twin 2)
• Pediatrician and anesthesiologist on standby

• Managed as for singleton
• Episiotomy liberally

• Ideally within 15–20 minutes
• After Twin 1 delivery: check lie of twin 2 by abdominal palpation + ultrasound
• If cephalic: await spontaneous labor OR rupture membranes + augment
• If transverse: External cephalic version (ECV) or internal podalic version (IPV) + breech extraction

• Hand introduced into the uterus under deep anesthesia
• One or both feet grasped and pulled down
• Baby delivered as breech

• High risk of postpartum hemorrhage (overdistended uterus → uterine atony)
• Active management mandatory
• Oxytocin infusion maintained for at least 2 hours postpartum

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Complications

Maternal Complications

Fetal/Neonatal Complications

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DC Dutta Key Points

• DZ twins are more common; MZ twinning rate is constant worldwide (~3.5/1000)
• Chorionicity (not zygosity) determines perinatal risk — establish at first-trimester ultrasound
• MCDA twins carry highest risk of TTTS
• Twin 1 always determines route of delivery
• PPH after twin delivery must be anticipated and actively managed

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Question 20: Preterm Labor

Definition (DC Dutta)

Sub-classification by gestational age:

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Etiology

Maternal Factors

• Infections/Chorioamnionitis (most common cause) — ascending genital tract infection (GBS, Ureaplasma, BV organisms), UTI, pyelonephritis, systemic infections (malaria, typhoid)
• Uterine overdistension — polyhydramnios, multiple pregnancy
• Cervical incompetence — painless cervical dilatation
• Uterine anomalies — bicornuate, subseptate uterus
• Antepartum hemorrhage — placenta praevia, abruptio placentae
• Preeclampsia / hypertensive disorders
• Medical illnesses — diabetes, renal disease, anaemia
• Trauma — abdominal surgery, amniocentesis
• Socioeconomic factors — poor nutrition, heavy work, low BMI, smoking

Previous Obstetric History

• Prior preterm birth (strongest risk factor — 3× increased risk)
• Prior second-trimester abortion
• Short interpregnancy interval (<6 months)

Fetal Factors

• Fetal anomalies
• IUGR
• Fetal death

Cervical Factors

• Short cervical length (<25 mm on transvaginal ultrasound at 20–24 weeks — significant predictor)
• Previous cervical surgery (LLETZ/cone biopsy)

Idiopathic

• ~50% of cases have no identifiable cause

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Diagnosis of Preterm Labor

1. Gestational age 20–37 weeks
2. Regular uterine contractions — at least 2 in 10 minutes, each lasting ≥30 seconds
3. Cervical changes — effacement ≥80% or dilatation ≥2 cm

• Fetal fibronectin (fFN): Cervicovaginal swab at 22–34 weeks. Negative result (< 50 ng/mL) has high negative predictive value — delivery within 7 days very unlikely
• Transvaginal ultrasound cervical length: < 25 mm indicates high risk
• Urine culture — to exclude UTI
• High vaginal swab — for BV, GBS
• CBC, CRP — if chorioamnionitis suspected
• Ultrasound — gestational age, fetal weight, liquor, presentation

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Management

General Approach

• Confirm diagnosis (exclude false/prodromal labor)
• Assess gestational age accurately
• Identify and treat underlying cause
• Decide: arrest labor (tocolysis) vs. allow delivery

Criteria for Attempting to Arrest Labor (Tocolysis)

• Gestation 24–34 weeks (most benefit)
• No contraindications (see below)
• Cervical dilatation ≤4 cm
• Membranes intact
• No signs of chorioamnionitis
• No fetal distress
• No severe maternal disease

Contraindications to Tocolysis

• Gestational age >34 weeks (fetal lungs mature)
• Severe preeclampsia/eclampsia
• Antepartum hemorrhage (significant)
• Chorioamnionitis
• Fetal distress or lethal fetal anomaly
• Cervical dilatation >4 cm

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Measures to Arrest Preterm Labor (Tocolytic Agents)

1. Beta-2 Adrenergic Agonists — Ritodrine / Salbutamol / Terbutaline

• Mechanism: Stimulate β₂ receptors → ↑ cAMP → relaxation of uterine smooth muscle
• Ritodrine: 50–100 mcg/min IV infusion (first-line in many units per DC Dutta)
• Salbutamol: 10–45 mcg/min IV infusion
• Side effects: Maternal tachycardia, palpitations, hypotension, hypokalemia, pulmonary edema (most dangerous), hyperglycemia
• Contraindications: Cardiac disease, diabetes, hyperthyroidism

