Background: Seroma formation after modified radical mastectomy (MRM) is a frequent complication which 
predisposes to other complications. Different surgical strategies have been practiced looking for its 
prevention. We aimed with this study to analyze the different methods of dissection that participate in seroma 
formation after MRM and accordingly standardizing the best operative technique with the least incidence of 
seroma formation. 
Patients and Methods: A prospective randomized study included females who had MRM for early breast 
cancer from April 2011 to August 2013, at Sohag University Hospital. Patients were classified into 3 groups 
according to breast dissection with electrocautery, conventional scalpel, and harmonic scalpel to analyze its 
effects in seroma formation. Also timing of drain removal, postoperative use of pressure garment, and timing 
of postoperative shoulder exercise were analyzed for the same purpose.
Results: The study included 50 females with 16% incidence of postmastectomy seroma. All were treated with 
aspiration, but drain replacement was necessary in one case (12.5%) with axillary seroma. The use of
electrocautery, early removal of drains, and early active shoulder exercise, all were highly significant factors
(P= 0.001) in development of postmastectomy seromas and proved to be independent factors. Neglection of 
the wear of pressure garment was nonsignificant (P= 0.25).
Conclusion: Prevention of seroma or decreasing its incidence after MRM can be achieved by the use of 
ordinary scalpel or far better harmonic scalpel in breast dissection, delayed removal of drains, use of pressure 
garment postoperative, and also delayed active shoulder exercise.