Abnormal lie:-Transverse lie, oblique lie and unstable lie :-

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Obstetrics


Abnormal lie:-Transverse lie, oblique lie and unstable lie :-

A transverse lie occurs when the fetal long axis lies perpendicular to that of the maternal long axis in which the fetus is positioned 90° with respect to the mother s dorsal column.
An oblique lie occurs when the long axis of the fetal body crosses the long axis of the maternal body at an angle close to 45 degrees(in which the fetus may be in transition from a vertical to a transverse lie).
Unstable lie is alternating between transverse, oblique and longitudinal, it is important to think of possible uterine or fetal causes. A fetus can be in an unstable or variable lie when the head is completely unengaged and floating. This situation is seen mostly in cases of severe polyhydramnios and prematurity.

In transverse lie, and oblique lie the fetal back is usually anterior with the head most often to mother s left, the fetal attitude is one of flexion. Thought the dorso-posterior position are less common they inevitably cause fetal extension with greater risk of arm prolapsed and associated twisting of the fetal spine.




Transverse lie: A Dorso-anterior B Dorso-posterior


Oblique lie

Any woman presenting at term with a transverse, oblique , or unstable lie is at potential risk of cord prolapse following spontaneous rupture of the membranes, and prolapsed of the hand, foot or shoulder presentation once in labour. In most cases, the woman is multiparous with a lax uterus and abdominal wall musculature, and gentle version of the baby’s head in the clinic or on the ward will restore the presentation to cephalic.

Incidence :-An incidence of 1/320 is recorded in historical studies.
Aetiology:-
1-There is an association with progressive multiparity which is likely to be related to progressive laxity of the uterine musculature with each pregnancy.
2-The presence of polyhydramnios gives greater freedom of fetal movement and can predispose to these abnormal lies.
3-Placenta praevia may act as a physical obstruction to fetal engagement, as may any pelvic tumour, significant uterine anomaly or, more rarely, a contracted maternal pelvis.
4-Hydrocephalus and fetal tumours of the neck or sacrum may prevent engagement of the fetal head in the pelvis.
5-Fetal neuromuscular dysfunction may impede engagement secondary to reduced fetal movement.
Clinical findings:-The diagnosis of transverse or oblique lie might be suspected by abdominal inspection: the abdomen often appears asymmetrical. The SFH may be less than expected, and on palpation the fetal head or buttocks may be in the iliac fossa. Palpation over the pelvic brim will reveal an ‘empty’ pelvis.
The absence of a fetal pole in the pelvis on abdominal or vaginal examination, either antenatally or in labour, should raise the likelihood of an unstable/non-longitudinal lie (transverse lie, and oblique lie).
Management:-
1- In case of transverse lie , clinical findings should be confirmed by ultrasound examination .This should also look for fetal anomaly, measure liquor volume and check placental site. The presence of pelvic tumours or congenital uterine anomalies may be difficult to identify in late pregnancy.
Following exclusion of placenta praevia, vaginal examination is usually sufficient to exclude significant pelvic deformity or space-occupying lesion. X-ray pelvimetry does not add additional useful information to aid management.
2-In the presence of obstructive fetal or uterine pathology that precludes vaginal delivery: Caesarean section should be planned at the appropriate gestation. This may need to be a classical caesarean depending on the extent of the anomaly, and the woman should be counseled regarding that possibility. The risk of cord prolapse in the event of contractions or rupture of membranes should also be discussed and women advised to attend hospital promptly if these occur.
3- Even in the absence of an obstructive cause, inpatient management should be recommended
from 37 weeks because of the risk of cord prolapse, to enable rapid intervention if required .
In the majority of cases, spontaneous version to longitudinal lie will occur prior to membrane rupture or labour onset.
? Conservative management involves daily review and discharge home after the lie stabilizing longitudinally for 48 hours.
? Active management involves attempting an external cephalic version( ECV),with discharge home if the lie remains longitudinal. However, recent RCOG guidelines suggest that ECV should only be done with immediate induction ‘stabilizing induction’.Stabilizing induction requires a favorable cervix and immediate facilities for caesarean section in the event of a cord prolapse. ECV should not be attempted if there is advance laboure,efficient uterine contraction or ruptured membranes
In the case of the membranes rupture and the fetus is still in the transverse lie,CS should be performed to avoid injury to the fetus or the uterus.
A woman with an unstable lie at term should be admitted to the antenatal ward. The normal plan would be to deliver by Caesarean section if the presentation is not corrected to cephalic in early labour or if spontaneous rupture of the membranes occurs. In a multiparous woman, an unstable lie will often correct itself in early labour (as long as the membranes are intact). ECV can be attempted but with immediate recourse to Caesarean section if unsuccessful..
4- If the fetal lie remain non-longitudinal post term, an elective caesarean section should be offered.
5- Internal podalic version:- is done in case of delivery of second twin.
6-Labour and spontaneous vaginal delivery is possible in extreme preterm, macerated dead fetuses.