Paraovarian cysts are fluid-filled sacs that develop near the ovaries or fallopian tubes. These cysts are typically benign and do not require immediate treatment unless they grow very large or cause complications. Although sometimes mistaken for ovarian cysts due to their proximity, paraovarian cysts are structurally distinct and do not arise from the tissue of the ovary itself. They account for a notable percentage of masses found in the pelvic area, making them a common finding during a person’s reproductive years.
Defining Paraovarian Cysts
A paraovarian cyst is an epithelium-lined, fluid-filled sac located in the adnexa, the region containing the ovaries and fallopian tubes. The term “paraovarian” literally means “beside the ovary,” accurately describing its position within the broad ligament, the protective sheet of tissue covering the reproductive organs. It is also frequently referred to as a paratubal cyst because of its close association with the fallopian tube.
The location within the broad ligament, specifically the mesosalpinx, means the cyst is completely separate from the ovarian tissue. This distinction is significant because the cyst does not originate from the hormone-responsive cells of the ovary, unlike true ovarian cysts. These structures typically present as simple, thin-walled sacs filled with clear, serous fluid.
Paraovarian cysts vary widely in size, though most commonly measure between 1 and 8 centimeters in diameter. In rare instances, they can grow substantially larger, sometimes exceeding 20 centimeters. These cysts are overwhelmingly non-cancerous, and their discovery usually indicates a benign condition.
Etiology and Associated Factors
The origin of paraovarian cysts is linked to developmental remnants from before birth, specifically from structures involved in the embryonic urogenital system. These cysts arise from residual tissues within the broad ligament left over during fetal development. The two primary embryonic structures implicated are the Wolffian, or mesonephric, ducts and the Müllerian, or paramesonephric, ducts.
The Müllerian ducts are the precursors that eventually form the uterus, fallopian tubes, and the upper part of the vagina in a female. Cysts arising from these remnants are the most common source of paraovarian cysts. The Wolffian ducts are precursors to the male reproductive system, which normally regress in females, but their remnants can persist and form a cyst.
Because they originate from these congenital remnants, paraovarian cysts are not considered an acquired condition like many functional ovarian cysts. While they can occur at any age, they are most frequently diagnosed in individuals during their reproductive years, generally between the ages of 20 and 40.
Diagnosis and Symptom Presentation
Most paraovarian cysts are asymptomatic and are discovered incidentally during a pelvic examination or imaging performed for other health concerns. When symptoms do occur, they are generally related to the cyst’s size, as a large mass can exert pressure on nearby organs.
The patient may experience a feeling of abdominal pressure, a sense of fullness, or intermittent pelvic pain. If the cyst is large enough, it can press on the bladder, leading to increased urinary frequency, or press on the bowel, causing constipation. These pressure-related symptoms are the most common indicators that a cyst is growing.
The primary diagnostic tool used is a pelvic ultrasound, which utilizes sound waves to create images of the pelvic organs. On ultrasound, the cyst usually appears as a simple, thin-walled, fluid-filled structure. A skilled radiologist can accurately distinguish a paraovarian cyst from a true ovarian cyst by visualizing that the structure is separate and distinct from the ovary.
In complicated cases, or when the imaging findings are uncertain, further studies such as a computed tomography (CT) scan or magnetic resonance imaging (MRI) may be used. An acute onset of severe pain, fever, and vomiting may indicate a complication, such as torsion, which requires immediate medical evaluation.
Management and Surgical Options
The standard approach for managing paraovarian cysts depends on their size, the presence of symptoms, and their imaging characteristics. For small, asymptomatic cysts, a management strategy known as “watchful waiting” or surveillance is generally recommended. This involves monitoring the cyst over time with repeat pelvic ultrasounds to ensure it remains stable.
Surgical intervention is typically reserved for cysts that are large, symptomatic, or have features suggesting a potential complication. Cysts exceeding 5 to 10 centimeters in diameter are considered for removal to prevent complications. Surgery is also indicated if a person experiences persistent pain, or if imaging reveals features like solid components or growths within the cyst.
The most common surgical method is minimally invasive laparoscopy, which involves making small incisions and using a camera and specialized instruments to remove the cyst. The goal of the procedure, called a cystectomy, is to carefully separate the cyst from the ovary and fallopian tube while preserving the health and function of those structures. In some instances, such as with very large cysts or in emergency situations, a traditional open procedure called a laparotomy may be necessary.
A serious, though uncommon, complication is torsion, where the cyst twists on its stalk, cutting off its blood supply. Torsion causes sudden, excruciating abdominal pain and requires emergency surgery to remove the cyst. Because the cyst is separate from the ovary, the prognosis after surgical removal is excellent, with a low chance of recurrence.