HUMEROSPINOUS DISTANCE MEASUREMENTS - ACCURACY AND USEFULNESS FOR PREDICTING SHOULDER DYSTOCIA IN DELIVERY AT TERM

Objective To investigate if the humerospinous distance, as an indicato r of shoulder width, could predict shoulder dystocia at term. Design P rospective cross-sectional study of a stratified reference group of he althy women and a test group of women with risk factors for shoulder d ystocia. Measurements were not revealed. Outcome measures were difficu lties with delivery of the shoulders and correlation with maternal bod y mass and birth weight.Subjects Seventy-two women with singleton preg nancies at a University Clinic: 32 women at 39-42 weeks for reference and 40 women in an at-risk test group (weight > 90 kg, weight gain > 2 0 kg, previous macrosomic baby, history of shoulder dystocial difficul t delivery, clinical suspicion of a large baby). Women with a breech f etus, twins and those not able to deliver vaginally were excluded. Met hods Fetal shoulders were measured from the convergence of the cervica l spinous processes at the approximate cervicothoracic vertebral junct ion to the medial border of the humeral head. Correlations were made w ith maternal body mass, birth weight, birth weight estimation, ultraso und and postnatal humerospinous measurements. Results One case of shou lder dystocia in a fetus with an average humerospinous measurement occ urred in the reference group and there were no cases in the test group . There was no predictive value of a large humerospinous measurement a nd no correlation with maternal or fetal size. Movement of the fetal a rm could change the humerospinous distance considerably, which could a ccount for the difference between a normal and large measurement. Conc lusion The humerospinous distance cannot be used to predict shoulder d ystocia.