Chapter 24 — Sexually Transmitted Diseases and Condylomatous Conditions with Anorectal Manifestations
The anorectal region can be affected by several sexually transmitted infections. This chapter covers the main conditions together, since they share overlapping presentation and examination principles. It covers anal warts, gonococcal and chlamydial proctitis, herpes proctitis, syphilis, and the role of HIV testing. This is the same pattern used for every disease chapter in this manual.
24.1 What Are Sexually Transmitted Anorectal Conditions
These conditions reach the anorectal region through sexual contact. Receptive anal intercourse is the main route. Some conditions spread by direct contact with infected skin or mucosa. Others spread through infected secretions.
More than one infection can be present at the same time. This is common, not rare. A full screen is needed whenever one condition is found, not just treatment of the obvious finding.
Approach every patient with sensitivity and without judgement. Follow the same trauma- informed principles described in Chapter 23, even though the circumstances here are different.
24.2 Condylomata Acuminata (Anal Warts)
Condylomata acuminata, or anal warts, are caused by the human papillomavirus, known as HPV. Most warts are caused by low-risk HPV types, mainly types 6 and 11. High-risk HPV types, mainly 16 and 18, carry a different concern. These types are linked to anal intraepithelial neoplasia, known as AIN, which can progress toward cancer over time.
Warts usually appear as small, painless growths. They may be single or multiple. They often have a cauliflower-like surface. They can cause itching, bleeding, or a feeling of a lump.
Inspection, described in Chapter 4, usually shows the diagnosis clearly. Proctoscopy, described in Chapter 6, checks for internal extension into the anal canal.
Condylomata acuminata must be distinguished from condylomata lata, a different lesion seen in secondary syphilis. Condylomata lata are flat and moist, not cauliflower-like. This distinction matters, since the underlying infection and treatment are entirely different.
Treatment options include topical agents, such as podophyllotoxin or imiquimod, for smaller lesions. Larger or more extensive lesions need excision, cautery, cryotherapy, or laser treatment.
A patient with extensive or recurrent warts, or with known high-risk HPV, should be considered for ongoing surveillance for anal intraepithelial neoplasia. Chapter 26 covers the assessment of anorectal malignancy in full.
24.3 Gonococcal and Chlamydial Proctitis
Neisseria gonorrhoeae and Chlamydia trachomatis are common causes of infectious proctitis. This is inflammation of the rectal lining, most often following receptive anal intercourse.
Many patients have no symptoms at all. When symptoms occur, they include anal discharge, pain, tenesmus, and bleeding. Tenesmus means a persistent feeling of needing to defecate, even after the bowel is empty.
Proctoscopy, described in Chapter 6, may show inflamed, friable mucosa, often with visible discharge.
A specific and more severe form of chlamydial infection, called lymphogranuloma venereum, or LGV, deserves separate mention. LGV causes a more invasive proctitis, sometimes extending to proctocolitis, inflammation reaching further into the bowel. It needs a longer course of treatment than ordinary chlamydial infection, and should always be considered in a patient with unusually severe or persistent proctitis symptoms.
Diagnosis for gonorrhoea, chlamydia, and LGV relies on a rectal swab, tested by nucleic acid amplification testing, known as NAAT. This is the standard modern diagnostic method.
Treatment follows current local or national antimicrobial guidelines, since resistance patterns and recommended regimens change over time. LGV specifically needs a longer treatment course than standard chlamydial infection.
24.4 Herpes Proctitis
Herpes simplex virus, known as HSV, can cause a painful proctitis. This is most severe during a primary, first-time infection.
Pain is often severe, and can seem out of proportion to what is visible on examination. Painful vesicles, small fluid-filled blisters, or ulcers may be seen on the perianal skin or within the anal canal. Tenesmus is common.
A severe case can also cause sacral radiculopathy. This means irritation of the sacral nerves, and can cause urinary retention or altered sensation in the buttocks or thighs. Recognise this as a genuine complication of herpes proctitis, not a separate, unrelated problem.
Diagnosis is confirmed by a viral swab, tested by polymerase chain reaction, known as PCR. Treatment is with an antiviral medication, such as aciclovir or valaciclovir, together with adequate pain control.
24.5 Syphilis
Syphilis is caused by the bacterium Treponema pallidum.
Primary syphilis causes a chancre, a painless ulcer at the site of infection. An anal chancre is easily mistaken for a fissure, described in Chapter 11, since both can present as a painless or minimally painful anal ulcer. Careful examination and a high index of suspicion are needed to avoid missing this diagnosis.
Secondary syphilis can cause condylomata lata, described already in Section 24.2. These are flat, moist, highly infectious lesions, distinct in appearance from the warts caused by HPV.
Diagnosis relies on blood serology. Dark-field microscopy of fluid from a chancre can also confirm the diagnosis directly, where this test is available. Treatment is with penicillin, following current local guidelines for dose and duration.
