Shoulder presentation

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Shoulder presentation
A shoulder presentation with a prolapsed arm, by William Smellie
SpecialtyObstetrics

A shoulder presentation is a

cesarean section
(C/S) is performed.

Frequency and causes

Shoulder presentations are uncommon (about 0.5% of births)

placenta previa
, a small fetus, or a fetus with some abnormality. Further, if the amniotic fluid sac ruptures, the shoulder or arm may become wedged as a shoulder presentation.

Diagnosis

Inspection of the abdomen may already give a clue as it is wide from side to side. Usually performing the Leopold's maneuvers will demonstrate the transverse lie of the fetus.[2] Ultrasound examination delivers the diagnosis and may indicate possible causes such as multiple gestation or a tumor. On vaginal examination, the absence of a head or feet/breech is apparent.

Shoulder presentations are classified into four types, based on the location of the scapula:

  • Left scapula-anterior (LSA)
  • Right scapula-anterior (RSA)
  • Left scapula-posterior (LSP)
  • Right scapula-posterior (RSP)

Management

While a transverse lie prior to labor can be manually versed to a longitudinal lie, once the uterus

cord prolapse as the shoulder may not completely block the birth canal. Thus the caesarean section
is ideally performed before the membranes break.

Delivery of the second twin

The delivery of the second twin in a transverse lie with a shoulder presentation represents a special situation that may be amenable to a vaginal delivery. As the first twin has just been delivered and the cervix is fully dilated the obstetrician may perform an internal version, that is inserting one hand into the uterus, find the baby’s feet, and then bring the baby into a breech position and deliver the baby as such.[3]

Impaction

During labor the shoulder will be wedged into the pelvis and the head lie in one iliac fossa, the breech in the other. With further uterine contractions the baby suffocates.

preterm or macerated and very small a spontaneous delivery has been observed.[1]

History

Internal version according to Siegemundin, 1690

Prior to the arrival of C/S the fetus usually died during protracted labor and the mother's life was at risk as well due to infection, uterine rupture and bleeding. On occasion, if the baby was macerated and small, it collapsed sufficiently to be delivered. The shoulder presentation was a feared obstetrical complication.

In 1690

Justine Siegemundin, a German midwife, published Die Kgl. Preußische und Chur-Brandenburgische Hof-Wehemutter. This treatise for midwives demonstrated abnormal presentations at birth and their management. She was the first to describe a two-handed method of performing an internal rotation of the baby to extract it as a breech (a variation of which is performed today on the second twin, see above) using a sling.[6] The procedure was useful provided the fetus was not impacted. Once the uterus had contracted around the baby tightly, destructive interventions were used to save the life of the mother.[7]

See also

References

  1. ^ a b c d Hellman LM, Pritchard JA (1971). Williams Obstetrics, 14th Edition. Appleton Century Crofts. p. 872ff.
  2. PMID 8240620
    .
  3. PMID 3347429
    .
  4. PMID 15770303
    .
  5. PMID 8674491
    .
  6. ISBN 0-8036-8070-8
    .
  7. PMC 2439677
    .

External links
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