Pelvic Inflammatory Disease

Definition/diagnostic criteria

Pelvic inflammatory disease (PID) is an infection of the female upper genital tract, including the uterus, fallopian tubes, and ovaries. It is primarily caused by sexually transmitted infections (STIs), notably chlamydia trachomatis and neisseria gonorrhoeae. The diagnostic criteria are largely clinical, based on the presence of pelvic pain, cervical motion tenderness, and adnexal tenderness in sexually active women at risk of STIs, in the absence of other identifiable causes. Additional criteria may include fever, abnormal cervical or vaginal discharge, and elevated inflammatory markers.

Epidemiology

In the UK, PID is a common condition among sexually active women, particularly those aged 15-24 years. The exact incidence is difficult to determine due to variations in diagnostic practices and underreporting but it is estimated that the rate of definite/probable PID diagnoses among women aged 15–44 years was 176 diagnoses per 100,000 person-years.

Diagnosis

Clinical features

The clinical presentation of PID can vary from mild and almost asymptomatic to severe and life-threatening. Key features include lower abdominal pain, abnormal vaginal discharge, dyspareunia, menstrual disturbances, and fever. Due to its broad spectrum of symptoms, PID can mimic other conditions, making the clinical diagnosis challenging.

Investigations

Investigations aim to support the clinical diagnosis and may include:

• Blood tests: Elevated white blood cell count (WBC) and C-reactive protein (CRP) indicating inflammation.
• Swabs for STIs: Cervical swabs to test for Chlamydia trachomatis and Neisseria gonorrhoeae.
• Other tests for STIs: likely to be arranged via local GUM clinic.
• Pelvic ultrasound: To detect signs of pelvic abscess or tubo-ovarian abscess.
• Endometrial biopsy, laparoscopy, and MRI may be used in complicated cases to aid diagnosis.

Treatment

The primary goal of treatment is to eradicate the infection, alleviate symptoms, and prevent complications. Empirical antibiotic therapy should be initiated as soon as PID is suspected, without waiting for the results of investigations. A commonly recommended regimen includes a combination of oral and intramuscular antibiotics, such as:

• A 14-day course of doxycycline and metronidazole,
• Plus a single dose of intramuscular ceftriaxone.

Hospitalisation may be required for severe cases, surgical intervention for abscesses, or in cases of failed medical management.

Prognosis

With prompt and appropriate treatment, the prognosis for most women with PID is good. However, delayed or inadequate treatment can lead to serious complications, including chronic pelvic pain, ectopic pregnancy, and infertility. Approximately 1 in 10 women with PID will become infertile as a result of the disease. Regular follow-up is essential to ensure resolution of the infection and to monitor for complications.