2. Calcium Channel Blockers — Nifedipine (currently preferred)

• Mechanism: Blocks calcium entry into smooth muscle → inhibits contractions
• Dose: 20 mg orally loading, then 10–20 mg every 4–6 hours
• Advantages: Oral administration, fewer maternal side effects than β-agonists
• Side effects: Headache, flushing, hypotension
• Avoid with magnesium sulfate (severe hypotension)

3. Prostaglandin Synthetase Inhibitors — Indomethacin

• Mechanism: Inhibits COX → ↓ prostaglandin synthesis → inhibits contractions
• Dose: 50 mg loading oral/rectal, then 25 mg every 6 hours
• Use: Before 32 weeks only
• Side effects: Premature closure of ductus arteriosus (after 32 weeks), neonatal oliguria, NEC
• Contraindicated after 32 weeks

4. Oxytocin Receptor Antagonist — Atosiban

• Mechanism: Competitively blocks oxytocin receptors
• Given IV; fewer maternal side effects
• Expensive; widely used in Europe

5. Magnesium Sulphate

• Mechanism: Competes with calcium at neuromuscular junction
• Now primarily used for neuroprotection (not first-line tocolytic)
• Loading dose: 4–6 g IV over 20 min; maintenance 1–2 g/hour
• Neuroprotection: Given when delivery <32 weeks anticipated → reduces risk of cerebral palsy

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Prevention of Preterm Labor

1. Antenatal Corticosteroids (Fetal Lung Maturation)

• Betamethasone: 12 mg IM × 2 doses, 24 hours apart — drug of choice (DC Dutta)
• Dexamethasone: 6 mg IM × 4 doses, 12 hours apart (alternative)
• Indication: 24–34 weeks when preterm delivery anticipated within 7 days
• Benefits: ↓ RDS, IVH, NEC, perinatal mortality
• Given alongside tocolysis to buy 48 hours for steroid effect

2. Cervical Cerclage

• Indication:
  • History of cervical incompetence (elective/prophylactic cerclage at 12–14 weeks)
  • Short cervix on TVU (<25 mm) with prior preterm birth history
  • Rescue cerclage (dilated cervix with membranes bulging — emergency cerclage)
• Technique:
  • McDonald's suture (most common) — purse-string suture at cervicovaginal junction
  • Shirodkar's suture — submucosal; more secure
• Suture removed at 37 weeks or onset of labor

3. Progesterone Supplementation

• 17-hydroxyprogesterone caproate (17-OHPC): Weekly IM injection from 16–20 weeks to 36 weeks — for women with prior spontaneous preterm birth
• Vaginal progesterone: 200 mg/night — for women with short cervix (≤25 mm) on TVU
• Mechanism: Maintains uterine quiescence, inhibits cervical ripening

4. General Preventive Measures

• Treatment of genital tract infections (BV, GBS, Chlamydia)
• Treatment of UTI/asymptomatic bacteriuria
• Cessation of smoking
• Adequate nutrition
• Avoid heavy physical work
• Correction of anaemia
• Psychosocial support
• Folic acid supplementation

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Neonatal Care Preparation

• Transfer to a center with Neonatal Intensive Care Unit (NICU)
• Pediatrician present at delivery
• Warm resuscitation environment
• Surfactant therapy for neonatal RDS

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DC Dutta Key Points

• Infection is the most common identifiable cause of preterm labor
• Prior preterm birth is the single strongest risk factor
• Tocolysis is a temporizing measure — goal is to achieve steroid effect and transfer, not to indefinitely arrest labor
• Betamethasone is the steroid of choice for fetal lung maturation
• Delivery at >34 weeks: tocolysis generally not warranted (risk:benefit unfavorable)
• Magnesium sulphate given <32 weeks for neuroprotection, not primarily tocolysis

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Question 23: Prolonged and Post-term Pregnancy

Definitions (DC Dutta)

• Post-term pregnancy: Pregnancy that has extended to or beyond 42 completed weeks (294 days) from the first day of the last menstrual period (LMP) — also called prolonged pregnancy or post-dates pregnancy
• Term pregnancy: 37–41 completed weeks + 6 days
• Incidence: ~7–12% of all pregnancies (if based on LMP alone); reduces to ~1–3% when confirmed by early ultrasound

DC Dutta emphasizes that accurate gestational age assessment (by early first-trimester USS) is essential before labeling a pregnancy as post-term, as many cases are due to incorrect dates.

