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Testicular torsion


I have long been fascinated by testicles. My first real encounter with the healthcare system took place when I was about seven years old and had to go into hospital for an orchidopexy, so I can empathize with all the young people who come through our emergency department with acute testicular pain.

This week, NCEPOD (National Confidential Enquiry into Patient Outcomes and Death) produced a much-anticipated report on how we manage acute testicular torsion in young people. They collected data over a one-year period from 635 sets of case notes, 574 clinician questionnaires, and 142 organizational questionnaires to see how we investigate and manage acute torsion and where we make mistakes.

How is the testicle formed?

The embryology of the testicle is a complex and fascinating process that begins early in fetal development and involves several key stages:

Formation of the Genital Ridge

Initially, the development of the testicles starts with the formation of the genital ridge during early embryonic development. The expression of the sex-determining region Y (SRY) gene on the Y chromosome initiates the differentiation of the indifferent gonads into testicular tissue.

Differentiation of the Testes

After the genital ridge forms, the testes undergo further differentiation. Seminiferous tubules, which will later serve as the site of sperm production, start to form. These tubules comprise various cell types, including Sertoli cells that support developing sperm cells and germ cells that eventually mature into spermatozoa. The cells that are crucial for testosterone production, the Leydig cells, located in the interstitial spaces of the testes, also form at this stage.

Descent of the Testes

The testes move from their original intra-abdominal location to the scrotum in a process involving two main phases: the transabdominal and the inguinoscrotal phases.

The transabdominal phase involves the movement of the testes from the posterior abdominal wall to the internal inguinal ring, and it is largely influenced by the gubernaculum.

The inguinoscrotal phase, which is androgen-dependent, involves the passage of the testes through the inguinal canal into the scrotum. This phase is characterized by several steps, including the formation of the processus vaginalis and the dilation of the inguinal canal, which facilitates the testicular descent.

Hormonal Regulation

The development of the testes is tightly regulated by hormones, including the gonadotropin-releasing hormone (GnRH) from the hypothalamus, which stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones are critical for testicular development and function. Testosterone, produced by Leydig cells, and anti-Müllerian hormone (AMH), secreted by Sertoli cells, also play vital roles in the development of male sexual characteristics and the inhibition of female reproductive structure development, respectively.

What is the anatomy of the testicle?

What is testicular torsion?

Testicular torsion occurs when a testicle rotates, twisting the spermatic cord that supplies blood to the scrotum. This can severely reduce blood flow, leading to sudden, intense pain and swelling. This is often associated with nausea and vomiting.

How common is testicular torsion?

The average boy in the NCEPOD cohort was 15 years old. The right testicle was more likely to undergo torsion (55.1%) than the left (43.9%). An unlucky 1% had bilateral torsion.

So, what are the findings of the NCEPOD report?

Increase public awareness

You might think that the diagnosis is obvious. The testicles are hanging outside the body, after all. But 65.7% of patients and 34.7% of parents/carers didn’t recognise the problem. This led to a delay in presentation, with only 73% of patients presenting to a healthcare worker within six hours.

Increased awareness and education may reduce embarrassment and get people talking.

Ensure pathways to minimise the need for transfers

Not every hospital has the facilities, in terms of trained staff, to manage a child with testicular torsion. 63.6% of hospitals reported that they had to transfer patients, leading to delays in definitive care.

Time is testicle

In the adult emergency department, aphorisms abound for time-based treatment targets. “Time is myocardium” encourages us to get patients to the cath lab promptly. “Time is brain” urges us to think about thrombolysis or clot retrieval in acute strokes. Time is testicle, reminding us that the sooner we get a definitive diagnosis and treatment, the more likely we are to save future generations.

One systematic review of 1283 patients showed that if you got to the operating room within 6 hours, you had a 97% chance of saving the testicle. This dropped to 79.3% by 18 hours, and if the diagnosis was delayed by more than 24 hours, the salvage rate was just 18.1%. According to Sleeman et al., every hour delay after 14 hours leads to a 4% increased risk of orchidectomy.

