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Appendix Testis Torsion

Editor: Stephen W. Leslie Updated: 11/28/2022 7:20:38 PM


Torsion of the testicular appendages is considered to be the most common cause of acute scrotal pain in prepubertal children and may even be the single most prevalent cause of pediatric orchalgia.[1] It should, therefore, be included in the differential for any male presenting with an acute scrotum but especially in the pediatric age group.[1] There are two testicular appendages that can twist and become symptomatic: the appendix testis and the appendix epididymis. 

The appendix testis, sometimes called hydatid of Morgagni, is a vestigial remnant of the Mullerian duct and is present in 76% to 83% of testes.[2] When present, it is located on the superior pole of the testicle between the testis and epididymis and is the most common testicular appendage to undergo torsion. It is homologous to the fimbriated end of the Fallopian tube in the female.

The appendix epididymis is a vestigial Wolffian (mesonephric) duct remnant and is present in 22% to 28% of testes.[2] When present, it occurs along the head of the epididymis. It is sometimes considered to be a detached efferent epididymal duct.


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Both testicular appendages are commonly pedunculated, predisposing them to torsion.[3] Beyond this, the actual cause of torsion is unknown but may be related to trauma and/or prepubertal enlargement, which would explain the peak age of occurrence being in 7 to 12-year-old boys. Some authors have proposed a seasonal etiology for both spermatic cord (testicular) and testicular appendage torsion with low temperatures during the winter leading to more episodes of torsion.[4][5]


The peak age of occurrence is 7-12 years, although it can occur at any age. More than 50% of boys presenting with acute scrotal pain will have torsion of a testicular appendage.[1][6] In one study of 238 boys aged 19 years and younger who presented to a children's hospital with acute scrotal pain, 46% were ultimately found to have torsion of the appendix testis, while 35% had epididymitis and only 16% demonstrated testicular torsion.[6]

History and Physical

The initial diagnosis is made clinically, although this can be challenging as the presentation is variable, and is easy to misdiagnose, with 45% of general practitioners making an incorrect initial diagnosis.[7] This frequent misdiagnosis is why imaging is recommended for all cases of acute scrotal pain.

Torsion of either testicular appendage commonly produces pain similar to that experienced with testicular torsion, although the onset is usually more gradual. Often, the pain is more localized to the upper pole of the testis or epididymis and does not usually correlate with any urinary symptoms nor with systemic signs such as fever, nausea, or vomiting. 

On initial physical examination of the condition, tenderness can often be localized to the upper pole of the testis or epididymis. There may be a palpable, localized mass in the area of maximum tenderness. The scrotum usually appears normal, and the cremasteric reflex is typically intact. With a normal cremasteric reflex, there would not be any "angel wing or bell clapper deformity" of the opposite testicle. The "angel wing deformity" is formed when a testicle lies horizontally rather than the usual vertical position, which widens the scrotum inferiorly creating the "angel wing" appearance. This is typically caused by inadequate fixation by the gubernaculum of the inferior pole of the testicle to the tunica vaginalis which predisposes to testicular torsion. 

A "blue dot sign" may also be present as a para-testicular nodule noted on the superior aspect of the testicle; this can be identified by stretching the scrotal skin overlying the superior pole of the testicle and is representative of an ischemic testicular appendage. While worth knowing, the "blue dot sign" is only present in about 21% (0 to 52%) of all torsed testicular appendages, and a false positive "blue dot sign" has been reported in the literature in a patient with testicular torsion.[8]

As the condition progresses, worsening inflammation may make physical exam findings less specific. These findings can include scrotal erythema and edema, as well as nonspecific tenderness of the entire testicle and epididymis.


Color Doppler ultrasonography is the imaging modality of choice for the evaluation of the acute scrotum in all age groups. It has been found to be superior to radionuclide imaging, is readily available on an emergency basis, and can be done more quickly. The normal ultrasonic appearance of a testicular appendage will typically show little or no vascular flow.[9][10] Ultrasound will only rarely demonstrate a testicular appendage, but it will typically show normal blood flow to the testicle on the affected side, ruling out testicular torsion, and usually shows hyperperfusion of the associated epididymis. If the testicular appendage is seen on ultrasound, a normal appendix testis will be less than 5.6 mm in size.

