The newborn infant has a range of normal appearances which also embraces the external appearance of the genital region.
Male neonates have a patent processus vaginalis in 90% of cases. This is a free pathway which communicates between the peritoneal cavity and the scrotum, allowing fluid, blood or air to move between them.
Scrotal Hematoma
The scrotum may be enlarged with blood in male neonates. This may be due to traumatic delivery, high birth weight, bleeding disorders, infections or hypoxia. Imaging is essential to exclude intra- or retroperitoneal haemorrhage extending into the scrotum. They are usually managed conservatively.
Scrotal Hydrocele
A hydrocele is due to fluid accumulating around the testicles, within the tunica vaginalis. If the fluid moves between the scrotum and the abdomen through a patent processus vaginalis, it is called a communicating hydrocele. Imaging differentiates between simple, complex and chronic hydroceles. Occasionally pyoceles may result from infection of the fluid or because of the spread of infection from elsewhere in the body.
Inguinal Hernia
These are masses which appear in the inguinal canal due to the passage of bowel through the patent processus vaginalis. Imaging is useful in diagnosis and surgical management is usually required.
Others
Free air in the abdomen, as occurs with a perforated bowel or necrotizing enterocolitis, can enter through the patent processus vaginalis into the scrotum.
Meconium periorchitis and abnormalities of the lymphatic system may also cause scrotal enlargement.
Birth-Associated Phenomena
Both male and female infants may develop swollen and red genitals during their passage through the birth canal. This is thought to be due to increased levels of hormones, or due to a prolonged labor. Fluid may also accumulate in some areas with loose tissue, such as the female vagina and labia, as well as in the face. Pregnancy leads to elevated levels of estrogen which acts upon these tissues, inducing edema and growth. The drop in hormone levels following delivery means that these infants are no longer subject to hormonal effects, which causes the swelling to recede over a couple of weeks at most.
Course and Treatment
Asymptomatic vaginal or scrotal swelling does not need any treatment. Simple observation is enough. At times, a small amount of clear white or pink fluid, or even a little blood, may leak from the vagina for the first few days of life - this is a normal result of the withdrawal of maternal hormones that were freely passing through the placenta and are now absent. This usually stops on its own and is not a matter of concern.
References
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4914382/
- https://medlineplus.gov/ency/article/001911.htm
- https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P02691
Further Reading
Cytomegalovirus in breast milk linked to changes in infant growth and gut microbiome