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Etiology

Known Causes

• Incorrect dates (most common "cause" — not true prolongation)
• Primigravida (slightly higher incidence)
• Male fetus
• Previous post-term pregnancy (recurrence rate ~30%)
• Placental sulfatase deficiency (rare X-linked disorder — lack of estrogen precursor → failure of normal labor initiation)
• Fetal anencephaly — absence of fetal adrenal cortex → ↓ cortisol → ↓ estrogen production → no labor trigger
• Hereditary/familial tendency

Pathophysiology of Normal Labor Trigger (DC Dutta)

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Effects / Complications

Placental Changes (Post-maturity Syndrome)

• Placental insufficiency develops progressively after 42 weeks
• Calcification, infarction, fibrin deposition → ↓ uteroplacental blood flow
• Oligohydramnios — reduced fetal urine output from renal hypoperfusion
• Meconium passage in amniotic fluid (thick meconium — risk of MAS)

Fetal Effects — Clifford's Syndrome (Postmature Baby)

Maternal Complications

Fetal/Neonatal Complications

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Diagnosis / Confirmation of Gestational Age

Methods:

1. LMP-based calculation (Naegele's rule) — reliable only with regular 28-day cycles
2. First-trimester ultrasound (crown-rump length) — most accurate (±5–7 days); gold standard
3. Second-trimester ultrasound (BPD, FL, HC, AC) — less accurate (±2 weeks)
4. Serial ultrasound — growth monitoring
5. Uterine size at first visit — fundal height correlation

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Antenatal Fetal Surveillance (after 41 weeks)

• 5 parameters: fetal breathing movements, gross body movements, fetal tone, NST, amniotic fluid volume
• Score ≥8/10: reassuring
• Score 6/10: equivocal — repeat in 24 hours or deliver
• Score ≤4/10: deliver immediately

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Management

Step 1: Confirm Gestational Age

• Verify dates with first-trimester USS
• If dates uncertain and USS shows <42 weeks, manage expectantly with surveillance

Step 2: Assess Cervix — Bishop Score

• Score ≥8: Favorable cervix — proceed to induction with oxytocin
• Score <6: Unfavorable cervix — cervical priming first

Step 3: Cervical Ripening (Unfavorable Cervix)

• Prostaglandin E2 (Dinoprostone):
  • Gel: 0.5 mg intracervically every 6 hours (max 3 doses)
  • Vaginal insert: 10 mg (slow release over 12 hours)
• Misoprostol (PGE1):
  • 25 mcg vaginally every 4–6 hours OR 50 mcg orally every 4 hours
  • Cheaper, stable at room temperature
  • Risk of uterine hyperstimulation
• Mechanical methods:
  • Foley catheter balloon (transcervical) — safe, no uterotonic risk
  • Hygroscopic dilators (laminaria tents)
• Membrane sweeping (stripping):
  • Digital separation of chorioamniotic membranes from lower uterine segment
  • Stimulates local prostaglandin release
  • Can be performed from 40–41 weeks
  • Reduces need for formal induction

Step 4: Induction of Labor

• 5 units in 500 mL NS or Ringer's lactate
• Start at 4–8 drops/min; increase by 4 drops every 20–30 min
• Target: 3 contractions in 10 min, each lasting 40–60 seconds
• Continuous CTG monitoring mandatory
• Maximum dose: 40 mU/min (60 drops/min)

Step 5: Intrapartum Management

• Continuous electronic fetal monitoring (CTG)
• Watch for: meconium-stained liquor, variable/late decelerations, fetal tachycardia
• Thick meconium → prepare for neonatal resuscitation; consider amnioinfusion
• Low threshold for cesarean section if fetal distress

Step 6: Cesarean Section Indications

• Failed induction (cervix not responding)
• Fetal distress on CTG
• Macrosomia with CPD
• Cord prolapse
• Non-reassuring BPP/NST despite interventions

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Timing of Delivery — DC Dutta Recommendations

