Overview

Endometriosis and endometritis are two distinct conditions affecting the uterus, though they are often confused due to their similar names. Endometriosis occurs when tissue similar to the lining of the uterus grows outside the uterine cavity, leading to pain, inflammation, and fertility issues.¹ In contrast, endometritis is the inflammation of the uterine lining, typically caused by infection, and is often associated with symptoms like fever, pain, and abnormal bleeding.² Understanding the differences between these conditions is crucial for accurate diagnosis and appropriate treatment.

Endometriosis

Definition

According to Endometriosis UK, endometriosis affects 10-15% of those who are of reproductive age.³ This condition results in the cells lining your uterus's inner lining (the endometrium) to grow elsewhere within your body. Typically, these cells grow in places such as the fallopian tubes, ovaries, and tissues that line your pelvis. However, in rarer cases of endometriosis growth of these cells can be seen elsewhere in the body.  During menstruation each month, these cells react the same way as the ones that line the endometrium, they break down and bleed. However, this blood cannot leave your body for the endometrial cells that have grown outside the uterine cavity and are being shed during menstruation. This sadly results in the formation of cysts known as endometriomas growing in the ovaries. In other areas, this can result in the inflammation of tissues and the development of scar tissue.

What are the causes of endometriosis?

The causes of endometriosis are sadly currently unknown. However, there are several theories, listed below, which suggest the cause of endometriosis:

• Genetics: evidence suggests that endometriosis can be passed down through families. However, the precise genetics of this and the genes involved are unknown
• Retrograde menstruation: retrograde menstruation occurs when part of the endometrium debris from menstruation flows back up through the fallopian tubes, and the debris deposits itself in the pelvic cavity. However, it is important to note that retrograde menstruation is a common occurrence, with 76-90% of those assigned female at birth suffering from this, and not all these individuals have endometriosis⁴
• Lymphatic or circulatory spread: occurs when endometrium debris travels through your body via either the lymphatic system or circulatory system. This causation of endometriosis could explain how endometrium debris travels to rarer locations in your body to be deposited, such as the eyes
• A problem with the immune system: your immune system is your body’s natural defence system against disease and infection, and a dysfunction in your immune system could make you more susceptible to endometriosis (NHS)
• Cellular metaplasia: According to the WHO, metaplasia is a condition where your cells can change into a different specialised cell. When discussing endometriosis, cells outside of your uterine cavity change and become endometrial-like cells

Symptoms

While the exact causes of endometriosis remain unknown, its symptoms are well-documented, with pelvic pain being the most common. According to the WHO and NHS, this pain tends to be more intense during menstruation, during or after sex, and when urinating or having a bowel movement. However, pelvic pain is just one of several symptoms associated with endometriosis. Other signs to watch for include:

• Difficulties getting pregnant
• Nausea
• Depression
• Diarrhoea
• Anxiety
• Bloating
• Fatigue
• Heavy bleeding when on your period
• Bleeding in between periods
• Blood in your stool

Recognizing these symptoms early is key to seeking timely medical advice and managing the condition effectively. 

Diagnosis

Endometriosis is diagnosed using a minimally invasive surgery known as laparoscopy, where small incisions are made at your navel, and a small camera is inserted to allow the surgeon to visualise inside your pelvis. This will allow any signs of endometriosis to be noted and a diagnosis to be made.

Treatment options

Although, unfortunately, there is no definitive cure for endometriosis, various treatment options are available and can be tailored to individual needs. The choice of treatment depends on factors such as age, symptom severity, personal preferences regarding surgery, and whether you plan to become pregnant. The following treatments are recommended by the NHS.

• Pain relief: Pain relief may come from using a heated wheat pack over your abdomen, however, pain medications may also be used. Pain medications include using ibuprofen or paracetamol
• Hormone treatment: Hormone treatments for endometriosis work via one key mechanism-stopping or reducing the amount of oestrogen your body produces, as oestrogen is the hormone that drives the process of the inner lining of your uterus growing and building during your menstrual cycle, and then shedding during menstruation. Reducing oestrogen production can limit the build-up of endometrial-like tissue growing in your body, and limit the pain this may cause you.
• Surgery: this is another avenue to consider, as destroying areas of endometrial tissue build-up can help to relieve some of the symptoms you are experiencing. Surgery options include laparoscopy or possibly a hysterectomy

Endometritis

Definition

Endometritis, similar to endometriosis, affects the inner lining of your uterine cavity, but instead of endometrial-like cells growing elsewhere, other than the uterine cavity, the endometrium becomes inflamed due to an infection from microorganisms. This inflammation of the endometrium can potentially spread to your fallopian tubes and your ovaries. Endometritis is divided into two different subtypes: acute and chronic.⁵

Acute endometritis can occur postpartum after pregnancy or may occur when your endometrium has sadly been infected for more than 30 days, potentially due to a sexually transmitted infection (STI) or bacterial vaginosis.⁵

On the other hand, chronic endometriosis is unrelated to pregnancy and occurs when microorganisms evade and infect the endometrium. Chronic endometriosis is related to miscarriage and infertility.⁵

Causes

Causes of acute endometriosis include:

• Caesarean section: postpartum endometritis has a higher chance of occurring after a caesarean section
• Sexually transmitted infections: More than 85% of cases of acute endometritis are due to bacteria that cause chlamydia (Chlamydia trachomatis), bacteria that cause gonorrhoea (Neisseria gonorrhoeae), and bacteria that cause bacterial vaginosis⁵

