Aphallia: Symptoms, Types, Causes and Treatment

Aphallia, also known as penile agenesis, is an exceptionally rare congenital condition characterized by the complete absence of the phallus at birth. This diagnosis, while extremely uncommon, carries profound medical, psychological, and social implications for affected individuals and their families. Historically, aphallia has been reported in an estimated 1 in 10 to 30 million live births, with fewer than 100 cases documented in the medical literature to date 1 5 6 7 12. The rarity of the condition has contributed to a scarcity of standardized guidelines, making awareness and multidisciplinary management crucial. This article provides a comprehensive overview of aphallia, detailing its symptoms, subtypes, causative factors, and modern treatment strategies.

Symptoms of Aphallia

Aphallia is most often recognized at birth due to the striking absence of the phallus. The key clinical feature is a complete lack of penile or clitoral corporal tissue, with otherwise normal-appearing external genitalia such as a well-formed scrotum (in genetic males) or fused labia majora (in genetic females) 1 6. However, the condition rarely occurs in isolation; a range of associated symptoms and anomalies typically accompanies aphallia:

Key Symptoms and Physical Findings

• Absence of the Phallus: The most defining symptom is the missing penis in genetic males or absent clitoral/corporal tissue in genetic females, despite normal development of other genital structures 1 6.
• Abnormal Urethral Opening: The urethral opening is often not present in the usual location. Instead, urine may pass through alternative routes, such as a urethrorectal or urethroscrotal fistula, or through an abnormal perineal skin tag 1 3 4 7.
• Skin Tags or Appendages: A small posterior skin tag, sometimes containing a rudimentary or stenotic urethra, may be present where the phallus would normally develop 1.
• Urinary Tract Symptoms: Many infants present early with symptoms related to urinary tract obstruction, such as urinary retention, hydronephrosis, or recurrent urinary tract infections. In cases with urethrorectal fistula, urine may exit through the anus, leading to recurrent epididymitis or pyelonephritis 1 4 5 7.
• Genital Ambiguity in Females: Rarely, aphallia may present in 46,XX females with severe urinary tract dysplasia and ambiguous genitalia 1.
• Associated Anomalies: Aphallia is frequently accompanied by anomalies of the urinary (e.g., vesicoureteral reflux, hydronephrosis), gastrointestinal (e.g., rectourethral or vesicorectal fistula), cardiovascular, and even adrenal systems 1 4 5 7.

Clinical Course

Symptoms often emerge shortly after birth, as caregivers note atypical genital appearance or abnormal urination. Complications such as urinary tract infections, sepsis, or renal impairment may prompt further investigation. The psychosocial impact on the family can be profound, necessitating early counseling and support 6.

Types of Aphallia

Given the spectrum of anatomical variations and associated anomalies, aphallia is classified according to the location of the urethral meatus and the presence or absence of fistulous connections. This classification not only aids diagnosis but also guides management strategies 8.

Classification Based on Urethral Meatus Location

1. Post-Sphincteric (Anal Verge) Aphallia
   • The ectopic urethral meatus is located on or near the anal verge, often on a skin tag or appendage.
   • This group has the highest survival rate (up to 87%) and the lowest incidence of other major anomalies 8.
2. Pre-Sphincteric (Prostatorectal Fistula) Aphallia
   • The urethra communicates with the rectum above the anal sphincter (prostatorectal fistula).
   • This form is associated with a higher rate of other anomalies and carries a significant risk of neonatal mortality (36%) 8.
3. Urethral Atresia
   • Complete absence of a urethral opening, resulting in urinary outflow obstruction.
   • This is the most severe form, with no survivors reported and the highest rate of associated anomalies 8.

Additional Phenotypic Types

• Atypical Aphallia: Cases with atrophic corporal remnants or anteriorly placed urethral openings, sometimes identified by advanced imaging 2.
• Isolated vs. Syndromic Aphallia: Isolated aphallia refers to cases with no other detectable congenital anomalies, whereas syndromic aphallia involves multiple system anomalies, most commonly affecting the urinary and gastrointestinal tracts 6 11.
• Male and Female Aphallia: While traditionally described in genetic males (46,XY), recent reports have identified aphallia in 46,XX females, expanding the definition to encompass the absence of corporal tissue in either sex 1.

Associated Anomalies

Aphallia is rarely an isolated anomaly. More than half of the cases are associated with complex malformations of the caudal axis, urinary tract, gastrointestinal tract (e.g., fistulas), and other systems 1 3 4 5 7 8. The severity and combination of these anomalies significantly influence prognosis and treatment options.

Causes of Aphallia

The exact cause of aphallia remains incompletely understood, but advances in embryology and genetics have provided important insights.

Embryological Origins

Aphallia results from the failure of the genital tubercle to form or properly develop during the early stages of embryogenesis (typically around the 4th to 6th week of gestation) 5 6. The genital tubercle is the precursor structure from which the phallus (penis or clitoris) and associated corporal tissues arise. When this structure fails to develop, all penile components are absent, but the scrotum and testes (in males) or labia (in females) may form normally.

