What is the Best Moment for Performing an HSG in Women With a Unfulfilled Childwish

Inclusion Criteria: * Women between 18-39 years of age * Spontaneous menstrual cycle * Perceived low risk for tubal pathology * Undergoing fertility work-up Exclusion Criteria: * Women with known endocrine disorders (e.g. the polycystic ovary syndrome, diabetes, hyperthyroidism and hyperprolactinemia. Except for well managed hypothyroidism with TSH between 0.3 and 2.5mIU/l) * Ovulation disorders defined as less than eight menstrual cycles per year * Iodine allergy * Male subfertility defined as a post-wash total motile sperm count \< 1 x10\^6 spermatozoa/ml * Not willing or able to sign the consent form