Pyometra is a rare condition that is defined as the accumulation of purulent material in the uterine cavity caused by an occlusion to the natural drainage of the uterus. Pyometra cases are seldom reported. The symptoms of pyometra may be non-specific, resulting in a delay or misdiagnosis that may subsequently increase the risk of perforation of the pyometra. Once a pyometra ruptures, the patient develops acute abdominal and generalized peritonitis. This case report describes diffuse peritonitis caused by the spontaneous perforation of a pyometra in a woman who was diagnosed preoperatively and treated successfully by emergency laparotomy.