Ventral Abdominal Wall Defects Sara A. Mansfield, MD, MS,* Tim Jancelewicz, MD, MA, MS* *Division of Pediatric Surgery, Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, TN Practice Gap Clinicians should be aware of the strategies for prenatal and postnatal management of infants with omphalocele and gastroschisis. Objectives After completing this article, readers should be able to: 1. Recognize the implications and differences in management between gastroschisis and omphalocele. 2. Review the initial stabilization and management of infants with omphalocele and gastroschisis. 3. Review the surgical management options and rationale for infants with ventral abdominal wall defects. INTRODUCTION Abdominal wall defects represent a wide spectrum of congenital anomalies. These can range from lethal limb-body wall syndrome to benign umbilical cord hernias. Gastroschisis and omphalocele are the 2 most common defects and are the focus of this review. Although both of these diseases affect the umbilical area, they differ widely in their underlying pathogenesis, genetics, and associated disorders. Consequently, their management techniques and outcomes are quite different. This article reviews the pathogenesis, genetics, diagnostics, and outcomes for each disease, followed by an in-depth review of recent management updates. OMPHALOCELE Pathogenesis Omphalocele (or exomphalos) is a herniation of the abdominal viscera through a midline abdominal wall defect (Fig 1). This defect is located at the base of the umbilical stalk, and herniated viscera are covered by a 3-layer membrane of peritoneum, Wharton jelly, and amnion. This contrasts with umbilical cord hernias, which are covered by intact skin and contain only a small protrusion of abdominal contents, and gastroschisis, which has no covering at all and occurs to the right of midline (Table). Omphaloceles are present in approximately 1 per 1,100 pregnan- cies. However, there is a high rate of spontaneous abortion, making the incidence of omphalocele per live birth approximately 1 per 4,000 to 1 per 6,000. (1)(2) During the fourth week of gestation, the flat embryonic disc undergoes a series of craniocaudal and lateral folding that creates a tubular, C-shaped embryo. Lateral AUTHOR DISCLOSURE Drs Mansfield and Jancelewicz have disclosed no financial relationships relevant to this article. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device. Vol. 40 No. 12 DECEMBER 2019 627 at Bibliotheque Univ Paris V on January 22, 2020 http://pedsinreview.aappublications.org/ Downloaded from
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Ventral Abdominal Wall DefectsSara A. Mansfield, MD, MS,* Tim Jancelewicz, MD, MA, MS*
*Division of Pediatric Surgery, Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, TN
Practice Gap
Clinicians should be aware of the strategies for prenatal and postnatal
management of infants with omphalocele and gastroschisis.
Objectives After completing this article, readers should be able to:
1. Recognize the implications and differences in management between
gastroschisis and omphalocele.
2. Review the initial stabilization and management of infants with
omphalocele and gastroschisis.
3. Review the surgical management options and rationale for infants with
ventral abdominal wall defects.
INTRODUCTION
Abdominal wall defects represent a wide spectrumof congenital anomalies. These
can range from lethal limb-body wall syndrome to benign umbilical cord hernias.
Gastroschisis and omphalocele are the 2 most common defects and are the focus
of this review. Although both of these diseases affect the umbilical area, they differ
widely in their underlying pathogenesis, genetics, and associated disorders.
Consequently, their management techniques and outcomes are quite different.
This article reviews the pathogenesis, genetics, diagnostics, and outcomes for
each disease, followed by an in-depth review of recent management updates.
OMPHALOCELE
PathogenesisOmphalocele (or exomphalos) is a herniation of the abdominal viscera through a
midline abdominal wall defect (Fig 1). This defect is located at the base of the
umbilical stalk, and herniated viscera are covered by a 3-layer membrane of
peritoneum,Wharton jelly, and amnion. This contrasts with umbilical cord hernias,
which are covered by intact skin and contain only a small protrusion of abdominal
contents, and gastroschisis, which has no covering at all and occurs to the right of
midline (Table). Omphaloceles are present in approximately 1 per 1,100 pregnan-
cies.However, there is a high rate of spontaneous abortion,making the incidence of
omphalocele per live birth approximately 1 per 4,000 to 1 per 6,000. (1)(2)
During the fourth week of gestation, the flat embryonic disc undergoes a series
of craniocaudal and lateral folding that creates a tubular, C-shaped embryo. Lateral
AUTHOR DISCLOSURE Drs Mansfield andJancelewicz have disclosed no financialrelationships relevant to this article. Thiscommentary does not contain a discussion ofan unapproved/investigative use of acommercial product/device.
