Pyometra

Definition

Pathophysiology

1. Obstruction of outflow - the cervical canal becomes stenosed, preventing normal drainage of uterine secretions
2. Ascending infection - bacteria ascend through the cervical canal, proliferate in the retained secretions, and form pus

• Escherichia coli
• Streptococcus spp.
• Bacteroides fragilis
• Peptostreptococcus anaerobius
• Staphylococcus spp.
• In endemic areas: Mycobacterium tuberculosis (genital TB)
• Others: Actinomyces, Fusobacterium, Clostridium, Pseudomonas

Causes / Etiology

Neoplastic (most important)

• Endometrial carcinoma - most common underlying malignancy; pyometra in a postmenopausal woman is highly suspicious for this
• Cervical carcinoma - associated with cervical stenosis, chronic inflammation
• Squamous carcinoma of the cervix is often associated with pyometra at diagnosis

Iatrogenic / Post-procedural

• Radiotherapy to the pelvis (causes cervical stenosis)
• Post-surgical scarring after conization (cold knife, LLETZ/LEEP, laser), cautery, or cryotherapy
• Prolapse surgery, endometrial ablation
• Uterine compression sutures (e.g., B-Lynch suture) used for postpartum haemorrhage
• Following egg retrieval in IVF

Benign Gynecological Conditions

• Fibroid degeneration / uterine leiomyomas
• Endometrial polyps
• Senile (atrophic) cervicitis - from estrogen deficiency in postmenopausal women
• Forgotten intrauterine device (IUD)

Infective

• Puerperal (postpartum) infections
• Genital tuberculosis

Congenital

• Congenital cervical anomalies / stenosis (usually at the internal os in nulliparous cervices)

Clinical Features

Symptoms

• Malodorous, blood-stained purulent vaginal discharge (most characteristic)
• Lower abdominal/pelvic pain
• Abnormal uterine bleeding (post-menopausal bleeding is a key red flag)
• Pyrexia - notably rare; a normal temperature and normal white cell count do not exclude infection

Important clinical pearl: Patients can harbor a significant amount of pus or even a tubo-ovarian abscess without systemic signs of infection. - Berek & Novak's Gynecology

Signs

• Symmetrical uterine enlargement on bimanual examination
• Uterus may be soft and tender
• Signs of peritonitis (if spontaneous perforation has occurred - extremely rare): rigidity, rebound tenderness, guarding - constituting a surgical emergency

Investigations

Microbiology

• Vaginal/cervical swabs - may be negative in up to 50% of cases, as anaerobes are difficult to culture
• Pus culture and sensitivity after drainage - guides antibiotic therapy
• If tuberculosis is suspected: tuberculin skin test (Mantoux), culture, histology, hysterosalpingogram (HSG), and PCR

Haematology & Biochemistry

• Full blood count (FBC): leukocytosis may be absent despite significant infection
• CRP / inflammatory markers: may be elevated but are unreliable to exclude disease
• Baseline renal/liver function

Imaging

• Pelvic ultrasound - the primary and initial investigation; demonstrates a fluid-filled, enlarged uterine cavity (anechoic or echogenic content), and can assess for concurrent hematometra. It evaluates canal anatomy and detects any associated pelvic mass.
• CT scan - required for assessment of perforated pyometra; shows pneumoperitoneum; also evaluates for an underlying malignancy and extent of disease
• MRI - superior soft tissue delineation; useful for characterising endometrial or cervical pathology and in staging malignancy. Doppler MRI can detect blood flow changes when pyometra complicates endometrial cancer.
• Plain X-ray: sub-diaphragmatic free gas indicates spontaneous perforation (pneumoperitoneum)

Endometrial Sampling

• Endometrial biopsy / curettage - mandatory in postmenopausal women to exclude endometrial carcinoma (highly suspect when pyometra is present post-menopause)
• Hysteroscopy - allows direct visualisation of the cavity and directed biopsies

Treatment and Management

1. Drainage (First-line)

• Cervical dilation and drainage of pus - the treatment of choice
  • Repeated dilation of the cervix with aspiration of pus every 2-3 days is more effective than a single procedure
  • Placement of a mushroom catheter through the cervix has been used, but this can become obstructed
• Interventional radiology - increasingly offered as an alternative to surgery, particularly in high-risk patients
• Note: Laminaria tents should NOT be used if pyometra is present or infection is suspected

2. Antibiotics

• Must cover Bacteroides species, anaerobic Staphylococcus and Streptococcus species, and aerobic coliform bacteria (E. coli)
• Typically: a combination such as metronidazole (anaerobic cover) + a broad-spectrum agent (e.g., cephalosporin or co-amoxiclav)
• Duration guided by culture and clinical response

3. Surgical Management

• Hysterectomy - advised when:
  • Underlying malignancy is confirmed (radical hysterectomy + pelvic lymphadenectomy in Stage I disease)
  • Recurrent or persistent disease after conservative management
  • Perforation with peritonitis
• Many women are managed conservatively with dilation/drainage + regular monitoring for recurrence

4. Treatment of Underlying Cause

• If cervical stenosis is causing obstruction: cervical dilation using progressive metal/plastic dilators, prostaglandin analogs (misoprostol), or osmotic dilators
• Misoprostol (2-4 x 200 mcg vaginally/buccally/sublingually 1-2 hours before the procedure) softens the cervix prior to instrumentation, though efficacy is less clear in postmenopausal women
• If due to radiotherapy and underlying malignancy: external beam radiotherapy can begin after the pyometra has healed; brachytherapy as indicated
• Anti-TB therapy if genital tuberculosis is the cause

5. Monitoring

• Repeat pelvic examination or pelvic ultrasound after drainage to ensure adequacy
• Close follow-up at 4-6 weeks after dilation for repeat assessment
• Long-term surveillance for underlying malignancy

Differential Diagnosis

• Hematometra (blood in uterine cavity - can be drained by cervical dilation and does not interfere with treatment)
• Other causes of uterine enlargement: fibroids, adenomyosis
• Endometrial polyps, endometrial cancer
• Gestational trophoblastic neoplasia
• Tubo-ovarian abscess
• In perforation: other causes of acute abdomen / pneumoperitoneum

Key Associations and Complications