Obstetrics Simplified - Diaa M. EI-Mowafi
Shoulder Presentation (Transverse or Oblique lie)
Definition
- The longitudinal axis of the foetus does not coincide with that of the mother.
- These are the most hazardous malpresentations due to mechanical difficulties that occur during labour .
- The oblique lie which is deviation of the head or the breech to one iliac fossa, is less hazardous as correction to a longitudinal lie is more feasible.
Incidence
3-4% during the last quarter of pregnancy but 0.5% by the time labour commences.
Aetiology
Factors that
- change the shape of pelvis, uterus or foetus,
- allow free mobility of the foetus or
- interfere with engagement as:
- Maternal:
- Contracted pelvis.
- Lax abdominal wall.
- Uterine causes as bicornuate, subseptate and fibroid uterus.
- Pelvic masses as ovarian tumours.
- Foetal causes:
- Multiple pregnancy.
- Polyhydramnios.
- Placenta praevia.
- Prematurity.
- Intrauterine foetal death.
- Maternal:
Positions
The scapula is the denominator
- Left scapulo-anterior.
- Right scapulo-anterior.
- Right scapulo-posterior.
- Left scapulo-posterior.
Scapulo-anterior are more common than scapulo-posterior as the concavity of the front of the foetus tends to fit with the convexity of the maternal spines.
Diagnosis
During pregnancy
- Inspection:
- The abdomen is broader from side to side.
- Palpation:
- Fundal level: lower than that corresponds to the period of amenorrhoea.
- Fundal grip: The fundus feels empty.
- Umbilical grip: The head is felt on one side while the breech one the other. In transverse lie, they are at the same level, while in oblique lie one pole, usually the head as it is heavier, is in a lower level i.e. in the iliac fossa.
- First pelvic grip: Empty lower uterine segment.
- Auscultation:
- FHS are best heard on one side of the umbilicus towards the foetal head.
- Ultrasound or X-ray:
- Confirms the diagnosis and may identify the cause as multiple pregnancy or placenta praevia.
During labour
In addition to the previous findings, vaginal examination reveals:
- The presenting part is high.
- Membranes are bulging.
- Premature rupture of membranes with prolapsed arm or cord is common. The dorsum of the supinated hand points to the foetal back and the thumb towards the head. The right hand of the foetus can be shacked, correctly by the right hand of the obstetrician and the left hand by the left one.
- When the cervix is sufficiently dilated particularly after rupture of the membranes, the scapula, acromion, clavicle, ribs and axilla can be felt.
Mechanism of Labour
As a rule no mechanism of labour should be anticipated in transverse lie and labour is obstructed.
If a patient is allowed to progress in labour with a neglected or unrecognized transverse lie, one of the following may occur:
- Impaction:
- This is the usual and most common outcome.
- The lower uterine segment thins and ultimately ruptures.
- The foetus becomes hyperflexed, placental circulation is impaired, cord is prolapsed and compressed leading to foetal asphyxia and death.
- Spontaneous rectification:
- Rarely the foetal lie may be corrected by the splinting effect of the contracted uterine muscles so that the head presents.
- Spontaneous version:
- Rarely, by similar process the breech may come to present.
- Spontaneous expulsion:
- Very rarely, if the foetus is very small or dead and macerated, the shoulder may be forced through the pelvis followed by the head and trunk.
- Spontaneous evolution:
- Very rarely, the head is retained above the pelvic brim, the neck greatly elongates, the breech descends followed by the trunk and the after -coming head, i.e. spontaneous version occurs in the pelvic cavity.
Management
External cephalic version
Can be done in late pregnancy or even early in labour if the membranes are intact and vaginal delivery is feasible. In early labour, if version succeeded apply abdominal binder and rupture the membranes as if there are uterine contractions.
Internal podalic version
It is mainly indicated in 2nd twin of transverse lie and followed by breech extraction.
Prerequisites:
- General or epidural anaesthesia.
- Fully dilated cervix.
- Intact membranes or just ruptured.
Caesarean section
- It is the best and safest method of management in nearly all cases of persistent transverse or oblique lie even if the baby is dead.
- As rupture of membranes carries the risk of cord prolapse, an elective caesarean section should be planned before labour commences.
Neglected (Impacted) shoulder
Clinical picture (impending rupture uterus)
- Exhaustion and distress of the mother.
- Shoulder is impacted may be with prolapsed arm and / or cord.
- Membranes are ruptured since a time.
- Liquor is drained.
- The uterus is tonically contracted.
- The foetus is severely distressed or dead.
Management
- Caesarean section is the safest procedure even if the baby is dead. A classical or low vertical incision in the uterus facilitates extraction of the foetus as a breech in such a condition.
- Any other manipulations will lead eventually to rupture uterus so they are contraindicated.
UNSTABLE LIE
Definition
A foetus which changes its lie frequently from transverse to oblique to longitudinal.
Aetiology
- Polyhydramnios.
- Prematurity and IUFD.
- Contracted pelvis.
- Placenta praevia.
- Pelvic tumours.
- Multiparae with a lax uterus and abdominal wall.
Management
- External cephalic (or even podalic) version:
- Can be done whenever the woman is examined but in majority of cases it will recur so it is better to defer it until full term (37-40 weeks).
- After correcting the foetal lie to longitudinal, apply an abdominal binder, start oxytocin infusion and do amniotomy when the uterine contractions started and the presenting part is well settled into the pelvic brim.
- Caesarean section is indicated in:
- Failure of external version .
- Some do it selectively in cases discovered after 40 weeks’ gestation.
Links
Edited by Aldo Campana,