Omphalocele

Overview

Definition

• A congenital defect of the anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen located at the base of the umbilicus in which the intestine and other abdominal viscera are only covered by the peritoneum Peritoneum The peritoneum is a serous membrane lining the abdominopelvic cavity. This lining is formed by connective tissue and originates from the mesoderm. The membrane lines both the abdominal walls (as parietal peritoneum) and all of the visceral organs (as visceral peritoneum). Peritoneum: Anatomy and amniotic membranes
• Giant omphalocele measure ≥ 4 cm, contain the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy, and are associated with small undeveloped abdominal and thoracic cavities.

Embryology

• Gastrointestinal (GI) system development from 3 germinal layers:
  • Mesoderm Mesoderm The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube. Gastrulation and Neurulation: connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology (wall of gut tube, blood vessels, smooth muscle)
  • Endoderm Endoderm The inner of the three germ layers of an embryo. Gastrulation and Neurulation: epithelial lining
  • Ectoderm Ectoderm The outer of the three germ layers of an embryo. Gastrulation and Neurulation: epidermis Epidermis The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of epithelium: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis). Skin: Structure and Functions and neural crest Neural crest The two longitudinal ridges along the primitive streak appearing near the end of gastrulation during development of nervous system (neurulation). The ridges are formed by folding of neural plate. Between the ridges is a neural groove which deepens as the fold become elevated. When the folds meet at midline, the groove becomes a closed tube, the neural tube. Hirschsprung Disease ( neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology of the GI tract)
• GI tract divisions:
  • Foregut Foregut Development of the Abdominal Organs: oral cavity to 1st part of the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy
  • Midgut Midgut Development of the Abdominal Organs: mid-duodenum to 1st ⅔ of the transverse colon Transverse colon The segment of large intestine between ascending colon and descending colon. It passes from the right colic flexure across the abdomen, then turns sharply at the left colonic flexure into the descending colon. Colon, Cecum, and Appendix: Anatomy
  • Hindgut Hindgut Development of the Abdominal Organs: last ⅓ of the transverse colon Transverse colon The segment of large intestine between ascending colon and descending colon. It passes from the right colic flexure across the abdomen, then turns sharply at the left colonic flexure into the descending colon. Colon, Cecum, and Appendix: Anatomy to upper anus
• 6th week of gestation:
  • Rapid growth of GI tract
  • Midgut Midgut Development of the Abdominal Organs herniates through umbilical ring, developing entirely outside the peritoneal cavity Peritoneal Cavity The space enclosed by the peritoneum. It is divided into two portions, the greater sac and the lesser sac or omental bursa, which lies behind the stomach. The two sacs are connected by the foramen of winslow, or epiploic foramen. Peritoneum: Anatomy.
• 10th week of gestation:
  • Abdominal cavity is large enough for developing midgut Midgut Development of the Abdominal Organs.
  • Midgut Midgut Development of the Abdominal Organs completes rotation Rotation Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. X-rays and returns to abdominal cavity.

Epidemiology

• Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency: 2.5 in 10,000 births
• Boys > girls
• Seen more commonly with younger or older mothers (< 20 or > 40 years old)
• More prevalent in Black patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
• 60%–70% have associated abnormalities, including cardiac and chromosomal. 
• May occur as part of syndromes:
  • Beckwith-Weidemann constellation of anomalies ( macroglossia Macroglossia The presence of an excessively large tongue, which may be congenital or may develop as a result of a tumor or edema due to obstruction of lymphatic vessels, or it may occur in association with hyperpituitarism or acromegaly. It also may be associated with malocclusion because of pressure of the tongue on the teeth. Wilms Tumor, macrosomia, hypoglycemia Hypoglycemia Hypoglycemia is an emergency condition defined as a serum glucose level ≤ 70 mg/dL (≤ 3.9 mmol/L) in diabetic patients. In nondiabetic patients, there is no specific or defined limit for normal serum glucose levels, and hypoglycemia is defined mainly by its clinical features. Hypoglycemia, visceromegaly, and omphalocele)
  • Cantrell’s pentalogy (cleft sternum Sternum A long, narrow, and flat bone commonly known as breastbone occurring in the midsection of the anterior thoracic segment or chest region, which stabilizes the rib cage and serves as the point of origin for several muscles that move the arms, head, and neck. Chest Wall: Anatomy, ectopia cordis, anterior midline diaphragmatic hernia Hernia Protrusion of tissue, structure, or part of an organ through the bone, muscular tissue, or the membrane by which it is normally contained. Hernia may involve tissues such as the abdominal wall or the respiratory diaphragm. Hernias may be internal, external, congenital, or acquired. Abdominal Hernias, cardiac anomalies, epigastric omphalocele)
  • Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 13, 18, or 21
  • Cloacal exstrophy (vesicointestinal fissure Fissure A crack or split that extends into the dermis Generalized and Localized Rashes)
• May be associated with prematurity Prematurity Neonatal Respiratory Distress Syndrome, intrauterine growth restriction
• Often seen in familial clustering

Pathophysiology

Pathophysiology is not definitively understood; 2 main theories:

• Failure of the midgut Midgut Development of the Abdominal Organs to return to the abdominal cavity by 10 weeks’ gestation results in omphalocele
• Failure of abdominal folds to seal, leaving midline defect and externalized abdominal organs

Clinical Presentation

• Newborn Newborn An infant during the first 28 days after birth. Physical Examination of the Newborn findings:
  • Full-thickness ventral wall defect
  • Herniation of intestines through umbilical ring, may also contain abdominal organs
  • Covered in clear sac composed of amniotic membrane and peritoneum Peritoneum The peritoneum is a serous membrane lining the abdominopelvic cavity. This lining is formed by connective tissue and originates from the mesoderm. The membrane lines both the abdominal walls (as parietal peritoneum) and all of the visceral organs (as visceral peritoneum). Peritoneum: Anatomy
  • Size usually varies from 4–12 cm 
  • Occur centrally, in epigastrium Epigastrium Surgical Anatomy of the Abdomen, or in hypogastrium Hypogastrium Anterior Abdominal Wall: Anatomy
• Delivery can be challenging and requires a specialist.
  • Rupture of omphalocele sac can occur in ⅕ of cases.
  • Umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity clamping must be carefully done to avoid damaging intestinal structures.

