Clinical overview
Acute pelvic infection in the South African registrar's clinic almost always means pelvic inflammatory disease (PID): ascending infection of the upper genital tract from the cervix. PID is the single most under-diagnosed and over-treated condition in gynaecology — under-diagnosed in young women with subtle symptoms in whom we miss the diagnosis, then over-treated empirically in women with non-specific pain in whom we hand out antibiotics without good reason. Both errors have consequences: missed PID damages tubes and leads to infertility, ectopic pregnancy, and chronic pelvic pain (chronic-pelvic-pain); over-treated PID misses an alternative diagnosis (appendicitis, ectopic, torsion, IBD) and exposes the patient to unnecessary antibiotics.
The chapter covers the spectrum from uncomplicated PID through tubo-ovarian abscess (TOA), endometritis (puerperal and post-instrumentation), pelvic peritonitis, and the related entities Bartholin's abscess and pyometra. We also cover the South African epidemiological context — high prevalence of chlamydia, gonorrhoea, Mycoplasma genitalium, and the substantial impact of HIV on presentation and management.
Core knowledge
Microbiology
PID is polymicrobial. The dominant pathogens in young, sexually active women in South Africa:
- Chlamydia trachomatis — commonest, often asymptomatic, accounts for ~30–40% of culturable PID.
- Neisseria gonorrhoeae — often more acute presentation.
- Mycoplasma genitalium — increasingly recognised, harder to detect (PCR), associated with macrolide resistance.
- Anaerobes — Bacteroides, Prevotella, Peptostreptococcus — common in TOA.
- Mycobacterium tuberculosis — important in SA; consider in chronic / recurrent presentations, especially with HIV.
- BV-associated organisms (Gardnerella, Atopobium) — disturb the cervical mucus barrier and facilitate ascent.
The "cervical barrier" — mucus plug, lactobacillus-dominated low pH — normally prevents ascent. Conditions that disrupt this barrier predispose: menses (loss of mucus plug), instrumentation (TOP, IUD insertion, hysteroscopy, D&C), bacterial vaginosis, HIV-related immune dysregulation.
Pathogenesis and staging
Ascending infection progresses from cervicitis and endometritis to salpingitis, pyosalpinx, TOA, and pelvic fluid.
Once organisms ascend through the cervical canal, they cause endometritis (often clinically silent), then salpingitis (the clinically dominant lesion), then potentially tubo-ovarian abscess and pelvic peritonitis. The Mahmood–Templeton anatomical staging (used at laparoscopy):
- Stage 1: mild — erythematous tubes, easily mobile.
- Stage 2: moderate — purulent exudate, tubes more rigid, may have peritoneal involvement.
- Stage 3: severe — pyosalpinx, TOA, dense adhesions.
- Stage 4: ruptured TOA, generalised peritonitis.
The 1990s Westrum and Eschenbach work established the long-term sequelae: tubal factor infertility (~10–20% after one episode, rising steeply with each subsequent episode), ectopic pregnancy (6-fold risk), chronic pelvic pain (~20%).
Fitz-Hugh-Curtis syndrome (perihepatitis) is upper-abdominal inflammation from transperitoneal/lymphatic spread of organisms (classically chlamydia) producing right upper quadrant pain and "violin-string" adhesions between liver capsule and abdominal wall — a clinical pearl that should not be forgotten because it mimics cholecystitis.
Bartholin's abscess
A unilateral posterior vestibular abscess is drained with a Word catheter to keep the blocked duct open.
The Bartholin's glands lie deep to the posterior labium minus at 4 and 8 o'clock. The duct can become blocked, producing a cyst, which can secondarily infect to form an abscess. Microbiology is polymicrobial — gut flora, anaerobes, sometimes gonorrhoea. Presentation is a unilateral, exquisitely tender, fluctuant labial mass with surrounding cellulitis. Management is incision and drainage with Word catheter placement (preferred over simple I&D because of high re-accumulation rate) or marsupialisation if recurrent. Antibiotics are not routinely needed unless cellulitis is extensive or the patient is systemically unwell. Send pus for culture. Consider biopsy in postmenopausal women (rule out vulval carcinoma).
Pyometra
Collection of pus in the uterine cavity, usually due to cervical stenosis (postmenopausal, post-radiation, malignancy at the os). Presentation: discharge, lower abdominal pain, fever, often a tender enlarged uterus. Management: cervical dilatation to drain, biopsy the endometrium for malignancy, antibiotics. Always consider underlying endometrial carcinoma — see endometrial-carcinoma.
