BackgroundMeasurement of colonic transit time (CTT) of different colon segments can help to find the subtype of constipation and the appropriate treatment. This study aimed to estimate the segmental and total CTT in patients with refractory chronic constipation who attended gastrointestinal clinics. MethodsA cross-sectional study was done in patients with refractory chronic constipation according to ROME IV criteria with normal colonoscopy. Patients with underlying diseases, including diabetes, hypoparathyroidism, hypothyroidism, anemia, past intestinal surgery, metabolic disorders, and recent medication use with constipation complications, were excluded. Every patient took a gelatin capsule containing ten 1–3 mm angiographic catheters for six consecutive days. On the seventh day, an upright abdominal x-ray was performed. The remaining markers were counted in three divided colonic segments, and the total CTT using radio-opaque markers was measured subsequently. Results40 patients were eventually included in this study. Twenty-eight were female (70%), and 55% of patients had standard body mass index (BMI). The mean age of patients was 43 years with a standard deviation of 18 years, while the mean total CTT was 37.05 h with a standard deviation of 24 h. Additionally, 60% had a normal CTT (≤45 h), and 40% had abnormal and prolonged CTT. ConclusionConstipation as a complaint is more common in women than men. Total CTT is slightly higher in men than women, but there is no significant difference. CTT may be normal in patients with refractory constipation despite all investigations. Additionally, there was no correlation between BMI and prolonged total CTT.