A shoulder presentation is a

malpresentation In obstetrics, the presentation of a fetus about to be born specifies which anatomical part of the fetus is leading, that is, is closest to the pelvic inlet of the birth canal. According to the leading part, this is identified as a cephalic, b ...

childbirth Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births glob ...

where the baby is in a transverse lie (its vertebral column is perpendicular to that of the mother), thus the leading part (the part that first enters the birth canal) is an

arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

, a

shoulder The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder mak ...

, or the trunk. While a baby can be delivered vaginally when either the head or the feet/buttocks are the leading part, it usually cannot be expected to be delivered successfully with a shoulder presentation unless a

cesarean section Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen, often performed because vaginal delivery would put the baby or ...

(C/S) is performed.

Frequency and causes

Shoulder presentations are uncommon (about 0.5% of births) since, usually, toward the end of

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pr ...

, either the head or the buttocks start to enter the upper part of the pelvis, anchoring the fetus in a longitudinal lie. It is not known in all cases of shoulder presentation why the longitudinal lie is not reached, but possible causes include bony abnormalities of the pelvis, uterine abnormalities such as malformations or tumors (fibroids), or other tumors in the pelvis or abdomen. Other factors are a lax abdominal musculature, uterine overdistension (i.e.,

polyhydramnios Polyhydramnios is a medical condition describing an excess of amniotic fluid in the amniotic sac. It is seen in about 1% of pregnancies. It is typically diagnosed when the amniotic fluid index (AFI) is greater than 24 cm. There are two clini ...

multiple gestation A multiple birth is the culmination of one multiple pregnancy, wherein the mother gives birth to two or more babies. A term most applicable to vertebrate species, multiple births occur in most kinds of mammals, with varying frequencies. Such ...

, 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 In obstetrics, Leopold maneuvers are a common and systematic way to determine the position of a fetus inside the woman's uterus. They are named after the gynecologist Christian Gerhard Leopold. They are also used to estimate term fetal weight. ...

will demonstrate the transverse lie of the fetus. 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 starts contracting the uterus normally will not allow any version procedure. A shoulder presentation is an indication for a

caesarean section Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen, often performed because vaginal delivery would put the baby or m ...

. Generally, as it is diagnosed early, the baby is not damaged by the time of delivery. With the rupture of the membranes, there is an increased risk of a

cord prolapse Umbilical cord prolapse is when the umbilical cord comes out of the uterus with or before the presenting part of the baby. The concern with cord prolapse is that pressure on the cord from the baby will compromise blood flow to the baby. It usua ...

as the shoulder may not completely block the birth canal. Thus the

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.

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. The uterus continues to try to expel the impacted fetus and as its retraction ring rises, the musculature in the lower segments thins out leading eventually to a uterine rupture and the death of the mother. Impacted shoulder presentations contribute to

maternal mortality Maternal death or maternal mortality is defined in slightly different ways by several different health organizations. The World Health Organization (WHO) defines maternal death as the death of a pregnant mother due to complications related to pre ...

. Obviously a cesarean section should be performed before the baby has died, but even when the baby has died or impaction has occurred, C/S is the method of choice of delivery, as alternative methods of delivery are potentially too traumatic for the mother. If the baby is preterm or macerated and very small a spontaneous delivery has been observed.

History

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 Justine Siegemund or Siegemundin (26 December 1636 – 10 November 1705) was a renowned midwife from Lower Silesia whose ''Court Midwife'' (1690) was the most read, but not the first, female-published German obstetrical manual. Early life She w ...

, a German

midwife A midwife is a health professional who cares for mothers and newborns around childbirth, a specialization known as midwifery. The education and training for a midwife concentrates extensively on the care of women throughout their lifespan; ...

, published ''Die Kgl. Preußische und Chur-Brandenburgische Hof-Wehemutter''. This treatise for midwives demonstrated abnormal

presentation A presentation conveys information from a speaker to an audience. Presentations are typically demonstrations, introduction, lecture, or speech meant to inform, persuade, inspire, motivate, build goodwill, or present a new idea/product. Presenta ...

s 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. 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.

References

External links

Institute and Museum of History of Science, see models 36-42
{{DEFAULTSORT:Shoulder Presentation Complications of labour and delivery Midwifery