Ovarian Endometrioma: Symptoms, Types, Causes and Treatment

Ovarian endometrioma, sometimes called a “chocolate cyst,” is a distinct manifestation of endometriosis that can significantly impact a woman’s health, fertility, and quality of life. This detailed guide will help you understand its symptoms, types, causes, and available treatments, drawing on the latest research to support each section.

Symptoms of Ovarian Endometrioma

Ovarian endometriomas can be silent troublemakers or cause distressing symptoms. Their clinical presentation varies widely, affecting each woman differently. For many, the symptoms not only cause physical discomfort but also emotional and social challenges.

Symptom	Description	Frequency/Impact	Sources
Pelvic Pain	Persistent or cyclical, often worsens with menstruation	Most common, can be severe	2 6 7 9
Infertility	Difficulty conceiving due to ovarian/follicular changes	Up to 50% in endometriosis	2 4 5 7
Adnexal Mass	Palpable or visible cyst on imaging	Often detected incidentally	2 7
Dysmenorrhea	Painful periods, sometimes debilitating	Common in affected women	6 7
Dyspareunia	Pain during intercourse	Reported by many patients	7 9
Asymptomatic	No symptoms; found during imaging for other reasons	Not uncommon	2 7

Table 1: Key Symptoms

Understanding the Clinical Picture

Most women with ovarian endometriomas present with chronic pelvic pain. This pain is often cyclical, intensifying before and during menstruation, and can sometimes persist throughout the month. The inflammation and immune dysregulation characteristic of endometriomas are thought to amplify this pain response 2 6 7.

Infertility and Reproductive Challenges

Ovarian endometriomas are closely linked with infertility. Up to half of all women struggling with infertility have endometriosis, and endometriomas are present in a significant portion of these cases 2 4 5 7. The cysts can disrupt ovarian architecture, reduce ovarian reserve, and create a hostile environment for egg development 4 5.

Other Presentations

Women may also present with:

• Adnexal masses detected during pelvic exams or imaging 2 7
• Dysmenorrhea (painful periods) and dyspareunia (pain during intercourse) 6 7 9
• Some women, however, are completely asymptomatic, with endometriomas only discovered incidentally during imaging for unrelated reasons 2 7.

Types of Ovarian Endometrioma

Ovarian endometriomas are not all alike. Their types can vary in appearance, size, and underlying biology, which influences symptoms and management strategies.

Type	Key Features	Size Range	Sources
Small, Fibrotic	Dense, fibrous cyst wall	1–3 cm	2
Large, Adhesive	Extensive adhesions, can distort anatomy	Up to 20 cm+	2
Single	One cyst in one ovary	Any size	2 7
Multiple	Multiple cysts, one or both ovaries	Variable	2 7
Simple	Thin-walled, less adhesions	Usually smaller	2
Complex	Thick, irregular wall, more adhesions	Any size	2 7

Table 2: Types of Ovarian Endometrioma

Phenotypic Variability

Endometriomas can range from small (1–3 cm) fibrotic cysts to very large cysts exceeding 20 cm. The degree of fibrosis, wall thickness, and presence of adhesions can vary greatly 2. Some are simple, with thin walls and minimal adhesions, while others are complex, with thickened walls and firm attachments to pelvic structures 2 7.

Single vs. Multiple Cysts

Endometriomas may appear as a single cyst on one ovary or as multiple cysts on one or both ovaries. Multiple or bilateral endometriomas can increase the risk of ovarian reserve compromise and complicate treatment decisions 2 7.

Phenotype and Function

The differences in type may reflect underlying mechanisms of formation and can affect:

• The degree of pain experienced
• The extent of fertility impairment
• The risk and technical difficulty of surgical removal 2

However, whether clinical management or malignant risk varies by endometrioma type remains an area of ongoing research 2.

Causes of Ovarian Endometrioma

The origins of ovarian endometriomas are complex and still under scientific investigation. Multiple mechanisms have been proposed, encompassing hormonal, genetic, immunological, and developmental factors.

Cause/Mechanism	Description	Impact	Sources
Retrograde Menstruation	Menstrual tissue enters ovary, forms cyst	Most common theory	5
Metaplasia	Transformation of ovarian surface cells	Explains some cases	2 5
Inflammation	Chronic immune activation, cytokine release	Drives local damage	3 5 6
Hormonal Factors	Estrogen/progesterone sensitivity, stimulation	Promotes cyst growth	5 6
Genetic/Epigenetic	Genetic mutations, altered gene expression	May increase risk	1 3
Oxidative Stress	Reactive oxygen species in cyst fluid	Damages ovarian tissue	3 6

Table 3: Causative Factors

Retrograde Menstruation & Metaplasia

The most widely accepted theory is retrograde menstruation, where menstrual debris flows backward through the fallopian tubes, implanting on the ovary and forming a cystic structure 5. Over time, these cells proliferate and respond to hormonal cycles, causing the cyst to fill with old blood — hence the term “chocolate cyst.”

