PURPOSE: To evaluate the effect of surgeon-performed ultrasound on acute abdomen in specific patient subgroups regarding the diagnostic accuracy and further management. METHODS: Eight hundred patients attending the emergency department at Stockholm South General Hospital, Sweden, for abdominal pain, were randomized to either receive or not receive surgeon-performed ultrasound as a complement to routine management. Patients were divided into subgroups based on patient characteristics, symptoms or first preliminary diagnosis set at the emergency department before randomization. Outcomes measured were diagnostic accuracy, admission rate and requests for further examinations. Timing of surgery was evaluated for patients with peritonitis. RESULTS: Increased diagnostic accuracy was seen in patients with body mass index > 25, elevated C-reactive protein, peritonitis, age 30-59 years and/or upper abdominal pain. Decreased need for further examinations and/or fewer admissions were seen in all groups except in patients with a preliminary diagnosis of appendicitis. Among patients with non-specific abdominal pain, admission frequency was decreased with 14% when ultrasound was used (P = 0.007). Among patients with peritonitis, requiring surgery, 61% in the ultrasound group were admitted for surgery directly from the emergency department compared to 19% in the control group. CONCLUSION: In different ways, surgeon-performed ultrasound is helpful for the majority of patients admitted to the emergency department for abdominal pain. Taking into account other shown benefits and the lack of adverse effects, we find the method worth consideration for routine implementation.