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Assessment of the undescended testis
Mini-symposium
Endocrine
Assessment of the undescended testis
S. W. Beasley The testis descends from the urogenital ridge to the scrotum in two phases: the first, transabdominal migration, appears to be dependent on Mullerian Inhibiting Factor substance; and the second stage, inguinoscrotal descent, relies on androgens. A peritoneal extension, the processus vaginalis, elongates into the gubernaculum, which in turn migrates into the scrotum. Between weeks 26 and 28 of gestation the testis descends through the processus vaginalis in the inguinal canal to reach the scrotum by 35-40 weeks.
Definitions Undescended testis An undescended
testis is one that does not reside spontaneously in the scrotum and cannot be manipulated to the bottom of the scrotum without undue tension on the spermatic cord. Intra-abdominal testis
An intra-abdominal testis is located in the abdominal cavity, usually near the internal inguinal ring. The vas deferens and testicular vessels reach it extraperitoneally. An intra-abdominal testis is impalpable but may be seen on laparoscopy. Clinically, it is not easy to distinguish from an intracanalicular testis or absent testis.
the external oblique - except when it can be coerced distally to appear at the external ring; when this happens it is described as being an ‘emergent’ testis. Testis in ‘superficial inguinalpouch’
A testis which has descended through the external inguinal ring, but does not lie within the scrotum, can be found in the subcutaneous tissue in the region of the external inguinal ring. This is the usual position in which an undescended testis can be found. Sometimes a fascial barrier may prevent the testis from entering the scrotum. The term ‘superficial inguinal pouch’ is an archaic term to describe a testis in this position, and is used less frequently these days, mainly because there is no actual pouch. Ectopic testis
An ectopic testis is one which lies outside the normal line of descent of the testis. It can be femoral, perineal, pubopenile, or transverse (crossed) testicular, according to its final position. Ectopic testes are relatively uncommon. Retractile testis
A retractile testis is one which is descended, but the cremasteric reflex is active and causes it to retract out of the scrotum. This reflex can be invoked by cold temperature, anxiety, nervousness or local stimulation, particularly in the region of the cutaneous distribution of the genitofemoral nerve. Retractility of the testis is a normal physiological response to contraction of the cremaster muscle, and has a direct relationship to age. The cremasteric reflux is either absent, or extremely weak at birth, and most pronounced between 3 and 9 years of age. A retractile testis can be manipulated well into the
Intra-canalicular testis
The intra-canalicular testis lies spontaneously within the inguinal canal. It is difficult to palpate on clinical examination because it is behind the aponeurosis of Spencer W. Beadey MS, FRACS, Senior Lecturer in Paediatric
Surgery, University of Melbourne, and Consultant Surgeon, Royal Children’s Hospital, Flemington Road, Parkville, Victoria 3052, Australia. Correspondence and requests for offprints to SWB. Current Paediatrics (1994) 4, 1746177 0 1994 Longman Group Ltd
174
ASSESSMENT OF THE UNDESCENDED
scrotum and when released, will remain there for at least a short period. Most paediatric surgeons would agree that a descended testis which shows marked retractility should be followed up on a regular basis, as a proportion of them subsequently ‘ascend’. Ascending testis
An ascending testis is one that was in the scrotum during infancy, but adopts a higher position as the boy grows. It may require orchidopexy later in childhood. Until recently, the existence of ‘ascending testis’ was disputed, even amongst paediatric surgeons, but it is now generally accepted that the phenomenon is a genuine one. Its cause is unclear, but may result from tethering of the spermatic cord by the processus vaginalis, such that it is unable to elongate in proportion to the growth of the boy.
Diagnosis of undescended testis
TESTIS
175
Associated inguinal hernia
Normally, the patent processus vaginalis begins to close when the testis has descended. In the premature infant in particular, the testis may hold the processus open, making it more likely that bowel will herniate through the internal ring. This produces a symptomatic indirect inguinal hernia. Occasionally, a strangulated inguinal hernia may occur in an infant with an undescended testis. A tender, irreducible lump appears at the external inguinal ring, and the ipsilateral scrotum is empty. Examination will reveal two components to the lump, one being the testis, the other the irreducible contents of the hernial sac. The hernia can usually be reduced by gentle manipulation. Orchidopexy is then performed at the time of herniotomy. Failure to do this creates major technical problems later, since adhesions and scar tissue in the region of the internal inguinal ring make a later orchidopexy extremely difficult. Orchidopexy in infancy is a difficult operation which should always be done by a specialist
The clinical diagnosis of undescended testis is usually straightforward. However, many boys are referred to paediatric surgeons with normal (but retractile) testes, which could not be located by the primary practitioner; others present in late childhood or at infertility clinics as adults, with previously unrecognised cryptorchidism. Clinical examination should identify the presence of a testis and determine the lowest position in the line of descent that it can achieve. The examination is conducted in warm relaxed surroundings with the child on a couch at a height comfortable for the clinician.
paediatric surgeon.