Directing patients to hospitals where surgery for testicular torsion can be undertaken will minimise the need for transfer and reduce the risk of delay to theatre.

Urgent senior review, decision making and operation

31.3% of patients were first seen by a junior specialist trainee. Over a quarter of patients (26.3%) had not been seen by a senior decision-maker within two hours of arrival, and 9.3% had not been reviewed by four hours.

How do you diagnose torsion?

The gold standard – the only way you will know if there is a torsion is to take a look in the operating theatre. If you read the classics, you will find many signs that are supposed to make a torsion more or less likely. These include Prehn’s sign – the absence of the cremasteric reflex on the affected side.

The cremasteric reflex

The cremasteric reflex is a superficial reflex in males, triggered by lightly stroking the inner part of the thigh. The cremaster muscle contracts, elevating the testicle on that side. This reflex requires input via sensory fibres from the ilioinguinal nerve and output via motor fibres from the genital branch of the genitofemoral nerve.

Apparently, rats also have a cremasteric reflex. Curious surgeons artificially torted the testicles of a number of anaesthetized rats and looked for a cremasteric reflex while simultaneously measuring the electrophysiological response of the genitofemoral nerve. They couldn’t confirm the absence of the reflex when twisting the testes.

What about real humans, not animals? You will never get ethical approval to do the same experiment on children. A number of case series have shown that an absent cremasteric had a sensitivity of 100% (CI 91-100%) but a specificity of 66% (59-72%). However, there are also case reports of children with torsion and active reflexes. And not every male child has a cremasteric reflex. A review of 225 normal boys by Caesar and Kaplan found that the reflex was absent in 52% of newborns and 55% of boys aged 1 to 30 months. It is fully developed by 30 months.

Where does this leave us?

Every piece of evidence pushes the needle in one direction or the other. This is the essence of Bayesian thinking. An absent cremasteric reflex gives a positive likelihood ratio of 7.9, whereas tenderness of the testicle pushes the needle a little (+ve LR 1.6). What is more useful is the lie of the testicle. A horizontal lie gives you a positive LR of 72.

These signs, plus the history, have also been thrown into a blender to try and come up with a variety of decision tools designed to rule out torsion. Unfortunately, none of these are very sensitive.

The TWIST score

The Testicular Workup for Ischemia and Suspected Torsion (TWIST) score is designed to help clinicians assess the likelihood of testicular torsion. It comprises five criteria: testicular swelling, hard testis, absent cremasteric reflex, nausea or vomiting, and a high-riding testis, with a scoring system that helps categorize the risk level of torsion.

Low risk = 0-2; Intermediate risk = 3-4; high risk = 5-7

The idea is that patients with a high score go to the operating theatre, those with a low score go home, and those in the Goldilocks zone go for imaging.

A systematic review and meta-analysis by Choudhary et al. from last year tried to unpack the score from 14 datasets with 1940 patients. 479 had confirmed torsion. Those with a confirmed torsion had a TWIST score of 5.13 (+/- 1.53). Those who did not have a torsion had an average score of 1.5 (+/-1.4). All patients with the maximum TWIST score of 7 had testicular torsion, but some of those with a score of zero also had torsion.

Using a cut-off score of 2 to rule out a torsion gives a sensitivity of 76% and a specificity of 95%. With this cut-off, 5 of 100 patients with testicular torsion would be falsely classified as low-risk.

Alternative scoring systems, like the BAL-score that use (1) pain duration less than 24 h, (2) nausea or vomiting, (3) high position of the testis, and (4) abnormal cremasteric reflex, also exist but have been little studied.

What is the role of ultrasound?

Whilst we all love to wield the ultrasound probe, its use in diagnosing torsion remains controversial. Whilst most of us have a second testicle to compare Doppler flow, it is possible to have a complete torsion with preserved flow. It is also possible for a child to have intermittent torsion – pain for a few hours that then resolves as the testicle rotates back to normal. This means that Doppler ultrasound can give false negatives (they had a torsion, but it is not seen in the US) and false positive results (identified as having a torsion when they do not).