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Almost half of these infants will have a major congenital heart
defect. The long-termoutcomes aredirectly related to these other
anomalies rather than to the abdominalwall defect itself. Isolated
omphalocele has a survival rate of more than 95%. (5) Overall
survival has been difficult to assess given the high spontaneous
and elective termination rate. (6) Survival rates have been cited at
less than 20% to 50% in prenatally diagnosed cases, which
includes cases of termination. (1)(6)
Omphalocele is frequently seen as part of genetic disor-
ders and syndromes. Approximately 10% of infants with
Figure 1. A. Lateral view of a newborn with an omphalocele containing liver and intestine. B. Anterior view. C. Two-year-old girl with a giantomphalocele that was completely epithelialized. The defect contained the entire liver and intestines. D. First-stage closure of a giant omphalocele, withpartial reduction of contents due to lack of abdominal domain. E. Second-stage closure of a giant omphalocele, 3 months after the first stage. Primaryfascial closure was achieved with this approach.
TABLE. Defining Characteristics of Abdominal Wall Defects
abnormalities are identified in approximately one-third of
infants with omphalocele and include trisomy 12, 18, and 21.
Other conditions that result from incomplete folding of the
body wall folds during embryogenesis manifest as variants
of omphalocele. Infraumbilical omphalocele is often asso-
ciated with genitourinary abnormalities and includes blad-
der or cloacal exstrophy as part of OEIS association
(omphalocele, exstrophy of the bladder, imperforate anus,
and spinal defects) (Fig 2A).
Pentalogy of Cantrell is a rare lesion (5.5 per 1 million live
births) consisting of epigastric omphalocele, inferior sternal
defect, anterior diaphragmatic defect, and intracardiac and
pericardial defects (Fig 2B). The heart is positioned outside
the thoracic space within the epigastric defect (Video 1).
There is a spectrum of severity, and survival is related, in
general, to the type of cardiac defect; incomplete or partial
pentalogy tends toward more favorable outcomes than com-
plete pentalogy. (7) When associated with complete ectopia
cordis, survival is extremely poor (Fig 2C).
Prenatal Diagnosis and ManagementOmphaloceles are usually diagnosed prenatally in the latefirst
or second trimester. Elevated maternal serum a-fetoprotein
levels should raise suspicion of an abdominal wall defect.
Ultrasonography has a sensitivity of 75% to 80% and a
specificity of approximately 95% for both omphalocele and
gastroschisis. (1)(8) As mentioned previously, the midgut
undergoes physiologic herniation during the sixth week of
gestation and does not fully return to the abdomen until week
11 or 12. Therefore, a diagnosis of omphalocele should not be
made before the 12th week of gestation. Karyotype analysis is
indicated for all cases of suspected omphalocele. Often the
prenatal diagnosis is straightforward, allowing providers to
adequately counsel the patient and provide perinatal plan-
ning. However, it is important to note that prenatal imaging
and karyotyping may miss 30% to 40% of associated anom-
alies that are subsequently found after birth. (2)
In cases in which the diagnosis is not evident, further
imaging may be necessary. Fetal magnetic resonance imag-
ing (MRI) has been advocated to better delineate anatomy,
allowing for more accurate prenatal counseling. (9) Umbil-
ical cord hernia, which has an excellent prognosis and a low
likelihood of associated anomalies, can be difficult to dif-
ferentiate from gastroschisis and omphalocele on conven-
tional ultrasonography. However, in the second and third
trimesters, the intact skin seen in umbilical hernias be-
comes apparent on MRI. If an umbilical cord hernia is
present, knowledge of this finding should be communicated
to delivery room staff to avoid injury to the bowel when
clamping the umbilical cord.
