Any amount of rectal bleeding can be alarming. It isn’t something that we’re used to seeing, so you may immediately wonder whether there’s something wrong with your health.
Although we usually think of penile or vaginal symptoms when we suspect a sexually transmitted infection (STI), you may be surprised to learn that rectal bleeding can also be caused by an STI. That doesn’t automatically mean that all instances of rectal bleeding are caused by a sexually transmitted disease, but it’s definitely something that you should keep in mind.
Let’s go over some of the causes of rectal bleeding, and the signs that tell you that you should seek medical attention.
Causes of rectal bleeding
As we mentioned above, certain STIs can cause rectal bleeding. However, that doesn’t necessarily mean that STIs are always the cause. There are many different conditions that can lead to rectal bleeding.
Proctitis is caused by inflammation of the rectum. Swollen mucous membranes are more likely to suffer small tears and bleed, leading to rectal bleeding. It can also lead to rectal purulent discharge, pain, and constipation.
Common causes of proctitis include:
- Inflammatory bowel disease
- Crohn’s disease
- Ulcerative colitis
- Non-sexually transmitted infections
- Autoimmune diseases
Gonorrhea, caused by Neisseria gonorrhea, is an STI that can be transmitted through anal sex and lead to rectal symptoms. Anywhere between 35 to 50 percent of women with cervical gonorrhea could also have anal gonorrhea, even if it’s asymptomatic in many cases. This condition is also common among men who engage in anal sex.
Symptoms of anorectal gonorrhea can include:
- Anal discharge
- Anal bleeding
- Ulcers around the anal sphincter
- Anal fissures
- Perirectal abscesses
- Painful bowel movements
Chlamydia is another common STI — in fact, it’s been estimated to be the most prevalent STI in the entire world — that can also affect the rectum and anal canal. Both anal sex and anal-oral sex could cause a chlamydia infection.
This STI, caused by Chlamydia trachomatis, is commonly asymptomatic. But when it’s not, it can lead to several different anal symptoms, such as:
- Fragile, swollen rectal mucosa
- Rectal bleeding
- Rectal discharge
- Watery diarrhea
- Perirectal abscesses
- Fissures and/or fistulas
Human papillomavirus (HPV)
There are more than a hundred types of HPV, although not all of them are considered to cause STIs. HPV is a very common infection, and a large percentage of the world’s population has probably been exposed to at least one strain of HPV at some point in their lives. Fortunately, not all strains are considered to be high-risk; however, a few strains are known to cause warts and cancer.
High-risk HPV strains can cause different types of cancer, including cervical cancer, anal cancer, oropharyngeal cancer, vulvar cancer, vaginal cancer, and penile cancer.
HPV can also cause warts or condylomas that can affect the cervix, skin, anus, and other parts of the body. Symptoms of anal HPV can include:
- Skin-colored “cauliflower-like” warts or spots that grow over time
- Anal itching or bleeding
- Anal mucous discharge
Syphilis is an STI caused by Treponema pallidum that can be spread through oral, vaginal, or anal sex; it can also be spread by kissing near a lesion, or from mother to child during pregnancy or birth.
Symptoms of anorectal syphilis can include:
- Chancre, or skin ulceration
- Pseudotumors, or mass-like lesions
- Anal discharge that can be purulent, mucous, or stained with blood
- Urgency to defecate
- Tenesmus (ineffectual and often painful straining to defecate)
Chancroid is an STI caused by Haemophilus ducreyi, which typically causes ulcers in the affected area. This disease is transmitted during sexual contact through small lesions in the skin. It can affect male or female genitals, but also the anus and rectum. Symptoms of anorectal chancroid include:
- Pain on defecation
- Painful ulcers around the anus
- Rectal swelling and pain
- Rectal bleeding
- Perianal abscesses
Rectal bleeding can simply be the result of fissures, which are small tears in the rectal mucosa. And although fissures can be the result of the inflammation caused by many different STIs, they can also have much simpler causes.
Causes of anal fissures include:
- Straining during bowel movements
- Inflammatory bowel disease (IBD)
- Chronic diarrhea
- Engaging in anal sex without proper prepation (lack of lubrication, insertion of foreign objects, etcetera)
When to see a doctor
Although rectal or anal STIs are more common in men who have sex with men, they can affect anyone who engages in anal sex. And since many anorectal STIs may not cause very significant symptoms, any instance of rectal bleeding should be studied by a healthcare professional.
Your doctor will most likely perform a thorough physical examination and ask questions about your medical history. In some cases, it may be necessary to take a sample of any discharge coming from the anal sphincter, or even a small biopsy if any lesions are present. This will make it possible to reach an accurate diagnosis and provide the right treatment.
If rectal bleeding is caused by other issues — such as digestive issues or anal sex —, your doctor will also be able to provide recommendations. Rectal bleeding caused by fissures should be properly addressed, since these small lesions can become infected. If you engage in anal sex, make sure to use enough lubricant and go slow to prevent fissures from developing.
Written by Andrea Pinto on June 18, 2021
- Sexually transmitted infections of the anus and rectum - ncbi.nlm.nig.gov
- Gonorrhea - CDC Fact Sheet (Detailed Version)- cdc.gov
- Bacterial Sexually Transmitted Diseases - ncbi.nlm.nih.gov
- Cancers associated with human papillomavirus - cdc.gov
- Anal Warts and Anal Dysplasia Expanded Information - fascrs.org
- Primary chancre in the rectum: an underdiagnosed cause of rectal ulcer- scielo.isciii.es