Factors in pregnancy
Pelvimetry
Using ultrasound
The parents
Overdue baby
Possible signs in labour
Severe shoulder dystocia is a rare complication, but many caregivers place a great deal of emphasis on trying to predict and / or intervene, in efforts to avoid it happening. Unfortunately, the methods available at present for predicting which babies will experience shoulder dystocia are not very accurate. Yet they are frequently relied upon to support the use of early inductions and Caesareans for 'large babies'.
Factors in pregnancy
Pregnant women with diabetes are monitored and managed specifically to avoid the complication of having a large (or 'macrosomic') baby, and possibly shoulder dystocia.
Women who are not diabetic may be viewed 'at risk' of having a macrosomic baby, if the caregiver suspects they have an altered carbohydrate metabolism (described previously). If the woman goes over her due date and the baby 'feels big', this will add to their possible concern. While these may help 'build a picture' for the caregiver, they cannot 'predict' who will experience shoulder dystocia.
Pelvimetry
Some caregivers perform what is called a 'clinical pelvimetry' during one of the pregnancy visits. This involves doing an internal vaginal examination, using their fingers to feel the size and shape of the woman's pelvis.
This procedure is not an accurate way of measuring the actual 'size' of the pelvis. It also does not take into account the pelvis' ability to 'stretch', due to the relaxed ligaments, during the labour. It may be able to detect what is called a 'platypelloid' shaped pelvis, as opposed to the more expected 'gynaecoid' shaped pelvis. This is a rare shaped pelvis, which tends to be flatter and narrower in shape.
Image 6-48 shows the different shapes of a 'gynaecoid' and 'platypelloid' pelvis.
In the past, many caregivers used to use X rays to look at the size of the woman's pelvis.