Obstetrics and Gynaecology
Abnormal Labour and Operative Obstetrics
Dystocia, malpresentation, obstructed labour, cord prolapse and operative delivery for MBBS, including caesarean and instrumental delivery, mapped to NMC codes OG14 and OG15.
MedNext Academy | 3 min read
Abnormal Labour and Operative Obstetrics
Dystocia, malpresentation, obstructed labour, cord prolapse and operative delivery for MBBS, including caesarean and instrumental delivery, mapped to NMC codes OG14 and OG15.
This chapter covers labour that deviates from normal and the operative interventions used to deliver safely. It addresses dystocia and its causes, malpresentations and external cephalic version, obstructed labour and cord prolapse as emergencies, and the indications, technique and complications of caesarean section and instrumental delivery.
High-yield: Abnormal Labour and Operative Obstetrics
- Dystocia is difficult or abnormally slow labour, arising from problems with the power, the passage or the passenger.
- Failure to progress in the active phase is defined on the partograph and may be corrected by augmentation with oxytocin if the pelvis is adequate.
- The commonest malpresentation is breech; external cephalic version can be offered from about 37 weeks to turn the foetus to cephalic.
- Face and brow presentations result from deflexion of the foetal head; a persistent brow usually needs caesarean delivery.
- Obstructed labour presents with a tonically contracted uterus, a Bandl's ring, maternal exhaustion and foetal distress.
- Neglected obstructed labour can cause uterine rupture, obstetric fistula and maternal death.
- Cord prolapse is an emergency; the presenting part is pushed up and the woman placed knee-chest or head-down while preparing urgent delivery.
- A palpable pulsating cord below the presenting part after membrane rupture confirms cord prolapse.
- Caesarean section is delivery through incisions in the abdominal and uterine walls, most commonly via a lower segment transverse incision.
- Vaginal birth after caesarean is possible in selected women but carries a small risk of scar rupture.
- Forceps and vacuum extraction are instrumental deliveries used in the second stage when conditions such as full dilatation and engaged head are met.
- Vacuum extraction carries a risk of foetal scalp injury and cephalhaematoma, while forceps can cause maternal genital tract trauma.
- A failed instrumental delivery should be recognised early and converted to caesarean rather than repeatedly attempted.
- Prerequisites for instrumental delivery include full dilatation, ruptured membranes, an engaged head, known position, adequate analgesia and an empty bladder.
Operative obstetric essentials
- **Obstructed labour signs:** Bandl's ring, exhaustion, foetal distress; risk of rupture and fistula.
- **Cord prolapse:** Push up presenting part, knee-chest position, urgent delivery.
- **Caesarean section:** Usually lower segment transverse incision; VBAC risks scar rupture.
- **Instrumental delivery prerequisites:** Full dilatation, ruptured membranes, engaged head, known position, analgesia, empty bladder.
NMC competencies in this chapter
- **OG14.1:** Abnormal labour: dystocia, protraction, arrest and augmentation
- **OG14.2:** Malpresentations: breech, external cephalic version, face and brow
- **OG14.3:** Obstructed labour: causes, signs, complications and prevention
- **OG14.4:** Cord prolapse: risk factors, diagnosis and emergency management
- **OG15.1:** Caesarean section: indications, technique, complications and VBAC
- **OG15.2:** Instrumental delivery: forceps, vacuum extraction and failed instrument
Frequently Asked Questions
What are the causes of abnormal labour?
Problems with the power (inadequate contractions), the passage (a contracted or abnormal pelvis) or the passenger (malposition, malpresentation or a large foetus), the classic three Ps.
How is cord prolapse managed?
It is an emergency. The presenting part is pushed up off the cord, the woman is placed knee-chest or head-down, and immediate delivery, usually by caesarean, is arranged.
What are the signs of obstructed labour?
A tonically contracted uterus with a Bandl's ring, maternal exhaustion and foetal distress. If neglected it can lead to uterine rupture and obstetric fistula.
What conditions must be met before an instrumental delivery?
Full dilatation, ruptured membranes, an engaged head with a known position, adequate analgesia and an empty bladder. A failed attempt should be converted to caesarean promptly.
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