Pelvic Inflammatory Disease

A syndrome spanning a spectrum of inflammatory disorders of the upper female genital tract — any combination of endometritis, salpingitis, tubo-ovarian abscess and pelvic peritonitis. Most common in young women (<25). Risk factors: recent partner change, a partner with an STI or STI symptoms, recent uterine instrumentation or pregnancy.

Causes

Polymicrobial — up to 70% of cases have no identified cause.

• Sexually acquired: chlamydia/gonorrhoea, causing salpingitis.
• Endogenous infection: E. coli, Bacteroides fragilis — occurs after disruption of the cervical barrier (abortion, IUD placement, recent pregnancy, D&C), allowing vaginal bacteria to ascend to the upper genital tract.
• Actinomycosis: rare, can mimic malignancy; associated with prolonged IUD use — look for Actinomyces israelii on culture and get expert advice.

Can present acutely (rapid symptom onset) or chronically (slow worsening, either following an acute infection or de novo).

Clinical features

Consider PID in a young sexually active woman <30, or any woman with a new partner or recent uterine instrumentation, presenting with recent-onset lower abdominal pain and tenderness — especially cervical, uterine or adnexal tenderness on examination.

Symptoms are often non-specific, making diagnosis difficult.

Acute: fever, moderate–severe lower abdominal pain, dyspareunia, intermenstrual/heavy menstrual bleeding, irregular periods, dysmenorrhoea, vaginal discharge, urinary frequency/urgency.

Chronic: often afebrile; low back ache or mild lower abdominal pain.

Examination

Vital signs (tachycardia, fever); abdominal exam for tenderness and signs of peritonism; pelvic exam for cervical motion, uterine and adnexal tenderness; speculum — mucopurulent cervical discharge supports the diagnosis.

Investigations

Diagnosis is clinical (definitive diagnosis needs laparoscopy, impractical for most cases) — keep a low threshold of suspicion given variable severity.

• Pregnancy test — exclude ectopic with urgent pelvic ultrasound if positive.
• Endocervical swab (NAAT) for chlamydia, gonorrhoea and M. genitalium, plus culture for sensitivities.
• Urinalysis to exclude UTI.
• Pelvic ultrasound — detects alternative causes of pain; in PID the scan may be normal or show non-specific inflammatory changes.

Management

Refer to ED for IV antibiotics if any of: pregnancy, inability to tolerate oral therapy, severe pain, fever >38°C, systemic features (tachycardia, vomiting), sepsis, or suspected tubo-ovarian abscess.

Outpatient treatment (STI-associated or post-instrumentation):

• Ceftriaxone 500 mg IMI (in 2 mL 1% lignocaine) plus metronidazole 400 mg PO BD for 14 days plus doxycycline 100 mg PO BD for 14 days — OR azithromycin 1 g stat then a further 1 g one week later.
• If M. genitalium confirmed: moxifloxacin 400 mg daily for 14 days.
• Post-instrumentation only (STIs already excluded before the procedure): amoxicillin-clavulanate 875/125 mg BD for 14 days.
• Remove an IUD if there’s no response to treatment in 24–72 hours.

General measures: avoid intercourse for a week after treatment or until symptomatically better; rest and simple analgesia; consider prophylactic antifungal treatment; treat current sexual partners empirically for chlamydia (and gonorrhoea if likely) regardless of test results; follow specific contact-tracing guidelines once an organism is identified.

Long-term sequelae & fertility (why early treatment matters)

PID is frequently subtle or subclinical, so keep a low threshold to suspect and treat — start empirical antibiotics on clinical suspicion rather than waiting for swab results. Even with a good antimicrobial response, the risk of long-term complications is high:

• Tubal-factor infertility — tubal scarring from salpingitis; risk rises with each episode and with delayed treatment.
• Ectopic pregnancy — from tubal damage.
• Chronic pelvic pain — from adhesions.

Because of this, a history of PID warrants early review in couples planning conception — refer for fertility assessment if spontaneous conception hasn’t occurred, rather than waiting the usual 12 months, so tubal patency and assisted-reproduction options can be discussed. Rates of PID are disproportionately high in some populations — reported up to ~32% in some Aboriginal and Torres Strait Islander communities — so be proactive about STI screening and treatment.

For the general asymptomatic STI screening algorithm (which tests for whom, and how), see STIs (screening & overview).