Q&A: Diagnosis of Sexually Transmitted Infections (STIs)

Sexually transmitted infections (STIs) are a major public health problem in both resource-rich and limited settings. STIs are frequently asymptomatic and can lead to various complications. The immediate goal of screening for STIs is to identify and treat infected persons before they develop complications and to identify, test, and treat their sex partners to prevent transmission and reinfections.

This article is for Medical Students & Professionals

This is a Question & Answer revision article designed for medical students and professionals preparing for the PLAB, MRCP or USMLE examinations. They are based on actual questions from these examinations. You may find the Sexually Transmitted Infections (STIs) article more useful, or one of our many articles on Diseases & Conditions, Medical Syndromes, Health & Wellness or Home Remedies.

In this article:
Screening for STI
MCQ exam: clinical scenario
MCQ exam: answer
MCQ exam: explanation

Screening for STI

Complications of untreated sexually transmitted infections (STIs) include upper genital tract infections, infertility, chronic pelvic pain, cervical cancer, and chronic infection with hepatitis viruses and HIV. The approach to STI diagnosis and management is based upon disease or symptom-specific syndromes, including vaginal discharge, urethral discharge, ulcerative genital disease, nonulcerative genital disease, and pelvic pain. However, many patients have asymptomatic disease, which increases the risk of complications and sustained transmission in the community. Thus, screening is an important approach to identify and treat infected individuals, who would otherwise go undetected. Routine screening for all potential STIs in all patients is cost-prohibitive; targeted screening of asymptomatic patients in specified risk groups is more feasible.

MCQ exam: clinical scenario

A 31 year old male develops a sudden onset of small boils on his genitals rapidly becoming painful open sores. He is noted, on examination, to have large swollen, tender lymph nodes in the groin.

A likely diagnosis is:

a) Gonorrhea
b) Human papilloma virus
c) Herpes
d) Hemophilus Ducreyi
e) Syphilis

MCQ exam: answer

The correct answer is D.

MCQ exam: explanation

Chancroid is caused by a bacterium known as Hemophilus Ducreyi. Chancroid may be transmitted through oral, vaginal, or anal intercourse. The infection begins with the appearance of painful open sores on the genitals, sometimes accompanied by swollen, tender lymph nodes in the groin. These symptoms occur within a week after exposure. Symptoms in women are often less noticeable and may be limited to painful urination or defecation, painful intercourse, rectal bleeding, or vaginal discharge. Women may have no sores, but they may have painful urination or bowel movements, painful intercourse, rectal bleeding, or vaginal discharge.

Men are more commonly infected than women.

Untreated chancroid can infect and swell the lymph glands located in the groin. Chancroid is especially dangerous because the sores it causes increase the chances of getting HIV. First, a small boil or ulcer - 'bubo' - appears, usually on the genitals. But it does not heal like a common pimple. Later, the bubo becomes an open sore. There may be pus and pain. Chancroid buboes can be confused with herpes, syphilis, and other conditions. Microscopic examination of the discharge from the bubo is necessary.

Both partners can be treated successfully with oral antibiotics. Chancroid lesions may be difficult to distinguish from ulcers caused by genital herpes or syphilis. A physician must therefore diagnose the infection by excluding other diseases with similar symptoms. Chancroid is one of the genital ulcer diseases that may be associated with an increased risk of transmission of the human immunodeficiency virus (HIV), the cause of AIDS.

Reference(s)
1). UpToDate: Screening for sexually transmitted infections. Available online: https://www.uptodate.com/contents/screening-for-sexually-transmitted-infections