When an omphalocele is diagnosed, prenatal evaluation
should focus on identifying associated cardiac and central
nervous system defects because these are the major deter-
minants of outcome. Although ultrasonography is highly
accurate at diagnosing omphalocele, (10) fetal MRI can add
more information to the prediction of postnatal morbid-
ity. (11)(12) The degree of pulmonary hypoplasia can be
Figure 2. A. Classic cloacal exstrophy with open cecum and prolapsed terminal ileum (TI); visible is 1 hemibladder (HB). B. Pentalogy of Cantrell withepigastric omphalocele, sternal defect, anterior diaphragmatic defect, and pericardial defect, allowing the heart (H) to be visible in the epigastrium; thischild was discharged from the hospital with staged repair planned at a later date. C. Complete ectopia cordis and pentalogy of Cantrell, with the heart(H) completely outside the chest; this newborn died within 24 hours of birth.
Video.due to the sternal defect, abdominal wall defect, anterior diaphragmaticdefect, and absent pericardium.
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Pentalogy of Cantrell. The beating heart is visible under the skin
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11.1). (31) The 1-year survival of babies with isolated ompha-
locele is greater than 90%, compared with 27% in those
with chromosomal anomalies. (32)
GASTROSCHISIS
PathogenesisGastroschisis is a defect of the abdominal wall located 1 to 2
cm to the right of the umbilicus (Fig 3), and it has a very
different clinical picture from an omphalocele. Gastroschi-
sis is a herniation of the bowel without a membranous
covering (Table) and is typically an isolated finding, without
associated congenital anomalies. The morbidity seen in
gastroschisis is directly related to the gastrointestinal dys-
motility that results from exposure to amniotic fluid during
gestation. Intestinal atresias are seen in approximately 6%
to 28% of infants with gastroschisis. (33)(34)(35) This is
thought to be due to trauma of the bowel against the
abdominal wall or vascular compromise from segmental
volvulus.
The incidence of gastroschisis has nearly doubled during
the past few decades, with a current rate of approximately 2
to 5 per 10,000 live births. (36)(37) The most significant risk
factor seems to be young maternal age, with a sevenfold
Figure 3. A. Gastroschisis with moderate bowel edema and fibrinous exudate from amniotic exposure. B. The bowel was placed into a silo to allow slowreduction over 2 to 3 days. C. Complex gastroschisis with herniated liver (L) and at least 1 intestinal atresia with visible mucosa (M); this child requiredvery slow reduction along with stoma creation, which was very difficult due to lack of abdominal wall surface. D. Sutureless (nonoperative) closure ofgastroschisis: (i) initial presentation with minimal bowel edema; (ii) successful reduction without a silo, showing the residual defect; (iii) coiling of theumbilical cord over the defect, followed by application of an occlusive dressing; (iv) appearance of the defect after 1 week of coverage; and (v)appearance of the umbilicus at 1 year of age (no umbilical hernia in this case).
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incidence among teenage mothers. Tobacco, (38)(39) recre-
ational drug, (40) and certain decongestant (41)(42) use have
also been implicated. These risk factors have been the basis
for embryologic theories. The association with sympatho-
mimetic agents such as smoking, cocaine, amphetamines,
and decongestants supports a vascular accident hypothe-
sis. Theories regarding the embryogenesis of gastroschisis
include failure of lateral body wall folding, localized para-
umbilical tissue weakness associated with regression of the
right umbilical vein, and vascular accidents of the vitelline
artery. (43)
In some cases, the abdominal wall defect may close
before birth. If bowel is present in the defect, this can result
in strangulation, necrosis, and possible amputation. This
phenomenon is referred to as “vanishing gastroschisis.”
Occasionally the bowel will be seen emerging from the
abdomen (Fig 4). The proximal bowel is typically dilated
and dysmotile. In severe situations, a large mass of bowel is
compromised and can lead to devastating short bowel
syndrome. Smaller abdominal wall defects are associated
with complex gastroschisis (vanishing gastroschisis, atresia,
necrosis, perforation, etc). (44)
Prenatal Diagnosis and ManagementUnlike omphalocele, intrauterine demise is uncommon
with gastroschisis. Whereas infants with omphalocele are
typically born at term, those with gastroschisis have an
average gestational age of 34 to 37 weeks. (18) Gastroschisis
is associated with higher maternal a-fetoprotein levels than
an omphalocele (7–9 times normal versus 4 times normal).
On ultrasonography, the umbilical cord insertion site is
normal, but the free-floating bowel is seen outside the
abdomen. The defect can be seen in a paramedian location,
usually to the right of the umbilicus. Gastroschisis most
commonly occurs as an isolated finding, but it is important
to look for additional malformations. Approximately 10% of
fetuses with gastroschisis will have an additional anomaly.