Puerperal endometritis
Postpartum infection of the uterine cavity — see puerperal-complications for full coverage. Mention here because it presents as acute pelvic infection but the management pathway is different (postpartum context, retained products possible, breastfeeding compatibility of antibiotics).
Assessment
History
- Sexual history: new partner in last 6 months, multiple partners, partner with STI symptoms, condom use, sex worker contact.
- Contraception, particularly recent IUD insertion (highest risk first 3 weeks).
- Pain character: bilateral lower abdominal, deep dyspareunia, worse on movement.
- Discharge: increased, malodorous, change in colour.
- Bleeding: intermenstrual or postcoital bleeding is a classic but often-missed symptom of chlamydia cervicitis.
- Systemic: fever, malaise, nausea.
- Right upper quadrant pain → Fitz-Hugh-Curtis.
- Recent instrumentation (TOP, hysteroscopy, D&C).
- HIV status; previous STI episodes; previous PID; obstetric history.
Examination
- Vitals: fever may be modest in PID; high fever and tachycardia suggest TOA or peritonitis.
- Abdominal: bilateral lower abdominal tenderness; guarding suggests peritonitis.
- Speculum: mucopurulent discharge from the os, inflamed friable cervix that bleeds on contact. Cervical mucopus is highly suggestive of cervicitis.
- Bimanual: cervical motion tenderness (CMT), uterine tenderness, adnexal tenderness ± mass.
The diagnosis of PID is clinical. Diagnostic criteria (CDC, adopted internationally):
- Minimum criteria — start empirical treatment in any sexually active young woman with pelvic/lower-abdominal pain plus one of: cervical motion tenderness, uterine tenderness, adnexal tenderness.
- Additional criteria (supportive): fever >38.3°C, mucopurulent cervical discharge, abundant WBC on wet mount, raised CRP/ESR, lab confirmation of chlamydia/gonorrhoea/M. genitalium.
- Definitive criteria: endometrial biopsy with histopathology of endometritis, TVS showing thickened fluid-filled tubes, laparoscopy showing salpingitis.
The threshold to treat empirically is low because the cost of missing PID (infertility, ectopic) is high.
Investigations
- β-hCG — always.
- Endocervical (or vulvovaginal self-collected) swabs for chlamydia, gonorrhoea, M. genitalium — PCR.
- HVS for BV, candida, trichomonas (microscopy + culture / PCR).
- HIV test — offer always.
- Syphilis screening (RPR/TPHA).
- FBC, CRP, U&E.
- Transvaginal ultrasound: free fluid, thickened tubes ("cogwheel" sign), TOA (multiloculated complex adnexal mass), free fluid in pouch of Douglas, endometrial fluid.
- Blood culture if febrile or systemically unwell.
- Pregnancy considerations: PID is rare in pregnancy after 12 weeks; if suspected, manage carefully because of antibiotic restrictions and risk to pregnancy.
Differential diagnosis
Always consider — and rule out where possible:
- Ectopic pregnancy (ectopic-pregnancy-management).
- Ovarian torsion.
- Acute appendicitis (especially right-sided pain — atypical presentations are common in young women).
- Endometriosis flare.
- Ovarian cyst rupture or haemorrhage.
- UTI / pyelonephritis.
- Bowel pathology (diverticulitis, IBD).
- TB-PID in HIV-positive patients — chronic presentations, sterile pyuria, raised inflammatory markers, weight loss; consider laparoscopy with biopsy and TB culture.
Management
Uncomplicated PID — outpatient
For ambulant, afebrile, non-pregnant patients with mild-to-moderate disease, oral therapy is acceptable. The most pragmatic SA-context regimen aligned with WHO/CDC and the SA NDoH STG:
- Ceftriaxone 500 mg IM single dose (covers gonorrhoea — local resistance to oral options is too high; the dose was raised from 250 mg to 500 mg per SAHCS 2022 / CDC 2021 because of rising MIC creep).
- Doxycycline 100 mg PO 12-hourly for 14 days (covers chlamydia).
- Metronidazole 400 mg PO 12-hourly for 14 days (covers anaerobes and trichomonas).
Add macrolide (azithromycin 1 g PO weekly × 2) or moxifloxacin if M. genitalium confirmed; treatment of M. genitalium is increasingly difficult due to macrolide resistance.
Review at 72 hours: if not improving, escalate to IV.
