Ovarian Cysts
Summary
Ovarian cysts are fluid-filled sacs within or on the surface of an ovary. They are extremely common, particularly in women of reproductive age, and the vast majority are benign and functional (Related to ovulation). Functional cysts include Follicular Cysts and Corpus Luteum Cysts, which typically resolve spontaneously within 2-3 menstrual cycles. Other types include Endometriomas ("Chocolate cysts" – containing old blood), Dermoid Cysts (Mature Teratoma) – containing tissue such as hair, teeth, and fat, and Cystadenomas. Most ovarian cysts are asymptomatic and discovered incidentally on ultrasound. Symptomatic cysts may cause pelvic pain, bloating, or menstrual irregularities. Complications include Torsion (Twisted ovary – Surgical emergency!), Rupture, and Haemorrhage. Management depends on the patient's age, cyst characteristics, symptoms, and risk of malignancy (Assessed using RMI – Risk of Malignancy Index). Most simple cysts in premenopausal women can be managed conservatively (Observation + Repeat USS). [1,2,3]
Clinical Pearls
"Simple Cyst less than 5cm = Watch and Wait": In premenopausal women, simple cysts less than 5cm almost always resolve spontaneously. Repeat USS in 8-12 weeks.
"Torsion = Twisted Ovary = Emergency": Acute severe unilateral pelvic pain + Nausea/Vomiting. Requires urgent surgery. Time is ovary – Untwist before necrosis.
"Postmenopausal Cyst ≠ Ignore": Any new cyst in a postmenopausal woman needs careful assessment (RMI, CA-125). Higher risk of malignancy.
"Dermoid = Teeth, Hair, Fat": Mature cystic teratoma. Benign but can cause torsion (Heavy) and ovarian accidents.
Demographics
| Factor | Notes |
|---|---|
| Prevalence | Extremely common. ~10% of women will have surgery for an ovarian mass in their lifetime. |
| Age | Functional cysts common in reproductive age. Dermoids common in younger women. Malignancy risk increases with age (Postmenopausal). |
| Incidental Finding | Many cysts are asymptomatic and found incidentally on USS. |
Types by Frequency
| Type | Notes |
|---|---|
| Functional (Follicular / Corpus Luteum) | Most common. Resolve spontaneously. |
| Dermoid (Mature Teratoma) | Most common benign ovarian tumour in young women (~20% of benign ovarian neoplasms). |
| Endometrioma | Common in women with endometriosis. "Chocolate cyst". |
| Cystadenoma | Serous or Mucinous. Benign epithelial tumours. Can be large. |
| Malignant | ~20% of all ovarian tumours. Risk increases with age. |
Functional Cysts
| Type | Features |
|---|---|
| Follicular Cyst | Follicle fails to rupture. Usually less than 5cm. Resolves in 1-3 cycles. |
| Corpus Luteum Cyst | Corpus luteum fills with blood/fluid. May cause pain. Resolves in few weeks. Can rupture. |
Benign Ovarian Neoplasms
| Type | Features |
|---|---|
| Dermoid Cyst (Mature Teratoma) | Contains tissue from all three germ layers: Hair, Sebum, Teeth, Bone. Benign. May cause torsion (Heavy). Classically has "Dermoid plug" or "Rokitansky nodule". |
| Serous Cystadenoma | Thin-walled. Clear fluid. Can be large. |
| Mucinous Cystadenoma | Multiloculated. Thick mucoid fluid. Can be VERY large (>30cm). |
| Fibroma | Solid. Benign. Associated with Meigs' Syndrome (Fibroma + Ascites + Pleural effusion). |
Endometrioma
| Type | Features |
|---|---|
| Endometrioma ("Chocolate Cyst") | Contains old, thick, dark blood (Looks like chocolate). Associated with endometriosis. May impact fertility. |
Symptoms
| Symptom | Notes |
|---|---|
| Asymptomatic | Most common. Incidental finding on USS. |
| Pelvic Pain | Dull, Aching. May be unilateral. |
| Bloating / Abdominal Distension | Large cysts. |
| Pressure Symptoms | Urinary frequency (Bladder pressure), Constipation (Bowel pressure). |
| Menstrual Irregularities | Functional cysts may affect cycle. |
| Dyspareunia | Deep pain during intercourse. |
Complications (Acute Presentations)
