Pelvic Inflammatory Disease
Pelvic inflammatory disease is infection of the upper female genital tract—the uterus, fallopian tubes, and surrounding structures—usually caused by bacteria ascending from the cervix. Most cases follow a sexually transmitted infection, commonly chlamydia or gonorrhoea, though many involve a mixture of organisms. Its defining problem is that symptoms are often mild or absent while damage accumulates silently: scarring of the fallopian tubes can follow even a single episode and leads to infertility, ectopic pregnancy, and chronic pelvic pain. Because of this, and because no single test reliably confirms the diagnosis, clinicians deliberately treat on suspicion rather than waiting for certainty. Treated promptly, most women recover fully.
What is it?
The lower genital tract—the vagina and cervix—normally contains a large population of bacteria, most of which are harmless or beneficial. The upper tract above the cervix is normally sterile, protected by cervical mucus and by the direction of fluid flow.
Pelvic inflammatory disease occurs when organisms breach this barrier and ascend into the uterus, fallopian tubes, and surrounding pelvic tissues. The term covers a spectrum of related infections: endometritis in the uterine lining, salpingitis in the fallopian tubes, oophoritis involving the ovaries, pelvic peritonitis, and tubo-ovarian abscess at the severe end.
The fallopian tubes bear the most consequential damage. Their inner lining is delicate and carries fine hair-like cilia that sweep an egg toward the uterus. Inflammation destroys these cilia and produces scarring, and this damage does not repair. The tube may become blocked entirely, or—more insidiously—partially damaged, so that it remains open enough for sperm to pass but no longer capable of transporting a fertilised egg properly. This partial damage is what produces ectopic pregnancy.
The critical implication is that tubal damage occurs during the inflammatory episode itself and is permanent. Treating the infection stops further damage but does not reverse what has already happened, which is why speed of treatment matters so much and why treating on suspicion rather than waiting for confirmation is deliberate policy rather than carelessness.
The organisms involved vary. Chlamydia trachomatis and Neisseria gonorrhoeae are the classic causes and account for a substantial proportion, particularly in younger women. However, many cases are polymicrobial, involving organisms from the normal vaginal flora including anaerobes, and Mycoplasma genitalium is increasingly recognised as a cause. In a meaningful proportion of cases no organism is identified at all. This is why treatment regimens cover a broad range of organisms rather than targeting a single one, and why a negative chlamydia and gonorrhoea test does not exclude the diagnosis.
Chlamydia deserves particular attention because of how it behaves. It frequently causes no symptoms whatsoever—in the majority of infected women—while ascending and damaging the tubes. A woman can therefore develop significant tubal damage without ever having felt unwell, and discover the consequence years later when trying to conceive. This silent progression is the single strongest argument for screening.
Risk factors reflect exposure and barrier breaches. Younger age is prominent, both because of behavioural factors and because the cervix in young women has a larger exposed transformation zone that is more susceptible to infection. Multiple or new sexual partners, inconsistent condom use, and a partner with an untreated infection all increase risk. A previous episode substantially raises the risk of another, partly because of altered tubal defences and partly because of continued exposure.
Procedures that breach the cervical barrier carry a small risk: uterine instrumentation including termination of pregnancy, endometrial sampling, hysteroscopy, and insertion of an intrauterine device.
The intrauterine device association deserves a precise statement, because it is widely misunderstood. Risk of pelvic infection is increased only in the first few weeks after insertion, reflecting organisms introduced at the time of the procedure. Beyond that window, having an intrauterine device does not meaningfully increase risk. This is a modern and well-established position, and outdated concerns should not deter women from using this method.
Vaginal douching disrupts the normal vaginal flora and is associated with increased risk, and is not recommended for any purpose.
The symptoms are the central difficulty with this condition, and they warrant an honest description.
Pelvic inflammatory disease frequently produces mild, vague, or no symptoms. Studies of women found to have tubal damage often identify substantial numbers who never recall an episode of illness. Where symptoms occur, they are commonly subtle enough to be attributed to period pain, a urinary infection, thrush, or ordinary discomfort.
