Nine trials (n=1,715 patients, range 50 to 392 patients) were included in the analysis: one RCT, one prospective study and seven retrospective controlled studies. Only three studies reported controlling for confounding factors. Most studies had no loss to follow-up; those that did lost between 12 and 219 patients.
Meta-analyses: Compared to control groups, the odds of malignant cytology (positive peritoneal ctyologic features) were significantly higher in women who had undergone hysteroscopy before operation (OR 1.78, 95% CI 1.13 to 2.79, I2=0%; nine studies). The odds of disease upstaging due solely to the presence of malignant cells in the peritoneal cavity were also higher (OR 2.61, 95% CI 1.47 to 4.63, I2=0%; seven studies).
Sensitivity analyses: Using only trials that reported using isotonic sodium chloride as a distension medium, the odds of malignant cytology were higher (OR 2.89, 95% CI 1.48 to 5.64, I2=0%; six studies). Using only trials in which inflation pressure reached or exceeded 100mmHg, the odds of malignant cytology were higher in the hysteroscopy group, but the result was statistically non significant (OR 3.23, 95% CI 0.94 to 11.09, I2=0%; four studies).
A number of secondary outcomes were reported.