Serial ultrasonography is important to monitor bowel
viability. Bowel loops may appear thickened as irritation
from amniotic fluid worsens. Bowel dilation can be seen,
and if severe should be a warning of an underlying atresia.
Worsening dilation and echogenicity should raise the con-
cern of threatened, ischemic bowel. Some experts recom-
mend early delivery when signs of bowel compromise
develop. Survival for infants with gastroschisis decreases
to 70% if ischemia, perforation, or atresias are present at
birth. A recent meta-analysis reported correlations between
sonographic evidence of intra-abdominal bowel dilation and
polyhydramnios with the presence of bowel atresia, as well
as a correlation between gastric dilation and neonatal death.
(45)
As with omphalocele, vaginal delivery is preferred unless
an indication for cesarean delivery is present for obstetric
reasons or fetal distress. Currently, there is no difference in
outcomes between cesarean and vaginal delivery in the
literature. A recent meta-analysis of available observational
studies found no difference in overall mortality, ability to
undergo primary repair of the abdominal wall defect, inci-
dence of necrotizing enterocolitis, sepsis, time to full feeds,
or duration of hospital stay. (46) There has been debate over
the timing of delivery. Some groups advocate that preterm
delivery is associated with shorter duration of exposure to
amniotic fluid and, thus, less bowel dysmotility. Multiple
studies, including a Cochrane review, showed no difference
or higher rates of adverse outcomes associated with delivery
before 36 weeks, which exposes the infant to undue risks of
prematurity. (47)(48)(49)Most centers wait until the natural
onset of labor.
Postnatal ManagementImmediately after birth, the bowel must be protected from
the environment to conserve humidity and temperature.
The “bowel” bag, or Lahey bag, is the most common option.
The lower half of the infant is placed into the sterile bag,
Figure 4. A. Appearance of vanishing gastroschisis at birth with infarcted intestine and a tiny residual gastroschisis defect. B. Appearance of the proximaldilated small intestine and resected infarcted segment in the same patient at laparotomy. A primary serial transverse enteroplasty procedure wasperformed on this patient, and she became independent of parenteral nutrition within a year of birth.
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and organ injury (renal failure, bowel ischemia). The most
common closure method is suturing of the abdominal wall
fascia. Most recently, a “sutureless” closure is gaining
popularity. (51) With this approach, the bowel is reduced,
and the umbilical cord remnant is positioned over the
abdominal wall defect (Fig 3). A tight adhesive dressing is
placed over this and changed every few days until the fascial
defect has closed. Some infants may initially develop an
umbilical hernia, but many will close over time. Sutureless
closure can be performed at the bedside without general
anesthesia, a benefit over sutured fascial closure; (52) there
is also a lower rate of required mechanical ventilation.
(53)(54) The only randomized controlled trial on the matter
showed no benefit of sutureless (n¼19) compared with
classic sutured (n¼20) closure in length of stay or time
to full enteral feeding. (55)
If there is too much eviscerated bowel or if the bowel is
too edematous to immediately reduce, a preformed silastic
silo is placed (Fig 3B). This can be performed in the NICU.
The silo is then tightened once or twice daily until the
contents are fully reduced. These reductions can also be
performed at the bedside with a small amount of sedation.
Constant attention is given to the hemodynamics of the
infant during reduction. Once fully reduced, the defect can
then undergo surgical closure or sutureless closure. With
any of the closure methods, the bowel should be inspected
for the presence of intestinal atresias before definitive
closure.
In babies with complex gastroschisis (atresia, perfora-
tion, necrosis), a bowel resection or ostomymay be required.
The bowel is typically too edematous to safely repair intes-
tinal atresias immediately at birth. Therefore, these are
addressed after 4 to 6 weeks, when an anastomosis is
feasible. A contrast enema is usually performed to confirm
the level of the lesion(s).
The bowel is nonrotated in babies with gastroschisis.
However, the degree of intestinal adhesions in these infants
is usually significant enough that volvulus is a rare event.
(28)
OutcomesAfter surgical correction, infants with gastroschisis are still
faced with significant ileus and bowel dysmotility, result-
ing in hospitalization for weeks tomonths. Total parenteral
nutrition should be started soon after birth in anticipation
of lack of enteral nutrition, as ileus averages 2 to 3 weeks.