The most common symptom is lower abdominal or pelvic pain, usually bilateral, frequently a persistent dull ache rather than severe pain. Abnormal vaginal discharge is common. Deep pain during intercourse is characteristic and is one of the more specific symptoms. Abnormal bleeding—between periods, after intercourse, or heavier periods—occurs in many women. Urinary discomfort or frequency can occur and may direct attention toward a urinary infection.
Fever is present in only a minority, so a normal temperature does not make the diagnosis less likely.
Right upper abdominal pain occurs in around one in ten women, from inflammation of the liver capsule and adhesions between the liver and the abdominal wall—Fitz-Hugh-Curtis syndrome. It can dominate the presentation and be mistaken for gallbladder disease.
Severe disease presents with marked pain, high fever, rigors, and vomiting, and raises concern for tubo-ovarian abscess or peritonitis.
Diagnosis is clinical, and this is an important point to understand rather than a shortcoming to apologise for.
No single test confirms pelvic inflammatory disease. Laparoscopy is the most definitive investigation but is invasive, is not justified in most cases, and can still miss mild endometritis. Clinical criteria are therefore used: pelvic or lower abdominal pain in a sexually active woman, together with tenderness on moving the cervix, or uterine tenderness, or adnexal tenderness on examination, with no other explanation identified.
These criteria are deliberately broad and have modest specificity, meaning some women treated do not have the condition. This trade-off is intentional. The consequences of missing pelvic inflammatory disease—permanent tubal damage, infertility, ectopic pregnancy—substantially outweigh the cost of a two-week antibiotic course given to a woman who did not need it. Guidelines across countries are explicit about this, and it is worth knowing if empirical treatment is offered without a definite diagnosis.
Supporting features that increase confidence include fever, abnormal cervical or vaginal discharge, white cells visible on microscopy of vaginal fluid, raised inflammatory markers, and documented chlamydia or gonorrhoea infection. Notably, the absence of white cells in vaginal fluid makes the diagnosis considerably less likely and is a useful negative finding.
Testing for chlamydia and gonorrhoea is essential, using self-taken or clinician-taken swabs, alongside testing for Mycoplasma genitalium where available and broader screening including HIV and syphilis. A negative result does not exclude the diagnosis but does guide partner management.
A pregnancy test is mandatory in every case. Ectopic pregnancy presents similarly and requires entirely different urgent management.
Pelvic ultrasound is frequently normal in mild disease, and a normal scan does not exclude the diagnosis—a point that causes confusion, since women often expect imaging to settle the question. Its value lies in identifying complications and alternatives: tubo-ovarian abscess, a dilated fluid-filled tube, free pelvic fluid, ovarian torsion, an ovarian cyst, or an ectopic pregnancy.
CT and MRI are used where the diagnosis is unclear or an abdominal cause is possible, and can show tubal thickening, inflammatory change in the pelvic fat, and abscess formation.
The differential includes ectopic pregnancy, appendicitis, ovarian torsion, ruptured or haemorrhagic ovarian cyst, endometriosis, urinary tract infection, inflammatory bowel disease, and irritable bowel syndrome.
Important to Know
The defining principle in managing pelvic inflammatory disease is that treatment should start early and on suspicion, because tubal damage accumulates during the episode and cannot be undone afterwards. Care is typically provided by sexual health services, primary care, and gynaecology, with hospital admission for severe cases.
Antibiotic treatment covers chlamydia, gonorrhoea, and anaerobic organisms simultaneously, since the infection is frequently polymicrobial and the causative organism is often never identified. Regimens typically combine an injected cephalosporin with oral doxycycline and metronidazole over about two weeks, with specifics varying by country and adjusted for local gonorrhoea resistance, which has become a significant concern. Completing the full course matters even after symptoms settle, since the infection may persist in the tubes after pelvic pain has resolved.