Location of testis
Undescended testis versus retractile testis
When a testis is not evident in the scrotum it is probably lying near the external inguinal ring or overlying the pubic tubercle. It is best felt when the flat of the fingers of the left hand milk it along the line of the inguinal canal towards the scrotum (Figure). While the testis is being manipulated over the pubis, the thumb and fingers of the right hand grasp it through the thin scrotal skin. It is drawn into the scrotum to assess the lowest level to which it can be manipulated. The testis is undescended if tension on the cord prevents the testis reaching the bottom of the scrotum, or if, when pulled to the bottom of the scrotum under tension, it disappears into the groin as soon as it is released.
An undescended testis must be distinguished clinically
Examination of the premature infant
At birth, the testes of many infants born before the seventh month of gestation will not have descended as far as the scrotum. The majority of these testes subsequently descend normally, usually by term. An undescended testis at 3 months post-term will remain undescended until treated.
Testicular torsion and apparent cryptorchidism
Testicular torsion usually occurs during adolescence in boys with fully descended testes: only rarely are undescended testes involved. However, when the mesorchium twists it lifts the testis towards the neck of the scrotum and may give a false impression that the testis is ‘high or undescended. It is likely the testis was fully descended prior to torsion.
from a retractile testis. A true undescended testis cannot be manipulated to the bottom of the scrotum and stay there. Some can be coerced into the upper scrotum, but further traction causes pain from stretching of the spermatic cord. On the other hand, a retractile testis is one that may be found initially outside the scrotum, but can be brought down into the normal position in the scrotum. The testis stays in the scrotum unless the cremasteric reflex is stimulated. In many normal boys, the testes are always at the bottom of the scrotum and the cremasteric reflex produces only a small upward movement allowing the testes to remain within the scrotum. One testis may be stable at the bottom of the scrotum, whereas the other will retract. The retractile testis is normal in size, similar to the contralateral, normallydescended testis. The difficulty in distinguishing a retractile testis from an undescended testis has encouraged some clinicians to use human chorionic gonadotrophin (hCG) on the grounds that failure of hCG to achieve
176 CURRENT PAEDIATRICS
Figure-Technique of examination to locate position of testis (A). The right testis (arrow) is ‘milked’towards the scrotum along the line of the inguinal canal by the left hand (B). The left hand maintains its position to prevent retraction of the testis while the right hand grasps the testis within the scrotum (C). The left hand is removed while the right hand holds the testis in the scrotum in its most distal position (D). The testis is released. It immediately disappears from view because it is undescended. A retractile testis would have stayed in the scrotum for a period. (By kind permission of Chapman & Hall Medical Publishers from Pediatric Diagnosis-An Illustrated Guide to Disorders of Surgical Significance, 1993.)
testicular descent and inhibit retractility suggests that the testis is truly undescended. It is claimed that in a small proportion of boys, hCG may cause temporary descent of an undescended testis.
Impalpable testis An impalpable testis is either (a) absent, or (b) intracanalicular or intra-abdominal in location. If a testis is present it should be relocated because of the potential for sterility and malignancy if left untreated. Many apparently ‘impalpable’ testes can be palpated by an experienced paediatric surgeon, particularly in the obese older child with markedly retractile testes and a small scrotum. An attempt should be made to coerce the intracanalicular testis through the external ring. Infants and small children with bilateral impalpable testes should have an hCG stimulation test with measurement of stimulated testosterone levels to confirm that functional testicular tissue is present. A number of investigations have been used to assist in locating impalpable testes:
Ultrasonography is non-invasive, but has proved disappointing in detecting intra-abdominal testes. It is unreliable unless the testis is already palpable. CT Scanning is used rarely because of the radiation required and the necessity for intravenous contrast injection to distinguish major vessels from undescended testes. The false negative rate is as high as 44%. It is not effective in accurately identifying the position of a testis at one year of age, the age at which orchidopexy is currently performed. Magnetic resonance imaging involves a noninvasive, non-ionising technique which may prove reliable, but its disadvantages include: (a) the long scanning-time, which is poorly tolerated by children; (b) the need for sedation in children under 5 years of age; (c) the expense; and (d) the lack of gastro-intestinal contrast media, compromising detection of an intra-abdominal testis. Spermatic venography and arteriography are invasive and risk damage to the vessels and to the testis - and are no longer used.
