Ovarian Torsion

Introduction

Ovarian torsion is the rotation of the ovary, often together with the fallopian tube (adnexal torsion), around its supporting ligaments (the infundibulopelvic and utero-ovarian ligaments), which compromises its blood supply.¹ It is a gynaecological emergency: the longer the ovary remains twisted, the greater the risk of irreversible ischaemic necrosis and loss of the ovary.

Torsion accounts for a small but important proportion of women presenting with an acute abdomen, and should be actively considered in any woman or girl with sudden-onset unilateral pelvic pain, alongside ectopic pregnancy and appendicitis. It can occur at any age, including in prepubertal girls, where a normal ovary can twist even without a mass present.

Pathophysiology

As the ovary rotates on its vascular pedicle, the thinner-walled, lower-pressure veins and lymphatics are compressed first, while the thicker-walled artery often continues to deliver some blood initially. This causes venous congestion and lymphatic obstruction, leading to progressive oedema and enlargement of the ovary - which in turn increases the degree of twist and tension on the pedicle.¹

As swelling progresses, arterial inflow eventually becomes compromised too, causing ischaemia and, if untreated, infarction and necrosis of the ovary (and tube, if involved). Because venous compromise typically precedes arterial compromise, the ovary can appear congested and dusky rather than frankly dead even after several hours of torsion, and often remains salvageable if promptly detorted - this is the rationale for a strong bias towards ovarian conservation at surgery.

Risk factors

• Ovarian mass, especially over 5 cm: the single strongest risk factor - dermoid cysts (mature cystic teratomas) are classically implicated due to their weight and heterogeneous, sometimes eccentric content
• Pregnancy (the corpus luteum of pregnancy enlarges the ovary, and ovarian mobility increases as the uterus enlarges)
• Ovulation induction/assisted reproduction (ovarian hyperstimulation enlarges the ovaries)
• Reproductive age, though torsion of a normal ovary is more common in children and adolescents, in whom the utero-ovarian ligament is relatively longer and more mobile
• Previous torsion (recurrence risk, particularly if the predisposing anatomy persists)

Clinical features

The classic presentation is sudden-onset, severe, unilateral iliac fossa or pelvic pain, often with nausea and vomiting out of proportion to what might be expected from the pain alone - a pattern that mirrors testicular torsion and reflects visceral peritoneal irritation.²

• Sudden, severe unilateral pelvic or lower abdominal pain
• Pain that may be colicky or intermittent if the ovary partially detorts and retorts spontaneously ('twist and untwist')
• Nausea and vomiting, often prominent
• Low-grade fever may develop as ischaemia progresses
• History of a known ovarian cyst, recent ovulation induction, or pregnancy
• Tenderness, sometimes with a palpable adnexal mass and guarding, on abdominal and pelvic examination

Differential diagnosis

• Ectopic pregnancy: always perform a pregnancy test first
• Ruptured or haemorrhagic ovarian cyst: can mimic torsion closely
• Appendicitis: particularly for right-sided pain
• Pelvic inflammatory disease / tubo-ovarian abscess
• Renal colic: flank pain radiating to the groin
• Degenerating fibroid

Investigations

Bedside

Pregnancy test in every woman of reproductive age presenting with acute pelvic pain, urinalysis to help exclude a urinary cause, and basic observations to assess for systemic upset.

Bloods

Full blood count and CRP (may show a mild leucocytosis and raised inflammatory markers as ischaemia progresses, though these are non-specific and can be normal early on), and group and save if surgery is likely.

Transvaginal ultrasound with Doppler

The first-line imaging test. Typical findings include an enlarged, oedematous ovary (often significantly larger than the contralateral side), free pelvic fluid, and peripherally displaced follicles ('string of pearls' sign from oedema pushing follicles to the ovarian periphery). The 'whirlpool sign' - a twisted, coiled appearance of the vascular pedicle on colour Doppler - is a specific finding when present.³

Diagnostic laparoscopy

The definitive investigation, allowing direct visualisation of the twisted adnexa and immediate treatment in the same procedure. If clinical suspicion is high, diagnostic laparoscopy should not be delayed while awaiting ultrasound, particularly out of hours - imaging supports the decision but should not hold up surgical review when the diagnosis is strongly suspected clinically.

Management

Ovarian torsion is a surgical emergency. Analgesia and antiemetics are given while arranging urgent gynaecological review and theatre.¹

Laparoscopic detorsion

The ovary (and tube, if involved) is untwisted at laparoscopy. Even if the ovary appears dusky, blue-black or congested, current practice strongly favours conservative management with detorsion alone rather than removal, because the ovary frequently regains normal colour and function within minutes of being untwisted, and appearance at the time of surgery correlates poorly with eventual viability.⁴

Cystectomy

If an underlying cyst is the cause, it is typically removed (cystectomy) at the same procedure, or at a planned interval procedure once the acute oedema has settled, to reduce the risk of recurrent torsion.

Oophorectomy

Reserved for an ovary that is clearly and irreversibly necrotic, or where malignancy is suspected. This is now a minority of cases given the shift towards conservative surgery.

Complications

• Ovarian necrosis and loss of the ovary if detorsion is delayed
• Reduced fertility if bilateral or recurrent torsion leads to loss of ovarian tissue
• Peritonitis if a necrotic ovary is not addressed
• Recurrence, particularly if a predisposing mass or anatomical laxity is not corrected
• Venous thromboembolism from a severely ischaemic, congested adnexa (rare)

Torsion in pregnancy and children

Torsion is more common in early pregnancy, when the corpus luteum is physiologically enlarged, and again as the growing uterus displaces the ovaries and increases their mobility. Diagnosis is complicated by the overlapping differential of other causes of pain in pregnancy, but the same principle applies: clinical suspicion should prompt laparoscopy without delay, which is safe to perform at any gestation.¹

In prepubertal girls and adolescents, torsion of a structurally normal ovary is relatively more common than in adults, related to a longer, more mobile utero-ovarian ligament - the absence of a mass on ultrasound should not lower suspicion in this age group.

Prognosis

With prompt detorsion, the majority of ovaries recover normal function and appearance, even after several hours of torsion, reflecting how resilient ovarian tissue is to transient ischaemia. Outcomes worsen the longer surgery is delayed, which is why torsion is managed as a time-critical surgical emergency rather than awaiting definitive imaging confirmation. Recurrence is possible, particularly if the underlying cause (a mass, or anatomical laxity of the ligament) is not addressed at the same time.