Contributing Factors and Hypotheses

• Developmental Arrest: Failure of mesenchymal proliferation and migration leads to the absence of the phallus, while other genital structures may develop normally 5 6.
• Genetic Factors: Chromosomal abnormalities have been reported in some cases, such as excess heterochromatin on chromosome 9 (46,XY with 9qh+), though most cases have a normal male karyotype 4. No single gene mutation has been consistently linked to aphallia.
• Chromosome Polymorphism: Variations in chromosomal structure may play a role in some cases 4.
• Environmental Factors: While not well established, in utero exposure to teratogens or maternal health issues could theoretically disrupt genital tubercle development, but no causal links have been proven.
• Association with Other Malformations: The frequent co-occurrence of urinary, gastrointestinal, and musculoskeletal anomalies suggests a broader disturbance of caudal embryonic development 1 5 7.

Given the complexity and rarity of the condition, most cases are considered sporadic, with no clear familial or hereditary pattern identified.

Treatment of Aphallia

The management of aphallia is highly individualized, reflecting the rarity, complexity, and profound psychological implications of the condition. A multidisciplinary, staged approach is widely advocated, involving pediatric urologists, surgeons, endocrinologists, psychologists, and social workers 6 11.

Immediate and Short-Term Management

Initial priorities include:

• Assessment and Stabilization: Evaluation of associated anomalies (especially life-threatening urinary or gastrointestinal malformations) and overall stabilization of the neonate 11.
• Urinary Drainage: Establishing adequate urinary outflow is critical. This may involve urinary diversion, perineal urethrostomy, or creation of a new external urethral orifice to prevent urinary tract infections, reflux, and renal damage 1 4 11.
• Imaging and Laboratory Workup: Comprehensive urinary tract imaging (e.g., ultrasound, voiding cystourethrography), renal function tests, and genetic studies are recommended to delineate anatomy and plan interventions 1.

Intermediate Management

Addressing Fistulas and Associated Anomalies:

• Surgical Repair of Fistulas: Closure of urethrorectal or vesicorectal fistulas is often necessary to prevent recurrent infections and preserve renal function 3 4 5 7 11.
• Urinary Tract Reconstruction: Correction of associated urinary tract anomalies, such as vesicoureteral reflux or ureteral obstruction, may require staged reconstructive procedures 1.
• Temporary or Palliative Phalloplasty: In certain settings, preliminary penile reconstruction using local tissue flaps may be considered to provide a male appearance prior to definitive surgery 9.

Long-Term Management

Definitive Reconstruction and Psychosocial Support:

• Neophalloplasty (Phallic Reconstruction): Surgical creation of a neophallus is the cornerstone of treatment for individuals raised as males. Various techniques are available:
  • Microsurgical Methods: Radial forearm free flap, osteocutaneous fibular flap, and myocutaneous latissimus dorsi flap are among the most effective, offering good cosmetic and functional outcomes 9 10.
  • Non-Microsurgical Methods: Use of local groin, abdominal, or scrotal flaps may be chosen where microsurgical expertise is unavailable 10.
  • Timing: Definitive phalloplasty is generally postponed until adolescence or adulthood, when tissue availability and patient cooperation are optimal. However, preliminary procedures may be justified in childhood to address social and psychological concerns 9 10.
• Urethroplasty: Reconstruction of the urethra to permit voiding through the neophallus is often performed alongside or subsequent to phalloplasty 9 10.
• Prosthesis Placement: In select cases, penile prostheses may be implanted to enhance sexual function and cosmetic appearance in adulthood 11.
• Psychological Counseling: Ongoing support and counseling for the patient and family are essential, addressing issues of gender identity, body image, and social integration 6 11.
• Long-Term Surveillance: Regular follow-up is necessary to monitor renal function, surgical outcomes, and psychosocial well-being 1 11.

Gender Assignment Considerations

Historically, female gender assignment was commonly recommended for 46,XY infants with aphallia, often involving orchiectomy, labial construction, and urethral transposition 8 12. However, contemporary evidence indicates that most affected individuals identify as male and experience significant psychological distress if assigned female at birth 9 10. Therefore, current best practices advocate for raising patients according to their genetic and hormonal sex, reserving gender reassignment for select cases with clear indications and after thorough counseling 9 10 12.

Multidisciplinary and Individualized Approach

Given the complex medical, surgical, and psychosocial needs of patients with aphallia, care should be delivered by a specialized, multidisciplinary team. Shared decision-making with the family is crucial, particularly regarding timing and type of surgical interventions, and in consideration of cultural, social, and individual values 6 11.

Conclusion

Aphallia remains one of the rarest and most challenging congenital anomalies of the genitourinary system. Its presentation is marked by the complete absence of the phallus and is often overshadowed by severe anomalies of the urinary and gastrointestinal tracts. Advances in surgical reconstruction have greatly improved outcomes, making neophalloplasty the preferred approach for most genetic males. Early, multidisciplinary intervention—encompassing medical stabilization, detailed anatomical assessment, staged surgical correction, and lifelong psychological support—offers the best chance for affected individuals to achieve functional, cosmetic, and psychosocial well-being. As our understanding grows and surgical techniques evolve, the outlook for patients born with aphallia continues to improve, underscoring the importance of awareness, empathy, and coordinated care in this rare condition.