1. ABNORMAL LIE & PRESENTATION
Associate Professor Dr Hanifullah Khan
2. 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
3. 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
4. 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
5. 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
6. 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
7. 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.
8. 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
10. 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)
12. 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)
13. 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.
15. 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
23. 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
23
27. 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)
28. 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)
29. 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
30. 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)
31. 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.
33. 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
34. 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).
