Fever of Unknown Origin

Question 1

Define fever of unknown origin.

Answer 1

Fever (>38.3 degrees celsius) lasting >3wks with no obvious source despite appropriate investigation

Question 2

What is the relevant history in fever of unknown origin?

Answer 2

Fever pattern:

• rapidly fluctuating, does not correspond with tachycardia or sweating = ?factitious fever
• tertian/quartan = malaria

Severity: how it affects work/physical activities

Localising symptoms

Travel Hx: e.g. TB, malaria, hepatitis, typhoid, parasites, Rocky Mountain spotted fever, Lyme disease

Animals e.g. tularaemia, brucellosis, psittacosis

Night sweats: may be associated with TB, autoimmune disorders, haematological malignancies

Weight loss: malignancy, TB, HIV, endocrine

DVT: calf swelling, pain, redness

Question 3

What are the relevant examinations in fever of unknown origin?

Answer 3

• heart: new/changing murmur ?infective endocarditis
• lungs: acute/chronic lung disease
• pulse-temperature disassociation (relative bradycardia) = typhoid, ?Q fever
• hepatosplenomegaly: malignancy, autoimmune
• abdominal tenderness: intra-abdominal infections, IBD
• palpable lymph nodes: infection, haematological malignancy
• sinusitis/oral lesions: chronic infection, autoimmune, malignancy
• joint inflammation: infection, autoimmune
• rashes/skin lesions: SLE, sarcoidosis, HIV, Epstein-Barr virus

Question 4

What are the relevant investigations in fever of unknown origin?

Answer 4

Bloods:

• FBC
• U&Es
• LFTs
• creatinine
• ESR
• blood culture
• serology

Urine culture

TB Quantiferon

Imaging: CXR, MRI in ?osteomyelitis, CT chest/abdo

Subsequent cultures from affected areas, biopsy of rashes/palpable lymph nodes

Question 5

What are the common causes of fever of unknown origin?

Answer 5

Infective endocarditis

TB

Abdo/pelvic abscess

HIV

Acute/chronic sinusitis

Question 6

What are the uncommon causes of fever of unknown origin?

Answer 6

INFECTIVE: dental abscess, osteomyelitis, CMV, EBV, rheumatic fever, Lyme disease

INFLAMMATORY: polymyalgia rheumatica, SLE, giant cell arteritis, sarcoidosis, IBD, adult-onset Still’s disease

MALIGNANT: renal cancer, colorectal cancer, pancreatic cancer, myelodysplastic syndrome, phaeochromocytoma, chronic myeloid leukaemia, (non)-Hodgkin’s lymphoma, metastatic

OTHER: drug-induced, prostatitis

Question 7

What are the features of infective endocarditis?

Answer 7

Cause of fever + new murmur until proven otherwise

Of normal valves:

• causes acute heart failure +/- emboli
• risk factors = dermatitis, IV injections, renal failure, organ transplantation, diabetes, post-op wounds

Of abnormal valves:

• causes subacute heart failure
• risk factors = aortic/mitral valve disease, tricuspid valves in IVDU, coarctation of aorta, PDA, VSD, prosthetic valves

Question 8

What are the investigations indicated in infective endocarditis?

Answer 8

Bloods: blood cultures, normocytic normochromic anaemia, neutrophilia, increased ESR/CRP

Urinalysis: microscopic haematuria

CXR: cardiomegaly

ECG: long PR interval

Echo: vegetations, aortic root abscesses, mitral lesions

Question 9

What is the management of infective endocarditis?

Answer 9

Abx

Surgery indicated if:

• valvular obstructions
• repeated emboli
• fungal endocarditis
• persistent bacteraemia
• myocardial abscess
• unstable infected prosthetic valves

Question 10

What are the features of abdominal abscesses?

Answer 10

Usually bacterial

Pain depends on location:

• slow/dull pain in area containing abscess
• lower back pain in area behind abscess
• diarrhoea

Imaging: US, CT, MRI, abscess fluid analysis

Drainage and Abx

Question 11

What are the features of pelvic abscesses?

Answer 11

Male: between bladder and rectum
Female: between uterus and pos. fornix of vagina and rectum posteriorly, tubo-ovarian PID abscess

Pain, deep tenderness 
Diarrhoea, tenesmus, mucous discharge per rectum 
Urinary frequency, dsyuria 
Vaginal bleeding/discharge 
Partial obstruction of small intestine 

Ix: FBC, US, CT, MRI

Drainage and Abx

Question 12

What are the features of sinusitis?

Answer 12

S&S:

• pain: maxillary, ethmoidal, worse on bending forward
• nasal discharge
• nasal obstruction/congestion
• anosmia, cacusmia (sensation of foul smell with no external source)
• systemic e.g. fever

Aetiology:

• most follow viral infection –> mucosal oedema –> reduced cilia action –> mucus retention –> secondary bacterial infection
• other causes: dental root infection, swimming in infected water, polyps, ITU, systemic

Acute/single episode: self-limiting; after 5 days consider steroids/decongestants and nasal irrigation; Abx may prevent complications

Chronic/recurrent episodes: if Abx fail refer for functional endoscopic sinus surgery