Sexually Transmitted Infections in the Emergency Department: Essential FRCEM SBA Practice Questions Explained

FRCEM SBA practice questions is a core part of UK Emergency Medicine practice. Sexually transmitted infections (STIs) occupy an increasingly prominent position in UK Emergency Medicine practice, and examiners know it. With gonorrhoea diagnoses in England reaching a 45-year high in 2023 according to UK Health Security Agency surveillance data, and STI diagnoses nationally exceeding 400,000 that year, the ED registrar who cannot confidently differentiate pelvic inflammatory disease from appendicitis, or recognise disseminated gonococcal infection in a young adult with a rash and monoarthritis, is not exam-ready and is not clinically safe. The FRCEM SBA exam tests precisely these discriminatory skills, embedding STI scenarios within undifferentiated presentations of pelvic pain, scrotal pathology, sepsis, and systemic illness. This article works through the essential clinical knowledge, maps it to the RCEM curriculum, and provides the kind of structured reasoning that separates a confident FRCEM SBA candidate from one who loses marks to predictable pitfalls.

Epidemiology and Clinical Context in UK Emergency Medicine

The epidemiological landscape of STIs in the United Kingdom has shifted substantially over the past decade. Chlamydia remains the most commonly diagnosed STI, predominantly affecting those aged 15 to 24, and is often entirely asymptomatic, making the ED presentation usually one of its complications rather than the index infection itself. Syphilis incidence has risen sharply, particularly among men who have sex with men (MSM), with rates not seen since the post-war era. This matters in the ED because secondary syphilis mimics a range of conditions, including drug eruptions, pityriasis rosea, and viral exanthems, and is regularly missed by clinicians who do not include it in the differential of a rash involving the palms and soles.

The ED is not a genitourinary medicine clinic, but it functions as one by default, particularly out of hours, for patients who perceive their symptoms as acute emergencies, for those with complications, and for vulnerable groups including victims of sexual assault. Understanding this epidemiological burden, and its reflection in the FRCEM SBA syllabus, is the first step in effective exam preparation. The RCEM curriculum explicitly expects competence in managing urethritis, cervicitis, PID, epididymo-orchitis, and the systemic complications of STIs including sepsis.

Pathophysiology: Understanding the Mechanisms the Exam Tests

Neisseria gonorrhoeae is a Gram-negative diplococcus with a remarkable capacity for antigenic variation and rapid acquisition of antimicrobial resistance mediated through plasmid and chromosomal mechanisms. Its tropism for columnar and transitional epithelium explains the clinical syndromes of urethritis, cervicitis, proctitis, and pharyngitis. When local defences are overwhelmed or infection ascends, PID or epididymo-orchitis results. Haematogenous dissemination produces DGI, characterised by immune-complex deposition causing dermatitis and, in a minority, septic arthritis with frank joint infection.

Chlamydia trachomatis is an obligate intracellular organism that accounts for 40 to 50 percent of PID cases in the UK, per NICE clinical guidance. Its intracellular lifecycle means that cell-wall-active agents such as beta-lactams are ineffective; treatment requires tetracyclines or macrolides. Reactive arthritis (formerly Reiter syndrome) represents an HLA-B27-associated post-infectious inflammatory arthropathy triggered by chlamydial or enteric infection, presenting as the classic triad of urethritis, arthritis, and uveitis.

Primary genital herpes caused by HSV-1 or HSV-2 can produce urinary retention through sacral nerve root involvement (sacral radiculopathy), a presentation easily mistaken for spinal cord pathology or acute urinary obstruction. HSV-1 now accounts for a significant and growing proportion of primary genital herpes diagnoses in the UK, reflecting changing sexual behaviours. Neonatal herpes, though rare, carries substantial morbidity and mortality; the ED clinician should consider this in the neonate with unexplained sepsis born to a mother with active genital lesions.

Treponema pallidum is a spirochaete that cannot be cultured on standard media; diagnosis depends on serology and, for primary chancre, darkfield microscopy or direct fluorescent antibody testing. The stages of syphilis each carry distinct ED relevance: the painless primary chancre is often missed; secondary syphilis produces constitutional upset with the hallmark palmoplantar rash; neurosyphilis and cardiovascular syphilis represent tertiary manifestations that may present acutely with stroke, aortitis, or psychosis.

