A paratubal cyst is a fluid-filled sac that forms in the adnexa, the region adjacent to the uterus, specifically located near the fallopian tube or between the fallopian tube and the ovary. These masses are frequently called paraovarian cysts because of their close proximity to the ovary, but they do not arise from the ovarian tissue itself. They are almost always benign and typically remain small and asymptomatic. Understanding the origin and size of these cysts is how clinicians determine the level of clinical risk and the appropriate management strategy.
Defining Paratubal Cysts and Their Origin
Paratubal cysts originate from remnants of embryonic structures that normally regress during fetal development. Specifically, they are thought to arise from the mesonephric (Wolffian) or paramesonephric (Müllerian) ducts, which are precursors to the male and female reproductive organs, respectively. Remnants of either structure can persist in the broad ligament, the tissue that supports the uterus, ovaries, and fallopian tubes.
The formation of these vestigial remnants, such as the hydatid cysts of Morgagni, occurs between the folds of the broad ligament. These cysts are a relatively common finding, constituting approximately 10% of all masses discovered in the adnexal region. Because most paratubal cysts are small, ranging from 2 millimeters to 2 centimeters, they often cause no symptoms and are discovered incidentally during imaging for unrelated concerns. Symptoms typically only arise when the cyst enlarges significantly or when a complication such as twisting occurs, causing non-specific pelvic pain or a feeling of pressure in the lower abdomen.
Interpreting Cyst Size and Clinical Risk
The size of a paratubal cyst is the primary factor used by healthcare providers to assess risk and guide clinical decisions, as there is no single, standardized “size chart” publicly available. Size is directly correlated with the probability of complications like adnexal torsion or mass effect. Torsion is a specific medical emergency where the cyst twists on its stalk, potentially cutting off blood supply to the fallopian tube and ovary, causing acute, severe pain.
Small Cysts
Cysts measuring less than 5 centimeters in diameter carry a low risk of complications. Many paratubal cysts begin at less than 1 centimeter and may regress spontaneously, often requiring no formal follow-up. The risk of a small cyst causing torsion or rupture is minimal, making them suitable for a watchful waiting approach.
Medium Cysts
Cysts between 5 and 10 centimeters necessitate closer monitoring, as the risk of complications increases. Cysts in this size range have a greater potential to cause intermittent pelvic discomfort or undergo torsion due to their increased mass. Physicians often discuss the possibility of surgical removal at this threshold, especially if the patient is symptomatic or if the cyst shows rapid growth on follow-up scans.
Large Cysts
A cyst that exceeds 10 centimeters is considered large and significantly increases the risk of complications. The mass can produce mass effect symptoms, causing pressure on nearby organs like the bladder or bowels, which may lead to frequent urination or constipation. The risk of adnexal torsion is elevated at this size, making surgical intervention a strong consideration regardless of the patient’s symptoms.
Giant Cysts
In rare instances, a paratubal cyst can exceed 15 centimeters in diameter. These “giant” cysts present the highest risk profile due to their potential to cause severe compressive symptoms and acute torsion. Management of these very large cysts is almost always surgical to prevent complications and alleviate pressure on surrounding pelvic anatomy.
Management and Treatment Options
The management of a paratubal cyst is based entirely on its size, the presence of symptoms, and any signs of potential complications. For the vast majority of patients with small, asymptomatic cysts, the recommended approach is watchful waiting. This protocol involves periodic transvaginal or pelvic ultrasounds, often scheduled every six to twelve months, to monitor the cyst’s size and characteristics. The goal of this non-operative management is to confirm that the cyst remains stable and does not develop features that suggest a higher risk, such as solid components or rapid enlargement.
Surgical intervention is recommended when the cyst is consistently associated with severe pain, has caused an acute complication like torsion, or exceeds 10 centimeters. The procedure of choice is usually a minimally invasive laparoscopic cystectomy, which involves removing the cyst through small incisions in the abdomen. This approach is preferred because it allows for a faster recovery and minimizes scarring.
During the surgery, the primary objective is to carefully separate the cyst from the fallopian tube and ovary, preserving these structures to maintain fertility. For cysts under 3 centimeters, a surgeon may opt for simple puncture and drainage followed by coagulation of the cyst wall, rather than full removal. Open surgery, or laparotomy, is reserved for extremely large or complicated cysts where a minimally invasive approach is not feasible.