Objectives: In spite of mounting evidence to the contrary, plaintiffs' expert witnesses continue to maintain that brachial plexus impairment is almost always the result of excessive lateral traction on the head during the last phase of delivery. Case studies are presented to challenge this concept.
Study design: Examples encountered in medicolegal consultations were analyzed with this purpose as our focus.
Results: Cases of brachial plexus impairment were encountered in which there was no evidence of shoulder dystocia or extreme lateral traction on the fetal head. In one in which shoulder dystocia was recorded, there was also incontrovertible evidence of intrauterine maladaptation. In another, the posterior shoulder was involved.
Conclusion: To propose that shoulder dystocia with extreme lateral traction on the fetal head after its delivery is not a factor in some cases of brachial plexus impairment would be insupportable. Conversely, to maintain a posteriori that brachial plexus impairment in itself is evidence that such pressure must have been used is untenable.