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Ovarian torsion refers to the complete or partial rotation of the ovary on its ligamentous supports, often resulting in ischaemia.

Ovarian Torsion is a true gynaecological emergency that requires urgent surgical intervention to prevent ovarian necrosis. 

The fallopian tube often twists along with the ovary; when this occurs, it is referred to as adnexal torsion or tubo-ovarian torsion.

The condition can be acute, intermittent or sustained (i.e chronic)

Ovarian torsion is a difficult diagnosis to make.

US, CT or MRI scanning can assist in diagnosis, but ovarian torsion may ultimately have to be a clinical diagnosis in the first instance, based on the nature of the clinical presentation, the age group and known risk factors. 

A definitive diagnosis of ovarian torsion can only be made by direct visualization of a rotated ovary at the time of surgical evaluation, by either laparoscopy or laparotomy.

Timely laparoscopic evaluation with the aim of preservation of ovarian function and prevention of potentially serious complications is the cornerstone of treatment.

Mortality resulting from ovarian torsion is rare.

Epidemiology

Ovarian torsion is an uncommon but important condition.

The majority of cases occur in young women of reproductive age of around 25 – 35 years.

However, it can occur in all age groups, with a significant proportion of cases being seen in premenarchal, postmenopausal, and pregnant patients.

Pathology

Ovarian torsion refers to the complete or partial rotation of the ovary on its ligamentous supports, often resulting in ischemia.

This can be acute, intermittent or sustained, (i.e chronic).

Torsion results in compression of the ovarian vasculature, initially reducing lymphatic and venous outflow. Lymphatic and venous outflow are compromised first due the thinner, more compressible walls of those vessels.

Arterial perfusion with blocked venous outflow results in edema and ovarian enlargement, further worsening compression of the vasculature, eventually leading to impaired arterial inflow with resulting ischemia, and necrosis of the ovary.

The mobility of the left ovary tends to be limited somewhat by the sigmoid colon, hence about two thirds of adnexal torsions are right sided.

Causes:

Torsion of a normal ovary/ adnexa is uncommon, and it is usually the result of an underlying risk factor.

Torsion may occasionally occur however in patients with no apparent underlying risk factor, particularly in premenarchal girls.

Recognized risk factors include:

1.         Developmental abnormalities leading to hypermobility of the ovary (< 50 % of     cases).

●          Here there is an excessively long fallopian tube or an absent mesosalpinx   that can predispose to torsion.

            It may be seen in younger girls/ even children.         

2.         Adnexal mass lesions (approximately 50 – 80 % of cases).

These may be:

●          Ovarian tumours:

These may be:

♥          Benign (such as dermoid cysts)

♥          Malignant

Malignant tumours are less likely to undergo torsion due to the presence of cancerous adhesions that fix the ovary to the surrounding structures.

Thus, tumours that have undergone torsion are most likely to be benign, with dermoid tumours the most commonly implicated.

●          Ovarian physiologic cysts.

●          Polycystic ovaries

●          Paraovarian cysts

♥          A paraovarian cyst may be associated with ovarian or tubal torsion             or a paratubal cyst may tort around its own pedicle.

As the size of the ovarian mass increases, the risk of torsion increases, until the mass becomes large enough to be fixed in place in the pelvis.

Mass lesions that are between 5-10 cm appear to be most at risk of torting.

3.         Pregnancy:

●          Enlarged corpus luteum cysts and the laxity of supporting structures in       pregnancy can predispose to torsion.

The rate of torsion increases by 5 times during pregnancy.

The corpus luteum regresses in the second trimester, hence the risk of torsion is greatest in the first trimester and decreases thereafter.

4.         Assisted conception:

●          The induction of ovulation during infertility treatment can lead to ovarian             hyperstimulation syndrome and expansion of the ovarian volume thus         predisposing to torsion.

5.         Previous pelvic surgery:

●          Previous pelvic surgery, especially tubal ligation, can have an increased   risk of torsion, possibly via adhesions, although the exact mechanism for            this remains unclear.

6.         A history of a prior ovarian torsion

7.         Strenuous activity:

●          Some data suggest that ovarian torsion may occur following strenuous       exercise or a sudden increase in abdominal pressure.

Complications:

Complications include:

1.         Ovarian loss with necrosis:

The end result of the vascular compromise of ovarian torsion is hemorrhagic infarction and necrosis.

            In severe cases infarction can occur within hours of torsion onset.  

            Spontaneous de-torsion has been reported.

