Anal Swab RT‑PCR Ct Values and Gastrointestinal Symptoms in Adult COVID‑19 Patients: A Cross‑Sectional Study

Abstract

Background: Anal swab RT‑PCR can detect SARS‑CoV‑2 RNA in patients with gastrointestinal (GI) symptoms, yet how cycle threshold (Ct) values from anal swabs relate to GI manifestations remains unclear. Methods: We performed an analytical cross‑sectional study using secondary, de‑identified hospital records from three Indonesian centers (July–November 2020). Adults with positive RT‑PCR from anal swabs and available Ct values were included. Ct values were categorized as low (<25) vs high (≥25). GI symptoms recorded were nausea, vomiting, abdominal pain, diarrhea, and constipation. The primary outcome was the association between Ct category and presence of GI symptoms, analyzed using Fisher’s exact test with prevalence ratio (PR) and 95% confidence interval (CI). Results: Thirty‑seven patients met inclusion criteria (43.2% men; mean age 44.8±13.2 years). One patient (2.7%) had low Ct and 36 (97.3%) had high Ct. Overall, 22/37 (59.5%) had ≥1 GI symptom; the most frequent was nausea (54.1%), followed by vomiting (18.9%), abdominal pain (16.2%), and diarrhea (13.5%); no constipation was recorded. There was no significant association between Ct category and GI symptoms (p=0.595; PR 1.048, 95% CI 0.956–1.148). Conclusions: Among adults with positive anal swab RT‑PCR, Ct category did not correlate with GI symptom presence. These null findings suggest that Ct values from anal swabs should be interpreted cautiously for symptom prognostication and underscore the need for larger, prospectively collected datasets.