ASSESSMENT OF THE UNDESCENDED
TESTIS
177
Laparoscopy is used to identify an impalpable testis on the assumption that the vas deferens and epididymis are rarely separated from the testis, so that visualisation of the vas will lead to the testis, if it is present. It can be used as an adjunctive procedure prior to inguino-abdominal exploration. The technique is also useful in the older child who has undergone previous (but deemed inadequate) inguinal exploration for an impalpable testis, where either no testis was identified or where only a vas with no testicular vessels was seen.
that the testis will be either in the abdomen, in the inguinal canal, or absent. This surgery is best performed by a specialist paediatric surgeon. Most impalpable testes are intracanalicular or intra-abdominal, just within the internal ring. To locate the intra-abdominal testis, the peritoneum at the internal inguinal ring may have to be opened, or the retroperitoneal course of the vas deferens followed.
If a normal vas is seen running from the pelvis to the internal ring, converging with the gonadal vessels, groin exploration will locate the testis in the inguinal canal. If the vas and vessels end abruptly, antenatal or early postnatal torsion has probably occurred: the so-called ‘intra-abdominal vanishing testis’. The commonest finding is that of a testis within a cm or two of the internal ring. Complete absence of a vas or vessels within the peritoneal cavity suggests true congenital absence of the testis: extensive dissection to the lower pole of the kidney will be unrewarding.
The optimal age for orchidopexy is 9-12 months, post-term. The operation is delicate and best performed by paediatric surgeons, most of whom routinely use loupe glasses for magnification. It is performed as a day case under light general anaesthesia with local bupivicaine infiltration. The child is allowed home within an hour or two of surgery. In the hands of specialist paediatric surgeons, the results of orchidopexy are excellent, and it is anticipated that the earlier age of orchidopexy will translate into improved fertility.
??
Surgical exploration Primary surgical exploration for an impalpable testis can be performed without prior radiological or laparoscopic investigation. In unilateral cryptorchidism, the operation is commenced in the knowledge
Age at orchidopexy
Further reading Hutson JM, Beasley SW. Descent of the Testis, Edward Arnold, London, 1992. Beasley SW, Hutson JM, Myers NA. Undescended testis. In: Pediatric Diagnosis: an Illustrated Guide to Disorders of Surgical Significance. London: Chapman & Hall Medical, 1993, pp 241-244.
Endocrine
Assessment of the undescended testis
S. W. Beasley The testis descends from the urogenital ridge to the scrotum in two phases: the first, transabdominal migration, appears to be dependent on Mullerian Inhibiting Factor substance; and the second stage, inguinoscrotal descent, relies on androgens. A peritoneal extension, the processus vaginalis, elongates into the gubernaculum, which in turn migrates into the scrotum. Between weeks 26 and 28 of gestation the testis descends through the processus vaginalis in the inguinal canal to reach the scrotum by 35-40 weeks.
Definitions Undescended testis An undescended
testis is one that does not reside spontaneously in the scrotum and cannot be manipulated to the bottom of the scrotum without undue tension on the spermatic cord. Intra-abdominal testis
An intra-abdominal testis is located in the abdominal cavity, usually near the internal inguinal ring. The vas deferens and testicular vessels reach it extraperitoneally. An intra-abdominal testis is impalpable but may be seen on laparoscopy. Clinically, it is not easy to distinguish from an intracanalicular testis or absent testis.
