To investigate the incidence of pain in patients during transvaginal real-time three-dimensional hysterosalpingo-contrast-sonography (TVS RT 3D-HyCoSy, hereinafter referred to as HyCoSy) examination and to identify its main risk factors.

From March 2020 to March 2022, 963 patients diagnosed with infertility who underwent HyCoSy at the Department of Ultrasound of Tangdu Hospital of the Air Force Medical University were selected, and their clinical data were collected. Data collected included the incidence of pain, pain degree, and possibly related factors of pain at six different time points (intrauterine catheterization, water sac adjustment, during HyCoSy, 30 minutes after HyCoSy, 1 hour after HyCoSy, and 24 hours after HyCoSy). Statistical analyses were performed to determine the factors associated with pain in patients undergoing HyCoSy. Univariate analysis and Logistic regression analysis were used to screen the risk factors for pain and complications and calculate the odds ratio (OR).

Among the 963 patients who underwent HyCoSy, the rate of pain was 78.6% after intrauterine catheterization, 57.9% at water sac adjustment, 75.8% during HyCoSy, 48.6% at 30 min after HyCoSy, 31.5% at 1 h after HyCoSy, and 14.6% at 24 h after HyCoSy. After intrauterine catheterization, water sac was identified to be an independent risk factor for pain during intubation, with a 7.829-fold increase in the risk of pain for every 1 ml increase in water sac (OR=7.829, P<0.05). During HyCoSy, poor patency of the fallopian tube, high pressure of contrast agent injection, large water sac, contrast agent countercurrent, and previous dysmenorrhea were identified to be high risk factors for pain in patients, among which the risk correlation coefficient of pain caused by poor patency of the fallopian tube was the highest (OR=3.066, P=0.001). There were significant differences in the distribution of patients with high contrast agent injection pressure and poor tubal patency between the pain and painless groups at different time points after HyCoSy (P<0.05). At 30 min after HyCoSy, the incidence of contrast reflux was higher in the pain group (24.79% vs 16.36%, χ²=10.488, P=0.001), but over time, the proportion of patients with contrast counterflow did not differ significantly between groups (P>0.05). The proportion of patients with pain at 30 min and 1 h after HyCoSy was significantly higher than that of the group without pain (56.20% vs 46.06%, χ²=9.890, P=0.002; 59.41% vs 50.15%, χ²=12.541, P=0.001). At 24 h after HyCoSy, 49 of 86 pain patients (56.98%) had a history of dysmenorrhea, but there was no significant difference in its distribution between the groups (P>0.05).

Before contrast injection, the adjustment of the water sac size can effectively correct the pain level of patients, so as to truly reflect the pain level of patients during the HyCoSy. During HyCoSy, the degree of tubal patency, the pressure of contrast agent injection, and the history of dysmenorrhea are the continuous factors causing pain, while the size of water sac is an immediate influencing factor.