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DC Dutta Key Points

• Post-term pregnancy is confirmed only after accurate gestational age assessment — incorrect dates is the commonest cause
• Perinatal mortality doubles by 43 weeks and trebles by 44 weeks compared to 40 weeks
• Oligohydramnios is the most reliable indicator of placental insufficiency in post-term pregnancy
• Membrane sweeping at 40–41 weeks reduces the formal induction rate
• Induction at 41–42 weeks reduces perinatal mortality without increasing CS rate
• Clifford's syndrome (postmature baby) is the hallmark of true placental insufficiency

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Question 24: Contracted Pelvis

Definition (DC Dutta)

• True conjugate (TC) <10 cm OR
• Diagonal conjugate <11.5 cm OR
• Transverse diameter of outlet <8 cm

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Variations of the Female Pelvis

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Etiology of Contracted Pelvis

Nutritional/Metabolic

• Rickets (Vitamin D deficiency) — most common cause in developing countries
  • Softening of bone → weight-bearing flattens sacral promontory forward → flat/rachitic pelvis
  • True conjugate reduced; transverse diameter relatively preserved
• Osteomalacia — adult form; severe pelvic deformity
• Malnutrition in childhood

Developmental/Congenital

• Naegele's pelvis — absence/failure of development of one sacral ala → obliquely contracted pelvis (one side only)
• Robert's pelvis — bilateral absence of sacral alae → transversely contracted
• Assimilation pelvis — high: last lumbar vertebra fuses with sacrum (long narrow pelvis); low: S1 fuses with coccyx
• Congenital hip dislocation → acetabular protrusion

Traumatic / Pathological

• Pelvic fractures
• Spondylolisthesis — forward slipping of L5 on S1 → reduces true conjugate
• Tuberculosis of spine (Pott's disease) → kyphosis → kyphotic pelvis
• Tumors/exostoses
• Hip joint disease (ankylosis, tuberculosis)
• Poliomyelitis → asymmetric muscle pull

Hormonal

• Tall stature with delayed puberty → android or anthropoid tendency
• Short stature (<145 cm) → generally smaller pelvis

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Pelvic Measurements (DC Dutta)

External Measurements (Pelvimetry)

Internal Measurements (Vaginal Examination)

Radiological Pelvimetry

• X-ray pelvimetry — gives accurate measurements but involves radiation; reserved for selected cases
• CT pelvimetry — less radiation; more accurate
• MRI pelvimetry — no radiation; best soft tissue detail; becoming gold standard

Ultrasound

• Fetal head size (BPD, HC)
• Estimation of fetal weight
• Presentation and position

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Diagnosis of Contracted Pelvis

During Pregnancy

1. History: Short stature, childhood rickets, previous difficult labor/CS, previous stillbirth/birth injury
2. General examination:
   • Height <145 cm → suspect small pelvis
   • Limping gait, kyphosis, scoliosis, signs of rickets
   • Prominent sacral promontory
3. Abdominal examination:
   • Head not engaged at term in primigravida (normally engages by 36–38 weeks)
   • "Head above brim" in primigravida at term → significant
4. Pelvic assessment (internal examination):
   • Diagonal conjugate measurement
   • Pelvic shape, sidewall convergence, sacral curve, ischial spines, subpubic arch
5. Investigations: X-ray/CT/MRI pelvimetry if needed

During Labor

• Failure of engagement despite good contractions
• Slow cervical dilatation
• Caput succedaneum and molding despite adequate uterine action
• Obstructed labor signs (Bandl's ring, maternal distress)

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Effects of Contracted Pelvis on Pregnancy

• Non-engagement of head at term (primigravida)
• Malpresentation: Breech, transverse lie, oblique lie — because head cannot engage
• Unstable lie — head bobs above the brim
• Cord prolapse risk (presenting part not fitting pelvis)
• Premature rupture of membranes — poorly applied presenting part

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Effects of Contracted Pelvis on Labor

Inlet Contraction

• Head remains high → prolonged latent phase
• Cervical dilatation slow — head not pressing on cervix
• Increased risk of cord prolapse (forewaters bulging)
• Abnormal uterine action (incoordinate or inertia)
• Obstructed labor if untreated

Mid-cavity Contraction (prominent ischial spines / convergent walls)

• Deep transverse arrest — head arrested in transverse diameter at level of spines
• Most common type in android pelvis
• Forceps delivery may be possible if head is low enough; otherwise CS