Another mechanism is metaplasia, where ovarian surface or peritoneal cells transform into endometrial-like tissue, leading to cyst formation 2 5.

Inflammatory and Immune Dysfunction

Endometriomas are highly inflammatory. The cyst fluid contains high concentrations of cytokines (e.g., IL-6, IL-8, TNF), chemokines, and prostaglandins, creating a chronic inflammatory microenvironment 3 5 6. This environment:

• Damages surrounding ovarian tissue
• Triggers fibrosis and smooth muscle changes
• Promotes premature follicular activation and atresia (loss) 3 4 5 6

Hormonal, Genetic, and Oxidative Factors

Endometriomas are hormonally responsive, growing in response to estrogen and progesterone fluctuations 5 6. Genetic mutations and altered gene expression, particularly in pathways related to inflammation and cell growth (e.g., ERBB and PI3K pathways), may also play a role 1 3. Oxidative stress — high levels of reactive oxygen species in the cyst — further damages ovarian tissue and follicles 3 6.

Impact on Ovarian Reserve

The presence of an endometrioma is strongly associated with reduced follicular density and fibrosis in the ovarian cortex, independent of the cyst’s physical size 3 4 5. Thus, diagnosing and managing endometriomas promptly is important for protecting ovarian function.

Treatment of Ovarian Endometrioma

Managing ovarian endometriomas is complex and highly individualized, aiming to relieve pain, preserve fertility, and reduce recurrence. Treatment choices depend on the patient’s age, symptoms, reproductive desires, and cyst characteristics.

Treatment	Main Approach/Outcome	Key Considerations	Sources
Expectant Management	Monitoring without intervention	Small/asymptomatic cysts	9 11
Medical Therapy	Hormonal suppression (e.g., dienogest)	Reduces pain/cyst size, preserves ovarian reserve	8 9
Surgical Excision	Laparoscopic cystectomy	Best for pain/large cysts, risks reserve loss	2 7 9 11
Ablation/Sclerotherapy	Destroys cyst wall	Higher recurrence, less effective for fertility	2 7 9
Assisted Reproduction	IVF/ICSI for infertility	Consider for persistent infertility	9 10 11

Table 4: Treatment Options

Expectant Management

Small, asymptomatic endometriomas can often be monitored with regular imaging. This approach avoids surgical risks but requires vigilance for cyst growth or symptom development 9 11.

Medical Therapy

Hormonal treatments, such as oral contraceptives or progestins (notably dienogest), can suppress ovulation, leading to reduction in cyst size and significant pain relief 8 9. Dienogest has been shown to:

• Reduce cyst diameter and pain scores
• Preserve ovarian reserve (no significant decline in AMH)
• Increase antral follicle count 8

Medical therapy does not eliminate the cyst or restore fertility directly, but it helps control symptoms and may be a good option for women not currently seeking pregnancy 8 9.

Surgical Management

Laparoscopic cystectomy (removal of the cyst wall) is preferred for symptomatic, large (>3–5 cm), or suspicious cysts, as well as for women with infertility not responding to other treatments 2 7 9 11. Surgery provides:

• Pain relief
• Reduced recurrence risk
• Pathological diagnosis to rule out cancer 2 9 11

However, surgery can also reduce ovarian reserve, especially if excessive tissue is removed or if energy devices are overused 2 7 9 11. Ablation (destroying the cyst wall) or sclerotherapy (injecting agents to shrink the cyst) are less effective for fertility and pain control and have higher recurrence rates 2 7 9.

Key surgical considerations:

• Minimal use of bipolar energy to reduce ovarian damage 7 11
• Individualized approach based on ovarian reserve and reproductive goals 7 9 11
• Surgery may not improve IVF outcomes unless the cyst is very large (>5 cm) or causes pain 10 11

Assisted Reproductive Technology

For women with persistent infertility, particularly those with diminished ovarian reserve or multiple failed attempts at conception, IVF/ICSI is a valuable option 9 10 11. Surgery prior to IVF may be considered if the cyst is large or at risk of rupturing during egg retrieval 11.

Conclusion

Ovarian endometrioma is a multifaceted condition with significant implications for pain, fertility, and quality of life. Understanding its symptoms, types, causes, and treatments is essential for individualized, evidence-based care.

Key Points Covered:

• Ovarian endometriomas typically cause pelvic pain, infertility, and sometimes present as adnexal masses or are asymptomatic.
• Types vary by size, number, wall characteristics, and complexity, affecting both symptoms and management.
• Causes include retrograde menstruation, metaplasia, chronic inflammation, hormonal and genetic factors, and oxidative stress.
• Treatments include monitoring, hormonal suppression, surgical excision, or assisted reproduction, tailored to patient needs and reproductive goals.

Remember: Early diagnosis and individualized management are critical to preserving ovarian health and improving quality of life for women with ovarian endometrioma.