Testicles normally descend into the scrotum before birth, completing their journey by about the 35th week of pregnancy, so most boys are born with both testes already in place. If you can feel two roughly equal, oval-shaped structures sitting in the scrotum, your testes have descended normally. The question sounds simple, but the reality involves a few wrinkles: testes that retract temporarily, testes that descend late, and a small percentage that never make it down at all. Understanding what “dropped” actually means and what to look (and feel) for matters more than people realize.
What “Dropping” Actually Means
During fetal development, testicles form near the kidneys, deep in the abdomen. Over several months they migrate downward through the abdominal wall and into the scrotum. This happens in two distinct stages. The first phase occurs roughly between weeks 8 and 15 of pregnancy, when a hormone called insulin-like hormone 3 causes a structure called the gubernaculum to swell, anchoring the testis near what will become the inguinal canal (the passageway through the lower abdominal wall). Testosterone also plays a supporting role by loosening the ligament that holds the testis in its original position.1PubMed. Regulation of testicular descent
The second phase, from about week 25 to 35, is the one people think of as the testes “dropping.” The gubernaculum pushes out through the inguinal canal and guides each testis down into the scrotum, steered largely by testosterone acting through a nerve that releases a signaling molecule to direct the path.2PubMed Central. The role of the gubernaculum in the descent and undescent of the testis By birth, both testes should be sitting in the scrotum. In most full-term boys, they are.
How to Check Whether Testes Are in the Scrotum
For parents of infants, pediatricians routinely check testicular position at well-child visits. But whether you’re a parent checking a baby or a teenager checking yourself, the basic approach is the same: a warm, relaxed environment is essential. Cold air or anxiety triggers the cremaster muscle, which pulls the testes upward toward the body. A warm bath is the easiest way to get an accurate read, because heat relaxes that muscle and lets the testes hang naturally.
With clean hands, gently feel the scrotum. You should be able to identify two separate, oval-shaped structures, one on each side. They should feel smooth and firm but not hard, roughly the size of a large grape in younger boys or a small plum in older teens and adults. If you can feel both and they sit comfortably in the scrotum without needing to be coaxed down from the groin area, they have descended normally.
If one or both sides of the scrotum feel empty, or you can feel a lump up in the groin crease that might be a testis sitting in the inguinal canal, that warrants a visit to a doctor. Referral to a specialist is recommended by six months of corrected gestational age if a testis has not descended on its own, or immediately upon detection if discovered later.3PubMed Central. Practical approach to evaluating testicular status in infants and children
Retractile Testes and the Disappearing Act
This is the situation that causes the most confusion. A retractile testis is one that has descended normally but gets pulled back up into the groin by an overactive cremaster muscle. It can be gently coaxed back down into the scrotum and will stay there, at least temporarily. This is extremely common in boys between about ages 2 and 10, and it is not the same thing as an undescended testis.
The distinction matters. A truly undescended testis (cryptorchidism) cannot be manually guided into a normal scrotal position and stay there. A retractile testis can. One study using ultrasound to evaluate over a hundred testes found that retractile testes were most common in the 6-to-8 age group and tended to appear on both sides, while truly undescended testes were more often one-sided and located higher up in the inguinal canal.4PubMed. Ultrasound in the evaluation of retractile and truly undescended testes Research into the cremasteric reflex has shown that boys with undescended testes tend to have a more hyperactive version of this reflex, with faster and more sustained muscle contractions compared to boys with normally descended testes.5Journal of Pediatric Surgery. Cremasteric reflexes of boys with descended, retractile, or undescended testes: An electrophysiological evaluation
If you or your child has a testis that sometimes seems to vanish from the scrotum but can be moved back down easily during a warm bath, it is likely retractile and usually resolves on its own by puberty. Still, retractile testes should be monitored at regular checkups because a small number of them can “ascend” and become truly undescended over time.
What Happens When They Don’t Come Down on Their Own
About 2 to 4 percent of full-term boys are born with at least one undescended testis. In premature infants the rate is considerably higher because the second phase of descent happens late in pregnancy. The good news is that many of these testes descend spontaneously within the first few months of life. One study found that spontaneous descent could occur in up to 70 percent of cases overall, with most descending between 3 and 6 months of age. In full-term infants, no further spontaneous descent occurred after the fourth month.6PubMed. Testicular descent: when to interfere?
For testes that remain undescended past six months, the window for spontaneous descent is essentially closed. A separate study looking at boys re-examined at age one or older found that spontaneous descent occurred in fewer than 7 percent of cases, and every boy who eventually experienced spontaneous descent had first been identified as cryptorchid before six months of age. Nobody who first presented after six months experienced descent on their own.7PubMed. What is the rate of spontaneous testicular descent in infants with cryptorchidism?