A necrotic ovary can become infected and cause:

2          A local abscess

3.         Generalized peritonitis.

4.         Hemorrhage, (though this is not usually severe).

In the longer term:

5.         Impaired fertility:

●          The necrotic tissue will involute over time, but there may be secondary      pelvic adhesion formation, which can result in chronic pelvic pain or infertility.

●          Unrecognized tubal torsion will result in loss of tubal function, and likely hydrosalpinx or necrosis with eventual resorption of the damaged tissue.

Clinical features

Diagnosis of ovarian torsion can be extremely difficult. When the presentation is “classical” the diagnosis is readily considered, however, presentations are frequently not classical.

The classic presentation of ovarian torsion involves:

●          Nausea and vomiting

          Sudden onset of severe, unilateral, lower abdominal / pelvic pain

●          A woman of reproductive age.  

●          The presence of a risk factor such as an ovarian mass or prior ovarian torsion

Many presentations, however are not “typical”.

Important points of History:

1.         Pain (by far the most common presenting problem).

            ●          Moderate to severe lower abdominal/ pelvic in around 90% of cases

                        However, in up to 10% of cases the condition can be relatively painless.  

●          Sudden onset.

♥          However, only around 50% of cases will present with sudden         onset of severe pain.

            The condition can be intermittent or sustained.

Sometimes the patient may therefore describe recurrent episodes of pain over the course of hours, days, or even weeks, if the ovary has been torting intermittently.

●          Unilateral (though not invariably).

2.         Nausea and vomiting

          In around 70% of cases, however around 30% do not have nausea or          vomiting. 

3.         Frequently the patient will also have a recognized risk factor, but in some cases     there will be no recognized risk factor.

Important points of Examination:

1.         Observations:

●          Necrosis of the ovary may lead to late systemic findings such as pyrexia, tachycardia and hypotension.

2.         Abdominal examination

●          Typically, unilateral tenderness, however findings may be surprisingly       minimal. 

●          Signs of frank peritonism are more ominous, and indicate possible           infarction / peritonitis.  

3.         PV:

●          There may be adnexal tenderness or the possible suggestion of a mass,       however, this examination is invasive and probably pointless when            imaging is to be undertaken. 

Investigations

US, CT or MRI scanning can assist in diagnosis, but ovarian torsion may ultimately have to be a clinical diagnosis in the first instance, based on the nature of the clinical presentation, the age group and known risk factors. 

A definitive diagnosis of ovarian torsion can only be made by direct visualization of a rotated ovary at the time of surgical evaluation, by either laparoscopy or laparotomy.

Blood tests:

1.         FBE:

          An elevated white cell count is commonly seen, but is a nonspecific           finding and of limited value.

2.         CRP:

A significantly elevated level suggests:

●          A severe complication such as necrosis / secondary infection 

●          A possible alternate diagnosis, such as appendicitis.

3.         U&Es/ glucose:

●          Electrolyte disturbances may be seen in cases where there has been            persistent vomiting.

4.         Beta HCG:

            Beta-HCG should be done in all cases to exclude:

            ●          A concomitant pregnancy

            ●          A ruptured ectopic pregnancy (as an important differential diagnosis).

Ultrasound

Ultrasound is currently considered the first line imaging modality for the evaluation of ovarian torsion.

It may make the diagnosis; however, it cannot definitely exclude it. 

The preferred method is a trans-vaginal ultrasound.

The next best option – in particular for children – is a transabdominal ultrasound, preferably with a full bladder, (however there should not be excessive delays in attempting to achieve a full bladder).

Ultrasound features of ovarian torsion include:

1.         Ovarian tenderness to transducer pressure.

2.         An enlarged hypo or hyperechoic ovary:

●          The main feature of torsion is ovarian enlargement.

            This is due to venous/ lymphatic engorgement, oedema and hemorrhage. 

3.         A long-standing infarcted ovary may have a more complex appearance with        cystic or hemorrhagic degeneration

4.         Abnormally placed ovary:

●          The normal location of the ovaries is lateral to the uterus, but in torsion,     they may be located more towards the midline.

5.         A “string of pearls” sign

●          Here ovarian follicles are seen to be congregated around the periphery of the ovary, (hence “string of pearls”).

6.         Free pelvic fluid:

            ●          Seen in > 80 % of cases.

7.         An underlying ovarian lesion:

            ●          A possible lead point for torsion.

●          An ovarian mass causing the torsion must always be looked for.

