What is the natural history of internal rectal prolapse?

AIM: The nature and clinical significance of internal rectal prolapse is controversial. Its natural history is unclear. Longitudinal cohort studies show rare progression to external prolapse but lack adequate follow-up. We aimed to study the relationship of age to various stages of internal rectal prolapse using the Oxford Rectal Prolapse Grade (ORPG) and evaluate the influence of sex and vaginal delivery on this relationship.

METHOD: Internal rectal prolapsed (IRP) diagnosed at proctography and external rectal prolapse were graded using the ORPG. Age, sex and obstetric history were documented. Mean age of each prolapse grade (1-5) was analysed and regression analysis performed for age and prolapse. Subgroup analyses were made for males, and females with (V+) and without (V0) history of vaginal delivery.

RESULTS: Sixty males (11%) and 471 females (89%) were studied. The difference in the mean ages of each group was statistically significant (grade 1,38.6; grade 2, 52.1; grade 3, 56.0; grade 4, 60.3 and grade 5, 66.5, P < 0.0001). On average male (8.7 years) and V0-group (8.0 years) were younger than V+ group (95% CI difference 4.5-12.9 years, P < 0.0001, and 3.8-12.2 years, P < 0.0001, respectively). Males and V0-group had weaker correlation between age and prolapse grade (r = 0.16 and r = 0.17, respectively, vs 0.41), and a faster prolapse progression rate than the V+ group.

CONCLUSION: These data demonstrate a strong relationship between age and prolapse grade, supporting the view of internal rectal prolapse as a precursor to external prolapse in the spectrum of rectal prolapse disease.