Endometritis is inflammation of the uterine lining. It can affect all layers of the uterus. The uterus is typically aseptic. However, the travel of microbes from the cervix and vagina can lead to inflammation and infection. This condition usually occurs as a result of the rupture of membranes during childbirth. Endometritis is the most common postpartum infection. Puerperal endometritis is 25 times more common in patients that underwent cesarean sections. Most cases of postpartum endometritis are polymicrobial, involving aerobic and anaerobic bacteria.
Endometritis results from the travel of normal bacterial flora from the cervix and vagina. The uterus is sterile until the amniotic sac ruptures during childbirth. Bacteria is more likely to colonize uterine tissue that has been devitalized, bleeding, or otherwise damaged (such as during a cesarean section).
Between 60% and 70% of infections are due to both aerobes and anaerobes. Examples of anaerobic species are Peptostreptococcus, Peptococcus, Bacteroides, Prevotella, and Clostridium. Examples of aerobic species are primarily groups A and B Streptococci, Enterococcus, Staphylococcus, Klebsiella pneumoniae, Proteus species, and Escherichia coli. Uterine tissue damaged by cesarean section is particularly susceptible to Streptococcus pyogenes and Staphylococcus aureus. Chlamydia endometritis often presents at a later date, seven or more days postpartum.
Puerperal endometritis is the most common postpartum infection. In patients without risk factors, following normal spontaneous vaginal delivery, there is an incidence of 1% to 2%. Risk factors, however, can increase this rate to a 5% to 6% risk of infection following vaginal delivery. Risk factors include chorioamnionitis, low socioeconomic status, prolonged labor, membrane rupture, multiple cervical examinations, internal fetal monitoring, young maternal age, nulliparity, obesity, meconium-stained amniotic fluid and bacterial colonization of the lower genital tract with bacteria such as Group B streptococcus (GBS), Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum, or Gardnerella vaginalis. The route of delivery is the most significant risk factor for endometritis, with cesarean deliveries (especially for multifetal gestation) having a much higher likelihood of leading to endometritis and a 25-fold increase in infection-related mortality.
Most cases of endometritis result from childbirth. Specifically, the rupture of the amniotic sac allows translocation of normal bacterial flora from the cervix and vagina to the usually aseptic uterus. This bacteria is more likely to colonize uterine tissue that has been devitalized, bleeding, or otherwise damaged (such as during a cesarean section). This bacteria can invade the endometrium-, myometrium-, and perimetrium, causing inflammation and infection.
Patients with endometritis often have fever as their first sign of infection. Additional common complaints are abdominal pain (commonly suprapubic in location), foul-smelling and purulent lochia. Like many infections, the grade of the fever is often indicative of the severity of the infection. On physical exam, suprapubic and uterine tenderness are often present on abdominal and pelvic exams, respectively. Vital sign abnormalities such as fever, tachycardia, and hypotension may also be present. Endometritis caused by Group A streptococcus is often particularly severe, resulting in a clinical picture consisting of sepsis, diarrhea, pain out of proportion. This condition can quickly develop into toxic shock, and necrotizing fasciitis, so great care is necessary when looking after such patients.
Endometritis is primarily a clinical diagnosis based on the history, physical, and presence of risk factors. In equivocal cases or to establish the severity of infection, laboratory and imaging evaluation can be helpful.
A leukocytosis of 15000 to 30000 cells/microL is common. Vaginal delivery, and cesarean section particularly, however, can cause an inflammatory leukocytosis. The CBC, therefore, is just one set of values in the greater clinical picture that will help aid the correct diagnosis. Cervical cultures obtained before antibiotic administration can be helpful for appropriate antibiotic selection. Vaginal cultures are often contaminated and can mislead providers to inadequate antibiotic coverage. Blood cultures should be obtained if there is a high enough clinical suspicion for sepsis and/or bacteremia.