Normal testicle buddy views with colour. The buddy view is the best place to start when performing testicular ultrasound to compare the echogenicity, size, blood flow, and position of the testicles.

Contributor: Paul Khalil, MD Nicklaus Children’s Hospital @khalil3paul
15 yo M with sudden onset testicular pain (left) and vomiting. POCUS shows decreased flow to the left testicle, consistent with torsion. he was taken immediately to the OR.

Contributor: Kathryn Pade, MD, Rady Children’s Hospital-San Diego

Current NHS guidance suggests…

In patients with a history and physical examination suggestive of torsion, imaging studies should NOT be performed.

Combining the TWIST score and Doppler ultrasound increased the percentages of torsions fund at exploration from 18% to 53%. Ultrasound seems more valuable when the symptoms have been present for over 24 hours where an alternative diagnosis is more likely.

No blood or urine test can reliably rule out testicular torsion.

How is torsion treated?

Once the scrotum has been explored, there are two options. If the testicle is viable, it is fixed in place with a stitch—an orchidopexy. This should prevent further incidents. If it is not viable, it is removed—an orchidectomy. Surgeons routinely fix the other testicle in place at the same time—just in case.

Urgent review by senior decision-makers and access to senior specialists in urology, paediatric surgery or general surgery for urgent surgery is essential for prompt treatment.

Extended follow-up

The NCEPOD report shows that follow-up after an orchidectomy is variable. Although they may not have been thinking about it at the time, removal of the testicle can lead to problems with fertility and psychosexual function later in life, with 46-60% of patients developing late testicular atrophy.

Many patients may wish to consider a prosthetic implant later,

Patient-initiated follow-up after surgery may encourage patients to seek psychological support and/or the use of prosthetic implants.

What about the hydatid?

The hydatid of Morgani is a tiny embryological remnant on the upper pole of the testis. Think of it as a tiny mushroom sticking out from the field. Occasionally, this can become torted and presents as an acute scrotum. The torted hydatid can look like a blue dot when seen through the skin of the scrotum. Whilst ultrasound may show a normal testicle and torted hydatid, scrotal exploration is the gold standard if there is any doubt.


Aggarwal, D., Parmar, K., Sharma, A.P., Tyagi, S., Kumar, S., Singh, S.K. and Gupta, S., 2022. Long-term impact of testicular torsion and its salvage on semen parameters and gonadal function. Indian Journal of Urology: IJU: Journal of the Urological Society of India38(2), p.135.

Bandarkar, A.N. and Blask, A.R., 2018. Testicular torsion with preserved flow: key sonographic features and value-added approach to diagnosis. Pediatric radiology48, pp.735-744.

Barbosa, J.A., de Freitas, P.F.S., Carvalho, S.A.D., Coelho, A.Q., Yorioka, M.A.W., Pereira, M.W.A., Borges, L.L., Srougi, M., Nahas, W.C. and Arap, M.A., 2021. Validation of the TWIST score for testicular torsion in adults. International urology and nephrology53, pp.7-11.

Barbosa, J.A., Tiseo, B.C., Barayan, G.A., Rosman, B.M., Torricelli, F.C.M., Passerotti, C.C., Srougi, M., Retik, A.B. and Nguyen, H.T., 2013. Development and initial validation of a scoring system to diagnose testicular torsion in children. The Journal of Urology189(5), pp.1859-1864.

Beni-Israel, T., Goldman, M., Chaim, S.B. and Kozer, E., 2010. Clinical predictors for testicular torsion as seen in the pediatric ED. The American Journal of Emergency Medicine, 28(7), pp.786-789.

Caesar, R.E. and Kaplan, G.W., 1994. The incidence of the cremasteric reflex in normal boys. The Journal of Urology152(2), pp.779-780.

Choudhury, P., Saroya, K.K., Anand, S., Agarwal, P., Jain, V., Dhua, A.K., Yadav, D.K., Agarwala, S., Bajpai, M., Mawar, S. and Afroz, M., 2023. Unjumbling the TWIST score for testicular torsion: systematic review and meta-analysis. Pediatric Surgery International39(1), p.137.

