Cryptorchidism is the absence of at least one testicle from the scrotum. It is the most common birth defect involving male genitalia. About 3% of ...NCBISkiptomaincontentSkiptonavigationResourcesHowToAboutNCBIAccesskeysMyNCBISignintoNCBISignOutNCBIBookshelf.AserviceoftheNationalLibraryofMedicine,NationalInstitutesofHealth.StatPearls[Internet].TreasureIsland(FL):StatPearlsPublishing;2021Jan-.StatPearls[Internet].ShowdetailsTreasureIsland(FL):StatPearlsPublishing;2021Jan-.SearchtermCryptorchidismStephenW.Leslie;HussainSajjad;CarlosA.Villanueva.AuthorInformationAuthorsStephenW.Leslie1;HussainSajjad2;CarlosA.Villanueva3.Affiliations1CreightonUniversityMedicalCenter2RMUandAlliedHospitals3Children'sHospitalandMedicalCenterLastUpdate:April7,2021.ContinuingEducationActivityCryptorchidismistheabsenceofatleastonetesticlefromthescrotum.Itisthemostcommonbirthdefectinvolvingthemalegenitalia.About3%offull-termand30%ofprematuremaleinfantsarebornwithoneorbothtesticlesundescended.Approximately80%ofcryptorchidtestesdescendbythethirdmonthoflife.Thismakesthetrueincidencearound1%.Cryptorchidismmayoccurononeorbothsidesbutmorecommonlyaffectstherighttesticle.Thetesticlemaybeanywherealongthe"pathofdescent,"suchas:Locatedhighintheretroperitonealabdomentotheinguinalring;Intheinguinalcanal;ectopicfromthepathofdescent;hypoplastic;dysgenetic;missingorabsent;unilateral(two-thirds).Theundescendedtesticlecanusuallybepalpatedintheinguinalcanal.Inaminorityofpatients,themissingtesticlemaybelocatedintheabdomenorbenonexistent.Undescendedtesticlesareassociatedwithdecreasedfertility(bilateralcases),increasedtesticulargermcelltumors(overallriskunder1%),testiculartorsion,inguinalhernias,andpsychologicalproblems.Withoutsurgicalcorrection,anundescendedtesticlemaydescendduringthefirstthreemonthsoflife.Toreducerisks,undescendedtestesmaybebroughtintothescrotumwithanorchiopexy.Cryptorchidism,hypospadias,testicularcancer,andpoorsemenqualitymakeuptesticulardysgenesissyndrome(TDS).Thissyndromeisthoughttobeduetoharmf