Partner notification and treatment is mandatory. Public health implications — assist with contact tracing; use SA's national STI partner notification framework.
Severe PID — inpatient
Indications for admission: severe illness (vomiting, dehydration, high fever), pregnancy, suspected TOA, failed outpatient therapy, surgical emergency cannot be excluded, immunocompromised (HIV with low CD4).
Regimen (NDoH STG):
- Ceftriaxone 1 g IV daily
- Doxycycline 100 mg PO 12-hourly (oral usually tolerated even in admitted patients).
- Metronidazole 500 mg IV 8-hourly (or 400 mg PO if tolerating oral).
Continue IV until afebrile + CRP falling for 24–48 hours, then convert to oral to complete 14 days total.
If chlamydia confirmed and severe: consider azithromycin 1 g IV daily for 2 days, then 500 mg PO daily — useful in pregnant patients where doxycycline contraindicated.
Tubo-ovarian abscess
TOA is an adnexal abscess involving tube and ovary; large or non-improving collections need drainage.
Hospital admission, IV antibiotics as above. Then:
- Drainage of any abscess ≥6 cm or any abscess not improving on antibiotics within 48–72 hours.
- Image-guided percutaneous drainage is first-line for accessible unilocular abscesses.
- Laparoscopic drainage for multiloculated abscesses or where access is poor.
- Open surgery for ruptured TOA with peritonitis — this is a surgical emergency.
Counsel the patient that fertility may be compromised; ensure follow-up with a fertility specialist if she wishes to conceive.
IUD considerations
Current evidence: do not routinely remove the IUD in mild PID — outcomes are similar with or without removal. Remove if no clinical improvement after 48–72 hours of appropriate antibiotics. If the IUD was inserted in the last 3 weeks, removal threshold is lower.
Pregnancy
PID is rare in pregnancy after 12 weeks (cervical mucus plug and decidual reaction protect). If diagnosed, admit, IV antibiotics avoiding contraindicated agents (no doxycycline in pregnancy — use erythromycin or azithromycin), and monitor closely.
HIV co-infection
PID in HIV-positive women may present more severely, with higher rates of TOA and lower CD4 counts associated with worse outcomes. Antibiotic regimen is the same but threshold for admission and surgical intervention is lower. Always ensure HIV treatment is optimised and adherent. See hiv-gynaecology and hiv-counselling.
TB-PID
Chronic/atypical PID, especially in HIV-positive women, must raise the possibility of genital TB. Diagnosis is by endometrial biopsy with TB culture and PCR (GeneXpert), or laparoscopy with biopsy. Treatment is standard 4-drug anti-TB therapy in liaison with TB services.
Follow-up
- Review at 72 hours and 2 weeks.
- Confirm partner has been treated.
- Repeat testing for chlamydia/gonorrhoea at 3 months (test of reinfection, not test of cure).
- Discuss long-term implications: fertility, ectopic risk, chronic pain.
- Counsel on safe sex, condom use, regular STI screening.
- Document HIV status and link to care if positive.
Red flags / pitfalls
- Treating PID without excluding pregnancy or ectopic — β-hCG is mandatory before starting antibiotics.
- Missing TB-PID in HIV-positive or chronically symptomatic patients — consider biopsy.
- Failure to treat the partner — re-infection is common and undermines treatment.
- Inadequate antibiotic duration — 14 days is the minimum.
- Removing an IUD prematurely — only after 72 h failed response or per consent.
- Anchoring on PID and missing appendicitis — particularly right-sided pain in a young woman.
- Not screening for HIV — South African practice mandates routine offer.
- Discharging a TOA on oral antibiotics — bound to fail; needs IV and consideration of drainage.
- Missing Fitz-Hugh-Curtis in a woman with RUQ pain — perform pelvic exam, take swabs, treat as PID.
- Postmenopausal pyometra dismissed as "just an infection" — always biopsy for endometrial cancer.
Evidence anchors
- RCOG Green-top Guideline No. 32 — Management of Acute PID.
- BASHH 2018 UK National Guideline for PID Management.
- CDC STI Treatment Guidelines (2021).
- South African National Department of Health STI Management Guidelines and STG/EML, latest editions.
- WHO Sexually Transmitted Infections Treatment Guidelines.
- Westrom L, Eschenbach D. Pelvic Inflammatory Disease. In: Sexually Transmitted Diseases, Holmes et al.
- Workowski KA, et al. — CDC PID evidence reviews.
- South African HIV Clinicians Society Adult ART Guidelines (2023).