Shoulder presentation
Encyclopedia
A shoulder presentation refers to a malpresentation at childbirth
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 enters first the birth canal) is an arm
, shoulder
, 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 (C/S) is performed.
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), and other tumors in the pelvis or abdomen can also lead to a shoulder presentation. Other factors are a lax abdominal musculature, uterine overdistension (i.e. polyhydramnion), multiple gestation, 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.
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:
the uterus normally will not allow any version procedure. A shoulder presentation is an indication for a C/S. 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
as the shoulder may not completely block the birth canal. Thus the C/S is ideally performed before the membranes break.
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 presentation
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.
, a complication during the birth of a baby in a vertex presentation.
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
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 enters first the birth canal) is an arm
Arm
In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...
, shoulder
Shoulder
The human shoulder is made up of three bones: the clavicle , the scapula , and the humerus as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints. The major joint of the shoulder is the glenohumeral joint, which...
, 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 (C/S) is performed.
Frequency and causes
Shoulder presentations are uncommon (about 0.5% of births) as usually towards the end of gestationGestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
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), and other tumors in the pelvis or abdomen can also lead to a shoulder presentation. Other factors are a lax abdominal musculature, uterine overdistension (i.e. polyhydramnion), multiple gestation, 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 maneuversLeopold's maneuvers
In obstetrics, Leopold's 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 contractingChildbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
the uterus normally will not allow any version procedure. A shoulder presentation is an indication for a C/S. 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 prolapse
Umbilical cord prolapse happens when the umbilical cord precedes the fetus' exit from the uterus. It is an obstetric emergency during pregnancy or labor that imminently endangers the life of the fetus. Cord prolapse is rare...
as the shoulder may not completely block the birth canal. Thus the C/S 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
Without medical intervention, a natural resolution with the birth of a live infant at term is impossible. 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. 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
In 1690 Justine Siegemundin, a German midwife, published Die Kgl. Preußische und Chur-Brandenburgische Hof-Wehemutter. This treatise for midwives demonstrated abnormal presentation
Presentation (Obstetrics)
In obstetrics, the presentation of a fetus about to be born refers to 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, breech, or shoulder presentation...
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.
Note
Shoulder presentation is a malpresentation that is not to be confused with shoulder dystociaShoulder dystocia
Shoulder dystocia is a specific case of dystocia whereby after the delivery of the head, the anterior shoulder of the infant cannot pass below the pubic symphysis, or requires significant manipulation to pass below the pubic symphysis. It is diagnosed when the shoulders fail to deliver shortly...
, a complication during the birth of a baby in a vertex presentation.