For imaging, ultrasound often helps to rule out other diagnoses in the postpartum patient with abdominal pain and fever. Such diagnoses include retained products of conception, infected hematoma, and uterine abscesses. For patients with endometritis, findings consist of a thickened, heterogeneous endometrium, intracavitary fluid, and foci of air. Some of these findings, however, may be present as normal variants, so a good clinical acumen is necessary when comparing ultrasound results to other diagnostic findings. For instance, up to 24% of normal postpartum patients may have clots and debris in the uterus. Gas in the endometrium may also be normal for up to 3 weeks postpartum. Conversely, patients with endometritis may have a normal pelvic ultrasound. Computed tomography can show the same positive findings as ultrasound plus possible perimetrium and/or intrauterine inflammation and infection.
The threshold for obstetrics should be low in any provider considering a diagnosis of endometritis. Oral antibiotic regimens are an option for mild disease. The options are similar to those used for pelvic inflammatory disease:
For patients with moderate to severe endometritis and/or patients with endometritis s/p cesarean section, intravenous antibiotics and admission are recommended. Options are as follows:
Clinical improvement in response to antibiotics typically occurs in 48 to 72 hours. If there is no clinical improvement within 24 hours, providers should consider adding ampicillin 2 g initially, followed by 1 g every 4 hours for enhanced Enterococcus coverage. For those that do not improve within 72 hours, providers should broaden their differential diagnosis to include other infections such as pneumonia, pyelonephritis, pelvic septic thrombophlebitis. IV antibiotics should continue until the patient becomes afebrile for at least 24 hours in addition to an improvement in the patient’s pain and leukocytosis. At this time, there is no substantial evidence demonstrating that continuing antibiotics in PO form following such clinical improvement improves significant patient-oriented outcomes.
In the patient with postpartum fever and abdominal pain, diagnoses other than endometritis that merit consideration include urinary tract infections (including pyelonephritis), pneumonia, septic pelvic thrombophlebitis. The clinician should keep an open mind to these diagnoses, especially if antibiotic and/or surgical management for endometritis is not leading to clinical improvement.
If untreated, the fatality rate of endometritis is approximately 17%. Thankfully this is reduced to 2% with proper recognition and treatment. Cesarean deliveries (especially for multifetal gestation) have a 25-fold increase in infection-related mortality.
Approximately 1% to 4% of patients will have complications such as sepsis, abscesses, hematomas, septic pelvic thrombophlebitis, and necrotizing fasciitis. Such complications can then lead to uterine necrosis, requiring a hysterectomy for infection resolution. Surgical intervention may also be necessary if the infection has produced a drainable fluid collection.
Due to the increased prevalence and mortality of endometritis secondary to cesarean sections, ACOG recommends prophylactic antibiotics before cesarean deliveries. A recent Cochrane review showed a significant reduction in the risk of postpartum infections, including endometritis, when such antibiotics were given. Furthermore, obstetricians should have a thoroughly informed consent conversation regarding the cesarean section, specifically including the risks of postpartum infections. Risks and benefits regarding vaginal vs. cesarean delivery should undergo review, and the patient should make a properly-educated decision.
Endometritis is the most common postpartum infection. Disease severity can range from mild to severe, with treatment regimens ranging from outpatient PO antibiotics with adequate obstetrics follow up and return precautions to inpatient hospitalization with IV antibiotics and surgery (hysterectomy, fluid drainage, for example).
Patients will often present to generalists: non-obstetrics primary care providers, urgent care centers, and emergency departments. Early obstetric consultation is critical. Such a consult can help aid efficient and appropriate diagnostics and treatment. If imaging is needed, ultrasonographers, radiology technicians, and diagnostic radiologists may all prove useful. This is why an interprofessional team approach to patient care is necessary. For ideal antibiotic choice, dosing, and administration, a clinical pharmacist may be helpful; they can validate antimicrobial therapy against the latest antibiogram data, check for interactions, and alert the staff to potential adverse effects. If operative intervention is required, an anesthesiologist is also necessary for a successful surgery.
To ensure that a patient with endometritis receives optimal care, an effective interprofessional approach is crucial. Prompt involvement of appropriate specialists, as well as strong communication between providers, can make a significant difference in the patient's clinical course, morbidity, and mortality. Obstetrical nurses should promptly report fevers to managing providers, administer treatment, and educate patients. With interprofessional collaboration, patient outcomes will improve. [Level 5]
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