obstetrics Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a su ...

, a shoulder presentation is a malpresentation at

childbirth Childbirth, also known as labour, parturition and delivery, is the completion of pregnancy, where one or more Fetus, fetuses exits the Womb, internal environment of the mother via vaginal delivery or caesarean section and becomes a newborn to ...

where the baby is in a transverse lie (its

vertebral column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmente ...

is perpendicular to that of the mother), thus the leading part (the part that first enters the

birth canal In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The vaginal int ...

) 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 ...

, 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 m ...

, or the trunk. While a baby can be delivered vaginally when either the

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple ani ...

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, cesarean, or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen. It is often performed because vaginal delivery would ...

(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 pregn ...

, 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 line 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,

placenta previa Placenta praevia or placenta previa is when the placenta attaches inside the uterus but in a position near or over the cervical opening. Symptoms include antepartum bleeding, vaginal bleeding in the second half of pregnancy. The bleeding is bright ...

, 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. 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, cesarean, or caesarean delivery, is the Surgery, surgical procedure by which one or more babies are Childbirth, delivered through an incision in the mother's abdomen. It is often performed because va ...

. 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 Cord or CORD may refer to: Common meanings * String (structure), String * Thin rope * Twine * Cord (unit) used for measuring wood * Power cord * Umbilical cord Cord or CORD may also refer to: Places * Cord, Arkansas People * Alex Cord ( ...

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 p ...

. 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 Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is betwee ...

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, a German

midwife A midwife (: midwives) is a health professional who cares for mothers and Infant, newborns around childbirth, a specialisation known as midwifery. The education and training for a midwife concentrates extensively on the care of women throughou ...

, 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