ED Assessment and Management: A Structured Approach

History and Examination

A focused sexual history is a clinical skill, not an optional courtesy. In the ED context, the minimum dataset includes recent sexual contacts and their gender, symptoms in partners, contraceptive and barrier method use, prior STI diagnoses, last menstrual period in women, and any immunosuppression including HIV status. In adolescents, safeguarding considerations must be front of mind; the Fraser guidelines inform competency assessment for under-16s, and any concern about coercion or exploitation mandates a safeguarding referral in line with GMC confidentiality guidance and local child protection procedures.

Pelvic examination in women with lower abdominal pain should include assessment for cervical motion tenderness (CMT), adnexal tenderness, and abnormal cervical discharge. The presence of CMT with lower abdominal tenderness and either adnexal tenderness or mucopurulent cervical discharge constitutes a clinical diagnosis of PID sufficient to initiate treatment, even before microbiological results return. Empirical treatment should not be withheld pending results; delayed treatment increases the risk of tubal damage and subsequent infertility.

Investigations

Nucleic acid amplification testing (NAAT) is the investigation of choice for gonorrhoea and chlamydia from vulvovaginal swabs, urethral swabs, and first-catch urine. NAATs have superior sensitivity compared to culture, though culture remains important for antimicrobial susceptibility testing in gonorrhoea. Point-of-care testing platforms for gonorrhoea and chlamydia are increasingly available in UK EDs and can return results within 90 minutes, facilitating targeted treatment. Syphilis serology (treponemal enzyme immunoassay with reflex RPR) and HIV testing should be offered routinely in line with NICE NG60, particularly when indicator conditions are present.

In suspected PID, pelvic ultrasound is indicated if a tubo-ovarian abscess is suspected; this investigation does not exclude PID if negative. A raised CRP supports but does not confirm the diagnosis. In DGI, joint aspiration should be performed when an effusion is present; synovial fluid in DGI is typically inflammatory (white cell count 30,000 to 100,000 per microlitre) but gonococci are cultured in only 25 to 50 percent of cases. Blood cultures should be taken in all patients with suspected DGI or sepsis.

Management Regimens

For uncomplicated gonorrhoea, current guidance supports ceftriaxone 1g intramuscularly as a single dose. Azithromycin is no longer routinely co-prescribed given emerging resistance data. For PID, NICE guidance on PID supports an outpatient regimen of intramuscular ceftriaxone 1g single dose, followed by oral doxycycline 100mg twice daily and metronidazole 400mg twice daily for 14 days in mild to moderate disease. Inpatient intravenous therapy with cefoxitin or clindamycin plus gentamicin is indicated for severe PID, peritonism, failed outpatient treatment, or when a tubo-ovarian abscess is identified.

For epididymo-orchitis in sexually active men under 35, empirical treatment mirrors that for PID: a single dose of ceftriaxone 500mg intramuscularly followed by doxycycline 100mg twice daily for 10 to 14 days. In men over 35, enteric organisms predominate and a quinolone such as ofloxacin 200mg twice daily for 14 days is appropriate, provided local quinolone resistance rates permit. Scrotal support, analgesia, and urology follow-up are adjuncts. Testicular torsion is a surgical emergency and must be excluded before a diagnosis of epididymo-orchitis is accepted; if there is genuine uncertainty, scrotal exploration takes precedence over antibiotic prescribing.

Primary genital herpes causing severe systemic upset, urinary retention, or neurological involvement warrants intravenous aciclovir 5mg/kg three times daily with admission. Oral aciclovir 400mg three times daily for five days is appropriate for less severe presentations. The British National Formulary provides current dosing and renal dose adjustment guidance.

How the FRCEM SBA Exam Tests This Topic

FRCEM SBA practice questions on STIs characteristically present undifferentiated clinical scenarios rather than straightforward factual recall. Expect a 28-year-old woman with lower abdominal pain and cervical motion tenderness, where the distractors include appendicitis, ectopic pregnancy, and ovarian torsion; the question tests whether the candidate applies clinical diagnostic criteria for PID before choosing the correct antibiotic regimen. Alternatively, a young man with monoarthritis, a pustular rash on the hands, and a recent unprotected sexual contact challenges the candidate to identify DGI rather than crystal arthropathy or reactive arthritis.

