Ovarian torsion, also known as adnexal torsion, occurs when the ovary, and often the accompanying fallopian tube, twists completely or partially around the ligaments that support it. This twisting action constricts the blood vessels traveling through the pedicle, the structure attaching the ovary to the pelvic wall, leading to a disruption of blood flow. The condition is considered a time-sensitive surgical emergency because the resulting lack of blood supply can cause tissue death, or ischemia. This article details how frequently ovarian torsion occurs and outlines its anatomical and clinical factors.
Statistical Reality: How Often Does Ovarian Torsion Occur?
Compared to common gynecological conditions, ovarian torsion is relatively infrequent in the general population, affecting approximately 6 out of every 100,000 women each year. It is recognized as the fifth most common gynecologic surgical emergency, accounting for about 3% of all acute gynecologic emergencies presenting to hospitals.
The incidence increases significantly among patients undergoing surgical treatment for ovarian masses. Between 2% and 15% of individuals requiring surgery for an adnexal mass are found to have ovarian torsion. Although the overall risk is low, the condition is a frequent cause of acute pelvic pain necessitating immediate surgical intervention. Ovarian torsion occurs most often during the reproductive years, though it can affect females of any age.
Anatomical Basis and High-Risk Factors
The mechanism of torsion involves the ovary rotating around its vascular pedicle. Once the ovary twists, the veins are typically compressed first, causing blood to pool in the ovary, leading to swelling and edema. If the twisting continues, the arterial blood supply is eventually cut off, resulting in tissue death from ischemia.
The primary factor driving risk is any anatomical change that increases the ovary’s size or mobility. Ovarian masses, such as benign cysts or tumors, are implicated in 50% to 60% of torsion cases because they destabilize the organ. The risk is particularly elevated when an ovarian mass measures 5 centimeters or larger, as this size provides a leverage point for twisting. Pregnancy is also a known risk factor, accounting for about 20% of cases, often due to hormonal laxity of supporting ligaments and enlarged corpus luteum cysts.
Other factors include prior pelvic surgery, which can create adhesions that serve as a fixed point for the pedicle to rotate around. The use of fertility treatments, which stimulate the ovaries to produce multiple follicles and cysts, also increases the likelihood of torsion. In younger patients, torsion can sometimes occur even with a normal-sized ovary, possibly due to naturally elongated ovarian ligaments or excessively long fallopian tubes.
Recognizing the Medical Emergency
Ovarian torsion typically presents with a sudden onset of severe, sharp pain localized to one side of the lower abdomen or pelvis. This intense pain is often accompanied by nausea and vomiting, which occurs in a majority of patients and can complicate the diagnosis. The pain may not always be constant; in cases of partial torsion, the ovary may twist and then untwist spontaneously, causing intermittent waves of pain.
Diagnosis begins with a strong clinical suspicion, especially when a patient reports sudden and severe pain. The initial imaging study of choice is an ultrasound, typically performed with Doppler flow studies, to evaluate the size of the ovary and assess blood flow. While the absence of blood flow is a strong indicator of torsion, normal flow does not entirely rule out the condition due to the ovary’s dual blood supply.
Surgical intervention is the definitive method for both diagnosis and treatment, and it must be performed quickly to preserve the ovary’s function. The goal of surgery, usually performed laparoscopically, is to untwist the ovary, a procedure called detorsion. If the tissue has been deprived of blood flow for too long and is necrotic, removal of the ovary and tube (oophorectomy) may be necessary to prevent further complications.