the external oblique - except when it can be coerced distally to appear at the external ring; when this happens it is described as being an ‘emergent’ testis. Testis in ‘superficial inguinalpouch’
A testis which has descended through the external inguinal ring, but does not lie within the scrotum, can be found in the subcutaneous tissue in the region of the external inguinal ring. This is the usual position in which an undescended testis can be found. Sometimes a fascial barrier may prevent the testis from entering the scrotum. The term ‘superficial inguinal pouch’ is an archaic term to describe a testis in this position, and is used less frequently these days, mainly because there is no actual pouch. Ectopic testis
An ectopic testis is one which lies outside the normal line of descent of the testis. It can be femoral, perineal, pubopenile, or transverse (crossed) testicular, according to its final position. Ectopic testes are relatively uncommon. Retractile testis
A retractile testis is one which is descended, but the cremasteric reflex is active and causes it to retract out of the scrotum. This reflex can be invoked by cold temperature, anxiety, nervousness or local stimulation, particularly in the region of the cutaneous distribution of the genitofemoral nerve. Retractility of the testis is a normal physiological response to contraction of the cremaster muscle, and has a direct relationship to age. The cremasteric reflux is either absent, or extremely weak at birth, and most pronounced between 3 and 9 years of age. A retractile testis can be manipulated well into the
Intra-canalicular testis
The intra-canalicular testis lies spontaneously within the inguinal canal. It is difficult to palpate on clinical examination because it is behind the aponeurosis of Spencer W. Beadey MS, FRACS, Senior Lecturer in Paediatric
Surgery, University of Melbourne, and Consultant Surgeon, Royal Children’s Hospital, Flemington Road, Parkville, Victoria 3052, Australia. Correspondence and requests for offprints to SWB. Current Paediatrics (1994) 4, 1746177 0 1994 Longman Group Ltd
174
ASSESSMENT OF THE UNDESCENDED
scrotum and when released, will remain there for at least a short period. Most paediatric surgeons would agree that a descended testis which shows marked retractility should be followed up on a regular basis, as a proportion of them subsequently ‘ascend’. Ascending testis
An ascending testis is one that was in the scrotum during infancy, but adopts a higher position as the boy grows. It may require orchidopexy later in childhood. Until recently, the existence of ‘ascending testis’ was disputed, even amongst paediatric surgeons, but it is now generally accepted that the phenomenon is a genuine one. Its cause is unclear, but may result from tethering of the spermatic cord by the processus vaginalis, such that it is unable to elongate in proportion to the growth of the boy.
Diagnosis of undescended testis
TESTIS
175
Associated inguinal hernia
Normally, the patent processus vaginalis begins to close when the testis has descended. In the premature infant in particular, the testis may hold the processus open, making it more likely that bowel will herniate through the internal ring. This produces a symptomatic indirect inguinal hernia. Occasionally, a strangulated inguinal hernia may occur in an infant with an undescended testis. A tender, irreducible lump appears at the external inguinal ring, and the ipsilateral scrotum is empty. Examination will reveal two components to the lump, one being the testis, the other the irreducible contents of the hernial sac. The hernia can usually be reduced by gentle manipulation. Orchidopexy is then performed at the time of herniotomy. Failure to do this creates major technical problems later, since adhesions and scar tissue in the region of the internal inguinal ring make a later orchidopexy extremely difficult. Orchidopexy in infancy is a difficult operation which should always be done by a specialist
The clinical diagnosis of undescended testis is usually straightforward. However, many boys are referred to paediatric surgeons with normal (but retractile) testes, which could not be located by the primary practitioner; others present in late childhood or at infertility clinics as adults, with previously unrecognised cryptorchidism. Clinical examination should identify the presence of a testis and determine the lowest position in the line of descent that it can achieve. The examination is conducted in warm relaxed surroundings with the child on a couch at a height comfortable for the clinician.
paediatric surgeon.
Location of testis
Undescended testis versus retractile testis
When a testis is not evident in the scrotum it is probably lying near the external inguinal ring or overlying the pubic tubercle. It is best felt when the flat of the fingers of the left hand milk it along the line of the inguinal canal towards the scrotum (Figure). While the testis is being manipulated over the pubis, the thumb and fingers of the right hand grasp it through the thin scrotal skin. It is drawn into the scrotum to assess the lowest level to which it can be manipulated. The testis is undescended if tension on the cord prevents the testis reaching the bottom of the scrotum, or if, when pulled to the bottom of the scrotum under tension, it disappears into the groin as soon as it is released.
An undescended testis must be distinguished clinically
Examination of the premature infant
At birth, the testes of many infants born before the seventh month of gestation will not have descended as far as the scrotum. The majority of these testes subsequently descend normally, usually by term. An undescended testis at 3 months post-term will remain undescended until treated.
Testicular torsion and apparent cryptorchidism
Testicular torsion usually occurs during adolescence in boys with fully descended testes: only rarely are undescended testes involved. However, when the mesorchium twists it lifts the testis towards the neck of the scrotum and may give a false impression that the testis is ‘high or undescended. It is likely the testis was fully descended prior to torsion.
from a retractile testis. A true undescended testis cannot be manipulated to the bottom of the scrotum and stay there. Some can be coerced into the upper scrotum, but further traction causes pain from stretching of the spermatic cord. On the other hand, a retractile testis is one that may be found initially outside the scrotum, but can be brought down into the normal position in the scrotum. The testis stays in the scrotum unless the cremasteric reflex is stimulated. In many normal boys, the testes are always at the bottom of the scrotum and the cremasteric reflex produces only a small upward movement allowing the testes to remain within the scrotum. One testis may be stable at the bottom of the scrotum, whereas the other will retract. The retractile testis is normal in size, similar to the contralateral, normallydescended testis. The difficulty in distinguishing a retractile testis from an undescended testis has encouraged some clinicians to use human chorionic gonadotrophin (hCG) on the grounds that failure of hCG to achieve
176 CURRENT PAEDIATRICS
Figure-Technique of examination to locate position of testis (A). The right testis (arrow) is ‘milked’towards the scrotum along the line of the inguinal canal by the left hand (B). The left hand maintains its position to prevent retraction of the testis while the right hand grasps the testis within the scrotum (C). The left hand is removed while the right hand holds the testis in the scrotum in its most distal position (D). The testis is released. It immediately disappears from view because it is undescended. A retractile testis would have stayed in the scrotum for a period. (By kind permission of Chapman & Hall Medical Publishers from Pediatric Diagnosis-An Illustrated Guide to Disorders of Surgical Significance, 1993.)
