BACKGROUND Persistent nonspecific symptoms such as epigastric pain, bloating, nausea, and bilious vomiting are common following cholecystectomy. The etiology of these symptoms is unknown, but abnormal antroduodenal motility associated with duodenogastric reflux (DGR) is a possible cause. METHODS Sixteen postcholecystectomy patients and 19 healthy volunteers ("normals") were studied. Ten of the patients were asymptomatic and 6 were symptomatic. The study consisted of a 4-hour 99mTc-DISIDA (diisopropyl imidodiacetic acid) infusion and gastric aspiration, 24-hour intragastric pH monitoring, and 24-hour ambulatory antroduodenal manometry. RESULTS The postcholecystectomy patients showed increased DGR of the infused 99mTc-DISIDA. The data are given as coulter counts x 10(6)/min. The increase was more marked in symptomatic postcholecystectomy patients (2.54 +/- 0.15) compared to asymptomatic patients (1.21 +/- 0.46) or normals (0.26 +/- 0.15). Postcholecystectomy patients had increased percentage of time with intragastric pH > 3. In the supine period in particular, the pH was > 3 in symptomatic patients 25.4% +/- 7.7% of the time versus 8.1% +/- 4.3% for asymptomatic patients (P < 0.01). The antral phase III frequency after cholecystectomy was 2.5 +/- 0.09 cycles/min compared to 3.2 +/- 0.08 cycles/min in normals (P < 0.0001). Furthermore, propagation of the phase III front in the duodenum was significantly slowed to 0.14 +/- 0.02 cm/s after cholecystectomy compared to 0.27 +/- 0.02 cm/s in normals (P < 0.001). The duration of phase III in the proximal duodenum after cholecystectomy was also decreased to 4.3 +/- 0.27 min compared to 5.9 +/- 0.35 min in normals (P < 0.005). CONCLUSIONS Fasting antroduodenal motility is altered after cholecystectomy. The abnormality is associated with increased DGR, which is more marked in symptomatic patients.