Outlet Contraction

• Narrow subpubic angle/short intertuberous diameter
• Head deflected posteriorly → perineal tears
• Posterior perineal triangle must accommodate head
• Operative delivery required if outlet diameter <8 cm

Progressive Effects of Prolonged Obstruction

1. Caput succedaneum — progressive scalp edema
2. Molding — overlapping of skull bones (Mento-vertical → suboccipito-bregmatic compression)
3. Uterine changes — retraction ring (Bandl's ring) forms; risk of uterine rupture
4. Maternal distress — exhaustion, dehydration, ketosis
5. Fetal distress — hypoxia, acidosis, birth asphyxia
6. Vesicovaginal/rectovaginal fistula — pressure necrosis (if obstruction unrelieved)

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Management

Antenatal Management

• Clinical pelvimetry
• Estimated fetal weight (ultrasound)
• Head-fitting test / engagement assessment

Trial of Labor (DC Dutta)

• Cephalic presentation
• No gross fetal anomaly
• Single pregnancy
• No previous uterine scar
• TC ≥8.5 cm (or diagonal conjugate ≥10 cm)
• Good uterine contractions
• Experienced obstetrician and NICU available
• Facility for immediate CS

1. Admit at onset of labor; IV access; cross-match blood
2. Monitor: contractions, cervical dilatation (partogram), fetal heart rate (CTG)
3. Adequate analgesia (epidural preferred)
4. Oxytocin augmentation is permissible but with great caution
5. Progress assessed every 2–4 hours

• No progress in cervical dilatation for 2 hours with adequate contractions
• Excessive caput or molding (grade 3+)
• Bandl's ring visible
• Fetal distress (CTG changes)
• Maternal distress
• Cord prolapse

Cesarean Section

• Absolute disproportion (TC <8 cm)
• Failed trial of labor
• Obstructed labor
• Fetal distress
• Malpresentation with contracted pelvis
• Previous CS

Destructive Operations (Craniotomy)

• Only when fetus is dead + vaginal delivery attempted
• Perforator + cranioclast used to reduce head volume
• Very rarely practiced today

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DC Dutta Key Points

• Rickets is the most common cause of contracted pelvis in developing countries
• Non-engagement of the head at term in a primigravida is the first clinical sign of possible contracted pelvis
• True conjugate is the most important diameter — obtained by subtracting 1.5 cm from diagonal conjugate
• TC <10 cm = contracted inlet; TC <8.5 cm = absolute indication for CS
• Trial of labor is appropriate for borderline cases; abandon early if signs of failure appear
• Deep transverse arrest = hallmark of mid-cavity (android) contraction

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Question 25: Disproportion — Diagnosis

Definition (DC Dutta)

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Causes of Disproportion

1. Pelvic Causes (Small Pelvis)

• Contracted pelvis (see Q24)
• True conjugate <10 cm
• Android or platypelloid pelvis
• Mid-cavity contraction (prominent ischial spines)
• Outlet contraction

2. Fetal Causes (Large Head)

• Macrosomia (birth weight >4 kg) — most common fetal cause
  • Maternal diabetes (fetal macrosomia)
  • Prolonged/post-term pregnancy
  • Multiparity, large parents
• Hydrocephalus — grossly enlarged head (BPD may exceed 12–13 cm)
• Deflexed head attitudes:
  • Brow presentation — mento-vertical diameter (13.5 cm) presenting — almost always causes disproportion
  • Face presentation (mento-posterior) — cannot deliver vaginally
• Asynclitism — parietal bone presenting obliquely → effective diameter increased

3. Combined (Both)

• Moderately large baby + borderline pelvis (most common clinical scenario)

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Diagnosis of Disproportion

A. During Pregnancy (Antenatal Assessment)

1. History

• Short stature (<145 cm)
• Previous difficult labor, instrumental delivery, stillbirth, birth injury, CS for CPD
• Large baby in previous pregnancy
• Childhood rickets

2. General Examination

• Height measurement — <145 cm warrants pelvic assessment
• Gait, deformities (kyphosis, limp, asymmetry)
• Weight and BMI

3. Abdominal Examination

• Fundal height: Large for dates (macrosomia, hydrocephaly)
• Head engagement:
  • Primigravida: head normally engages at 36–38 weeks
  • Non-engagement at term in primigravida = suspect CPD until proven otherwise
  • Multigravida: engagement may not occur until labor starts → less reliable sign

