ABNORMAL LIE & PRESENTATION

Associate Professor Dr Hanifullah Khan

2

Objectives

Understand fetal skull & pelvic anatomy

Basic definitions in obs

Identify types of abnormal lie and presentation

Identify causes of each abnormal lie and presentation

Making a diagnosis which includes history taking,

physical examination and investigation

Pelvis

• Space or compartment surrounded by the pelvic girdle

(bony pelvis)

• Subdivided into greater and lesser pelvis

– greater pelvis affords protection to inferior abdominal viscera

– lesser pelvis provides the skeletal framework for both the

pelvic cavity and the perineum

Normal pelvis - anatomy

• The bony pelvis is formed by 4 bones:-

a. Right and left hip bones (fusion of Ilium, Ischium and Pubis)

b. Sacrum (fusion of 5 sacral vertebrae)

c. Coccyx

• Joints :-

– 2 Sacroilliac joints

– Pubic Symphysis and

– Sacrococcygeal joint Clinically Oriented Anatomy, 5th

Edition, Moore, Keith L.; Dalley,

Arthur F. page 357

Pelvic inlet

• Bounded:

– anterior by Pubic

symphysis

– laterally by upper margin

of pubic bones, the

ileopectineal line & ala of

the sacrum

– Posteriorly by the sacral

promontory.

• Normal Transverse

diameter = 13.5 cm

• Anterior-Posterior

diameter = 11.0 cm

Inlet – side view

• The angle of the inlet:

– -normally 60° to the

horizontal in the erect

position.

– Increase in angle may

delay the head entering the

pelvis in labour

Pelvic mid cavity

• area bounded:

– anteriorly by middle of Symphysis Pubis

– -laterally by pubic bones and inner aspect of the ischial spine and bone

– posteriorly by junction of 2nd and 3rd sacral section.

• Cavity almost rounded. Transverse &AP diameter are similar at 12cm.

• The ischial spines are palpable vaginally and used as landmarks to assess the station and pudendal anaesthetic block.

Pelvic outlet

• Bounded:

-anteriorly by the lower margin of the of SP

-laterally by the descending ramus of the pubic bone, ischial tuberosity and sacrotuberous ligament

-posteriorly bounded to last segment of sacrum

Pelvic outlet diameters

Transverse diameter =

11 cm

AP diameter = 13.5 cm

Types of pelves

• 4 common pelvic shapes in female

-Gynaecoid pelvis(most favourable for labour)

-Android pelvis(predispose to deep transverse arrest)

-Anthropoid pelvis (encourage occipito-posterior position)

-Platypelloid pelvis(increase risk of obstructed labour)

Pelvic shapes

Fetal skull

Made up of:

• Vault (formed by the

parietal bones, part of the

occipital, frontal and

temporal bones), Face

and Base.

• Sutures-sagittal, coronal,

frontal, temporal

• Fontanelles(anterior and

posterior)

Skull diameters

• The fetal head is ovoid

in shape.

• The attitude of the fetal

head refers to the

degree of the extension

or flexion at the upper

cervical spine.

Attitudes & diameters

Basic Definition

• Lie – Relationship between long axis of fetus and long

axis of uterus

• Presentation- Part of the fetus that presents to the

maternal pelvis

Types

Abnormal lie Abnormal presentation

Transverse Breech

Oblique Face

Unstable Brow

Shoulder

Abnormal lie

Abnormal

presentation

Causes & associations

Unknown

Cephalopelvic disproportion

Risk factors:

Preterm delivery

Small for dates

Fetal anomalies

Polyhydramnios

Multiparous /high parity

• Others

Placenta praevia

fetal thyroid

enlargement

Uterine & abd wall

laxity

Uterine abnormality

Abnormal fetal

position

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BREECH PRESENTATION

Definition: Baby presents with the buttocks or feet rather

than the head first (cephalic presentation)

20

21

Classification of Breech

Presentations

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Face Presentation

Face: presenting part is the face, denominator is mentum

Brow Presentation

Brow: when the portion

of the fetal skull just

above the orbital ridge

presents

Should be suspected in

unexpectedly prolonged

labour with failure to

progress

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Transverse Lie

Shoulder

presentation

CLINICALDIAGNOSIS

Important

• Dates must always be determined

– By history

● Regularity of periods

● Dates of onset of pregnancy symptoms

● Date of quickening

– Examination

● Uterine size & fundal assesment

– Ix

● Ultrasound scanning (esp. 1st trimester)

Discrepancy in dates

• This can lead to a wrong diagnosis of abnormal lie

• Preterm fetuses are prone to abnormal lie

• Confirmation of dates can rule out macrosomia (a cause

of abn lie & presentation)

History taking

• Assess pregnancy for risk factors

• Previous or current history of vaginal bleeding includes

onset, duration, amount, character and aggravating factor (to

rule out placenta praevia)

• Ask for any history of decreased fetal movement

• Any previous or current history of multiple pregnancy

Past History

• Previous history of abnormal lie and presentation.

• Previous history of preterm delivery

• History of fetal anomalies (eg:hydrocephalus)

• History of tumour (thyroid, pelvis)

Physical examination

• Inspection (asymmetrical or fullness at certain areas of

abdomen)

• Palpation – – measure the SF height (whether it corresponds to date)

– assess number of fetal poles

– grip palpation to assess fetal lie and presentation

– leopold maneuvers

– palpation of pelvic brim might reveal an empty pelvis

– assess adequacy of liqour

– Estimate fetal weight

• Vaginal examination- can be empty or other parts

besides fetal head.

Leopold’s maneuver

Investigations

• Ultrasound scan

- to rule out any fetal anomalies and assess amount of

liqour)

- to check for the presentation and lie of the fetus

• MOGTT – for gestational diabetes

Management

• Caesarean section is the form of delivery

• Well planned vaginal delivery may be attempted

– in cases of abnormal cephalic presentations e.g. face

• External cephalic version: maneuvering infant to a vertex

position (only if breech is diagnosed before onset of

labour).