What is a mass in the left pelvic area?: Causes, Diagnosis, and Treatment

September 23, 2025 •

5 min read

According to the Cleveland Clinic, approximately 1 in 10 women will develop an adnexal mass at some point in their lifetime. A mass in the left pelvic area refers to any abnormal growth or enlargement in the lower-left abdominal region, originating from a variety of organs.

Quick Summary

A mass in the left pelvic area can be a lump or swelling caused by numerous gynecological conditions, such as ovarian cysts or fibroids, or non-gynecological issues, including problems with the intestines or appendix. While many masses are benign, a medical evaluation is essential to determine the precise cause and appropriate course of action.

Key Points

Diverse Origins: A left pelvic mass can arise from gynecological organs (ovaries, uterus, fallopian tube) or non-gynecological ones (intestines, appendix, bladder).
Mostly Benign: The majority of masses, particularly fluid-filled cysts, are not cancerous and can resolve on their own.
Medical Evaluation Required: Accurate diagnosis necessitates professional medical evaluation, including a physical exam and imaging such as ultrasound, CT, or MRI.
Symptoms Vary: Symptoms range from being completely absent to causing pain, bloating, or changes in urinary and bowel habits.
Emergency Signs: Severe, sudden pelvic pain, accompanied by fever or vomiting, warrants immediate medical attention to rule out complications like a ruptured cyst or ectopic pregnancy.
Treatment Depends on Cause: Management options range from watchful waiting to surgery, based on the specific cause, size, and symptoms of the mass.
Seek Specialist Care: If cancer is suspected, consulting a gynecologic oncologist is recommended for expert diagnosis and treatment.

The Anatomy of the Left Pelvic Region

To understand why a mass might form, it is helpful to know the anatomy of the left pelvic area. This region is home to several organs and structures, and a mass could originate from any of them. These include the left ovary and fallopian tube, the left side of the uterus, the intestines (including the colon and appendix), the bladder, and major blood vessels. The variety of potential origins is why a precise medical diagnosis is crucial for identifying the cause of any observed mass.

Gynecological Causes of a Left Pelvic Mass

Many pelvic masses in women arise from the reproductive organs. Understanding these conditions can help in recognizing potential causes.

Ovarian Cysts

Ovarian cysts are fluid-filled sacs that can develop on or inside an ovary. They are very common and often resolve on their own, especially in women of reproductive age.

Functional Cysts: These form as part of the menstrual cycle. A follicular cyst develops if the sac holding an egg doesn't release it. A corpus luteum cyst can form after the egg is released, filling with fluid. These are almost always benign.
Endometriomas: These are cysts filled with blood, formed when tissue similar to the uterine lining grows on the ovaries. They are a sign of endometriosis.
Dermoid Cysts: These cysts contain various types of tissue, such as hair, fat, or skin, and are typically benign.

Uterine Fibroids

Uterine fibroids are benign muscle tumors that grow in the wall of the uterus. While most are symptom-free, their location and size can cause them to be felt as a mass on the left side, especially if they are subserosal (on the outer wall).

Ectopic Pregnancy

This is a medical emergency where a fertilized egg implants and grows outside the uterus, most often in the fallopian tube. A mass in the left fallopian tube accompanied by severe pain and internal bleeding is a critical sign.

Tubo-ovarian Abscess (TOA)

Resulting from an infection, a TOA is a pocket of pus involving the fallopian tube and ovary. It requires immediate medical attention, usually with antibiotics and potential surgical drainage.

Non-Gynecological Causes of a Left Pelvic Mass

Not all masses in the left pelvic area originate from the reproductive system. Other systems can also be the source of a mass.

Gastrointestinal Issues

Diverticulitis: Inflammation of small, bulging pouches in the digestive tract, most commonly in the colon. An abscess can form, feeling like a mass.
Appendicitis: While the appendix is usually on the right, it can be located differently or an abscess can form and present on the left side.
Crohn's Disease: This inflammatory bowel disease can cause inflammation and swelling in the intestines, potentially forming a palpable mass.

Urinary System Problems

Pelvic Kidney: A congenital condition where a kidney is located in the pelvis rather than the abdomen.
Bladder Diverticulum: A pouch-like sac in the bladder wall.

Other Causes

Other possibilities include vascular abnormalities or the spread of cancer from other areas.

