factor. The student will discuss the assessment of shoulder dystocia, the complication for fetus and mother, identification of risk factor, and management
10.1. DEFINITION
After the birth of the head, external rotation will take place which causes axis of the head to be on the normal axis to the spine. Generally shoulder will be on the oblique axis
under the pubic ramus. Pushing of the mother will cause the anterior shoulder become under the pubis. If the shoulder fails to hold a rotation of adjusting to the axis of tilted pelvis and
remain in the anteroposterior position, the baby will most collision front shoulder to the symphysis.
1,2
Shoulder dystocia is mainly caused by deformities of the pelvis, the failure of the shoulder to folded into the pelvis eg on macrosomia caused by active phase and short
second stage of labor in multiparas so the descence of the head is too quickly, causing the shoulder does not fold through the birth canal or head has through the middle pelvis after a
prolong of the second stage of labor before the shoulder successfully folded into the pelvis.
3
The main mechanism behind the occurrence of shoulder dystocia is the reten- tion of
the anterior shoulder behind the pubic symphysis, while the posterior shoulder is usually located in the maternal pelvis Figure 10.1.. In rare situations, both shoulders are retained
above the pelvic brim.
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Figure 10.1. The main mechanism behind the occurrence of shoulder dystocia –
retention of the anterior fetal shoulder above the pubic symphysis
10.2. INCIDENCE
An over- all incidence between 5.8-7 in 1000
of vaginal deliveries is reported in the largest observational studies
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, while others studies find incidence of 1-2 in 1000 birth and 16 in 1000 birth of baby weight more than 4000 gram.
3
Medical Education Unit Faculty of Medicine Udayana University
54
10.3. RISK FACTORS
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The main risk factors for shoulder dystocia are listed in Table 10.1. Previous shoulder dystocia stands out as a major risk factor for recurrence, and it is reported to be 10
times higher than in the general population, for an overall incidence of 1–25. The anatomical characteristics of the maternal pelvis that predispose to shoulder dystocia and
may cause it to be recurrent in nature are poorly understood. When additional risk factors are present, such as maternal diabetes or suspected fetal macrosomia or when previous fetal
injury occurred in association with shoulder dystocia, serious consider- ation should be given to elective caesarean delivery, and this option should be discussed with the mother.
4
Another major risk factor is fetal macrosomia, and when coexistent with poorly controlled maternal diabetes, an additional 2–4-fold risk is present, posed by the increased
diameter of the fetal shoulders.
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Table 10.1. Main Risk Factors for Shoulder Dystocia
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Risk Factor Previous shoulder dystocia
Fetal macrosomia and its associated risk factors Pre-existing or gestational diabetes
Maternal obesity Excessive weight gain during pregnancy
Post-term pregnancy Slow progress of labour vaginal delivery
Prolonged first andor second stage Need for labour acceleration
Instrumental
The majority of cases of shoulder dystocia occur in pregnancies that have no risk factors, and when one is present, the majority of cases do not develop this complication.
There is therefore wide agreement within the medical community that shoulder dystocia is generally an unpredictable situation. Nevertheless, identification of risk factors is useful for
anticipating of the situation, so that an experienced team can be on hand at the time of delivery.
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10.4. COMPLICATIONS