testicular descent and inhibit retractility suggests that the testis is truly undescended. It is claimed that in a small proportion of boys, hCG may cause temporary descent of an undescended testis.
Impalpable testis An impalpable testis is either (a) absent, or (b) intracanalicular or intra-abdominal in location. If a testis is present it should be relocated because of the potential for sterility and malignancy if left untreated. Many apparently ‘impalpable’ testes can be palpated by an experienced paediatric surgeon, particularly in the obese older child with markedly retractile testes and a small scrotum. An attempt should be made to coerce the intracanalicular testis through the external ring. Infants and small children with bilateral impalpable testes should have an hCG stimulation test with measurement of stimulated testosterone levels to confirm that functional testicular tissue is present. A number of investigations have been used to assist in locating impalpable testes:
Ultrasonography is non-invasive, but has proved disappointing in detecting intra-abdominal testes. It is unreliable unless the testis is already palpable. CT Scanning is used rarely because of the radiation required and the necessity for intravenous contrast injection to distinguish major vessels from undescended testes. The false negative rate is as high as 44%. It is not effective in accurately identifying the position of a testis at one year of age, the age at which orchidopexy is currently performed. Magnetic resonance imaging involves a noninvasive, non-ionising technique which may prove reliable, but its disadvantages include: (a) the long scanning-time, which is poorly tolerated by children; (b) the need for sedation in children under 5 years of age; (c) the expense; and (d) the lack of gastro-intestinal contrast media, compromising detection of an intra-abdominal testis. Spermatic venography and arteriography are invasive and risk damage to the vessels and to the testis - and are no longer used.
ASSESSMENT OF THE UNDESCENDED
TESTIS
177
Laparoscopy is used to identify an impalpable testis on the assumption that the vas deferens and epididymis are rarely separated from the testis, so that visualisation of the vas will lead to the testis, if it is present. It can be used as an adjunctive procedure prior to inguino-abdominal exploration. The technique is also useful in the older child who has undergone previous (but deemed inadequate) inguinal exploration for an impalpable testis, where either no testis was identified or where only a vas with no testicular vessels was seen.
that the testis will be either in the abdomen, in the inguinal canal, or absent. This surgery is best performed by a specialist paediatric surgeon. Most impalpable testes are intracanalicular or intra-abdominal, just within the internal ring. To locate the intra-abdominal testis, the peritoneum at the internal inguinal ring may have to be opened, or the retroperitoneal course of the vas deferens followed.
If a normal vas is seen running from the pelvis to the internal ring, converging with the gonadal vessels, groin exploration will locate the testis in the inguinal canal. If the vas and vessels end abruptly, antenatal or early postnatal torsion has probably occurred: the so-called ‘intra-abdominal vanishing testis’. The commonest finding is that of a testis within a cm or two of the internal ring. Complete absence of a vas or vessels within the peritoneal cavity suggests true congenital absence of the testis: extensive dissection to the lower pole of the kidney will be unrewarding.
The optimal age for orchidopexy is 9-12 months, post-term. The operation is delicate and best performed by paediatric surgeons, most of whom routinely use loupe glasses for magnification. It is performed as a day case under light general anaesthesia with local bupivicaine infiltration. The child is allowed home within an hour or two of surgery. In the hands of specialist paediatric surgeons, the results of orchidopexy are excellent, and it is anticipated that the earlier age of orchidopexy will translate into improved fertility.
??
Surgical exploration Primary surgical exploration for an impalpable testis can be performed without prior radiological or laparoscopic investigation. In unilateral cryptorchidism, the operation is commenced in the knowledge
Age at orchidopexy
Further reading Hutson JM, Beasley SW. Descent of the Testis, Edward Arnold, London, 1992. Beasley SW, Hutson JM, Myers NA. Undescended testis. In: Pediatric Diagnosis: an Illustrated Guide to Disorders of Surgical Significance. London: Chapman & Hall Medical, 1993, pp 241-244.