This section addresses testing in:

• individual patients with symptoms and/or signs suggestive of genital chlamydial infection
• groups in the population who do not have symptoms of genital chlamydial infection but may have asymptomatic disease.

It is important that the reason for, implications of, and results of any test carried out are explained to the individual being tested.

3.1 Testing patients with symptoms/signs of chlamydial infection

Failure to diagnose or delay in the diagnosis of chlamydial infection is potentially harmful. Lower genital tract infection may spread to cause PID or epididymitis. Delay in treating PID increases the subsequent risk of infertility.³⁹ Failure to diagnose chlamydial infection as the cause of PID reduces the likelihood of contact tracing being carried out. This carries a risk of re-infection for the index case⁴⁰ along with a risk of morbidity for untreated sexual partners (see section 3.2). Evidence Level IIa

In women, symptoms of chlamydial infection include increased vaginal discharge, post coital and/or intermenstrual bleeding, lower abdominal pain and dysuria. Signs include a mucopurulent cervical discharge, cervical friability and adnexal tenderness on vaginal examination.^{13,15,39,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55} Evidence Level IIa

In men, symptoms include urethral discharge and /or dysuria. Signs include a mucoid or mucopurulent urethral discharge, microscopy of which reveals numerous pus cells.^56,57,58,59 Epididymo-orchitis causes scrotal pain and swelling, with tender swelling of the epididymis on examination.^{60, 61, 62} Evidence Level IIa

Reactive arthritis occurs in about 1% of men following chlamydial infection of the urethra^63,64 but occurs more rarely following chlamydial infection in women.⁶⁵ Rectal infection in either men or women rarely causes signs or symptoms. ⁶⁶ Chlamydial infection may present with right hypochondrial pain due to perihepatitis.⁶⁷ Evidence Level IIb

Testing for Chlamydia trachomatis infection should be performed in women and men with symptoms and signs which may be attributable to chlamydial infection: Women vaginal discharge post coital/intermenstrual/breakthrough bleeding inflamed/friable cervix (which may bleed on contact) urethritis pelvic inflammatory disease lower abdominal pain in the sexually active reactive arthritis in the sexually active Men urethral discharge dysuria urethritis epididymo-orchitis in the sexually active reactive arthritis in the sexually active.

3.2 Testing asymptomatic groups for chlamydial infection

3.2.1 SPECIFIC CIRCUMSTANCES FOR TESTING

The risk of morbidity from the spread of chlamydial infection is immediate in:

• Termination of pregnancy
  Failure to treat chlamydial infection carries approximately a 25% risk of post-abortal salpingitis. ^{7,8,9,68,69,70,71,72,73,74} Evidence level Ib
  
  Women undergoing TOP are at increased risk of chlamydial infection.^{69,74,75,76,77,78,79,80}Evidence level IIa
  
  
• IUD insertion
  No studies have specifically demonstrated the benefit of testing prior to IUD insertion (with a view to preventing ascending infection), but there have been two studies that showed that giving an antimicrobial agent effective against chlamydial infection at the time of IUD insertion reduced the rate of salpingitis.^10,11 Evidence level III
  
  
• Semen and egg donation
  Semen and egg donors should be tested for chlamydial infection to reduce the risk of transmission of infection to the recipient.⁸¹ Evidence level III
  

In most circumstances the goal is to reduce the long term morbidity for individuals, their sexual partners and the wider community. There is good evidence that specific groups of patients have an increased likelihood of being infected with Chlamydia trachomatis:

• Attenders at GUM clinics ^{2,12,82,83,84} and persons with STIs presenting in other clinics.^2,85,86,87 Evidence level IIb
• Sexual partners of chlamydia-positive individuals are clearly at risk of infection and therefore of morbidity.^{88,89,90,91,92} Treating them will also reduce the risk of re-infection of the index case. Evidence level IIb
• Sexual partners of those with conditions for which Chlamydia trachomatis is a frequent (but undiagnosed) cause, such as PID⁹³ or epididymo-orchitis.⁹⁴ Evidence level IV
• Mothers of infants with chlamydial conjunctivitis or pneumonitis are likely to have genital chlamydial infection. ^95,96,97 Evidence level IIb

Testing for genital Chlamydia trachomatis infection should be performed in the specific circumstances of:

all women undergoing termination of pregnancy

all patients attending genitourinary medicine clinics all patients with another STI, including genital warts sexual partners of those with chlamydial infection mothers of infants with chlamydial conjunctivitis or pneumonitis all women undergoing uterine instrumentation, including IUD insertion, who have risk factors for chlamydial infection (see section 3.2.2) semen and egg donors

sexual partners of those with suspected chlamydial infection.

In patients with another STI the test should be offered by the doctor providing initial care.

In women undergoing TOP, the ultimate responsibility for ensuring testing lies with the gynaecologist undertaking the procedure. However, local arrangements may favour the test being carried out by the referring doctor (see section 4.3).

3.2.2 OPPORTUNISTIC TESTING

Prevalence and risk factors for chlamydial infection have been identified from studies set in UK general practice^{28,42, 98,99,100,101,102,103,104} and family planning clinics.^{105,106,107,108,109,110} These studies have limitations in terms of representativeness, sample size, types of analyses conducted and testing strategies,¹¹¹ but the risk factors described in UK populations are similar to those reported from the United States.^{13,45,112,113,114,115,116} Risk factors consistently identified for chlamydial infection in women in these and other studies include age <25 years, two or more sexual partners within the last year and/or a recent partner change.^{15,46, 84,115,117,118} Evidence level IIa

One London study found that a selective screening strategy based on age <25 and two or more partners in the past year detected 87% of infections while testing only 49% of the study population.²⁸ Evidence level IIa

A randomised-controlled trial of population based screening using criteria such as these has demonstrated reduced PID morbidity over one year.⁴¹ Evidence level Ib

Opportunistic testing could be considered in the following groups of women: women younger than 25 years and sexually active women aged 25 years or older with two more partners in the last year or a change of sexual partner in the last year.

There are little data on men outwith GUM clinics. It is therefore not possible to make a recommendation on opportunistic screening in men.

There is increasing support for opportunistic screening in sexually active women attending general practice. However, questions remain about interval of screening, funding, training and organisational aspects.

All clinicians treating sexually active women should maintain a high level of awareness of the need to offer a screening test for genital Chlamydia trachomatis infection to women who have an increased risk of infection.

Testing should be carried out wherever the patient is seen, i.e. in general practice, antenatal clinics, family planning clinics or gynaecology departments. It is appreciated that opportunistic testing in general practice will most likely be offered during consultations relating to sexual health, e.g. contraception, cervical smears, pregnancy.

The guideline development group recognises the resource implications associated with these recommendations (see section 1.4).