Pelvic inflammatory disease (PID): symptoms, risks and treatment

Pelvic inflammatory disease, or PID, is one of the most important reasons that routine STI testing matters, even when you feel completely well. It usually starts as a silent infection like chlamydia that spreads upward, and it’s the point at which an untreated STI can start to affect fertility. The infection is very treatable — the key message is simply not to delay.

What is pelvic inflammatory disease (PID)?

PID is an infection of the upper reproductive organs — the uterus, fallopian tubes, ovaries and surrounding tissues — caused by bacteria spreading up from the vagina and cervix. It’s common, especially in younger sexually active women, and ranges from mild to severe. It’s very treatable, but if it’s missed or treated late it can cause lasting harm, including to fertility.

What causes PID?

Most PID is caused by STIs that have spread upward from the cervix — chlamydia is the most common, along with gonorrhoea and, increasingly, Mycoplasma genitalium. Because chlamydia and gonorrhoea so often cause no symptoms, an infection can sit unnoticed and ascend, with PID being the first sign anything was wrong.

Symptoms, and why it matters

Symptoms range from barely noticeable to clearly unwell: lower abdominal or pelvic pain (the most common), pain during sex felt deep inside, unusual discharge, abnormal bleeding (between periods, after sex, or heavier periods), pain passing urine, and in more significant cases fever and feeling unwell.

Silent and mild PID

PID can also be mild or almost silent — some women have only vague pelvic discomfort or spotting while inflammation quietly causes damage. This is part of why untreated chlamydia can affect fertility without an obvious illness, and why persistent mild pelvic symptoms shouldn’t be dismissed.

Diagnosis and treatment

PID is usually diagnosed from your symptoms and an examination rather than a single test, with tests taken for the STIs that cause it and sometimes an ultrasound. Because delay risks damage, treatment with antibiotics is often started on the clinical picture before all results are back. Most women are treated as outpatients; severe cases may need hospital care. The infection itself is cured with prompt, complete treatment — but any damage already done to the fallopian tubes before treatment can be permanent, which is why not delaying matters so much. Recent sexual partners need testing and treatment too, to prevent reinfection.

Preventing PID

The best prevention is preventing and promptly treating the STIs that cause it: regular STI testing to catch chlamydia and gonorrhoea early, prompt treatment of any infection and of a partner, and condoms to reduce risk. Because much PID begins as a silent infection, routine testing when you feel well is one of the most valuable steps.

When to seek urgent care

Seek urgent care for severe lower abdominal pain, high fever, vomiting, or feeling very unwell. Also seek urgent care for sudden severe one-sided pelvic pain with a missed or abnormal period, which can indicate an ectopic pregnancy and is an emergency. For milder but persistent symptoms, get assessed promptly rather than waiting them out.

Common questions

What is pelvic inflammatory disease (PID)?

PID is an infection of a woman’s upper reproductive organs — the uterus, fallopian tubes, ovaries and surrounding tissues — caused by bacteria spreading up from the vagina and cervix. It’s common, especially in younger sexually active women, and ranges from mild to severe. It’s very treatable with antibiotics, but if missed or treated late it can cause lasting harm, including to fertility.

What causes PID?

Most PID is caused by STIs that have spread upwards from the cervix — chlamydia is the most common cause, along with gonorrhoea and, increasingly, Mycoplasma genitalium. Because chlamydia and gonorrhoea so often cause no symptoms, an infection can sit unnoticed and ascend, with PID being the first sign anything was wrong.

What are the symptoms of PID?

PID symptoms vary from barely noticeable to clearly unwell. They can include lower abdominal or pelvic pain (the most common), pain during sex felt deep inside, unusual discharge, abnormal bleeding (between periods, after sex, or heavier periods), pain passing urine, and in more significant cases fever and feeling unwell. Pelvic pain with abnormal bleeding or discharge is a clear reason to be assessed promptly.

Can you have PID without symptoms?

Yes. PID can be mild or almost silent — some women have only vague symptoms like mild pelvic discomfort or spotting, or none at all, while inflammation quietly causes damage. This silent PID is part of why untreated chlamydia can affect fertility without an obvious illness. It’s why persistent mild pelvic symptoms shouldn’t be dismissed, and why STI testing matters even when you feel well.

How is PID diagnosed and treated?

PID is usually diagnosed from your symptoms and an examination rather than a single definitive test, with tests taken for the STIs that cause it and sometimes an ultrasound. Because delay risks damage, treatment with antibiotics is often started on the clinical picture before all results are back. Most women are treated as outpatients; severe cases may need hospital care. Complete the full course and attend follow-up.

Can PID affect fertility?

It can. Inflammation from PID can scar and block the fallopian tubes, which can make conceiving harder or, in some cases, impossible, and increases the risk of ectopic pregnancy. The risk rises with each episode of PID and with delayed treatment. This is the main reason PID is taken seriously and treated promptly — early treatment is what protects fertility.

What happens if PID is left untreated?

Untreated or repeated PID can cause lasting harm: scarring of the fallopian tubes leading to infertility, an increased risk of ectopic pregnancy (a medical emergency), and chronic pelvic pain. Severe untreated infection can also form an abscess needing urgent treatment. These serious outcomes are exactly what prompt antibiotic treatment is designed to prevent.

How can I prevent PID?

The best prevention is preventing and promptly treating the STIs that cause it: regular STI testing to catch chlamydia and gonorrhoea early before they ascend, prompt treatment of any STI found and of a partner, and condoms to reduce risk. Because much PID begins as a silent infection, routine testing when you feel well is one of the most valuable steps.