| Complication | Presentation |
|---|---|
| Torsion | Sudden severe unilateral pelvic pain + Nausea/Vomiting. May have intermittent pain (Partial torsion). SURGICAL EMERGENCY. |
| Rupture | Sudden sharp pain. May have intraperitoneal bleeding (Haemoperitoneum). Peritonism. |
| Haemorrhage | Bleeding into cyst. Pain, Enlarging mass. |
| Infection | Rare for simple cysts. Can occur with endometriomas. |
Red Flags (Possible Malignancy)
| Feature | Notes |
|---|---|
| Postmenopausal with New Cyst | Higher risk of malignancy. |
| Solid Components | On USS. |
| Septations / Nodules | Complex cyst. |
| Ascites | Fluid in abdomen. |
| Bilateral Cysts | Increases suspicion. |
| Raised CA-125 | >35 U/mL. (Less specific in premenopausal – Elevated in endometriosis, Menstruation, Fibroids, PID). |
| Rapidly Growing | On serial imaging. |
Imaging
| Modality | Findings |
|---|---|
| Transvaginal Ultrasound (TVUS) | First-line. Characterise cyst: Simple (Anechoic, Thin-walled) vs Complex (Solid, Septations, Nodules). Measure size. |
| MRI Pelvis | Second-line. Characterise indeterminate lesions. Useful for endometriomas, Dermoids, Complex cysts. |
| CT | Not first-line for cyst characterisation. May be used if malignancy suspected for staging. |
USS Features
| Feature | Suggestive Of |
|---|---|
| Simple, Anechoic, Thin-Walled | Functional cyst. Benign. |
| "Ground Glass" Echogenicity | Endometrioma. |
| Fat/Dermoid Plug, Hair Strands, Calcification | Dermoid (Teratoma). |
| Multiloculated, Papillary Projections, Solid Components | Higher risk of malignancy. |
| Ascites | Suspicious for malignancy. |
Tumour Markers
| Marker | Notes |
|---|---|
| CA-125 | Elevated in Epithelial Ovarian Cancer. Also elevated in benign conditions (Endometriosis, Fibroids, PID, Menstruation, Pregnancy). More useful in postmenopausal women. |
| AFP (Alpha-Fetoprotein) | Yolk sac tumour (Rare). |
| HCG | Choriocarcinoma (Rare). |
| LDH | Dysgerminoma, Non-specific. |
| CEA | Mucinous tumours. GI malignancy. |
Risk of Malignancy Index (RMI)
Used to stratify risk, especially in postmenopausal women: RMI = USS Score x Menopausal Status x CA-125
| USS Score | Features |
|---|---|
| 0 | No features |
| 1 | 1 feature |
| 3 | ≥2 features |
| Features: | Multilocular, Solid areas, Bilateral, Ascites, Metastases |
| Menopausal | Score |
|---|---|
| Premenopausal | 1 |
| Postmenopausal | 3 |
| RMI Score | Risk | Management |
|---|---|---|
| less than 25 | Low | GP/General Gynae |
| 25-250 | Moderate | General Gynae |
| >250 | High | Referral to Gynae-Oncology MDT |
Management Algorithm
OVARIAN CYST IDENTIFIED
(USS +/- CA-125)
↓
EMERGENCY?
(Torsion / Rupture / Haemoperitoneum)
┌────────────────┴────────────────┐
YES NO
↓ ↓
**URGENT SURGERY** ASSESS CHARACTERISTICS
Laparoscopy - Simple vs Complex
Detorsion +/- Cystectomy - Size
+/- Oophorectomy if necrotic - Age (Pre/Postmenopausal)
- RMI Score
↓
PREMENOPAUSAL / SIMPLE CYST less than 5cm
┌──────────────────────────────────────────────────────────┐
│ CONSERVATIVE MANAGEMENT │
│ - Reassurance (Most resolve spontaneously) │
│ - Repeat USS in 8-12 weeks │
│ - If resolved → Discharge │
│ - If persistent/Growing → Consider Surgery │
└──────────────────────────────────────────────────────────┘
↓
SYMPTOMATIC / LARGE (>5cm) / COMPLEX / POSTMENOPAUSAL
┌──────────────────────────────────────────────────────────┐
│ SURGICAL MANAGEMENT │
│ - Laparoscopic Cystectomy (Preserve ovary if possible) │
│ - Laparoscopic Oophorectomy (If fertility not desired │
│ or suspicious features) │
│ - Laparotomy (If highly suspicious or very large) │
│ │
│ HIGH RMI (>250): │
│ - Refer to Gynae-Oncology MDT │
│ - Staging procedure by Cancer surgeon │
└──────────────────────────────────────────────────────────┘
Conservative Management Indications
- Simple cyst less than 5cm in premenopausal woman.
- Asymptomatic.
- Low suspicion of malignancy.