In contrast, a torsed testicular appendage will be over 5.6 mm and, depending upon the duration of torsion, may appear as an ovoid hypoechoic nodule in boys presenting before 24 hours compared to a hyperechoic or heterogeneous nodule after 24 hours.[11][12] A torsed appendix testis may also appear as an avascular lesion surrounded by a hyperemic epididymis with posterior enhancement.[13] The hyperemia of the surrounding structures may make it difficult to distinguish a torsed testicular appendage from epididymitis.[13] A large torsed appendage may even give the sonographic appearance of a pyocele, making the clinical history and physical examination even more important.[14]

The affected testicle is often found to be "high riding" in testicular torsion but not in a torsed testicular appendage.

Radionuclide imaging of the scrotum would demonstrate a "hot dot" sign at the site of the torsed testicular appendage but is useful only if the symptoms and torsion have been present for at least five hours. Even after five hours, this sign is only found in about 45% of patients ultimately found to have a torsed testicular appendage.[15] For these reasons, ultrasound imaging is usually the preferred option for the initial evaluation of all acute scrotal pathologies.[16]

If the patient is having voiding symptoms such as dysuria, urgency, or frequency, it will also be important to obtain a urinalysis with culture.

Treatment / Management

Torsion of a testicular appendage is generally a self-limiting condition and, as such, most cases receive conservative therapy. Conservative management includes bed rest, scrotal elevation, ice, nonsteroidal anti-inflammatory drugs, and analgesics. The inflammation and pain usually resolve within one week.

Surgery is rarely indicated for a torsed testicular appendage. A scrotal exploration should only be performed if it is difficult to differentiate from testicular torsion, if the pain is severe and uncontrollable by analgesics or if the pain is prolonged or recurrent. If there is any reasonable doubt about the diagnosis, a scrotal exploration should take place to exclude testicular torsion definitively. If surgery is ultimately the outcome for a torsed testicular appendage, there is no need to explore the opposite side as is typically done for testicular torsions.

Differential Diagnosis

In a patient presentation of acute scrotal pain, the differential includes ischemia (testicular torsion, torsion of a testicular appendage), infection (acute epididymo-orchitis), or trauma (scrotal contusion, testis rupture). However, the acute scrotum should be considered a surgical emergency until a testicular torsion is ruled out due to the potential catastrophic loss of a testicle. Testicular salvage is time-dependent, and most testicles remain viable if they are surgically detorsed within 6 hours of the onset of symptoms.

Testicular torsion usually has a more acute onset than torsion of an appendage, but this is variable. The cremasteric reflex is almost always absent on the affected side, and on physical exam, an abnormal transverse lie of the unaffected testicle may present. Lifting the affected testicle does not usually relieve pain (negative Prehn sign), but this is not considered a reliable indicator. Doppler ultrasound will show arterial flow to the affected testicle to be absent or minimal. Interestingly, onset during sleep has been found to be an indicator of testicular torsion.[16] The affected testicle is often found to be "high riding" in testicular torsion but not in a torsed testicular appendage.

Epididymo-orchitis, like torsion of a testicular appendage, will show hyperemia to the affected epididymis on color Doppler ultrasound but is likely to be more pronounced. They will often be associated with voiding symptoms such as dysuria, frequency and urgency, and possibly a history of urinary tract infections. Patients may also present with systemic signs and symptoms of fever, nausea, or vomiting. On physical exam, the epididymis and/or testis on the affected side will usually be enlarged and diffusely tender. Occasionally, elevating the affected testicle will relieve pain (positive Prehn sign). No "angel wing or bell clapper deformity" will be present.[10]

In doubtful cases, it is essential to perform an emergency scrotal exploration rather than wait and risk losing the testicle.[17]


The prognosis is good for torsion of either testicular appendage as they are both vestigial remnants with no known function. The pain and inflammation associated with the torsion are self-limiting, and the condition typically resolves within one week without the need for surgical intervention.