Symptoms That May Accompany a Pelvic Mass

While some masses are asymptomatic and discovered incidentally, others can cause noticeable symptoms. These may include:

Pain or pressure in the pelvis or lower back
A feeling of fullness or bloating
Changes in bladder habits, such as frequent or urgent urination
Changes in bowel habits, such as constipation
Abnormal menstrual bleeding or particularly heavy periods
Pain during sexual intercourse
Nausea or vomiting

Sudden, severe pelvic pain, especially when combined with fever or vomiting, requires immediate medical evaluation as it could indicate a serious complication like a ruptured cyst or ectopic pregnancy.

Diagnosing a Left Pelvic Mass

Diagnosing the specific cause involves a multi-step process undertaken by a healthcare professional.

Physical and Pelvic Examination: The doctor will perform a physical exam and, for women, a pelvic exam to check for any tenderness, irregularities, or palpable masses.
Pregnancy Test: This is a standard procedure for women of reproductive age to rule out an ectopic pregnancy.
Imaging Tests: These are the most common tools for determining the mass's nature.
- Transvaginal or abdominal ultrasound: Uses sound waves to create images of the pelvic organs. It can help distinguish between fluid-filled (simple) and solid (complex) masses.
- MRI or CT scan: Provides more detailed imaging, especially for complex or solid masses.
Blood Tests: Certain blood tests can help. For example, the CA-125 marker may be elevated in some cases of ovarian cancer, though it's not specific and can be raised by other conditions like endometriosis.

Treatment Options and Management

Treatment depends entirely on the cause, size, and nature of the mass. It is not a one-size-fits-all approach.


Condition	Common Management	Notes
Functional Ovarian Cyst	Watchful waiting and monitoring	Most resolve on their own within a few menstrual cycles.
Uterine Fibroid	Monitoring, medication, or surgery	Depends on size, location, and symptoms. Options include myomectomy or hysterectomy.
Ectopic Pregnancy	Immediate medical intervention	Requires medication or surgical removal to prevent a life-threatening rupture.
Endometrioma	Pain management or surgical removal	Surgery is considered if the cyst is large, painful, or causing fertility issues.
Tubo-ovarian Abscess	Antibiotics and potential drainage	Often requires immediate antibiotic therapy and sometimes surgery.
Suspicious Mass	Surgical removal and biopsy	If imaging suggests malignancy, surgical removal is necessary for a definitive diagnosis and treatment plan.

Seeking Medical Guidance

Given the wide range of potential causes, it is essential to consult with a healthcare provider for any unexplained pelvic mass or persistent symptoms. While many masses are benign and resolve without intervention, some, like an ectopic pregnancy or cancer, can be life-threatening. A proper diagnosis from a qualified professional is the only way to determine the correct course of action. If a mass is confirmed and malignancy is a concern, consulting a gynecologic oncologist, who specializes in reproductive system cancers, is highly recommended. For further information on adnexal masses and related conditions, you can consult a trusted medical resource like the Cleveland Clinic.

Conclusion

Identifying what a mass in the left pelvic area is requires a thorough medical evaluation. The causes are diverse, ranging from harmless, fluid-filled ovarian cysts to more serious or emergency conditions. The presence of a pelvic mass is not always cause for alarm, as many are benign. However, for an accurate diagnosis and the right treatment plan, it is crucial to seek professional medical advice and to not ignore persistent or severe symptoms.

Frequently Asked Questions

No, most pelvic masses are not cancerous. Common benign causes include ovarian cysts, fibroids, and endometriosis. However, a doctor must evaluate the mass to rule out malignancy, especially if imaging shows complex or solid features.

A simple pelvic mass is typically a fluid-filled cyst with thin walls, like a water balloon. A complex mass has thicker fluid, solid areas, or multiple compartments. Simple masses are generally benign, while complex masses may require closer monitoring or further testing to investigate the potential for cancer.

Common gynecological causes include ovarian cysts, uterine fibroids, endometriosis (tissue outside the uterus), ectopic pregnancy, and tubo-ovarian abscesses (infections).

Non-gynecological causes for a mass in the left pelvis include intestinal issues like diverticulitis, problems with the urinary system (bladder or kidney), or less commonly, vascular abnormalities. A medical evaluation will determine the origin.

You should see a doctor for any new or persistent pelvic pain, bloating, pressure, or changes in urination or bowel habits. Immediate medical care is necessary for severe, sudden pain accompanied by nausea, vomiting, or fever.

Diagnosis typically involves a physical and pelvic exam, followed by imaging tests such as a transvaginal ultrasound, CT scan, or MRI. A pregnancy test is also standard for women of childbearing age.

Treatment varies based on the underlying cause. Options can range from watchful waiting and monitoring for benign masses to medication, or surgical removal for symptomatic, growing, or suspicious masses. In an emergency like an ectopic pregnancy, immediate intervention is required.