OG13.1-8 | Normal Labour — Graded Quiz

Correct. When the sacral promontory cannot be reached (diagonal conjugate >12.5 cm), the obstetric conjugate is estimated as >11 cm — well above the critical threshold. This is a reassuring finding, NOT an indication for caesarean or further imaging.

Clinical pelvimetry rule: if the sacral promontory cannot be reached, the inlet is probably adequate. If reached, measure the diagonal conjugate and subtract 1.5 cm to estimate the obstetric conjugate.

NOT reaching the sacral promontory is REASSURING. It means the diagonal conjugate exceeds 12.5 cm; subtracting 1.5 cm gives an obstetric conjugate of likely >11 cm. The promontory can only be reached when it projects into the birth canal — i.e., in a contracted pelvis.

Correct. In persistent OP, the most common favourable mechanism is long rotation of 135° anteriorly to become OA, after which the normal mechanism of extension under the pubic arch proceeds. Short rotation (45° to direct OP) with face-to-pubis delivery also occurs but is less common.

Persistent OP can deliver: (1) long rotation 135° to OA — normal mechanism, (2) short rotation 45° to direct OP — face-to-pubis (military attitude). Long rotation is more common; OP is the most common malposition.

In OP position, two outcomes are possible: (1) long internal rotation of 135° → OA → normal delivery (most common favourable outcome), or (2) short rotation of 45° to direct OP → face-to-pubis delivery. Brow and transverse deliveries at the outlet are not physiological.

Correct. If no progress occurred in 2 hours (6 cm at 08:00 and still 6 cm at 10:00), and the alert line is now at 8 cm, the actual dilatation (6 cm) is 2 cm behind the alert line. This means the plot has crossed the alert line and she is at risk of crossing the action line — urgent assessment for cause and intervention is needed.

Crossing the alert line means progress is slower than 1 cm/hour. Re-evaluate the cause (inadequate contractions, malpresentation, CPD). If the action line is crossed (2 hours later), active intervention is mandatory.

The alert line at 10:00 hours represents expected progress of 1 cm/hour; if she was 6 cm at 08:00, the alert line at 10:00 should be at 8 cm. Actual dilatation at 6 cm is 2 cm behind the alert line — she has crossed it. Reassessing in 4 hours would allow the action line to be crossed without intervention.

Correct. Ergometrine causes sustained vasoconstriction and is contraindicated in hypertension (pre-eclampsia, chronic hypertension, cardiac disease) as it can precipitate severe hypertension, stroke, or MI. Oxytocin, misoprostol, and carboprost (with the caveat that carboprost is contraindicated in asthma) are safer in hypertensive patients.

Uterotonic contraindications: Ergometrine — contraindicated in hypertension/cardiac disease. Carboprost — contraindicated in asthma. Misoprostol — fever/hypersensitivity. Oxytocin — water intoxication risk with excess IV fluid, but safe in hypertension.

The contraindication to remember: ergometrine + hypertension = dangerous vasoconstriction. Carboprost is contraindicated in asthma (not hypertension per se). Oxytocin and misoprostol are safe in hypertension. The OG known-trap: PPH uterotonic contraindications — ergometrine is contraindicated in hypertension/cardiac disease.

Correct. At 41+4 weeks with a Bishop score of 4 (unfavourable, <6), cervical ripening with prostaglandins (PGE2 gel or misoprostol) is indicated before oxytocin induction. Post-dates pregnancy carries increasing risks of placental insufficiency, meconium, and stillbirth beyond 42 weeks.

Bishop score <6 = unfavourable cervix → cervical ripening (PGE2 gel or misoprostol) before oxytocin induction. Post-dates = ≥42 weeks; offer induction at 41–42 weeks to prevent stillbirth.

An unfavourable cervix (Bishop <6) is not an indication for immediate caesarean. Continuing to 43 weeks is not safe — national and WHO guidelines recommend offering induction between 41 and 42 weeks. ARM on an unfavourable cervix is unsafe and may result in failed induction or cord prolapse. Cervical ripening + induction is the standard of care.

Correct. In infection-driven preterm labour, bacterial components (LPS/endotoxins) activate macrophages and decidual cells → cytokine cascade (IL-1β, IL-6, TNF-α) → increased prostaglandin (PGE2 and PGF2α) synthesis → myometrial contractions and cervical ripening. This is the most evidence-supported mechanism.

Preterm labour pathophysiology: common final pathway = premature prostaglandin synthesis. In infection: LPS → cytokines (IL-1β, IL-6, TNF-α) → PGE2/PGF2α → myometrial activation. In other causes: abruption (thrombin), overdistension (stretch), ischaemia (CRH).

