Metritis is an infection of the uterine wall that extends through all its layers, including the inner lining, the muscle, and the outer covering. While the terms “endometritis” and “metritis” are sometimes used interchangeably, metritis more accurately describes an infection that penetrates deeper than just the endometrium (the inner lining). It most commonly occurs after childbirth, and the risk is significantly higher following cesarean delivery: 6% to 18% of cesarean births are affected, compared with 0.9% to 3.9% of vaginal deliveries.
How Metritis Differs From Endometritis
The uterus has three main layers. Endometritis is limited to the innermost layer, the endometrium. Metritis goes further, involving the muscular wall and potentially the outermost layer as well. This distinction matters because deeper infection tends to cause more severe symptoms and a stronger systemic response, including higher fevers and greater overall illness. On a tissue level, endometritis involves immune cells flooding into the lining, while metritis can cause widespread tissue death and bacterial colonization through the full thickness of the uterine wall.
Common Causes
Metritis is a polymicrobial infection, meaning multiple types of bacteria work together to cause it. These typically include a mix of aerobic bacteria (which thrive in oxygen) and anaerobic bacteria (which grow in oxygen-poor environments). The bacteria involved are often species that normally live in the vaginal or intestinal tract but cause problems when they ascend into the uterus, particularly after delivery when the cervix is open and the uterine lining is vulnerable.
Certain anaerobic bacteria are especially damaging. Some produce enzymes that break down tissue, release toxins, and evade the immune system, all of which help the infection establish itself and spread through the uterine wall.
Who Is Most at Risk
Cesarean delivery is the single biggest risk factor. Beyond that, several other conditions raise the likelihood of developing metritis:
- Chorioamnionitis: an infection of the membranes surrounding the baby during pregnancy
- Prolonged rupture of membranes: when the water breaks long before delivery
- Anal sphincter laceration: significant tearing during vaginal birth
- Higher body weight: specifically, weighing more than 200 pounds at the time of admission
The common thread is that anything exposing the uterus to bacteria for longer, or creating tissue damage that bacteria can exploit, increases risk.
Symptoms to Recognize
The hallmark sign of postpartum metritis is fever following a recent delivery or miscarriage. Early-onset disease appears within 48 hours of birth, while late-onset disease can develop anytime up to six weeks afterward. A temperature of 38°C (100.4°F) or higher within the first 10 days postpartum, or 38.7°C (101.7°F) within the first 24 hours, is a key diagnostic threshold.
Beyond fever, typical symptoms include significant lower abdominal and uterine tenderness, foul-smelling or purulent vaginal discharge (lochia), and a uterus that feels larger than expected for the number of days since delivery. Many people also experience chills, malaise, headache, and a rapid heart rate. In milder cases, fever and general discomfort may be the only signs. In more severe cases, the combination of high fever (above 102°F), rapid heart rate, fast breathing, or low blood pressure raises concern for sepsis.
How It Is Diagnosed
Uterine tenderness on physical examination is the most important finding. During a pelvic exam, pressing on the uterus will typically produce noticeable pain. The uterus may also feel enlarged and softer than expected. Foul-smelling discharge supports the diagnosis.
Blood tests usually show signs of infection, including elevated white blood cell counts and markers of inflammation. Vaginal discharge is often sampled for culture to identify which bacteria are involved. If there is concern about a more serious systemic infection, additional blood work and blood cultures are drawn. Imaging studies may be ordered if the clinical picture is unclear or if a complication like an abscess is suspected.
Treatment and Recovery
Metritis requires intravenous antibiotics. The standard first-line combination is clindamycin plus gentamicin, which is widely considered the gold standard because it covers the mix of aerobic and anaerobic bacteria responsible for the infection. This combination has been shown to result in fewer treatment failures than alternatives like cephalosporins or penicillin-based regimens.
Treatment typically continues until you have been fever-free for 24 to 48 hours. The average treatment course runs roughly five to seven days, though this varies based on how quickly the infection responds. Once the fever breaks and symptoms improve, some regimens transition to oral antibiotics to complete the course, while others stop treatment entirely after the afebrile period with no further antibiotics needed. Your care team will decide based on how your recovery is progressing.
Potential Complications
When treated promptly, metritis usually resolves without lasting problems. Delayed or inadequate treatment, however, can lead to serious complications. The infection can spread beyond the uterus into the surrounding pelvic tissue, causing pelvic cellulitis (infection of the soft tissues around the uterus) or a pelvic abscess, which is a walled-off collection of pus that may need drainage.
One of the more dangerous complications is septic pelvic vein thrombophlebitis, where infection causes blood clots to form in the pelvic veins. In rare cases, this can extend to larger veins, including the vena cava. A phlegmon, which is a firm mass of infected, inflamed tissue in the broad ligament next to the uterus, is another uncommon but serious outcome. These complications are rare with appropriate antibiotic treatment but underscore why postpartum fever should always be evaluated quickly.
Prevention After Delivery
The most effective prevention strategy is reducing the risk factors that lead to infection in the first place. Minimizing unnecessary cesarean deliveries, careful surgical technique when cesarean birth is needed, and avoiding prolonged labor with ruptured membranes all lower the chance of postpartum uterine infection. Prophylactic antibiotics given before cesarean delivery have significantly reduced infection rates and are now standard practice.
After delivery, close monitoring is key, especially for those with known risk factors. Watching for early signs of fever, increasing pain, or changes in vaginal discharge allows for prompt treatment before the infection progresses.
Metritis in Veterinary Medicine
If you came across the term “metritis” while researching animal health, it is worth noting that this condition is extremely common in dairy cattle. It affects up to 40% of dairy cows, typically within the first 7 to 10 days after calving. In cows, it presents as an enlarged, soft uterus with foul-smelling reddish-brown discharge, fever, loss of appetite, and decreased milk production. The economic impact is substantial: affected cows produce less milk, are harder to breed, and are more likely to be culled from the herd early. While the bacteria involved overlap somewhat with those seen in human cases, the management approach differs, and the routine use of preventive antibiotics in cattle is now discouraged due to concerns about antimicrobial resistance.