Congental Abdominal Wall Defects

8/13/2019 Congental Abdominal Wall Defects

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Congenital Abdominal

Wall Defects


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Introduction

Omphalos was the center stone in the

Temple of Apollo in Delphi. The term

was modified to name the center point of

a newborn infant, from which the termumbilical cord emanated. In Latin, umbo

denoted the ornamental stud at the

center of a shield, from which the term

for the umbilicus area was derived. The

Anglo-Saxon, nafe, meaning hub of a

wheel, was converted to navel.


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Uncommon in other animals, abdominal wall

hernias are among the most common of all

surgical problems. They are a leading cause

of work loss and disability and are sometimes

lethal.

Knowledge of herniasof the abdominal wall

(usual and unusual) and protrusions thatmimic hernias is an essential component of

the armamentarium of the general and

pediatric surgeon. Three types of herniaare

shown below.
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A 3-month-old girl with a large right

inguinal hernia.


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In this baby with gastroschisis, the bowel is

uncovered and presents to the right inferior

aspect of the cord


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Hernia of the umbilical cord

(omphalocele).


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Recent studies

In a study of 780 laparoscopic inguinalherniorrhaphies (in 569 patients), Coelho et al

investigated the types of intraoperative andpostoperative complications that can result from theprocedure. The authors found that hernias recurredin 14 patients (2.5%) and that intraoperativecomplications occurred in 28 patients (4.9%), the

most common of which was extensivesubcutaneous emphysema. Postoperativecomplications developed in 35 patients (6.2%).Small bowel perforation occurred in 1 patient, and

bladder perforation occurred in another. One cohortmember developed an extensive, preperitoneal

Mycobacterium massiliense infection. No cohortmembers died. The authors concluded that despitehaving a low mortality rate, laparoscopic inguinalherniorrhaphy can result in life-threateningcomplications


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History of the Procedure

Hippocrates used the Greek hernios for bud or bulge todescribe abdominal hernias. Statues of the era portray this

condition. The Ebers papyrus, from approximately 1550 BCE,

detailed the use of a truss. Celsius used transillumination to

differentiate a herniafrom a hydroceleand advocated gradual

pressure (taxis) in the management of incarcerated hernia

(also called irreducible hernia). The earliest recorded surgicalefforts were to reducethe hernia through a scrotal incision, to

remove the sac and the testis, and to close the area with

sutures that spontaneously extruded.

As the church forbade physicians from surgical procedures,

nonphysicians (barbers) began developing therapy for surgical

problems. De Chauliac advocated escharotics with gradual

cicatrization accompanied by prolonged bed rest as the

solution for inguinal hernias. Par followed the operation of

Gerald of Metz using a cerclage wire of gold to retard further

intestinal protrusion into the scrotum.
http://emedicine.medscape.com/article/428055-overviewhttp://emedicine.medscape.com/article/426142-overviewhttp://emedicine.medscape.com/article/1015147-overviewhttp://emedicine.medscape.com/article/178393-overviewhttp://emedicine.medscape.com/article/149608-overviewhttp://emedicine.medscape.com/article/1534321-overviewhttp://emedicine.medscape.com/article/1534321-overviewhttp://emedicine.medscape.com/article/1534321-overviewhttp://emedicine.medscape.com/article/1534321-overviewhttp://emedicine.medscape.com/article/149608-overviewhttp://emedicine.medscape.com/article/178393-overviewhttp://emedicine.medscape.com/article/1015147-overviewhttp://emedicine.medscape.com/article/426142-overviewhttp://emedicine.medscape.com/article/428055-overview


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In 1700, Littre reported an omphalomesenteric duct trapped in ahernia. Richter described an incarcerated but nonobstructinghernia in 1785. Hunter, in 1756, detailed the embryologic originof the indirect inguinal hernia. DeGimbernat advocated cuttingthe ligament that is eponymically associated with him inmanagement of incarcerated femoral hernia. Teale reported thefirst prevascular femoral hernia in 1846.