• Identifies the presenting part in the pelvic brim
• Head "floating" (not fixed) above brim at term in a primigravida = significant

• Patient empties bladder
• She is placed semi-recumbent; fundal pressure applied
• Examiner's other hand placed suprapubically to assess descent of head into pelvis
• If head enters pelvis → pelvis likely adequate
• If head remains above symphysis → suspect CPD

4. Internal (Vaginal) Examination

• Diagonal conjugate: <11.5 cm → reduced true conjugate
• True conjugate (DC − 1.5 cm): <10 cm = inlet contracted
• Pelvic shape: Android, platypelloid pelves unfavorable
• Ischial spines: Prominent → mid-cavity contraction
• Subpubic angle: <85° → android
• Intertuberous diameter: <8 cm → outlet contracted
• Sacral curve: Straight/convex → less room
• Sacral promontory: Reachable on VE → reduced AP diameter

5. Ultrasound Assessment

• Biparietal diameter (BPD): >9.5 cm at term → macrocephalic tendency
• Head circumference (HC)
• Estimated fetal weight (EFW): >4 kg → macrosomia
• Amniotic fluid, placenta, presentation

6. Radiological/Imaging Pelvimetry (Selected Cases)

• X-ray pelvimetry: Measures true conjugate, transverse inlet, bispinous, intertuberous diameters
• CT pelvimetry: Lower radiation; more accurate; preferred over X-ray when needed
• MRI pelvimetry: No radiation; most accurate; used in special cases

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B. During Labor (Dynamic Assessment)

Clinical Signs of Disproportion in Labor

• Cervical dilatation crossing to the right of the alert line on the partogram
• No descent of presenting part despite adequate contractions

• Head remains at or above the ischial spines (station 0 or above) despite full cervical dilatation

• Progressive scalp edema from venous obstruction
• Graded 0 to +++
• Grade 3 (+++): boggy, tense, obscures sutures → significant obstruction

• Overlapping of skull bones
• DC Dutta grading:

• Grade +++ molding = absolute indication to abandon labor → CS

• Visible transverse groove between upper and lower uterine segments
• Indicates obstructed labor with impending uterine rupture
• Emergency CS mandatory

• Exhaustion, dehydration, ketonuria
• Tachycardia, fever (if infection supervenes)

• Fetal distress: late decelerations, prolonged decelerations, fetal tachycardia
• Meconium-stained liquor

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Müller-Hillis Maneuver (Head Fitting Test in Labor)

• With a contraction, fundal pressure applied while examiner's hand suprapubically assesses head descent
• If head descends → pelvis adequate
• If head does not descend → CPD likely
• Not widely used in modern practice

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Assessment Summary — DC Dutta's Decision Framework

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Partogram — Key Role in Diagnosing Disproportion

• Alert line: Expected rate of cervical dilatation (1 cm/hour in active phase)
• Action line: 4 hours to the right of alert line
• Cervical dilatation curve crossing the action line → investigate and act (CPD, inadequate contractions, malpresentation)
• Descent of head plotted in fifths above brim — no descent with full dilatation = CPD

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Complications of Undiagnosed/Unmanaged Disproportion

• Obstructed labor
• Uterine rupture (especially in multiparae with oxytocin)
• Maternal death (hemorrhage, rupture, sepsis)
• Vesicovaginal fistula / rectovaginal fistula (pressure necrosis)
• Perinatal asphyxia and death
• Birth trauma (intracranial hemorrhage, Erb's palsy)

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DC Dutta Key Points

• Disproportion may be absolute or relative — the distinction determines management
• Non-engagement of head at term in a primigravida is the most important antenatal sign
• Grade +++ molding and Bandl's ring are the most dangerous intrapartum signs — demand immediate CS
• The partogram is the single most important tool for detecting disproportion in labor
• Trial of labor is appropriate for relative disproportion — abandon promptly if signs of failure appear
• Macrosomia (diabetic baby) is the most common fetal cause of disproportion

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• Definition (absolute vs relative CPD)
• Causes (pelvic, fetal, combined)
• Antenatal diagnosis (history, examination, head fitting test, ultrasound, pelvimetry)
• Intrapartum diagnosis (partogram, caput, molding grading, Bandl's ring)
• DC Dutta's decision framework table
• Complications of unmanaged disproportion