The Prevalence of Chlamydia Trachomatis and Neisseria Gonorrhoeae in Patients Suspected of Hemorrhagic Proctosigmoiditis
Conditions: Proctitis, Ulcerative, Sexually Transmitted Disease (STD), Ulcerative Proctosigmoiditis
Sponsor: University of Aarhus

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Cover page 
 
The prevalence of Chlamydia trachomatis and Neisseria 
gonorrhoeae in patients suspected of hemorrhagic proc-
tosigmoiditis (SOS Proctitis) 
 
A quality improvement project in the Central Denmark Re-
gion 
 
 
Clinical Trials Protocol 
 
Version 1., April 1st, 2025 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Background 
Chlamydia trachomatis and Neisseria gonorrhoeae can cause infectious proctitis, which macro-
scopically cannot be distinguished from haemorrhagic proctosigmoiditis (HP) caused by chronic 
inflammatory bowel disease. In Denmark, general practitioners are advised to consider whether pa-
tients presenting with proctitis symptoms might have a sexually transmitted infection (STI). How-
ever, there is no requirement for STI testing before referring the patient to a specialised department. 
At specialised departments, it is not standard practice to systematically inquire about sexual risk be-
haviour or to test for Chlamydia and Gonorrhoea. As a result, there is no data on how many pa-
tients diagnosed with HP due to chronic inflammatory bowel disease who are also positive for an 
STI—either as the sole cause or as a contributing factor to their inflammation. Chlamydia and Gon-
orrhoea are the most common causes of symptomatic, sexually transmitted proctitis and are increas-
ingly prevalent in Denmark. 
 
Aims 
We aim to investigate the proportion of patients with newly diagnosed proctosigmoiditis or treat-
ment-refractory disease who have an underlying STI. Furthermore, we aim to determine whether 
the prevalence of STIs varies across sex or age groups while also investigating whether STIs are 
prevalent in both newly diagnosed patients and patients with refractory disease. We also aim to 
monitor the effect of antibiotic treatment on proctitis progression. The implications of these findings 
could help determine whether screening for these pathogens should be implemented as part of the 
standard diagnostic process for haemorrhagic proctosigmoiditis.  
 
Materials and methods 
Since diagnosing haemorrhagic proctosigmoiditis requires an endoscopy (sigmoidoscopy or colon-
oscopy), all newly diagnosed patients will undergo such an examination. Moreover, an endoscopy is 
often performed in individuals with refractory proctosigmoiditis. If inflammation is observed up to 
35 cm from the anal opening, an additional swab will be taken during the procedure to test for Chla-
mydia and Gonorrhoea using standard PCR techniques. If the swab is not taken during the endos-
copy, it will be collected during a follow-up outpatient visit. The tests will be analysed immediately 
at the Department of Microbiology, Aarhus University Hospital. 
 
Over a 24-month period, we will examine all patients diagnosed with proctosigmoiditis at the 
Department of Liver, Digestive, and Gastrointestinal Diseases at Aarhus University Hospital 
(AUH), Viborg/Silkeborg Regional Hospital, Horsens Regional Hospital, Gødstrup Regional Hos-
pital and Randers Regional Hospital. This includes patients with inflammation extending from the 
anal opening to 35 cm proximally, as well as those with treatment-refractory proctosigmoiditis. 
All patient data will be prospectively collected through Region Midt EPJ, Denmark's electronic 
medical record system, and registered in a REDCap database.  
 
The tested patients will undergo standard follow-up at their respective departments. Supple-
mentary, patients who test positive for Chlamydia or Gonorrhoea will be offered treatment at the 
Venereology Outpatient Clinic, Aarhus University Hospital. If they are only on 5-ASA treatment 

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and it is found reasonable to pause their treatment, their IBD treatment will be paused during treat-
ment for STI. 
 
The studied patients will form a prospective cohort, and their disease progression, including the 
extent of haemorrhagic proctitis and current medication, will be recorded. 
 
Endpoints 
Primary endpoint:  
- 
Prevalence of Chlamydia and Gonorrhoea in our cohort of individuals with suspected haem-
orrhagic proctitis.  
Secondary endpoints:  
- 
Prevalence of Chlamydia and Gonorrhoea across gender 
- 
Prevalence of Chlamydia and Gonorrhoea across age groups 
- 
Prevalence of Chlamydia and Gonorrhoea depending on time for diagnosis 
- 
Frequency of clinical remission of proctitis after treatment with STI-related antibiotics 
- 
Differences in the frequency of clinical remission between those with a negative or positive 
STI test at inclusion 
 
Statistical analysis 
The statistical analyses will mainly be descriptive. For the primary and secondary outcomes, num-
bers with frequencies will be reported. Furthermore, appropriate statistical analyses will be applied 
to compare differences between those with a positive STI test and those with a negative test. 
The data collection period runs from October 1, 2024 until September 30, 2026. We expect to in-
clude at least 100 patients in the cohort but aim towards at least 200 patients. After 100 patients 
have been tested, we will assess whether we should continue to screen patients. If no positive pa-
tients have been found, we will terminate the study prematurely. By September 2025, we will con-
sider publishing the results if more than 5% of all patients examined are positive or if an isolated 
group has a more than 15% positivity percentage. 
 
The results will be submitted for publication regardless of the outcome. 
 
Ethical considerations  
To assess whether screening for STI in patients suspected of HP should be mandatory, screening for 
STI in patients suspected of HP has become a recommended clinical procedure in Region Midt in 
the current study period. All patients will give oral consent to perform the swab during the endos-
copy or in the outpatient ward. Local authorities have approved the collection of data for a quality 
improvement project.  
 
Perspectives 
If Chlamydia and Gonorrhea are found frequently, these results could indicate the necessity for in-
tegrating screening practices for all newly diagnosed HP patients and those with treatment-refrac-
tory disease. 

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If patients improve after pathogen-directed treatment and avoid treatment-refractory disease, 
there could be cost reduction if fewer biological therapies and ambulatory visits are required.