The primary complication of torsion of a testicular appendage is a misdiagnosis resulting in the loss of testis due to a missed testicular torsion. Ultrasonography can help avoid such misdiagnosis and is, therefore, the recommended diagnostic approach in all cases of acute scrotal emergencies.

Deterrence and Patient Education

Parents and patients diagnosed with testicular appendix torsion should be encouraged to adhere to all treatment recommendations. This includes bed rest, scrotal elevation, ice, nonsteroidal anti-inflammatory drugs, and analgesics. They should also be advised to follow up for reevaluation if symptoms worsen or do not resolve after 1 week.

Pearls and Other Issues

  • The "blue dot sign" is a classic physical exam finding unique to testicular appendix torsion. However, it is often absent in the setting of testicular appendix torsion and can be falsely positive in cases of true testicular torsion.
  • Because of their lack of function and potential to torse, the appendix testes and epididymal appendix are commonly removed if encountered during an elective scrotal exploration for other purposes. 
  • Often, testicular appendage torsion in prepubertal boys gets misdiagnosed as epididymitis based on scrotal ultrasound imaging, as both can demonstrate epididymal hypervascularity. Epididymitis should be considered highly unlikely in a pre-sexual boy with no urologic abnormalities, recent catheterization, or history of urinary tract infections.
  • If a testicular appendage is more than 5.6 mm on ultrasound, it should be considered suspicious for torsion of the appendage.
  • Patients with testicular appendage torsion are likely to be younger than those with testicular torsion. They also will lack the "angel wing deformity" and not demonstrate the "high riding" testicle position usually associated with testicular torsion.[16]
  • Rare causes of an acute scrotum can include incarcerated hernias and traumatic testicular ruptures. 
  • There have been reported cases of simultaneous testicular torsion with testicular appendage torsion.
  • It is possible to have torsion of a testicular appendage in an undescended testicle.

Enhancing Healthcare Team Outcomes

Management of the acute scrotum is a surgical emergency until proven otherwise. As patients with this condition usually present to the emergency department, the first person to encounter the patient is a triage nurse who must be cognizant of the urgency potential testicular torsion demands and immediately contact the clinical interprofessional team. The patient should be placed in a room promptly, and the clinician alerted of the patient's presence and chief complaint. Early history and physical exam should give the clinician some guidance and direction, usually necessitating a color Doppler ultrasound to be promptly read by a radiologist.

Once testicular torsion can safely be ruled out, other potential causes of acute scrotal pain, including testicular appendage torsion, can come under consideration and the patient can be appropriately treated. 

Management of pre-pubescent scrotal pain requires a coordinated interprofessional effort between clinicians, specialists, and nursing staff to lead to accurate and prompt diagnosis resulting in appropriately directed treatment. [Level 5]


(Click Image to Enlarge)
Blue dot sign
Blue dot sign
Image courtesy O.Chaigasame



Mushtaq I, Fung M, Glasson MJ. Retrospective review of paediatric patients with acute scrotum. ANZ journal of surgery. 2003 Jan-Feb:73(1-2):55-8     [PubMed PMID: 12534742]

Level 2 (mid-level) evidence


Jacob M, Barteczko K. Contribution to the origin and development of the appendices of the testis and epididymis in humans. Anatomy and embryology. 2005 Apr:209(4):287-302     [PubMed PMID: 15668777]

Level 3 (low-level) evidence


JONES P. Torsion of the testis and its appendages during childhood. Archives of disease in childhood. 1962 Apr:37(192):214-26     [PubMed PMID: 14452315]


Lyronis ID, Ploumis N, Vlahakis I, Charissis G. Acute scrotum -etiology, clinical presentation and seasonal variation. Indian journal of pediatrics. 2009 Apr:76(4):407-10. doi: 10.1007/s12098-009-0008-2. Epub 2009 Feb 10     [PubMed PMID: 19205631]

