Ovarian Torsion: Adnexal Rotation, Ischaemia, and Ovarian Necrosis
Ovarian torsion is an acute gynaecological emergency in which the ovary, often with the fallopian tube, twists around its supporting ligaments. This torsion compromises venous and lymphatic outflow and, if unresolved, arterial inflow, leading to progressive ovarian ischaemia and potential tissue necrosis. The onset of ovarian torsion pain is often sudden and severe, yet imaging can be misleading early. Rapid intervention is essential to preserve ovarian viability.
What You Need to Know
Ovarian torsion occurs when the ovary, often together with the fallopian tube, rotates around its supporting ligaments, twisting the vascular pedicle. The ovary is normally mobile to allow physiological movement during the menstrual cycle, but this mobility also creates susceptibility to rotation, particularly when ovarian size or weight is increased. Torsion initially obstructs venous and lymphatic outflow, leading to rapid congestion and swelling within the ovary. As the ovary enlarges within a confined space, pressure rises and further tightens the twist.
Progressive oedema compromises arterial inflow, sharply reducing oxygen delivery to ovarian tissue. The ovary has limited tolerance for ischaemia, and cellular energy failure develops quickly once arterial supply is impaired. Without timely detorsion, ischaemia progresses to infarction and irreversible tissue necrosis, resulting in loss of ovarian function. Pain and systemic symptoms arise from acute vascular compromise and tissue injury rather than from infection or slow inflammatory change.
Several interrelated mechanisms explain the urgency of ovarian torsion:
Venous obstruction causes rapid ovarian congestion and swelling
Rising tissue pressure worsens arterial compromise and accelerates ischaemia
Prolonged hypoxia leads to necrosis and loss of endocrine and reproductive function
Ovarian torsion is therefore a surgical emergency defined by time-dependent vascular injury. Delay in intervention allows progression from potentially reversible ischaemia to permanent ovarian damage, with implications for fertility, hormonal function, and systemic inflammatory response if necrotic tissue persists.
Beyond the Basics
Anatomical predisposition and mechanical instability
The ovary is suspended within the pelvis by the infundibulopelvic ligament and the utero-ovarian ligament, structures that provide support while allowing physiological mobility. This balance between fixation and movement becomes unstable when ovarian size or weight increases. Ovarian cysts, masses, or hormonally driven enlargement shift the centre of gravity of the ovary, increasing rotational torque on its supporting ligaments. Even in the absence of pathology, torsion can occur in younger individuals due to greater ligamentous laxity, meaning excessive mobility rather than abnormal anatomy alone predisposes to rotation.
Venous and lymphatic obstruction
Torsion first affects venous and lymphatic drainage because these vessels have thin walls and low intraluminal pressure. Arterial inflow may initially continue, creating a mismatch between blood entry and exit from the ovary. As blood and lymph accumulate, the ovary becomes congested and oedematous, and intratissue pressure rises. This swelling tightens the twist in the vascular pedicle, further impairing outflow and progressively worsening vascular compromise. The process reinforces itself, allowing rapid deterioration even without further rotation.
Arterial compromise and ischaemia
As intratissue pressure continues to increase, arterial inflow becomes restricted. Oxygen delivery falls abruptly, forcing ovarian cells into anaerobic metabolism with rapid depletion of ATP. Ovarian tissue has limited tolerance for hypoxia, and cellular dysfunction develops quickly once arterial compromise occurs. This explains the sudden escalation of pain and why the window for ovarian salvage is narrow. Continued arterial restriction leads to widespread ischaemic injury rather than gradual functional decline.
Cellular injury and necrosis
Prolonged ischaemia disrupts mitochondrial function, membrane integrity, and intracellular ion balance within ovarian cells. When hypoxia is sustained, injury progresses beyond reversible dysfunction and cells undergo necrosis rather than programmed cell death. Necrotic tissue releases inflammatory mediators that intensify pain and may provoke systemic inflammatory responses. Once infarction occurs, ovarian tissue cannot recover, and surgical removal becomes necessary to prevent further complications.
Intermittent torsion and diagnostic complexity
In some cases, partial twisting of the adnexa may spontaneously resolve, producing episodic pain with periods of apparent recovery. Intermittent torsion can preserve some blood flow between episodes, leading to misleading imaging findings and delays in diagnosis. Despite temporary symptom resolution, repeated torsion events cause cumulative ischaemic injury and increase the likelihood of progression to sustained torsion. This pattern explains why normal or fluctuating blood flow on imaging does not reliably exclude torsion.
Reperfusion injury
Restoration of blood flow following detorsion, whether spontaneous or surgical, may paradoxically worsen tissue injury. Reintroduction of oxygen generates reactive oxygen species and activates inflammatory pathways that extend cellular damage beyond that caused by ischaemia alone. Reperfusion injury contributes to postoperative pain, oedema, and impaired ovarian function even when the ovary is salvaged. Final tissue viability therefore depends on both the duration of vascular compromise and the biological response to reperfusion.
Clinical Connections
Ovarian torsion most often presents with sudden onset unilateral pelvic pain that is severe and persistent, frequently accompanied by nausea and vomiting due to visceral ischaemia rather than peritoneal inflammation. Pain may radiate to the back or thigh and can appear disproportionate to abdominal or pelvic examination findings, particularly early in the course. The ovary may remain mobile and non-peritonitic despite significant vascular compromise, which contributes to diagnostic uncertainty and delays when symptoms are attributed to less urgent causes of pelvic pain.
Several features help link the clinical picture to the underlying vascular mechanism:
Abrupt, severe unilateral pain driven by venous congestion and rising intratissue pressure
Nausea and vomiting reflecting autonomic response to acute ischaemia
Variable or intermittent symptoms when torsion partially resolves and recurs
Diagnosis is therefore clinical rather than purely radiological. Doppler ultrasound may demonstrate preserved or intermittent arterial flow because venous and lymphatic obstruction precede arterial compromise, or because the ovary untwists transiently. Reliance on imaging alone risks false reassurance while ischaemic injury continues. When torsion is suspected, timely surgical exploration is required to directly assess adnexal viability and relieve vascular compromise.
Management is focused on restoring perfusion before progression to infarction. Early detorsion can preserve ovarian endocrine and reproductive function, even when the ovary appears congested or discoloured intraoperatively. Delay allows ischaemia to progress to necrosis, increasing the likelihood of oophorectomy and long-term consequences for fertility and hormonal health. The urgency of intervention reflects the time-dependent nature of vascular injury rather than the severity of examination findings or imaging results.
Concept Check
Why are venous and lymphatic vessels affected before arterial supply in ovarian torsion?
How does ovarian swelling worsen vascular compromise?
Why can imaging appear normal in early or intermittent torsion?
How does prolonged ischaemia lead to ovarian necrosis?
Why is ovarian torsion considered a time-critical emergency?