Patients with Duchenne muscular dystrophy (DMD) tend to bleed more during 
surgery than do patients with other conditions. A retrospective analysis of 
blood loss after spinal surgery for scoliosis was therefore undertaken in 102 
patients undergoing surgery in the senior author's unit. These included 48 
patients with DMD, 26 patients with spinal muscular atrophy, and a miscellaneous 
group of 28 other patients most of whom had idiopathic scoliosis. For each 
patient the age at surgery, estimated blood volume, duration of operation, Cobb 
angle, and number of vertebrae fused were recorded and compared. Expression of 
dystrophin in skeletal muscle and the underlying gene mutation were also 
determined. The estimated blood loss in patients with DMD was significantly 
higher than that in patients with spinal muscular atrophy undergoing the same or 
similar procedure (P < 0.005) and was also significantly greater than that of 
the third group, which consisted mostly of patients with idiopathic scoliosis (P 
< 0.0005). Blood loss in the patient group with DMD showed a significant 
relationship with duration of surgery (P < 0.05). As most patients expressed no 
dystrophin, this did not correlate with the estimated blood loss. There was also 
no correlation between the estimated blood loss and the type of gene mutation 
found causing DMD. The authors' previous observations confirm the increased 
blood loss in patients with DMD who undergo scoliosis surgery. Because children 
with DMD lack dystrophin in all muscle types, including smooth muscle, the 
excessive blood loss may be because of a poor vascular smooth muscle 
vaso-constrictive response due to a lack of dystrophin.