Other eponyms associated with inguinal hernias relate toanatomical descriptions by Camper (fascia) (1801), Cooper(ligament) (1804), Cloquet (hernia) (1817), Grynfeltt (hernia)(1866), Hesselbach (triangle) (1814), Laugier (hernia) (1833),Nuck (canal) (1650-1692), Petit (hernia) (1783), and Scarpa(fascia) (1814). Scarpa also previously described a slidinghernia and a spigelian hernia in 1645.

The advent of antisepsis by Lister in 1865 paved the way for amore precise surgical approach to hernia. Finally, physicianscould expect success of an operation not being disrupted by

infection. In 1871, Marcy felt that closure of the fascia adjacentto the internal ring would provide a reliable repair of the inguinalhernia. Over a decade later, Bassini (1884) formulated anapproach to hernia repair that remains the foundation of themodern hernia repair, namely, reconstruction of the floor of theinguinal canal.
http://emedicine.medscape.com/article/1534281-overviewhttp://emedicine.medscape.com/article/1534281-overviewhttp://emedicine.medscape.com/article/1534281-overviewhttp://emedicine.medscape.com/article/1534281-overview


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Problem

Operative management of hernias,despite being described since antiquity

and constituting an essential part of the

general surgeon's repertoire of operations,

remains controversial. By definition, ahernia is an abnormal protrusion from

one anatomical space to another. Variants

on the definition of hernia exist with

regard to congenital abdominal walldefects. In this lecture, we will define

these protrusions, their presentations, and

their treatment.


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Note the translucent sac in this baby with

a large omphalocele.


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Note a baby with gastroschisis(the midgut viscera

protrude through a central abdominal fascial defect

and are not covered by a sac)
http://emedicine.medscape.com/article/975583-overviewhttp://emedicine.medscape.com/article/975583-overview


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Frequency

As much as 10% of the population developssome type of hernia during life. More than ahalf million hernia operations are performedin the United States each year. Fifty percentare for indirect inguinal hernias, with amale-to-female ratio of 7:1, while 25% arefor direct inguinal hernias. Fourteen percentare umbilical (female-to-male ratio, 1.7:1),5% are femoral (female-to-male ratio,1.8:1), and 10% are incisional (female-to-male ratio, 2:1). The prevalence of allvarieties of hernias increases with age.


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Etiology of the inguinal canal pathology

The embryology of the groin and of testicular

descent largely explains indirect inguinal hernias.An indirect inguinal hernia is a congenital herniaregardless of the patient's age. It occurs because of

protrusion of an abdominal viscus into an open

processus vaginalis. If the processus containsviscera, it is called an indirect inguinal hernia. Ifperitoneal fluid fluxes between the space and theperitoneum, it is a communicating hydrocele. Iffluid accumulates in the scrotum or spermatic cord

without exchange of fluid with the peritoneum, it isa noncommunicating scrotal hydrocele or ahydrocele of the cord. In a girl, fluid accumulationin the processus vaginalis results in a hydrocele of

the canal of Nuck.


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The inguinal canal forms by mesenchymecondensation around the gubernaculum,which is Latin for rudder because it guidesthe testis into the scrotum. During the firsttrimester, the gubernaculum extends fromthe testis to the labioscrotal fold. The

processus vaginalis and its fascial coveringsalso form during the first trimester. Abilateral oblique defect in the abdominalwall develops during the sixth or seventhweek of gestation as the muscular wall

develops around the gubernaculum. Theprocessus vaginalis protrudes from theperitoneal cavity and lies anteriorly,laterally, and medially to the gubernaculum

by the eighth week of gestation.


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Pathophysiology of inguinal hernias

The pinchcock action of the musculature of theinternal ring during abdominal muscularstraining prohibits protrusion of the intestine intoa patent processus. Paralysis or injury to themuscle can disable the shutter effect. In addition,the transversus abdominis aponeurosis flattensduring tensing, thus reinforcing the inguinalfloor. A congenitally high position of theaponeurotic arch might preclude the buttressing

effect. Neurapraxic or neurolytic sequelae ofappendectomy or femoral vascular proceduresmay contribute to a greater incidence of hernia inthese patients.


