Abdominal Wall Malformations abdominal cavity

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					 60                         A B D O M I N A L

                            M A L F O R M A T I O N S
                                                                                  W A L L


                            A     bdominal wall defects occur at two sites where or-
                            gans pass through: the umbilicus, where viscera formed
                            in the amniotic sac outside the abdomen pass into the
                            abdominal cavity; and the inguinal region, where testes
                            migrate from their retroperitoneal abdominal location to
                            the scrotum outside or external to the body. Of the two,
                            the latter is far more common.
                               This chapter describes the defects to be found at these
                            two sites and emphasizes the points in their differentia-
                            tion and treatment.

CASE 1                                                      CASE 2
OMPHALOCELE                                                 GASTROSCHISIS

A 30-year-old female was seen in the 6th month of her       A 4-hour-old female neonate was referred because of
second pregnancy. An abdominal ultrasound showed a          extra-abdominal viscera. She was delivered vaginally to a
male fetus with what was interpreted as extra-abdominal     32-year-old mother of three. The external bowels were
viscera. No other congenital defect was noted. An α-feto-   edematous, reddened, and covered in patches with a yel-
protein level later returned markedly elevated. She was     low-gray peel. They had been placed in a plastic sac for
informed of the findings and accepted that a cesarean sec-   transport.
tion delivery would be done before term. At operation, a        On arrival, the neonate appeared cold but otherwise
2,800-g male was delivered. At the base of the umbilical    healthy. She was placed on a warming blanket in the
cord was an intact 8-cm sac containing most of the small    neonate ICU. The abdomen was flat and underdeveloped.
bowel and a portion of the colon. The bowel appeared        To the right of the umbilicus was a 4-cm defect through
normal. There was no cardiac murmur. The following day      which passed most of her intestines. She was brought to
the neonate underwent operation. The sac was excised        operating room where a plastic tube (chimney) was sewn
and the defect repaired primarily. On follow-up examina-    to the skin edges around the defect with the bowels inside
tion 2 months later, there was normal growth and devel-     the tube. The other end of the plastic chimney was closed
opment of the infant.                                       and maintained vertically by a line attached to the end,

4 4 2      P E D I A T R I C       S U R G E R Y

and brought through a pulley with a weight at the end.                        GENERAL CONSIDERATIONS
During the following week, the edema in the extra-ab-
dominal loops of bowel receded and the intestines gradu-                   uring embryonic development the viscera devel-
ally slid into the abdomen. On the 9th day, a primary re-         ops in the amniotic sac outside of the abdominal cavity.
pair of the abdominal wall defect was done. There was             With maturity the sac is gradually reabsorbed and the vis-
normal growth and development of the neonate on follow-           cera (liver and bowels) are relocated into their proper
up visit at 2 months.                                             intra-abdominal sites. This generally takes place by the
                                                                  8th week of prenatal life.
                                                                      When this process is interrupted, usually because of
CASE 3                                                            genetic defects, the abdominal contents remain in the
INGUINAL HERNIA                                                   amniotic sac. The abdominal cavity is then severely under-
                                                                  developed. The sac may remain intact but is usually rup-
The mother of a 2-month-old male infant noted a bulge in          tured during birth. The viscera tends to be dilated, edem-
the right inguinal region when the infant cried. When the         atous, and covered with a gelatinous “peel” (Fig. 60.1).
infant was relaxed and not crying, the mass disappeared.          The genetic factors responsible may involve other organs,
The mass was not noticeably tender or firm when the                in particular the heart. Omphalocele is thus indicative of a
mother touched it. The pediatrician confirmed the pres-            very serious problem. It has a high mortality rate because
ence of a right inguinal hernia, probably indirect. No her-       of the associated congenital defects, in particular those of
nia or dilatated inguinal rings could be felt on the left side.   the heart.
A right inguinal hemography was done. On follow-up ex-                Another defect to be found about the umbilicus, in-
amination 4 months later, no inguinal masses or bulges            variably to the right of it (Fig. 60.2), is gastroschisis. Here
were found.                                                       again, there is bowel outside of the abdominal cavity. The

                                            FIGURE 60.1      (A & B) Omphalocele.
                                          A B D O M I N A L        W A L L       M A L F O R M A T I O N S                    4 4 3

                                           FIGURE 60.2     (A & B) Gastroschisis.

