# Malpresentations in Labour

> Malpresentations for FMGE obstetrics: face, brow, transverse lie, compound presentation and occipito-posterior position with modes of delivery.

- Canonical URL: https://prepelephant.com/topics/fmge/obstetrics-and-gynaecology/malpresentations-and-positions
- Exam / course: FMGE · Subject: Obstetrics and Gynaecology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Malpresentations in Labour", PrepElephant, https://prepelephant.com/topics/fmge/obstetrics-and-gynaecology/malpresentations-and-positions

## Direct answer

A malpresentation is any presenting part other than a well-flexed vertex — face, brow, shoulder (transverse lie), breech or compound presentation — complicating a few per cent of term labours. Face presentation with the chin anterior delivers vaginally; brow presentation with its 13.5 cm mentovertical diameter is undeliverable at term; and a transverse lie at term needs caesarean section, except the second twin, delivered by internal podalic version. Occipito-posterior position, the commonest malposition, usually rotates and delivers spontaneously, but persistence may require manual or instrumental rotation or caesarean. Recurring causes are prematurity, grand multiparity, placenta praevia, fibroids, polyhydramnios and fetal anomalies.

## What you must remember

- Face presentation: complete extension makes the submento-bregmatic diameter (9.5 cm) engage; mento-anterior delivers vaginally, while persistent mento-posterior is undeliverable at term and needs caesarean section.
- Brow presentation: partial extension presents the mentovertical diameter of 13.5 cm, the largest skull diameter — undeliverable at term unless it converts; caesarean is the rule.
- Transverse lie (shoulder presentation) in a singleton at term is delivered by caesarean for obstructed labour and cord prolapse risk; internal podalic version belongs to the second twin.
- Compound presentation (hand or arm beside the head) often delivers spontaneously, but carries a risk of cord prolapse.
- Occipito-posterior position, commoner with deflexion and in anthropoid pelves, mostly rotates anteriorly; deep transverse arrest or secondary arrest needs rotation, hands-and-knees posturing or caesarean.
- Face-to-pubis delivery in persistent OP traumatises the perineum and prolongs the second stage.
- An unstable lie near term in a grand multipara demands hospital delivery, because ruptured membranes convert it into cord prolapse or an obstructed transverse labour.

## Common confusion

The examiner contrasts the two chin positions: mento-anterior behaves like an occipito-anterior vertex and delivers, whereas mento-posterior is impacted and undeliverable — the most repeated fact here. Equally common is mixing brow with face: brow means mentovertical 13.5 cm (caesarean); face means submento-bregmatic 9.5 cm (vaginal if chin anterior). A transverse lie with ruptured membranes and a neglected shoulder is an obstructed-labour emergency.

## Exam-focused takeaway

FMGE pairs each presentation with its diameter and default route: face mento-anterior — vaginal; brow — caesarean; shoulder in a singleton — caesarean; OP with arrest — rotate or caesarean. Learn the aetiology lists (prematurity, multiparity, fibroid, praevia, hydramnios, fetal anomaly) and the cord-prolapse link. Face-to-pubis perineal injury and the neglected shoulder with Bandl ring are recurring image-style stems.

## Frequently asked questions

### Which face position can deliver vaginally?

Mento-anterior, with the chin under the symphysis and the submento-bregmatic diameter distending the perineum; persistent mento-posterior requires caesarean section.

### Why is brow presentation undeliverable at term?

Partial extension presents the mentovertical diameter of 13.5 cm — the largest skull diameter — which exceeds the capacity of the outlet.

### How is transverse lie managed at term?

By caesarean section for a singleton, ideally before membrane rupture; internal podalic version is reserved for the second twin.

### What is a compound presentation?

A fetal hand or arm alongside the head (or foot with a breech); many deliver naturally, but cord prolapse and obstructed labour are risks.

### How does occipito-posterior position usually deliver?

Most rotate anteriorly at the pelvic floor and deliver spontaneously; arrest calls for manual or instrumental rotation, maternal posturing or caesarean section.

### Which malpresentation carries the highest cord prolapse risk?

Transverse lie and shoulder presentation, followed by an unengaged high head and footling breech — all with a poorly fitting presenting part.