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Abdominal Wall Conditions

Overview of Anterior Abdominal Wall Defects

  • Frequent neonatal surgical condition involving failure of midgut return during embryonic development (11th week gestation).
  • Leads to abdominal contents protruding through the abdominal wall defect.

Omphalocele

  • Central abdominal wall defect > 4 cm with a membranous sac (outer layer: amnion, inner layer: peritoneum).
  • Smaller defects (< 4 cm): Referred to as umbilical cord hernias.
  • Associated anomalies (∼50%):
    • Beckwith-Wiedemann syndrome:
      • Gigantism, macroglossia, and umbilical defect.
    • Chromosomal abnormalities: Trisomies 13, 15, 18, 21.
    • Bladder or cloacal exstrophy, Pentalogy of Cantrell (omphalocele, anterior diaphragmatic hernia, sternal cleft, ectopia cordis, intracardiac defect).
  • Initial Management:
    • Preserve the intact omphalocele sac.
    • Prevent hypothermia.
    • Comprehensive diagnostic workup to identify associated anomalies.
  • Surgical Management:
    • Primary closure for small to medium defects.
    • Large defects: Closed with prosthetic patch (e.g., Gore-Tex), Surgisis, skin flap, or silo for staged reduction.
    • Giant omphaloceles: Treated with escharotic agents (e.g., povidone-iodine, silver nitrate) to thicken and epithelialize the sac.
  • Prognosis:
    • Dependent on lung maturity and the severity of associated anomalies.

Gastroschisis

  • Defect located to the right of an intact umbilical cord, typically 4 cm in diameter, with no sac covering the abdominal viscera.
  • Direct exposure to amniotic fluid causes intestinal thickening, edema, and inflammation.
  • Associated findings:
    • Intestinal atresia: Present in 15% of cases.
    • Other major anomalies are rare.
  • Initial Management:
    • Infants placed in a warm, saline-filled plastic bowel bag up to the nipple line to minimize heat and fluid loss.
    • Allows for inspection of the bowel to avoid twisting.
  • Surgical Management:
    • Primary reduction of eviscerated contents is successful in 50%-80% of cases.
    • If unsuccessful, a ringed silo bag is used for gradual reduction over several days, followed by operative closure.
    • Sutureless closure with a watertight clear dressing may also be performed.
    • Intra-abdominal pressure should be < 15 mm Hg to avoid compartment syndrome.
    • Delayed closure performed in cases of associated intestinal atresia or stenosis.
    • For larger defects, a prosthetic patch (Gore-Tex) is placed, followed by skin closure.
  • Complications:
    • Necrotizing enterocolitis (NEC): Reported in 20% of patients after gastroschisis repair.
    • Undescended testis: Found in 10%-20% of infants.
      • Testes are repositioned into the abdominal cavity without orchidopexy at the time of repair.
      • Orchidopexy performed later if necessary.
    • Prolonged ileus and risk of short gut syndrome.
    • Cholestasis due to prolonged total parenteral nutrition (TPN) support.

Hernias in Pediatric Surgery

Inguinal Hernia

  • Incidence:
    • Term infants: 3%-5%.
    • Premature infants: 9%-11%.
    • Affects boys six times more often than girls.
    • 60% on the right side, 30% on the left side, 10% bilateral.
    • Most are indirect and congenital in nature.

Pathophysiology

  • Caused by the persistence of the processus vaginalis, which normally obliterates by the ninth month of gestation or shortly after birth.
  • Can present as:
    • Scrotal hernia with protrusion of intestine, ovaries, omentum, or communicating hydrocele.

Diagnosis

  • Based on clinical history and physical examination.
  • Transillumination may not be reliable, as thin-walled bowel loops can transilluminate.
  • Silk glove sign: A diagnostic clue felt by palpation of the cord.
  • Ultrasound may be helpful if there is suspicion of associated conditions like epididymitis or testicular torsion.

Risks

  • Major risks include bowel incarceration and strangulation.
  • Premature infants have a higher risk of incarceration in the first year of life.

Timing of Surgery

  • Historically performed before hospital discharge in premature infants.
  • Current concerns involve the risk of neurodevelopmental delay with general anesthesia, favoring delayed repair.
  • Elective repair may be deferred until 1 year of age to reduce postoperative apnea risk.
  • Incarcerated hernia:
    • Reduction should be attempted first.
    • Surgery performed 24-48 hours later once tissue edema subsides.
    • Non-reducible incarcerated hernia is a surgical emergency.

Contralateral Exploration

  • Routine exploration for contralateral patent processus vaginalis is common due to its incidence (4%-65%).
  • The decision to explore the asymptomatic contralateral side in toddlers is still debated.
  • Many surgeons opt for contralateral exploration in children 2 years or younger.

Laparoscopic vs. Open Repair

  • Laparoscopic repair is increasingly used.
  • A meta-analysis comparing laparoscopic vs open repair showed no definite advantage for either technique.

Umbilical Hernia

  • Tends to close spontaneously in about 80% of cases.
  • Elective repair is generally deferred until the child is around 5 years of age.
  • Incarceration of umbilical hernias is extremely rare.

When to Consider Early Repair

  • If the hernia enlarges over time.
  • If the fascial defect is larger than 2 cm.
  • Large skin proboscis (>3 cm) may develop if left untreated, leading to poor postoperative cosmesis.

Surgical Approach

  • Primary repair is always performed.
  • Prosthetic patch should never be considered.

Key Terms Highlighted:

  • Inguinal hernia
  • Processus vaginalis
  • Bowel incarceration
  • Strangulation
  • Contralateral exploration
  • Laparoscopic repair
  • Umbilical hernia
  • Primary repair

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