The growth rates of solitary gallbladder polyps compared to multi-polyps: A quantitative analysis

Several studies suggest solitary gallbladder polyps (GBPs) have an increased malignancy risk compared to multi-polyps. Furthermore, some malignant GBPs possessed faster growth rates compared to benign GBPs. To our knowledge, no study has established a relationship between GBP number and growth rates. Hence, this study aims to: (i) determine whether there is a statistical significance in growth rates between solitary GBPs versus multi-polyps; (ii) determine, in a four-year period, the proportion of GBPs in this study's total cohort that exhibit growth compared to previous studies.

A retrospective, quantitative, cohort study was implemented utilising 100 consecutive patient records from three private radiology clinics. These were assessed against the eligibility criteria and allocated into the solitary or multi-polyp study group, depending on number of GBPs detected on initial and follow-up ultrasound examinations conducted 6-48 months later. Patient age, GBP sizes, time interval between initial and follow-up ultrasound examinations and GBP growth rates were compared between the study groups utilising Student's t tests.

No statistically significant difference was found between the study groups according to gender, age, GBP size and time between ultrasound examinations. Furthermore, there was no statistically significant difference between the growth rates of solitary and multi-polyp groups (P = 0.77). Most GBPs [92/100 (92%)] grew <2 mm in maximal diameter, while 8/100 (8%) of GBPs grew ≥2 mm in maximal diameter at follow-up.

The large majority of GBPs maintained size stability at follow-up. On average, solitary GBPs did not grow faster than multi-polyps, although further research is recommended to reinforce this.