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Repetitive stress as a factor in herniadevelopment is suggested by clinical

presentations. Increased intra-abdominalpressure is seen in a variety of disease states andseems to contribute to hernia formation in these

populations. Elevated intra-abdominal pressureis associated with chronic cough, ascites,

increased peritoneal fluid from biliary atresia,peritoneal dialysis or ventriculoperitonealshunts, intraperitoneal masses or organomegaly,and obstipation. (See images below.) Otherconditions with increased incidence of inguinal

hernias are extrophy of bladder, neonatalintraventricular hemorrhage, myelomeningocele,and undescended testes. A high incidence (16-25%) of inguinal hernias occurs in prematureinfants; this incidence is inversely related toweight.


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A 6-month-old boy with a

ventriculoperitoneal shunt, decreased

activity, and acute scrotal swelling.


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A 6-month-old boy with a ventriculoperitoneal shunt, decreased

activity, and acute scrotal swelling (same patient as in above image).

Abdominal radiograph shows incarcerated shunt within a

communicating hydrocele. Repair of the hydrocele relieved the

increased intracranial pressure.


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The rectus sheath adjacent to groin hernias is thinnerthan normal. The rate of fibroblast proliferation is lessthan normal, while the rate of collagenolysis appearsincreased. Sailors who developed scurvy had anincreased incidence of hernia. Aberrant collagen states,such as Ehlers-Danlos syndrome, fetal hydantoinsyndrome, Freeman-Sheldon syndrome, Hunter-Hurlersyndrome, Kniest syndrome, Marfan syndrome, andMorquio syndrome, have increased rates of hernia

formation, as do osteogenesis imperfecta, pseudo-Hurler polydystrophy, and Scheie syndrome. Acquiredelastase deficiency also can lead to increased herniaformation. In 1981, Cannon and Read found thatincreased serum elastase and decreased alpha1-

antitrypsin levels in people who smoke contribute toan increase in the rate of hernia in those who smokeheavily. The contribution of biochemical or metabolicfactors in the creation of inguinal hernia remainsspeculative.


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Umbilical hernias

Umbilical hernias in children are secondary to failure of

closure of the umbilical ring, but only 1 in 10 adultswith umbilical hernias reports a history of this defect asa child. The adult umbilical hernia occurs through acanal bordered anteriorly by the linea alba, posteriorly

by the umbilical fascia, and laterally by the rectussheath. Proof that umbilical hernias persist from

childhood to present as problems in adults is only hintedat by an increased incidence among black Americans.Multiparity, increased abdominal pressure, and a singlemidline decussation are associated with umbilicalhernias.

Congenital hypothyroidism, fetal hydantoin syndrome,Freeman-Sheldon syndrome, Beckwith-Wiedemannsyndrome, and disorders of collagen and polysaccharidemetabolism (such as Hunter-Hurler syndrome,osteogenesis imperfecta, and Ehlers-Danlos syndrome),should be considered as possibilities in children withlarge umbilical hernias.


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Congenital abdominal wall defects

The underlying embryogenic factor inomphalocele and gastroschisis is deficientclosure of the developing anterior wall at theumbilical stalk. Variations in lateral foldmigration can result in omphalocele and

gastroschisis.4 In addition, most children withomphalocele and all children withgastroschisis have intestinal malrotation, astheir extracoelomic location precludes normalattachment of the intestines to the posteriorperitoneum.