When Surgery Is Recommended
If a testis has not descended by six months of corrected gestational age, current guidelines from the American Urological Association recommend surgical correction (orchiopexy) within the next year, meaning the procedure should ideally be completed by about 12 to 18 months of age.8Journal of Urology. Evaluation and Treatment of Cryptorchidism European guidelines broadly agree, stating that the testis should be in its scrotal position by age one, with 18 months as the latest acceptable time.9PubMed Central. Are we still too late? Timing of orchidopexy
The surgery itself involves bringing the testis down from wherever it is stuck and securing it in the scrotum. It is a common pediatric procedure with high success rates. The emphasis on early timing is not arbitrary; as we will see, delaying the procedure affects both fertility and cancer risk.
What Undescended Testes Mean for Fertility
The scrotum exists for a reason. Sperm production requires a temperature a few degrees below core body temperature, and a testis that stays inside the abdomen or inguinal canal runs too warm. Over time, this damages the cells that produce sperm. The problem starts earlier than most people assume: even in infancy, important developmental steps are happening in the testes, and a testis that has not descended is already falling behind in the transformation of its germ cells.10PubMed Central. Undescended testicle: An update on fertility in cryptorchid men
The consequences in adulthood are real. A study of men who had been treated for undescended testes found significantly lower sperm concentrations, lower testosterone levels, and smaller testes compared to controls. Normal sperm concentrations were found in only about 21 percent of cases overall. Among men with bilateral undescended testes, roughly half had extremely low sperm counts and nearly half had no measurable sperm at all. The age at which the surgical correction was performed correlated directly with outcomes: earlier surgery meant better sperm counts and testicular volume.11PubMed. Delayed treatment of undescended testes may promote hypogonadism and infertility
If only one side was affected and treated in a timely way, the other testis often compensates well enough for fertility to be preserved. Bilateral cases are more concerning. Either way, the message is the same: catching and correcting cryptorchidism early makes a meaningful difference.12PubMed Central. Cryptorchidism and its impact on male fertility: a state of art review of current literature
The Cancer Risk
Men with a history of undescended testes face a higher risk of testicular cancer than the general population. One large cohort study found the overall relative risk to be about 7.5 times that of men without cryptorchidism, and the risk in the affected testis specifically was roughly 11 times higher.13PubMed. Risk of testicular cancer in cohort of boys with cryptorchidism Another study estimated the relative risk at about 3.7, with the risk increasing the later the correction was performed, and being highest in men whose cryptorchid testis was never surgically corrected.14JNCI: Journal of the National Cancer Institute. Testicular Cancer Risk Among Young Men: Role of Cryptorchidism and Inguinal Hernia
The range in those estimates reflects differences in study populations and follow-up periods, but the direction is consistent: an undescended testis carries elevated cancer risk, and delaying correction makes it worse. This is one of the key reasons guidelines push for early orchiopexy. Surgery does not eliminate the added risk entirely, but earlier treatment is associated with lower risk than late or no treatment.
Torsion Risk in an Undescended Testis
Testicular torsion, where the testis twists on its blood supply, is a medical emergency at any time. But a testis that has not descended normally is estimated to face roughly ten times the risk of torsion compared to a normally positioned one.15PubMed Central. Testicular torsion in undescended testis: A persistent challenge When torsion happens in an undescended testis sitting in the inguinal canal, the symptoms can be misleading. Instead of the classic sudden scrotal pain, the person may experience unexplained groin or lower abdominal pain, which can be confused with other conditions. Delayed diagnosis is a real problem and can lead to losing the testis entirely.16PubMed Central. Testicular torsion in an undescended testicle: chasing a diagnosis If you know you have an undescended or incompletely descended testis, sudden pain in the groin is something to take very seriously and get checked immediately.
When the Testis Is Not Just Undescended but Misplaced
There is a difference between a testis that stopped along its normal path (undescended) and one that took a wrong turn entirely (ectopic). An ectopic testis has wandered to a location outside the usual route of descent. Possible locations include the area just in front of the inguinal canal, the perineum (between the scrotum and anus), the base of the penis, the thigh, or even the opposite side of the scrotum.17PubMed Central. Ectopic perineal testicle: Case report and review of literature These situations are uncommon but important to know about, because a person might feel a lump in an unexpected place and not connect it to a missing testis. Ectopic testes always require surgical correction.