On Doppler ultrasound:

Doppler findings in torsion can be widely variable, but the following may be seen:

1.         Blood flow abnormalities:

            ●          Little or no intra-ovarian venous flow (common)

            ●          Absent arterial flow (less common, but poor prognostic sign)

            ●          Absent or reversed diastolic flow

Note that the absence of ovarian Doppler flow is highly specific for torsion, however normal Doppler flow does not completely exclude torsion.

Normal vascularity does not exclude intermittent torsion.

Normal Doppler flow can also occasionally be found due to a dual blood supply from both the ovarian and uterine arteries

2.         A “whirlpool sign” of a twisted vascular pedicle:

●          The whirlpool sign, is seen when a structure twists on itself.

It is most commonly described with regard to bowel rotating around its mesentery, with mesenteric vessels creating the whirls but is also seen in cases of ovarian torsion.

It appears as a twisted vascular pedicle.

right sided ovarian torsion radiopedia rID 30458
Right sided ovarian torsion. Radiopaedia rID 30458
CT scan:

If ultrasound examination is inconclusive, then a CT scan with contrast, of the abdomen and pelvis, can be done if clinical suspicion remains high.

CT scan is both highly specific and sensitive.

A CT scan with contrast can essentially rule out an ovarian torsion if normal ovary/adnexa is seen.

It is also useful in situations where US is not available in an appropriately timely manner

It is also helpful in ruling out other possible differential diagnoses of pelvic pain.

Highly suggestive signs of ovarian torsion include:

1.         Reduced or absent ovarian enhancement with contrast

2.         Peripherally displaced follicles

3.         Enlarged ovary with a follicular ovarian stroma

4.         A thickened fallopian tube with target/beak-like appearance.

Features that are not specific but may suggest torsion include:

1.         Periovarian fat stranding

2.         Adnexal wall thickening

3.         Free pelvic fluid

4.         Ovarian mass or enlargement

5.         Ovarian displacement towards the uterus or uterine deviation towards the torted ovary.

twisted ovarian pedicle radiopedia rID 28265
twisted ovarian pedicle. Radiopaedia rID 28265

MRI:

MRI remains an imaging option, when CT scan is unavailable or if there is a genuine contraindication to IV contrast

Note, however, that MRI is not the modality of choice if torsion is suspected, as urgent imaging is required.

MRI findings consistent with ovarian torsion include an enlarged, edematous ovary in an abnormal location and, with contrast enhancement, the coiled ovarian vessels may be visualized with the “whirlpool” sign.

Laparoscopy / laparotomy:

Ultimately if all imaging remains inconclusive, and yet clinical suspicion nonetheless remains high, laparoscopy (or laparotomy) remains the final option for definitive diagnosis.   

Management

Ovarian torsion is a gynecological emergency requiring urgent surgery to prevent ovarian necrosis. 

1.         Analgesia:

●          Pain is usually moderate to severe and titrated IV opioids will be required.

2.         Fluid resuscitation:

●          The patient is kept nil orally in anticipation of surgery.

●          Fluid resuscitation may be required for significant vomiting.

●          Rarely blood products may be required if there has been significant            hemorrhage.

3.         Antibiotics:

●          These may be required for late presentations complicated by infection.

4.         Surgery:

●          Minimizing ischemic time is vital, however, the time to necrosis in             ovarian torsion remains unclear based on the current literature.

Since venous and lymphatic flow are affected first, patients may have symptoms for a significant period of time before arterial flow is affected.

Critical ischemic time would also depend in whether the ovarian ischemia was partial or total.

In general terms, ovarian salvage rates decrease with increasing ischemic times, and so once the diagnosis is made (or strongly suspected), operation becomes urgent.

While there is no absolute cutoff to ensure viability, some studies have indicated that the best outcomes are achieved if the ovary is detorted within 8 hours, however viability will depend on the degree of ischemia as well as the time passed.

Ovarian salvage has been documented up to 36 hours in pediatric patients.

The important point is surgical intervention as soon as the diagnosis is made or strongly suspected.


References

FOAMed

Publications

Fellowship Notes

Dr Jessica Hiller LITFL Author

Doctor at Sir Charles Gairdner Hospital in Western Australia. Graduated from Curtin University in 2023 with a Bachelor of Medicine, Bachelor of Surgery. I am passionate about Obstetrics and Gynaecology, with a special interest in rural health care.

Physician in training. German translator and lover of medical history.

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