24.6 HIV and the Anorectal Examination
HIV does not by itself cause a distinct anorectal lesion. It matters greatly to this chapter for other reasons.
A patient with any of the conditions described in this chapter should be offered HIV testing, since the same sexual contact that transmits these infections can also transmit HIV. Chapter 23 describes HIV post-exposure prophylaxis in the specific context of sexual assault. The same principle of considering HIV risk applies here.
A patient with HIV may show more severe, more extensive, or more treatment-resistant presentations of any condition described in this chapter. Wound healing after any anorectal procedure may also be slower. Keep this in mind when planning both medical and surgical treatment.
24.7 Examination
Follow the sequence described in Chapter 3.
Inspection, described in Chapter 4, is usually the most informative step for warts, ulcers, and visible lesions.
Proctoscopy, described in Chapter 6, checks for internal extension of warts, and for the inflamed, friable mucosa typical of proctitis.
Approach every examination with sensitivity. Many patients feel embarrassed or anxious about this consultation. A calm, professional, non-judgemental manner encourages the patient to disclose their full history and return for follow-up.
24.8 Differential Diagnosis
Condylomata acuminata versus condylomata lata — described in Sections 24.2 and 24.5. The distinction changes both the diagnosis and the treatment.
An anal chancre versus a chronic anal fissure, described in Chapter 11. Both can present as a painless or minimally painful ulcer.
Infectious proctitis versus inflammatory bowel disease. Both can cause similar symptoms of pain, discharge, and altered bowel habit. Chapter 28 covers the anorectal manifestations of inflammatory bowel disease in full.
Skin tags or hypertrophied papillae, which can resemble small warts but are not infectious.
24.9 Investigations
A full sexually transmitted infection screen is appropriate whenever one of these conditions is diagnosed, since more than one infection is often present together.
This screen typically includes a rectal swab for NAAT testing of gonorrhoea and chlamydia. It also includes a viral swab for HSV PCR, if ulcers or vesicles are present. Syphilis serology and an HIV test complete the screen.
Consider screening for hepatitis B and hepatitis C as well, depending on the patient's risk factors and local guidelines.
24.10 Principles of Management
Treat the specific infection identified, following current local or national guidelines for antimicrobial or antiviral therapy.
Arrange partner notification and treatment wherever appropriate, since untreated partners lead to reinfection.
Offer clear counselling on safer sexual practices, delivered without judgement.
Arrange a test of cure where this is recommended for the specific infection treated, particularly for gonorrhoea, chlamydia, and LGV.
Discuss HIV testing, and HIV prevention options such as pre-exposure prophylaxis, where relevant to the patient's circumstances.
24.11 Special Situations
An immunocompromised patient, including a patient with HIV, may need a longer or more intensive course of treatment, and closer follow-up, for any of the conditions in this chapter.
Recurrent or extensive warts need ongoing surveillance for anal intraepithelial neoplasia, described in Section 24.2, rather than repeated treatment of the visible warts alone.
Suspected LGV needs its longer, specific treatment course, described in Section 24.3, rather than the standard regimen used for ordinary chlamydial infection.
24.12 Complications
Anal stricture, particularly after LGV, described in Section 24.3, or after severe, longstanding proctitis from any cause.
Progression of high-risk HPV infection toward anal intraepithelial neoplasia, and, in some cases, toward anorectal malignancy, described in Chapter 26.
Disseminated infection, if a condition such as syphilis is left untreated.
Ongoing transmission to sexual partners, if the infection is not identified and treated promptly.
24.13 Common Mistakes to Avoid
Treating one identified infection without screening for others that may be present at the same time.
Mistaking condylomata lata for condylomata acuminata, or the reverse, without careful clinical distinction.
Mistaking an anal chancre for a simple fissure, and missing the diagnosis of primary syphilis.
Not offering HIV testing to a patient presenting with any other sexually transmitted anorectal condition.
Under-treating LGV with a standard chlamydial regimen, rather than the longer course it requires.
Approaching the consultation with judgement rather than sensitivity, which discourages the patient from returning for follow-up or disclosing their full history.
24.14 Recording and Follow-Up
Record the specific findings, the tests sent, and the treatment given. For example: "Perianal condylomata acuminata, proctoscopy shows no internal extension. STI screen sent, including HIV test. Plan: topical treatment, partner notification advised, review in 4 weeks." Arrange follow-up to confirm treatment response, to review any pending test results, and to complete partner notification and safer sex counselling.
24.15 Why This Chapter Matters
Sexually transmitted anorectal conditions are common, and often overlap with one another. Screening fully, treating precisely, and approaching every patient without judgement together define good practice in this chapter. The next chapter turns to a common and often distressing symptom in its own right: pruritus ani.