Diagnosis

Most cases of omphalocele (90%) are diagnosed prenatally:

• Ultrasound:
  • Part of routine prenatal screening Screening Preoperative Care
  • Can show other associated abnormalities 
• Maternal serum ⍺-fetoprotein levels: Elevated levels are non-specific signs of omphalocele.
• If detected prenatally, parents should be offered:
  • Testing for Beckwith-Wiedemann syndrome
  • Microarray chromosomal analysis to evaluate for aneuploidy and trisomies 
  • Prenatal echocardiogram Echocardiogram Transposition of the Great Arteries

Management

Perinatal management

• Attend to vital signs and evaluate respiratory distress (due to lung hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS)).
• Avoid pressure and manual reduction.
• Cover omphalocele with non-moist dressing.
• Screen for hypoglycemia Hypoglycemia Hypoglycemia is an emergency condition defined as a serum glucose level ≤ 70 mg/dL (≤ 3.9 mmol/L) in diabetic patients. In nondiabetic patients, there is no specific or defined limit for normal serum glucose levels, and hypoglycemia is defined mainly by its clinical features. Hypoglycemia, associated with Beckwith-Weidemann syndrome.
• Apply nasogastric tube Nasogastric tube Malnutrition in children in resource-limited countries decompression.
• Administer prophylactic broad-spectrum Broad-Spectrum Fluoroquinolones antibiotics in case of rupture.
• Perform echocardiogram Echocardiogram Transposition of the Great Arteries prior to any surgical procedure.

Surgery

• Small-to-medium–sized defects with normal lung: early (within 24 hrs HRS Hepatorenal syndrome (HRS) is a potentially reversible cause of acute kidney injury that develops secondary to liver disease. The main cause of hrs is hypovolemia, often as a result of forced diuresis or drainage of ascites. This leads to renal vasoconstriction resulting in hypoperfusion of the kidneys. Hepatorenal Syndrome) primary repair (resection of membrane and closure of defect)
• Giant omphalocele: multi-staged procedure to allow intra-abdominal accommodation Accommodation Refractive Errors and pulmonary maturation 
• Enteral feeding can be established very early after closure.

Differential Diagnosis

• Gastroschisis Gastroschisis Gastroschisis is a congenital abdominal wall defect characterized by the complete lack of closure of the abdominal musculature. A portion of intestine does not return to the abdominal cavity, thereby remaining in its early embryonic herniated state but with no coverings. Gastroschisis: a full-thickness defect of the anterior abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen through which the intestine and/or other abdominal viscera freely protrude. No membrane or sac covers the bowel/intestine. Diagnosis is via prenatal ultrasound and treatment is surgical after birth. Gastroschisis Gastroschisis Gastroschisis is a congenital abdominal wall defect characterized by the complete lack of closure of the abdominal musculature. A portion of intestine does not return to the abdominal cavity, thereby remaining in its early embryonic herniated state but with no coverings. Gastroschisis is not commonly associated with other birth defects.
• Pentalogy of Cantrell: a rare syndrome consisting of multiple congenital abnormalities, including a lower sternal defect, anterior diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy defect, pericardial defect, abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen defect, and congenital heart anomalies. Diagnosis is made prenatally by ultrasonography. Treatment requires complex medical and surgical care.
• Bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess exstrophy-epispadias complex: a spectrum of congenital defects: epispadias Epispadias A birth defect due to malformation of the urethra in which the urethral opening is above its normal location. In the male, the malformed urethra generally opens on the top or the side of the penis, but the urethra can also be open the entire length of the penis. In the female, the malformed urethral opening is often between the clitoris and the labia, or in the abdomen. Penile Anomalies and Conditions (failed closure of urethra Urethra A tube that transports urine from the urinary bladder to the outside of the body in both the sexes. It also has a reproductive function in the male by providing a passage for sperm. Urinary Tract: Anatomy), bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess exstrophy, and cloacal exstrophy (most severe defect, which includes anal atresia Atresia Hypoplastic Left Heart Syndrome (HLHS) and omphalocele). Treatment is surgical, with goals to close abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen defect, achieve urinary continence, and reconstruct genito-urinary area.
• Umbilical hernia Umbilical Hernia A hernia due to an imperfect closure or weakness of the umbilical ring. It appears as a skin-covered protrusion at the umbilicus during crying, coughing, or straining. The hernia generally consists of omentum or small intestine. The vast majority of umbilical hernias are congenital but can be acquired due to severe abdominal distention. Abdominal Hernias: presents as a protrusion in the neonate Neonate An infant during the first 28 days after birth. Physical Examination of the Newborn’s umbilical area. There is incomplete closure of the fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis of the umbilical ring, but with intact skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions covering the ring. It is important to determine the reducibility, as incarcerated hernia Incarcerated Hernia Abdominal Hernias is a complication. Surgery is indicated for defects > 1.5 cm in those > 2 years of age and for complications such as strangulation Strangulation Inguinal Canal: Anatomy and Hernias, incarceration Incarceration Inguinal Canal: Anatomy and Hernias, or rupture.