bowel is similarly edematous, dilated, and covered with a            The last and most common benign defect of the um-
thick, gelatinous peel. Although there may be associated        bilicus is an umbilical hernia. Common in blacks, they
defects, they are exclusively of the bowel and include such     usually close as the infant grows.
things as atresias, volvulus, or areas of stenosis. These de-        Overall, inguinal hernias are the most common abdom-
fects are thought to result from vascular injuries and the      inal wall malformation. The testis, as it descends from its
effect of pressure on the bowel. However, other organs          retroperitoneal site of origin, is usually accompanied by a
are normal. This, together with a recently recorded signifi-     finger of the peritoneum (see Ch. 13), the processus vagi-
cant increase in the incidence of gastroschisis, implies that   nalis. Although this remnant coursing along the cord
environmental rather than genetic factors are responsible       structures is relatively common, only a few develop into
for its development. Gastroschisis has a much lower mor-        indirect hernias. In neonates and newborns, these usually
tality rate than omphalocele.                                   occur on the right and, not infrequently, bilaterally.
     Remnants of the connection between the bowel and
the yolk sac may persist at the umbilicus, namely, the om-
                                                                 K E Y        P O I N T S
phalomesenteric duct remnants. Because a duct may per-
sist or remain as an atrophic fibrous band, it can produce        • When developmental process interrupted, usually because of
intestinal obstruction as a segment of bowel gets caught or      genetic defects, abdominal contents remain in amniotic sac
wrapped about the band.                                          • Viscera tends to be dilated, edematous, and covered with
     The other remnant to be found in the umbilicus is a         gelatinous “peel” (Fig. 60.1)
remnant of the urachal duct connecting the umbilicus to          • Omphalocele is indicative of very serious problem; high mor-
the urinary bladder. The urachal duct and bladder are            tality rate because of associated congenital defects, in particular
retroperitoneal and therefore not associated with intesti-       those of the heart
nal obstruction.
4 4 4      P E D I A T R I C         S U R G E R Y

                                                                    T         DIFFERENTIAL DIAGNOSIS
 • Another defect to be found about umbilicus, invariably to the
 right of it (Fig. 60.2) is gastroschisis
                                                                          he finding of extracorporeal bowel covered with a
 • Although there may be associated defects, they are ex-
                                                                    thick, gelatinous peel at birth is due to either omphalocele
 clusively of the bowel and include such things as atresias,
                                                                    or gastroschisis.
 volvulus, or areas of stenosis; these defects are thought to
 result from vascular injuries and effect of pressure on the            Omphaloceles are readily diagnosed by the presence
 bowel                                                              of the omphalosac remnant in which the viscera are con-
                                                                    tained. The sac is found at the base of the umbilical cord
 • Gastroschisis has much lower mortality rate than omphalo-
 cele                                                               (Fig. 60.2). The sac is rarely intact. More frequently, a
                                                                    portion of it remains after the trauma of birth. The in-
 • Overall, inguinal hernias are most common abdominal wall
                                                                    testines are covered by thick, gelatinous peel. The finding
                                                                    of an associated cardiac defect suggests the diagnosis.
                                                                        Gastroschisis, by contrast, lacks a sac, and is found al-
                                                                    ways to the right of the umbilicus. It is not associated with

T         DIAGNOSIS                                                 cardiac or other defects, other than those of the bowel.
                                                                        Omphalitis, infection of the umbilicus, can produce a
       he diagnosis of congenital abdominal wall malforma-          discharge that resembles that of omphalomesenteric duct
tions can be made on careful inspection.                            remnant or of a urachus. Omphalitis, however, responds
     Large defects with the presence of extracorporeal              promptly to local hygiene and topical antibiotics, whereas
bowel are obvious. Grossly similar omphalocele and gas-             the drainage from the congenital duct elements persists.
troschisis can be further differentiated by careful exami-              Bulges in the groin include hydroceles and unde-
nation as discussed below.                                          scended testes. The scrotum must be carefully examined,
     The general use of ultrasonography during pregnancy            therefore, when the infant is thought to have an inguinal
has made possible prenatal detection of these defects.              hernia. Hydroceles contain clear peritoneal fluid. In a
Screening for elevated levels of serum α-fetoprotein                darkened room they transilluminate light readily, whereas
(AFP) also detects these defects.                                   hernias and undescended or retractile testes do not. The
     The discharge of bile-stained or feculent-like material        retractile testes can be replaced down into the scrotum,
suggests persistent omphalomesenteric duct. Contrast                whereas the undescended testis cannot.
studies showing the dye in the ileum confirm the diagno-
sis. A granulating, non-healing umbilicus may contain a              K E Y       P O I N T S
gastric mucosa found in these ducts.
                                                                     • Omphaloceles readily diagnosed by presence of omphalosac
     Clear fluid expressed from the umbilicus suggests a              remnant in which viscera are contained
urachal duct or cyst. Contrast die injected into the sinus
                                                                     • Gastroschisis lacks a sac and is found to right of umbilicus;
shows the course of the tract, often to the bladder.
                                                                     not associated with cardiac or other defects, other than bowel
     Umbilical hernias are usually evident on gross inspec-
                                                                     • Omphalitis, infection of umbilicus, can produce discharge
tions; less commonly, the defect is only found on palpa-
                                                                     that resembles that of omphalomesenteric duct remnant or of
tion. Hernias may become obvious when the child cries or
                                                                     • Bulges in groin include hydroceles and undescended testes;
     Inguinal hernias are evident as bulges or masses in the
                                                                     in darkened room, transilluminate light readily, whereas hernias
groin that become visible or more pronounced when the
                                                                     and undescended or retractile testes do not
child cries and increases the intra-abdominal pressure.
When not visible, a hernia should be considered in the in-
fant who cries when moving bowel or who appears restless