Surgical Management Indications
| Indication | Notes |
|---|---|
| Symptomatic | Significant pain, Pressure symptoms. |
| Large Cyst (>5-7cm) | Unlikely to resolve. Risk of torsion. |
| Complex Features | Solid, Septations, Nodules. |
| Postmenopausal | Higher malignancy risk. Lower threshold for surgery. |
| Persistent/Growing | Not resolved after observation period. |
| Torsion/Rupture | Emergency surgery. |
| High RMI | Gynae-Oncology involvement. |
| Complication | Notes |
|---|---|
| Torsion | Ovary twists on its pedicle → Ischaemia → Necrosis. Emergency. Risk factors: Large cyst, Dermoid (Heavy). |
| Rupture | Cyst contents spill into peritoneum. Can cause chemical peritonitis (Dermoid) or haemorrhage (Corpus luteum). |
| Haemorrhage | Bleeding into cyst or haemoperitoneum. |
| Malignant Transformation | Rare for benign cysts. Dermoids have ~1-2% risk of malignancy (Squamous cell carcinoma). |
| Infertility | Associated with endometriomas. Surgery on ovaries may reduce ovarian reserve. |
| Factor | Notes |
|---|---|
| Functional Cysts | Excellent. Resolve spontaneously in 1-3 cycles. |
| Dermoid Cysts | Benign. Good prognosis after surgical removal. |
| Endometriomas | May recur. Associated with endometriosis symptoms and fertility issues. |
| Malignant Cysts | Prognosis depends on stage and histology. Epithelial ovarian cancer has overall 5-year survival ~45%. |
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Management of Suspected Ovarian Masses | RCOG GTG 62 (2016) | RMI scoring. Conservative for simple cysts less than 5cm. Surgical for complex/Large/High RMI. |
| Ovarian Cysts in Postmenopausal Women | NICE / RCOG | CA-125 + USS. RMI. Low threshold for intervention. |
What is an Ovarian Cyst?
An ovarian cyst is a fluid-filled sac on or inside your ovary. They are very common and most women will have one at some point. Most cysts are harmless and go away on their own.
Why did I get one?
Most cysts develop as part of the normal menstrual cycle when an egg is released. These are called "functional cysts" and usually disappear within a few weeks.
What are the symptoms?
Many cysts cause no symptoms at all and are found by chance during a scan. Some may cause:
- Ache or discomfort in the lower tummy.
- Bloating.
- Pain during sex.
- Irregular periods.
When is it serious?
Most are not serious. However, seek urgent help if you have:
- Sudden severe pain.
- Feeling faint or sick.
- Fever. This could indicate the cyst has twisted (Torsion) or burst (Rupture).
What is the treatment?
- Watchful waiting: Many cysts go away on their own. Repeat scan in 8-12 weeks.
- Surgery (Keyhole): If the cyst is large, causing symptoms, or looks suspicious. Usually the cyst is removed, keeping the ovary.
Can cysts be cancer?
The vast majority of cysts are benign (Not cancer). However, we check features on the scan and sometimes do blood tests to make sure there are no concerning signs. If there are, you will be referred to a specialist.
Primary Sources
- Royal College of Obstetricians and Gynaecologists. Management of Suspected Ovarian Masses in Premenopausal Women (GTG 62). 2016.
- Goff BA, et al. Ovarian carcinoma diagnosis. Cancer. 2000;89(10):2068-2075. PMID: 11066048.
- National Institute for Health and Care Excellence. Ovarian cancer: recognition and initial management (NG122). 2011.
Common Exam Questions
- Most Common Type of Ovarian Cyst: "What is the most common type of ovarian cyst?"
- Answer: Functional Cyst (Follicular or Corpus Luteum).
- Dermoid Cyst Contents: "What tissues can be found in a Dermoid Cyst?"
- Answer: Tissues from all three germ layers: Hair, Sebum, Teeth, Bone, Skin.
- Torsion Presentation: "How does ovarian torsion present?"
- Answer: Sudden severe unilateral pelvic pain + Nausea/Vomiting + Tender adnexal mass.
- RMI: "What is the Risk of Malignancy Index used for?"
- Answer: To stratify risk of malignancy in ovarian cysts and guide referral (High RMI >250 = Gynae-Oncology MDT).
Viva Points
- CA-125 in Premenopause: Less specific – Elevated in endometriosis, Menstruation, PID, Fibroids. More useful in postmenopausal women.
- Simple Cyst less than 5cm = Observe: Reassurance and repeat USS in 8-12 weeks.
- Meigs' Syndrome: Ovarian Fibroma + Ascites + Pleural Effusion. Benign. Resolves after tumour removal.
- Endometrioma on USS: "Ground glass" appearance due to old blood.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.