The term “congenital micropenis” refers to a penis that, at birth, is shorter than expected for a male newborn. Although the definition of micropenis is relatively arbitrary, it is important to recognize it as it could indicate an underlying health issue that requires further investigation. Congenital micropenis can cause psychological stress for parents, and while it is reported that some young adults with this condition may have a lower quality of life, this is not always the case. Often, the initial management of this condition involves administering androgens to the child to try to increase penile size, but the effectiveness of this therapy, especially in the long term, remains uncertain. A better understanding of penile development, normal variations, the pathophysiology of micropenis, and standardized long-term follow-ups could improve the management of this condition.

Micropenis must be distinguished from conditions such as buried, webbed, or trapped penis. In the case of a webbed penis, the scrotal sac extends along the underside of the penile shaft, giving the visual impression of a small penis, but palpation of the corpora cavernosa reveals the true size. Approximately 3-4% of newborns may have a penile shaft buried in pubic fat, a phenomenon more common in older and overweight boys. A trapped penis occurs when the penis is imprisoned by scar tissue or by excessive excision of the foreskin or shaft skin, often following procedures like circumcision. Other associated malformations include “chordee,” a curvature of the penis that can make the penis appear smaller.

Before measuring penile length, it is necessary to carefully examine the penis and the rest of the genitalia. Penile length should be measured as SPL (stretched penile length): the suprapubic fat should be pressed as much as possible, the foreskin retracted, and the glans held between the thumb and index finger. The measurement should be taken from the pubic bone to the distal tip of the glans along the dorsal side. It has been reported that SPL measured in newborns within the first 12 hours of life is about 10% shorter than the actual length, possibly requiring reevaluation.

Micropenis is defined as a normally formed penis with a stretched length that is more than 2.5 standard deviations (SD) below the mean for the patient’s age and ethnicity. In full-term newborns, micropenis can be defined as a stretched penile length of less than 1.8 cm in Europe. Perhaps a measure of 2 cm could represent a more appropriate cutoff as an international standard, taking into account regional and genetic differences.

Surgical Treatment

In 1996, an international consensus provided guidelines for penile lengthening, suggesting that only men with a flaccid length of less than 4 cm or a stretched penile length of less than 7.5 cm should be considered for surgical treatment. Since the first reconstructive surgery reported by Hinman in the early 1970s, various surgical techniques have been developed. However, the role of surgery in the management of micropenis is limited, with many techniques described but few high-quality studies supporting clinical decisions. Surgery is performed only in adulthood and is reserved for the most extreme cases.

Surgical options are divided into techniques for lengthening the penis, increasing its circumference, making it appear larger, or completely replacing the phallus. To increase length, the suspensory ligament can be released, often combined with a dorsal V-Y incision. Other techniques include sliding elongation and penile disassembly. However, the increase in length is modest (1-2 cm), and scar formation can cause retractions and reductions in length. Additionally, there can be issues with erectile function and penile stability, affecting sexual function.

To increase penile circumference, substances such as hyaluronic acid or autologous fat can be injected around the penile shaft, but with limited success over time. The main issue is the resorption of the injected substances or the formation of scar tissue that can compromise function or cause penile retractions. The perceived length of the penis can be increased by removing suprapubic fat through weight reduction measures or liposuction or mini-abdominoplasty procedures.

The penis can also be replaced with a complete phalloplasty, meaning the creation of a new phallus, but this technique is used in the most severe cases. Currently, a free flap based on the radial artery of the forearm is used, offering reasonable aesthetic results and acceptable complications at the donor site. However, despite the evolution of these techniques, it is still not possible to fully replicate the normal anatomy and function of the penis.