Gopal, M., O’Connor, E., McDonald, L., Goaman, A., Radford, A., Melling, C., Henneyake, S., Kumbhar, V. and Dagash, H., 2021. Emergency scrotal exploration in children: Is it time for a change in mindset in the UK? Journal of Pediatric Urology17(2), pp.190-e1.

Kadish, H.A. and Bolte, R.G., 1998. A retrospective review of pediatric patients with epididymitis, testicular torsion, and torsion of testicular appendages. Pediatrics102(1), pp.73-76.

Klinke, M., Elrod, J., Stiel, C., Ghadban, T., Wenskus, J., Herrmann, J., Junge, C.M., Reinshagen, K. and Boettcher, M., 2020. The BAL-score almost perfectly predicts testicular torsion in children: a two-center cohort study. Frontiers in Pediatrics8, p.601892.

MacDonald, C., Kronfli, R., Carachi, R. and O’Toole, S., 2018. A systematic review and meta-analysis revealing realistic outcomes following paediatric torsion of testes. Journal of Pediatric Urology14(6), pp.503-509.

Mellick, L.B., Mowery, M.L. and Al-Dhahir, M.A., 2018. Cremasteric Reflex.

Mellick, L.B., Sinex, J.E., Gibson, R.W. and Mears, K., 2019. A systematic review of testicle survival time after a torsion event. Pediatric emergency care35(12), pp.821-825.

Nelson, C.P., Williams, J.F. and Bloom, D.A., 2003. The cremasteric reflex: a useful but imperfect sign in testicular torsion. Journal of pediatric surgery38(8), pp.1248-1249.

Qin, K.R. and Qu, L.G., 2022. Diagnosing with a TWIST: systematic review and meta-analysis of a testicular torsion risk score. The Journal of Urology208(1), pp.62-70.

Rabinowitz, R., 1984. The importance of the cremasteric reflex in acute scrotal swelling in children. The Journal of Urology132(1), pp.89-90.

Sazgar, M., Montazer, S.H., Hosseininejad, S.M., Jahanian, F., Rezaimehr, B., Behbohaninia, M. and Aminiahidashti, H., 2022. Clinical Predictors of Testicular Torsion in Patients with Acute Scrotum; a Cross-Sectional Study. Archives of Academic Emergency Medicine10(1).

Schwarz, G.M. and Hirtler, L., 2017. The cremasteric reflex and its muscle–a paragon of ongoing scientific discussion: A systematic review. Clinical Anatomy30(4), pp.498-507.

Soyer, T.U.T.K.U., Tosun, A., Somuncu, S.A.L.İ.H., Aydın, G., Akman, H., Inal, E., Kanmaz, T. and Cakmak, M., 2007. Electrophysiological evaluation of cremasteric reflex in experimental testicular torsion. European Journal of Pediatric Surgery, 17(04), pp.261-265.

Srinivasan, A., Cinman, N., Feber, K.M., Gitlin, J. and Palmer, L.S., 2011. History and physical examination findings predictive of testicular torsion: an attempt to promote clinical diagnosis by house staff. Journal of pediatric urology7(4), pp.470-474.

Steeman, A., Ngatchou, W., Ramadan, A.S., Entezari, K., Kirkove, P., Mélot, C., Mols, P., Bartiaux, M. and Youatou Towo, P., 2022. Impact of treatment delays on outcome of acute testicular torsion: a 15-year retrospective study. Acta Chirurgica Belgica122(2), pp.116-122.

Teurneau-Hermansson, K., Zindovic, I., Jakobsson, J., Navntoft, A., Nozohor Ekmark, A., Salö, M. and Wagenius, M., 2021. Doppler ultrasound improves diagnostic accuracy for testicular torsion. Scandinavian Journal of Urology55(6), pp.461-465.

Titi-Lartey OA, Khan YS. Embryology, Testicle. [Updated 2023 Apr 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from:




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