Option A conflates the progesterone withdrawal mechanism (relevant in term labour, not infection-driven). Option C is incorrect — infection does not act via beta-2 adrenergic receptors. Option D confuses neonatal surfactant deficiency (consequence) with a mechanism for triggering preterm labour. The cytokine-prostaglandin pathway is the established mechanism for infection-associated PTL.

Correct. Late decelerations with reduced variability indicate uteroplacental insufficiency — Category III (ominous) CTG. IMMEDIATE steps: STOP oxytocin (hyperstimulation is a reversible cause), left lateral positioning (relieve aortocaval compression), supplemental oxygen, IV fluid bolus, and urgent senior review for decision on delivery.

CTG late decelerations + reduced variability = Category III = urgent action: STOP oxytocin, left lateral tilt, O2, IV fluids, call senior. Consider emergency delivery if no improvement.

Increasing oxytocin when there is fetal distress from possible hyperstimulation is dangerous. ARM would not help and may worsen the situation. Tocolytics may be used as an acute resuscitation measure (terbutaline) in hyperstimulation, but STOPPING oxytocin is the first mandatory step.

Correct. Acute FHR bradycardia immediately after ARM is cord prolapse until proven otherwise. The first priority is immediate vaginal examination to feel for the cord in the vagina or cervix. If cord is felt, manage cord prolapse immediately (elevate presenting part, call for emergency caesarean).

Acute bradycardia after ARM = rule out cord prolapse FIRST by vaginal examination. Cord prolapse management: manual elevation of presenting part, knee-chest or Trendelenburg position, fill bladder with 400–500 mL saline if time permits, emergency LSCS.

While monitoring and oxygen are important, the FIRST action after acute bradycardia following ARM is to exclude cord prolapse by vaginal examination. Documentation and tocolysis are secondary. Trendelenburg positioning is part of cord prolapse management but only after confirming the diagnosis.

Correct. During the second stage, the delivering hand should apply GENTLE counter-pressure on the fetal head to CONTROL (not prevent) delivery — the Ritgen manoeuvre. Forcefully pushing the head back prevents the natural extension mechanism, may cause excessive perineal trauma, and risks hyperflexion injury to the neonatal neck.

Ritgen manoeuvre: right hand controls the head (finger tips on occiput), left hand presses through the perineum on the fetal chin to assist extension. Goal: controlled delivery to prevent rapid decompression and perineal tears.

Fundal pressure (Kristeller manoeuvre) is controversial and not recommended for routine delivery. The delivering hand should control (slow) the head's emergence with gentle counter-pressure, not push it back. The correct technique: thumb and fingers of right hand on occiput to control speed; left hand at perineum to support and flex the head for Ritgen manoeuvre.

Correct. Bohren's category 3 (non-dignified care) includes: shouting, scolding, dismissing concerns, using degrading language. Telling a frightened teenager 'don't cry' and issuing commands without explanation is dismissive and disrespectful — it fails to address her emotional needs and denies her information about her own care.

Bohren 2015 typology — 7 categories: (1) physical abuse, (2) sexual abuse, (3) verbal abuse, (4) stigma/discrimination, (5) failure to meet professional standards, (6) poor rapport/communication, (7) health system conditions. Non-dignified/dismissive communication = category 3/6.

Physical abuse (category 1) involves hitting, slapping, or non-consensual physical acts. Abandonment (category 5) means leaving women unattended at critical moments. Non-confidential care (category 6) involves sharing private information. The dismissive verbal response ('don't cry, just push') falls under non-dignified care.

Correct. PPROM at 34+2 weeks without signs of chorioamnionitis: expectant management is standard — give corticosteroids (betamethasone — she is <34+6), administer antibiotics to prolong the latency period (erythromycin/co-amoxiclav per ORACLE trial), and give GBS prophylaxis (penicillin or ampicillin, since GBS status unknown). Monitor for infection. Deliver at 34–37 weeks based on clinical course.

PPROM <34 weeks: corticosteroids + antibiotics (latency) + GBS prophylaxis. Monitor for chorioamnionitis signs: maternal fever >38°C, tachycardia, uterine tenderness, offensive liquor, raised CRP/WBC. Delivery if chorioamnionitis suspected regardless of gestational age.

Immediate caesarean is not indicated without fetal compromise or chorioamnionitis. Prostaglandins for induction are not first-line in PPROM (ARM has already occurred). Antibiotics ARE indicated in PPROM — they demonstrably prolong latency and reduce maternal and neonatal infection rates (ORACLE I trial evidence).