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Improper development of other portions of the abdominal wallleads to specific anomalies. In 1967, Duhamel proposed thatmaldevelopment of the superior (cephalad) of the 4 folds

producing the abdominal wall leads to the thoracic, sternal and

diaphragmatic, and abdominal wall defects that make up theupper midline syndrome or pentalogy of Cantrell. In thissyndrome, there is a bifid sternal cleft, anterior diaphragmaticdefect, anterior pericardial defect, epigastric omphalocele, andcongenital cardiac defects. Maldevelopment of the inferior(caudal) fold produces pelvic, hindgut, sacral, genital, and

bladder defects. Lower midline syndrome includes a

hypogastric omphalocele, extrophy of the bladder or cloaca,vesicointestinal fissure, colonic atresia, imperforate anus, sacralvertebral defects, and often meningoceles.

Lateral fold maldevelopment results in omphalocele andgastroschisis. It has been postulated that an omphalocele resultsfrom persistence of the umbilical stalk in the somatopleure.

Approximately 20% of infants with omphaloceles have anassociated chromosomal abnormality, such as trisomy 13,trisomy 18, trisomy 2, or Klinefelter syndrome. Anomphalocele-exstrophy-imperforate anus-spinal defects(OEIS) complex is characterized by a combination ofomphalocele, exstrophy of the bladder, an imperforateanus, and spinal defects.


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Over 50% of infants with omphaloceles have associatedneurologic, urinary tract, cardiac, and skeletal anomalies. The

liver is present in the omphalocele sac in 35% of patients. Insmall omphaloceles, there is a high coincidence of Meckeldiverticulum. Maternal smoking is associated with an increasedprevalence of omphalocele and gastroschisis. An increasedincidence of abdominal wall defects is related to surface wateratrazine and nitrate levels.6

Gastroschisis is thought to be the result of a failure of theumbilical coelom to develop to an appropriate size. Theintestine then ruptures out of the body wall to the right of theumbilicus, where a slight weakness exists secondary toresorption of the right umbilical vein early in gestation.Gastroschisis is associated with intestinal atresias in 10-15% ofcases, likely due to an interruption of the vascular supply to the

intestine. Experimentally, administration of the insecticidemethylparathion has produced gastroschisis. Transplacentaltransmission of such teratogens helps explain gastroschisis insiblings with different fathers.


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Other hernias

Aberrant formation of the decussations of the linea alba,leading to a midline pattern of single anterior and posterior

lines, predisposes to the formation of epigastric hernias

(epiploceles). Abnormal orientation of the semilunar and

semicircular lines, in combination with obesity, increased

intra-abdominal pressure, aging, and rapid weight loss,

leads to the production of spigelian hernias. Internal supravesical hernias probably arise from congenital

deficiency in the fasciae. The perihernial fasciae or

musculature may be malformed in lumbar, femoral, and

other abdominal hernias. Interparietal hernias are often a

product of ectopic testicular descent. Multiparity and age

produce laxity of the pelvic floor to cause obturator herniasand perineal hernias.


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Presentation

History and physical examination

remain the best means of diagnosing

hernias. The review of systems should

carefully seek out associated conditions,such as ascites, constipation, obstructive

uropathy, chronic obstructive

pulmonary disease, and cough.


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Inguinal hernia

The diagnosis of hernia is usually made because apatient, parent, or provider sees a bulge in theinguinal region or scrotum. This bulge may beintermittent as the herniating viscus may or maynot enter the space depending on intra-abdominal

pressure. In infants, the only symptom of a herniamay be increased irritability, especially with alarge hernia. Hernias in older children and adultsmay be accompanied by a dull ache or burning

pain, which often worsens with exercise or

straining (eg, coughing). Neuralgia of theilioinguinal nerve may present with a suddenstabbing pain in the distribution.


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A 5-years-old boy with a history of irritability

and vomiting for 36 hours. Local signs of

this magnitude preclude reduction attempts.


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A boy of 6 months with bilateral inguinal

hernias


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A child with 48 hours incarcerated inguinal

hernia. The bowel necrosis occurred.