The causes of chronic endometritis differ from the causes of acute endometritis, and are caused by:

• Chronic bacterial infection: This is commonly due to Mycobacterium tuberculosis (the bacteria that causes tuberculosis). It is important to note that other bacterial species have been located in the endometrium of those with endometritis too, these include E.coli²
• Infection from Chlamydia trachomatis or Neisseria gonorrhoeae: this occurs in 2-7% and 0-8% of cases of chronic endometritis respectively. These bacterial species typically cause acute endometritis²

Symptoms

The symptoms of endometritis can vary based on whether the condition is acute or chronic. Acute endometritis often presents with increased vaginal discharge, changes in colour and consistency, fever, pelvic pain, and abnormal bowel movements. In contrast, chronic endometritis may be asymptomatic for many individuals, but when symptoms do occur, they typically include pelvic pain, abnormal uterine bleeding, and painful sexual intercourse. Timely recognition of these symptoms is essential for effective diagnosis and treatment.^2,5

Diagnosis

Diagnosis of acute endometritis

The diagnosis of acute endometritis starts with taking swab samples from the cervix and microscopically examining vaginal discharge samples. Imaging techniques, such as ultrasound, may also be employed if you are experiencing pelvic pain. An ultrasound can help healthcare professionals visualize the endometrium and assist in confirming the diagnosis.²

Diagnosis of chronic endometritis

One method for diagnosing chronic endometritis involves taking a bacterial culture to identify the specific bacterial species present, which helps in determining the appropriate targeted treatment. Additionally, imaging techniques such as ultrasound, MRI, and CT scans may be used to assess the condition. An endometrial biopsy can also be performed for diagnostic purposes, providing further insight into the presence of endometritis.²

Treatment options

Treatment for both acute and chronic endometritis generally involves antibiotics. The specific antibiotic prescribed will vary depending on the type of microorganisms causing the infection, as well as the appropriate dosage needed to effectively address the condition.^2,5

Key differences between endometriosis and endometritis

Aetiology

The causes of endometriosis and endometritis are fundamentally different. The exact cause of endometriosis remains unknown, though several theories have been proposed, such as retrograde menstruation or genetic predispositions. In contrast, the aetiology of endometritis is well-established, primarily involving infections. Endometritis is often caused by postpartum infections, as well as bacteria associated with sexually transmitted infections (STIs), bacterial vaginosis, and, less commonly, tuberculosis. Understanding these underlying causes is crucial for diagnosing and developing targeted treatments for each condition.⁵

Pathophysiology

In endometriosis, the pathophysiology involves the presence of endometrial-like cells outside the uterine cavity. These cells, which normally line the inside of the uterus, grow and function in locations such as the ovaries, fallopian tubes, and pelvic peritoneum. During menstruation, these ectopic cells break down and bleed, causing inflammation, pain, and scar tissue formation due to the lack of an exit route for the blood.

In contrast, acute endometritis is characterised by the infiltration of specialized white blood cells called neutrophils into the endometrial glands, indicating an acute inflammatory response typically triggered by infection. Chronic endometritis, on the other hand, is marked by the presence of plasma cells, another type of white blood cell, within the endometrial stroma. These cells are involved in long-term inflammation and immune responses, contributing to the persistent nature of chronic endometritis. Understanding these underlying mechanisms is essential for diagnosing and effectively treating each condition.^1,6

Clinical presentation

Both endometriosis and endometritis commonly present with pelvic pain, but their symptom profiles can differ significantly. In endometriosis, the pain often correlates with the menstrual cycle and may be accompanied by symptoms such as heavy menstrual bleeding, pain during intercourse, and gastrointestinal issues like diarrhoea or constipation. The pain in endometriosis is usually chronic and can vary in intensity.

In contrast, endometritis generally presents with acute pelvic pain and may also include symptoms such as fever, abnormal vaginal discharge, and potentially abnormal bowel movements. The inflammation in endometritis is typically associated with recent childbirth, miscarriage, or surgical procedures, which can exacerbate the condition.

Understanding these symptom differences is crucial for accurate diagnosis and effective treatment. Each condition requires tailored management strategies to address the specific underlying causes and alleviate symptoms effectively.^2,5

Diagnostic approaches

The diagnosis of endometriosis typically involves laparoscopic surgery, as blood tests and bacterial cultures are not used for this condition. In contrast, diagnosing endometritis involves a more varied approach, including the use of different imaging techniques, cervical swabs, bacterial cultures, and microscopic analysis of vaginal discharge samples to reach a diagnosis.²

Management strategies

Endometriosis can be managed with pain relief medications and the use of hot wheat packs on the abdomen to alleviate discomfort. Unfortunately, there is no definitive cure for endometriosis. In contrast, endometritis is an infection that can often be effectively treated with antibiotics, leading to a complete resolution of the condition.^2,5

Summary

Endometriosis and endometritis are distinct conditions affecting the reproductive system, each with unique causes, symptoms, and treatment approaches. Endometriosis involves the growth of endometrial-like cells outside the uterus, leading to inflammation and scar tissue, and is managed through hormonal treatments, surgery, and pain relief. Although its exact cause remains unclear and no definitive cure exists, various theories provide insights into its development. On the other hand, endometritis is an infection-induced inflammation of the uterine lining, typically treated with antibiotics. Diagnosis for endometriosis is primarily through laparoscopy, while endometritis requires a range of diagnostic methods. Understanding these differences is crucial for effective management and treatment of both conditions, ultimately improving patient outcomes and quality of life.