or uncomfortable for no discernible reason. Careful palpa-                      TREATMENT
tion of the cord structure bilaterally will give the feeling of
a thickened, smooth structure (“silk-glove” sign) beneath                    mphalocele can be treated by gradual inversion of
the examining finger.                                                the sac, allowing the viscera to slowly be returned to the
                                                                    abdominal cavity. Alternatively, when most of sac has been
 K E Y       P O I N T S                                            lost, the viscera can be contained in a plastic bag anchored
 • Clear fluid expressed from umbilicus suggests urachal duct        to the abdominal wall, which serves the same function as
 or cyst                                                            the intact sac.
 • Inguinal hernias evident as bulges or masses in groin that be-        The treatment of this and other congenital disorders is
 come visible or more pronounced when child cries and in-           undergoing change because of accurate antenatal diagno-
 creases intra-abdominal pressure                                   sis by ultrasonography. Omphalocele and associated car-
                                                                    diac defects discovered early in the pregnancy pose the
                                              A B D O M I N A L         W A L L        M A L F O R M A T I O N S              4 4 5

question of terminating the pregnancy. When the preg-               SUGGESTED READINGS
nancy is continued, delivery by cesarean section is prefer-
able, as the intestines are normal in these instances. The          Bethel C, Seashore J, Touloukian R: Cesarean section does not
thick, gelatinous peel is related to normal labor and vagi-             improve outcome in gastroschisis. J Pediatr Surg 24:1, 1989
nal delivery.                                                            A consideration of the pros and cons of cesarean section in
     Gastroschisis, similarly, is best treated by cesarean sec-          the prevention of bowel complications in this condition.
tion delivery to avoid the morbidity from otherwise ede-
matous bowel covered by a peel. At delivery, the normal-            Hatat V, Baxter R: Surgical options in the management of large
appearing bowel is returned to the abdominal cavity, and                omphaloceles. Am J Surg 153:449, 1989
the abdominal wall defect is closed primarily. Gastroschi-               Elucidates the last treatment plans for these large, difficult
sis found during labor and vaginal delivery is treated by                lesions.
placing the swollen peel-covered bowel in a plastic sac
sewn to the edges of the defect. Gradually the swelling
subsides, the peel is slowly reabsorbed, and the bowel is           QUESTIONS
returned to the abdominal cavity. The abdominal wall de-
fect is then repaired. Omphalomesenteric duct remnant is            1. The thick, gelatinous peel found covering the extracor-
excised along with a short segment of the ileum into which          poreal intestines in either instance of omphalocele or gas-
it leads.                                                           troschisis is?
     Urachal duct remnant is excised and the bladder and                 A. Due to genetic or viral infections responsible for
umbilical defects closed.                                                   the development of both conditions.
     Umbilical hernias are observed until the child is about             B. Related to the extracorporeal location of the
5 years of age, as most will have closed by then. Those that                bowel antenatally in both conditions.
persist or become enlarged or systematic are treated by                  C. Related to the biochemical changes and trauma
repair of the defect.                                                       associated with normal labor and delivery.
     Inguinal hernia repair is perhaps the most common                   D. Cannot be prevented by any present means.
operation done in neonates and infants. In contrast to
                                                                    2. Of the two, omphalocele and gastroschisis?
adults (see Ch. 13), these are invariably indirect hernias.
Simple excision of the hernia sac, processus vaginalis, suf-            A. Omphalocele is the more lethal condition because
fices in neonates. In other infants, a repair of the inguinal                of associated cardiac defects.
                                                                        B. Gastroschisis is the more lethal condition because
region may be necessary.
                                                                            of the lack of the amino sac to protect the exposed
 K E Y       P O I N T S                                                    bowel from injury and infection.
                                                                        C. The prognoses are similar inasmuch as extracor-
 • When most of sac lost, viscera can be contained in plastic bag           poreal bowel is found in each and the difference
 anchored to abdominal wall, which serves same function as in-
                                                                            is primarily in the size and location of the abdomi-
 tact sac
                                                                            nal wall defect.
 • When pregnancy is continued, delivery by cesarean section is         D. None of the above.
 preferable, as intestines are normal in these instances
                                                                    3. Umbilical hernias are?
                                                                        A. Particularly common in premature infants and
                                                                           black infants.

R          FOLLOW-UP                                                    B. Benign, as most will close spontaneously with
                                                                           growth and development.
         epairs of abdominal wall defects need to be ob-                C. Treated when they fail to close in the first 5 years,
served over the following year to ensure that the repair                   enlarge, or become symptomatic.
does not fail and a defect recur. In addition, neonates born            D. All of the above.
with extracorporeal viscera are followed to ensure that in-
testinal complication of obstruction or malabsorption do
not occur.                                                          (See p. 604 for answers.)

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