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Hydrocele

A hydrocele usually transilluminates onexamination. However, gas-filled intestines alsotransilluminate, thus precluding diagnosticaspiration. If the scrotal size vacillates or one cansqueeze fluid from the sac into the peritoneum, acommunicating hydrocele is present.Communicating hydroceles without an obvioushernia component should be repaired electively.Hydroceles are insignificant if they are present at

birth, bilateral, soft, and peritesticular; do notpersist beyond 6 months; and do not fluctuate in

size. Since most physiologic noncommunicatinghydroceles resolve spontaneously, an operation isgenerally confined to those older than 1 year,those that develop communication, or those thatappear painful to the child (see image below).


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Bilateral hydroceles in a boy of 2 years


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An acute hydrocele may present in childhood as

a rapidly growing, painful scrotal swelling

simulating an incarcerated hernia. Palpation of

the cord structures at the internal ring while

assessing their mobility helps distinguish

between these 2 entities. A hydrocele is more

mobile, has a defined proximal margin, and is

not thick. A hydrocele of the cord presents in the

inguinal canal as a nontender, rubbery, round

mass.


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An abdominoscrotal hydrocele extends from the

abdominal cavity through the inguinal canal into

the scrotum. With an infant, a digital rectal

examination with careful internal examination of

the ring can differentiate an incarcerated hernia

from a hydrocele. The child should have an

operation for clarification if the situation is

equivocal or if the intra-abdominal component is

causing mass effect on other organs or obstructivesymptoms.


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Other hernias

Hernias are the leading cause of intestinal

obstruction in the world. Hidden hernias, such as

obturator, femoral, or lumbar hernias, should be

considered as causes of bowel obstruction.

Intense pain is suggestive of strangulation with

ischemic bowel. Torsion of the bowel on entry

into the sac may lead to precipitous symptoms,

while a more gradual onset of pain arises from

progressive lymphatic, venous, and then finally

arterial compromise secondary to occlusion at the

neck of the sac.


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Congenital abdominal wall defects

Maternal serum alpha-fetoprotein screening can

help identify ventral wall defects in the fetusduring the second trimester. Prenatalultrasonography can define the location of theabdominal wall defect, the status of the viscera,its involvement with associated structures, and

the presence of additional malformations.Recognition of a small omphalocele or hernia ofthe umbilical cord stalk may not occur until afterdelivery. This may result in compromise of thesmall bowel or damage to an omphalomesenteric

duct as the cord is clamped. Therefore, the cordshould be clamped well away from the abdomenin an infant with an unusual cord base or widenedumbilical cord base to prevent iatrogenic injury tothe intestine.


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Inguinal hernias

In general, the presence of an inguinal hernia in the

absence of mitigating factors dictates repair toprevent the complications of prolonged exposure,such as incarceration, obstruction, and strangulation.

Although pressure reduction of an incarceratedhernia is generally safe, failure to reduce is not

infrequent and mandates prompt exploration. Signsof inflammation or obstruction should obviateattempts at reduction. Difficult reduction should

promptly be followed by repair. Unintentionalreduction of the intestine with vascular compromise

leads to perforation and peritonitis with highmorbidity and mortality rates. En masse reductionfollowing vigorous attempts at reducing a herniawith a small fibrous neck results in ongoingcompromise of the entrapped bowel.


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Umbilical hernias

Umbilical hernia repair in the adult is indicated for

incarceration, a small neck in relation to the size of the hernia,ascites, chromatic skin change, or rupture. The approach to

management of an umbilical hernia in a child relates to the

natural history of umbilical hernias and their importance in

adulthood. Most umbilical hernias close spontaneously in

children during the preschool-aged period. Therefore, repair of

an umbilical hernia is not indicated in children younger than 5

years unless the child has a large proboscoid hernia with thin,

hyperpigmented skin or is undergoing an operation for other

reasons or if the hernia causes familial or social problems. The

size of the fascial defect rather than the size of the external

protrusion predicts potential for spontaneous closure. Walkerdemonstrated that fascial rings measuring less than 1 cm in

diameter usually close, while rings larger than 2 cm seldom

close spontaneously. Therefore, many pediatric surgeons will

repair umbilical hernias with large fascial defects (>2.5 cm)

li th th ll t t

Congental Abdominal Wall Defects

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