Level 2 (mid-level) evidence


Molokwu CN, Somani BK, Goodman CM. Outcomes of scrotal exploration for acute scrotal pain suspicious of testicular torsion: a consecutive case series of 173 patients. BJU international. 2011 Mar:107(6):990-3. doi: 10.1111/j.1464-410X.2010.09557.x. Epub 2010 Sep 21     [PubMed PMID: 21392211]

Level 2 (mid-level) evidence


Kim JS, Shin YS, Park JK. Clinical features of acute scrotum in childhood and adolescence: Based on 17years experiences in primary care clinic. The American journal of emergency medicine. 2018 Jul:36(7):1302-1303. doi: 10.1016/j.ajem.2017.10.063. Epub 2017 Oct 31     [PubMed PMID: 29100785]


Melekos MD, Asbach HW, Markou SA. Etiology of acute scrotum in 100 boys with regard to age distribution. The Journal of urology. 1988 May:139(5):1023-5     [PubMed PMID: 3361633]


Murphy FL, Fletcher L, Pease P. Early scrotal exploration in all cases is the investigation and intervention of choice in the acute paediatric scrotum. Pediatric surgery international. 2006 May:22(5):413-6     [PubMed PMID: 16602024]

Level 2 (mid-level) evidence


Johnson KA, Dewbury KC. Ultrasound imaging of the appendix testis and appendix epididymis. Clinical radiology. 1996 May:51(5):335-7     [PubMed PMID: 8641095]


Boettcher M, Bergholz R, Krebs TF, Wenke K, Treszl A, Aronson DC, Reinshagen K. Differentiation of epididymitis and appendix testis torsion by clinical and ultrasound signs in children. Urology. 2013 Oct:82(4):899-904. doi: 10.1016/j.urology.2013.04.004. Epub 2013 Jun 2     [PubMed PMID: 23735611]

Level 2 (mid-level) evidence


Park SJ, Kim HL, Yi BH. Sonography of intrascrotal appendage torsion: varying echogenicity of the torsed appendage according to the time from onset. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. 2011 Oct:30(10):1391-6     [PubMed PMID: 21968490]


Baldisserotto M, de Souza JC, Pertence AP, Dora MD. Color Doppler sonography of normal and torsed testicular appendages in children. AJR. American journal of roentgenology. 2005 Apr:184(4):1287-92     [PubMed PMID: 15788612]


Lev M, Ramon J, Mor Y, Jacobson JM, Soudack M. Sonographic appearances of torsion of the appendix testis and appendix epididymis in children. Journal of clinical ultrasound : JCU. 2015 Oct:43(8):485-9. doi: 10.1002/jcu.22265. Epub 2015 Feb 20     [PubMed PMID: 25704247]


Meher S, Rath S, Sharma R, Sasmal PK, Mishra TS. Torsion of a large appendix testis misdiagnosed as pyocele. Case reports in urology. 2015:2015():430871. doi: 10.1155/2015/430871. Epub 2015 Mar 15     [PubMed PMID: 25861514]

Level 3 (low-level) evidence


Melloul M, Paz A, Lask D, Luttwak Z, Mukamel E. The pattern of radionuclide scrotal scan in torsion of testicular appendages. European journal of nuclear medicine. 1996 Aug:23(8):967-70     [PubMed PMID: 8753687]

Level 2 (mid-level) evidence


Fujita N, Tambo M, Okegawa T, Higashihara E, Nutahara K. Distinguishing testicular torsion from torsion of the appendix testis by clinical features and signs in patients with acute scrotum. Research and reports in urology. 2017:9():169-174. doi: 10.2147/RRU.S140361. Epub 2017 Aug 28     [PubMed PMID: 28920055]


Nason GJ, Tareen F, McLoughlin D, McDowell D, Cianci F, Mortell A. Scrotal exploration for acute scrotal pain: a 10-year experience in two tertiary referral paediatric units. Scandinavian journal of urology. 2013 Oct:47(5):418-22. doi: 10.3109/00365599.2012.752403. Epub 2013 Jan 3     [PubMed PMID: 23281617]

Level 2 (mid-level) evidence