Hospital admission with intravenous treatment is appropriate for severe illness, suspected or confirmed tubo-ovarian abscess, pregnancy, inability to tolerate oral medication, failure to improve on outpatient treatment, or diagnostic uncertainty requiring surgical assessment.
Partner notification and treatment are essential rather than optional. Untreated partners cause reinfection, and each additional episode compounds tubal damage. Partners should be tested and treated even if they have no symptoms, which is common in men with chlamydia. Sexual health services manage this process and can notify partners anonymously where that is preferred, which removes a significant barrier for many women.
Abstaining from intercourse until both partners have completed treatment prevents reinfection, and this is a practical point frequently overlooked.
An intrauterine device does not usually need removing in mild to moderate disease, and evidence suggests outcomes are similar whether it is left in place or removed, provided appropriate antibiotics are given. Removal is considered in severe disease or where there is no improvement after a few days.
Follow-up within a few days assesses response, and review at two to four weeks confirms symptom resolution, checks that partners have been treated, and repeats testing where appropriate. Persistent symptoms warrant reassessment rather than another course of the same treatment, since abscess, an alternative diagnosis, or reinfection may be present.
The long-term consequences are the reason this condition matters so much, and they deserve clear statement.
Tubal factor infertility is the most significant. Risk rises with each episode—figures commonly cited suggest roughly 10% after one episode, rising substantially with second and third episodes, though estimates vary. Severity and delay in treatment both increase risk. Women who have had pelvic inflammatory disease and later struggle to conceive should be assessed earlier than the usual intervals, and in vitro fertilisation is effective where tubes are blocked.
Ectopic pregnancy risk increases severalfold, because a partially damaged tube allows sperm through but impedes the fertilised egg. Any woman with a history of pelvic infection who has a positive pregnancy test with pain or bleeding needs early assessment to locate the pregnancy.
Chronic pelvic pain affects a substantial proportion—commonly cited at around one in five—arising from adhesions and from changes in how pain is processed after prolonged inflammation. This is genuine, frequently dismissed, and deserves active management rather than being attributed to psychological causes.
Tubo-ovarian abscess is the most serious acute complication and may require drainage or surgery.
Recurrence is common, particularly with reinfection, and each episode compounds the risks above.
Prevention is effective and worth stating clearly. Consistent condom use prevents the infections that cause most cases. Chlamydia screening in sexually active women under 25 identifies asymptomatic infection before it ascends, and trial evidence shows this reduces rates of pelvic inflammatory disease. Prompt treatment of any diagnosed sexually transmitted infection, ensuring partners are treated, and avoiding douching all contribute. Regular sexual health screening when changing partners identifies infections that would otherwise go unnoticed.
A note on stigma is appropriate. Pelvic inflammatory disease is a common infection with serious consequences, and reluctance to seek care or to discuss sexual history contributes materially to delayed treatment and to preventable infertility. Sexual health services are confidential, are used routinely by large numbers of people, and are not judgemental. Seeking assessment early is the single most effective thing a woman can do to protect her future fertility.
Care is typically coordinated by sexual health services and primary care, with gynaecology and fertility services involved as needed. Clinical findings, test results, and imaging are interpreted together, with treatment often beginning before results are available.
Patient education plays an important role. Understanding that symptoms are often mild or absent, that treatment is started on suspicion for good reason, that a normal scan does not exclude the diagnosis, that partner treatment prevents reinfection, that damage occurs during the episode rather than afterwards, and that fertility can be affected and warrants early assessment all contribute to appropriate care.
Red flag symptoms include severe lower abdominal pain, particularly if worsening or becoming generalised; high fever with shaking chills; a rigid or exquisitely tender abdomen; persistent vomiting with inability to keep down fluids or medication; dizziness, fainting, a racing heart, or low blood pressure; failure to improve within 48 to 72 hours of starting antibiotics; and heavy vaginal bleeding. Any woman with pelvic pain and a positive pregnancy test requires urgent evaluation to exclude ectopic pregnancy. These warrant immediate medical assessment.