The RCEM curriculum mapping places STIs within the domains of infectious disease, gynaecological emergencies, and urological emergencies. The exam consistently tests knowledge of NICE and BASHH-aligned antibiotic regimens, the indications for inpatient versus outpatient management of PID, the role of NAAT versus culture, and the legal and ethical framework around consent, confidentiality, and partner notification in young and vulnerable patients. Common distractors exploit the overlap between STI presentations and non-infective pathology, and between different antibiotic choices where the distinction between gonococcal and non-gonococcal urethritis determines the regimen.

Revision Pearls: High-Yield Facts for FRCEM SBA Preparation

1. Cervical motion tenderness is the single most discriminating examination finding for PID; its absence should prompt consideration of alternative diagnoses including appendicitis and ectopic pregnancy.
2. DGI is the leading cause of septic arthritis in sexually active adults under 40; the triad of migratory polyarthralgia, tenosynovitis, and dermatitis is pathognomonic even when cultures are negative.
3. Chlamydia trachomatis is an obligate intracellular organism; beta-lactam antibiotics have no activity against it. Doxycycline or azithromycin are required.
4. NICE NG60 mandates opt-out HIV testing in EDs where diagnosed HIV prevalence exceeds 2 per 1,000 registered patients; the ED clinician must know the local prevalence figure and the list of indicator conditions.
5. Sacral radiculopathy causing urinary retention is a recognised complication of primary genital herpes and may be the presenting complaint in the ED; HSV PCR of a genital swab is diagnostic.
6. Secondary syphilis involving the palms and soles with concurrent constitutional symptoms and lymphadenopathy should always prompt syphilis serology, regardless of a negative sexual history; patients may not disclose.
7. Partner notification for gonorrhoea, syphilis, and HIV is a public health obligation. If GUM follow-up cannot be guaranteed from the ED, a direct referral or documented handover is required, not a verbal suggestion to the patient.

Common Pitfalls: Where FRCEM SBA Candidates Lose Marks

• Choosing azithromycin monotherapy for gonorrhoea, reflecting outdated guidance superseded by current resistance data.
• Failing to cover anaerobes in PID management, omitting metronidazole from the outpatient regimen.
• Diagnosing epididymo-orchitis without first addressing testicular torsion, which in an exam scenario will be presented as an unnecessary delay in surgical management.
• Treating non-gonococcal urethritis with ceftriaxone alone without doxycycline, leaving chlamydia untreated.
• Ignoring safeguarding red flags in STI presentations in under-16s or when there is evidence of coercion; the correct answer in these scenarios almost always involves a safeguarding referral as an immediate action.
• Selecting intravenous treatment for mild to moderate PID when oral outpatient regimens are guideline-supported and the clinical picture does not indicate severity criteria.

How EM Learning Centre Supports Your FRCEM Single Best Answer Revision

Mastering the clinical breadth required for the FRCEM SBA exam demands more than passive reading. The FRCEM Single Best Answer revision course at EM Learning Centre provides structured, examiner-authored FRCEM SBA practice questions mapped directly to the RCEM curriculum, with detailed written explanations that go beyond merely identifying the correct answer to articulate precisely why the distractors fail. This is the level of reasoning the exam rewards, and it is what distinguishes candidates who consistently score above the pass mark from those who plateau on repeated attempts.

Our question bank includes clinical scenarios across the full FRCEM SBA syllabus, including infectious disease, gynaecological emergencies, urological emergencies, and the ethical and legal frameworks that feature in questions on STIs, consent, and safeguarding. Every explanation is grounded in current NICE, RCEM, and BASHH-aligned evidence, ensuring that revision translates directly into safe clinical practice as well as exam performance. Whether you are beginning your FRCEM SBA exam preparation or refining your knowledge ahead of your sitting, the EM Learning Centre homepage is the place to start.

References

1. UK Health Security Agency. Sexually transmitted infections and screening for chlamydia in England: 2023 report. UK Health Security Agency (gov.uk)
2. National Institute for Health and Care Excellence. Pelvic inflammatory disease (NG208). NICE (nice.org.uk)
3. National Institute for Health and Care Excellence. HIV testing: increasing uptake among people who may have undiagnosed HIV (NG60). NICE (nice.org.uk)
4. British National Formulary. Aciclovir; Doxycycline; Ceftriaxone: dosing and clinical guidance. British National Formulary (bnf.nice.org.uk)
5. General Medical Council. Confidentiality: good practice in handling patient information. General Medical Council (gmc-uk.org)
6. Royal College of Emergency Medicine. RCEM Curriculum 2021: emergency medicine higher specialty training. Royal College of Emergency Medicine (rcem.ac.uk)