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  Chapter 35 Unstable lie of the fetus 

Disclaimer | Definition  | Contributing factors | Associated risk factors | Diagnosis | Management | Intrapartum management | References | Last reviewed
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Document title:                     Unstable lie of the fetus

First developed:                   26 July 2004

Subsequent updates:          21 October 2008

Last reviewed:                      26 July 2011

ISBN number:                       

Replaces document:            New document

Author:                                   South Australian Perinatal Practice Guideline Workgroup

Audience:                               Medical, midwifery and allied health staff in South Australia public and private maternity services

Endorsed by:                         South Australian Perinatal Practice Guidelines Workgroup

Contact:                                 South Australian Perinatal Practice Guidelines workgroup at:



The South Australian Perinatal Practice Guidelines have been prepared to promote and facilitate standardisation and consistency of practice, using a multidisciplinary approach.

Information in this guideline is current at the time of publication and use of information and data contained within this guideline is at your sole risk.

SA Health does not accept responsibility for the quality or accuracy of material on websites linked from this site and does not sponsor, approve or endorse materials on such links.

SA Health does not accept liability to any person for loss or damage incurred as a result of reliance upon the material contained in this guideline.

Although the clinical material offered in this guideline provides a minimum standard it does not replace or remove clinical judgement or the professional care and duty necessary for each specific patient case. Where care deviates from that indicated in the guideline contemporaneous documentation with explanation should be provided.

This guideline does not address all the elements of guideline practice and assumes that the individual clinicians are responsible to:

>  Discuss care with consumers in an environment that is culturally appropriate and which enables respectful confidential discussion. This includes the use of interpreter services where necessary

>  Advise consumers of their choice and ensure informed consent is obtained

>  Provide care within scope of practice, meet all legislative requirements and maintain standards of professional conduct

>  Document all care in accordance with mandatory and local requirements




>  Unstable lie refers to the frequent changing of fetal lie and presentation in late pregnancy (usually refers to pregnancies > 37 weeks) (MacKenzie, 2011)

>  Lie refers to the relationship between the longitudinal axis of the fetus and that of its mother, which may be longitudinal, transverse or oblique


Contributing factors

>  High parity

>  Placenta praevia

>  Polyhydramnios

>  Pelvic inlet contracture and / or fetal macrosomia

>  Pendulous abdomen

>  Uterine abnormalities (e.g. bicornuate uterus or uterine fibroids).

>  Fetal anomaly (e.g. tumours of the neck or sacrum, hydrocephaly, abdominal distension)


Associated risk factors

>  Cord presentation or prolapse if membranes rupture or at the onset of labour

>  Fetal hypoxia if left unattended in labour

>  Shoulder presentation and transverse lie in labour

>  Uterine rupture



>  Usually made when a varying fetal lie is found on repeated clinical examination in the last month of pregnancy



>  85 % of fetal lies will become longitudinal before rupture of the membranes or labour (MacKenzie, 2011)

>  Abdominal palpation to assess for polyhydramnios

>  Pelvic examination as indicated (assess pelvic size and shape)

>  Ultrasound to exclude mechanical cause

>  Inform woman of need for prompt admission to hospital if membranes rupture or when labour starts

>  Hospital admission from 37 weeks onwards is recommended

>  Immediate clinical assistance if membranes rupture or signs of labour

>  May attempt external version to cephalic presentation in early labour with access to facilities for immediate delivery if indicated

>  If cephalic presentation is maintained (spontaneously or otherwise) manage as normal 


Intrapartum management

Vaginal and pelvic assessment

>  Establish presentation

>  Exclude cord presentation

>  Assess if polyhydramnios  

>  Assess cervical dilatation

If the lie is longitudinal

>  Normal labour management

If the lie is not longitudinal

>  Consider external version to correct lie

>  ARM should be done with caution

If the lie is not longitudinal and cannot be corrected

>  Caesarean section



1.       MacKenzie IZ. Unstable lie, malpresentations, and malpositions. In:  James DK, Weiner CP, Steer PJ, Gonik B, Crowther CA, Robson SC, editors.  High risk pregnancy.  Fourth ed.  Philadelphia:  Elsevier; 2011. p. 1123-1137. (Level IV)

2.       Royal College of Obstetricians and Gynaecologists (RCOG).  Umbilical cord prolapse.  Green-top Guideline No. 50.  April 2008.  Available from URL:


First developed: 26 July 2004    Subsequent updates:  21 October 2008

Last reviewed: 26 July 2011

South Australian Perinatal Practice Guidelines. Please read our disclaimer.