Vanishing Testis Syndrome
Sometimes an empty scrotum is not caused by a testis that failed to descend. It is caused by a testis that began developing normally and then was lost, possibly due to a disruption in blood supply during fetal life. This is known as vanishing testis syndrome (or testicular regression syndrome). When surgeons explore these cases, they typically find a small nubbin of fibrous tissue where the testis should have been, often with signs of old bleeding. Functional testicular tissue is found in fewer than 10 percent of cases.18PubMed Central. Vanishing testes: a literature review A large review of over 300 cases found that only about 6 percent had any residual seminiferous tubules, and viable germ cells were present in just about 2 percent.19Frontiers in Pediatrics. Histopathological Features of Vanishing Testes in 332 Boys: What Is Its Significance? A Retrospective Study From S Tertiary Hospital
The remnant tissue is usually removed surgically, partly to confirm the diagnosis and partly because the theoretical risk of abnormal cell changes has not been entirely ruled out, even though no studies have actually found precancerous changes in these remnants.18PubMed Central. Vanishing testes: a literature review
Why Imaging Often Is Not the First Step
You might assume that if a testis cannot be felt, an ultrasound would be the obvious next step. Surprisingly, ultrasound is not very useful for finding a testis that cannot be felt on physical exam. For testes located above the inguinal canal (the ones that matter most), ultrasound has a sensitivity of only about 45 percent, meaning it misses more than half of them.20PubMed Central. Diagnostic Imaging in Cryptorchidism: Utility, Indications, and Effectiveness Another study found somewhat better numbers for ultrasound, with a sensitivity of 76 percent and an accuracy of 84 percent, but still far from reliable enough to rule out a hidden testis on its own.21PubMed. Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of non-palpable testis
This is why most specialists go straight to a diagnostic laparoscopy (a small surgical camera inserted through the abdomen) for testes that cannot be felt on examination, rather than relying on imaging that might give a falsely reassuring result. A skilled examiner’s hands are still the most important diagnostic tool for testes that can be felt anywhere in the groin or scrotum.
Normal Variation People Worry About Unnecessarily
Plenty of people wonder whether something is wrong when one testis hangs lower than the other, or when the two sides seem different in size. This is almost always normal. In a study of 345 healthy adolescent boys, about 59 percent had a smaller left testis and 41 percent had a smaller right, with a small but measurable difference in average volume between the two sides.22PubMed. Testicular asymmetry in healthy adolescent boys One testis hanging lower is the rule, not the exception, and is thought to prevent the two from compressing each other.
What should actually prompt concern is a sudden change: one testis becoming noticeably larger or harder over a short period, new pain, or a palpable lump on the surface. These are signs worth getting checked promptly and are unrelated to whether descent occurred normally.
Environmental Factors and Rising Rates
Cryptorchidism rates appear to be climbing in many countries, and researchers have been investigating whether environmental chemical exposure during pregnancy plays a role. Evidence is accumulating that prenatal exposure to endocrine-disrupting chemicals is associated with higher rates of undescended testes.23PubMed Central. The epidemiology of cryptorchidism and potential risk factors, including endocrine disrupting chemicals The strongest historical evidence comes from diethylstilbestrol (DES), a synthetic estrogen once prescribed to pregnant women, which was linked to increased cryptorchidism in their sons. Studies have also found associations between cryptorchidism and pesticide exposure, measured through chemical levels in maternal breast milk.24Molecular and Cellular Endocrinology. Cryptorchidism and endocrine disrupting chemicals
This is still an active area of research with plenty of unresolved questions about which specific chemicals matter most and at what exposure levels. But the trend is real enough that it adds another reason for physicians to check testicular position carefully at birth and during infancy.
Why Testicular Self-Examination Awareness Remains Poor
Testicular cancer is the most common solid tumor in young men, and catching it early makes treatment far more successful. Yet awareness of testicular self-examination is remarkably low across different populations. A study of over 500 Nigerian adolescent boys found that barely 1 percent had ever heard of testicular self-examination, and none had received information about it from a healthcare provider.25PubMed Central. Testicular-self examination among Nigerian adolescent secondary school boys: knowledge, attitudes and practices A study of Dutch young men aged 15 to 19 found that knowledge of testicular cancer and self-examination was very low, with only 2 percent reporting that they performed self-exams regularly.26Health Education Research. Testicular self-examination (TSE) among Dutch young men aged 15–19: determinants of the intention to practice TSE Research from the United Arab Emirates echoed these findings, highlighting a critical gap in awareness and practice.27PLOS ONE. Assessment of testicular self-examination awareness and practice among adult males in Ajman, United Arab Emirates: A cross-sectional study
Getting comfortable with what your own anatomy feels like when it is healthy is the foundation for noticing when something changes. Once a month after a warm shower, gently roll each testis between your thumb and fingers. Familiarize yourself with the normal texture, the soft ridge of the epididymis along the back, and the overall size. You are not diagnosing anything; you are establishing a baseline so that a new lump, a change in firmness, or an increase in size stands out instead of going unnoticed for months.