Differential Diagnosis for Joint Pain after Unprotected Sex
Single most likely diagnosis
- Reactive Arthritis (ReA): This condition is a type of arthritis that occurs as a reaction to an infection elsewhere in the body, often in the gastrointestinal tract or the urethra. Unprotected sex can lead to infections such as chlamydia, which is a common trigger for ReA. The onset of joint pain after such an exposure makes ReA a highly plausible diagnosis.
Other Likely diagnoses
- Gonococcal Arthritis: Caused by Neisseria gonorrhoeae, this condition can lead to joint pain and is directly related to unprotected sex, especially if the sexual partner is infected.
- Lyme Disease: If the patient has been exposed to ticks during outdoor activities, Lyme disease could be a consideration, although it's less directly linked to unprotected sex.
- Septic Arthritis: Although less common, if the patient has a bacterial infection that has spread to the joints, this could be a cause of joint pain.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Disseminated Gonococcal Infection (DGI): This is a serious condition where gonorrhea infection spreads through the bloodstream, affecting multiple sites including joints, skin, and sometimes the heart. It requires immediate antibiotic treatment.
- HIV-associated Arthritis: Early stages of HIV infection can manifest with various symptoms, including joint pain. Missing this diagnosis could lead to delayed treatment and significant morbidity.
- Syphilitic Arthritis: In the secondary stage of syphilis, patients can experience joint pain among other systemic symptoms. This diagnosis is critical due to the potential for long-term complications if left untreated.
Rare diagnoses
- Whipple's Disease: A rare, systemic bacterial infection that can cause joint pain, among other symptoms. It's extremely uncommon but could be considered in patients with unexplained, persistent symptoms.
- Brucellosis: Typically associated with exposure to infected animals or their products, brucellosis can cause joint pain. It's a rare consideration in the context of unprotected sex unless the patient has had relevant occupational or recreational exposures.