(43) After correction, the amount and character of the
nasogastric tube output is monitored before initiation of
enteral nutrition. Enteral feeds are then slowly advanced,
and the infant is monitored for tolerance. Standardization
of care may help with day-to-day management of these
infants. (56)(57) Overall survival in infants with gastro-
schisis is more than 90%. Interdisciplinary intestinal
failure teams should be involved to aid in long-term
dysmotility management.
References for this article are at http://pedsinreview.aappub-
lications.org/content/40/12/627.
SummaryOmphalocele and gastroschisis are 2 of the most commoncongenital abdominal wall defects. The 2 disorders vary widely inpresentation, embryologic origin, and management.• Based on some research evidence as well as consensus (Level B),outcomes with omphalocele are excellent in the absence of anysignificant associated anomalies. (31)(32)
• There is good evidence (Level A) that survival in gastroschisisexceeds 90%, with morbidity primarily in those with intestinalinjury or atresia. (45)(46)
• Based largely on mid-level evidence and a few randomized trials(Level B), there is general consensus regarding management ofaffected infants. (6)(17)(18)
• Based on Level B evidence, a multidisciplinary, standardizedapproach to treatment can lead to excellent long-term outcomes.(57)
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1. You are called to the hospital for the impending delivery of a 37-week neonate withprenatally diagnosed omphalocele. You discuss the planwith the delivery team and explainto the medical students on the team the anatomy of this condition. In your discussion,you explain that omphalocele is a herniation of the abdominal viscera through a defect inwhich of the following anatomical structures?
A. Abdominal wall.B. Amnion.C. Peritoneum.D. Umbilical stalk.E. Wharton jelly.
2. You are providing postnatal care for a term neonate with omphalocele. The baby was bornat term to a 22-year-old primigravida mother who received prenatal care. Prenatalultrasonography provided the diagnosis of abdominal wall defect along with severalcongenital anomalies. Pregnancy was complicated by oligohydramnios. You consultpediatric surgery and genetics. In considering the sources of greatest risk for morbidity inthis patient, which one of the following factors accounts for most of the potential cause ofmorbidity in this patient?
A. Associated congenital anomalies.B. Gastrointestinal dysmotility.C. Irritating effects of amniotic fluid exposure.D. Limited pulmonary capacity.E. Young maternal age.
3. The mother of a patient in your pediatric practice is pregnant with her second child. Shecontacts you to get your opinion on the result of her prenatal ultrasonography, which raisedconcern for omphalocele. Her serum a-fetoprotein levels were elevated. Which one of thefollowing diagnostic tests is indicated for all cases of suspected omphalocele based onultrasonography findings?
A. Biophysical profile.B. First trimester fetal magnetic resonance imaging.C. Karyotype analysis.D. Repeated serum a-fetoprotein level.E. Weekly nonstress testing.
4. The mother in question 3 is at 35 weeks’ gestation with a smooth pregnancy course. She isreferred to the nearby tertiary care hospital, where she will be delivered by her obstetrician.The neonatology team will be present at the delivery. Which of the following is the mostappropriate step to be considered in the peripartum and postnatal care of this infant?
A. Cesarean delivery.B. Emergent definitive surgical correction at day 0 after birth.C. Fluid restriction to avoid pulmonary edema.D. Induction of labor at 36 weeks’ gestation.E. Orogastric tube placement immediately after delivery.
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5. A newborn male infant with gastroschisis is born at 37 weeks’ gestation. The baby isadmitted to the NICU where he is stabilized. Surgical correction is planned in the nextfew weeks. The family asks how long they should anticipate their baby to remain in thehospital after surgical correction. Which of the following best describes the expectedinpatient stay after surgical correction for gastroschisis in this patient?
A. At least 72 hours, until oral feeds are tolerated.B. On average 10 days, until an antibiotics course is completed.C. Several days postoperatively, until the first bowel movement.D. Up to 3 weeks, until weight gain is established.E. Weeks to months, due to significant dysmotility.
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DOI: 10.1542/pir.2018-02532019;40;627Pediatrics in Review
Sara A. Mansfield and Tim JancelewiczVentral Abdominal Wall Defects
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