Inguinal and umbilical hernias belong to the most frequent surgical lesions in the first year of life. 1 to 4 percent of the younger children are involved, mostly boys.

A patent processus vaginalis which does not obliterate after testicular descent and additional factors contribute to a clinically apparent congenital inguinal hernia.
In contrast to the adult type of inguinal hernia with a hernia sac originating medially of the epigastric vessels due to a weakness of the abdominal wall, in congenital inguinal hernia the hernia sac originates laterally of these vessels (median versus lateral inguinal hernia). One possible additional factor is increased peritoneal fluid - for instance with a ventriculoperitoneal shunt - leading to a doubled incidence of congenital inguinal hernia (10%).
It is impossible to decide whether frequent crying in infancy is an important factor in an individual infant in the pathogenesis of a congenital inguinal hernia, or whether recurrent groin pains due to the traction imposed on the hernia sac by the recurrent descent of intestine leads to crying.
In adulthood the lateral inguinal hernia is slightly more frequent than the medial type. It is likely that at least a part of the lateral type hernia corresponds to a hitherto not recognized open processus vaginalis. In umbilical hernia the closure of the umbilical plate with connective tissue is either delayed or absent. In contrast to the processus vaginalis, this umbilical plate closes spontaneously in the first year of life in most cases. Therefore, most of the umbilical hernias are self-limited.

a) Inguinal hernia filling the first time or recurrently with abdominal structures, leading to a clinically apparent groin swelling. Reduction occurs either by finger pressure or spontaneously.
b) Irreducible inguinal hernia. The content of the hernia sac is not reducible, or only with an appropriate technique. This form occurs mainly in premature and newborn patients and young infants; especially in girls, the ovary and the fallopian tube remain in the hernia sac.
c) Incarcerated inguinal hernia. The circulation of the intestine, the testicle, and less often of the ovary, is compromised. Type a) may be called 'simple', types b) and c) 'complicated' inguinal hernia. Irreducibility and incarceration occurs rarely in umbilical hernia.

Inguinal hernia manifests as smooth swelling of the groin which continues in case of an inguinoscrotal hernia into the scrotum . During palpation, which is painless, parts of the intestine may be recognized. Following reduction, only the spermatic cord which is somewhat thickened when compared to the opposite side can be felt where it crosses the pubic tubercle (so-called silk glove sign).
In case of irreducible and incarcerated inguinal hernia, palpation is very painful, the swelling is tight, and redness of the overlying skin may be present. Possibly, there are signs of obstructive ileus.
An umbilical hernia manifests as painless and smooth swelling of the size of a fingertip or larger, and is easily reducible. Following reduction, or during the symptom-free interval, a small opening with sharp edges is palpable at the center of the umbilicus.

There is no spontaneous recovery of a patent processus vaginalis beyond one year of age in some infants. Therefore, a clinical manifestation of an inguinal hernia may occur in these individuals at any time in childhood, or later.

The differential diagnosis of the inguinal hernia includes the following topics:
1. Swelling of the groin for instance by a lymphadenopathy.
2. Swelling of the groin combined with a swelling of the scrotum for instance in hydrocele of the cord or in communicating hydrocele.
3. Surgical abdominal emergencies mainly in infants as for instance in intussusception.
4. Recurrent crying in infants for instance in evening colic and recurrent groin and/or abdominal pain in toddlers and schoolchildren for instance due to a lesion of the hip.

The differential diagnosis of the umbilical hernia includes: Hernias of the midline above the umbilicus, variations of the insertion of the umbilical cord at the level of the abdominal wall with either a flat and poorly epithelialized or with a broad and prominent umbilicus with redundant periumbilical skin, a granuloma of the umbilicus or a congenital malformation of the umbilicus as in omphalomesenteric duct remnants for instance a patent viteline duct.

Additional examinations are only necessary in complicated hernias or in some patients for differential diagnosis. Usually history and clinical findings are sufficient for diagnosis and differential diagnosis in simple inguinal and umbilical hernia.
In incarcerated inguinal hernia with suspected obstructive ileus plaine supine and upright abdominal radiographs are indicated, and in female infants with groin swelling and prolapse of the ovary ultrasound of the groin may be useful for the differentiation of an irreducible inguinal hernia from an inguinal lymphadenopathy.

Healing in inguinal hernia is only possible with a hernia repair. The younger the child the more urgent is surgery due to the danger of incarceration. In a wait and see policy the infant is suffering and there is an imminent danger of incarceration with emergency surgery and later sequels to the testicle.
Spontaneous healing occurs in many cases of umbilical hernia; on the other hand suffering in large types of umbilical hernia without spontaneous recovery should not be underestimated.
With surgery using an appropriate technique permanent healing is possible in nearly 100 percent.

Recurrences are due to
a) an incomplete resection of the hernia sac,
b) a medial type of inguinal hernia in cases with a weakness of the abdominal wall and c) a suspected healing following a silent period of one or a recurrent clinical manifestation.