Approach to abdominal wall defects: Clinical sciences

An abdominal wall defect refers to when abdominal organs, such as the intestines, protrude through a weakness or opening in the abdomen. These are typically congenital and present with a wide variety of clinical findings. Patients may present as unstable with abdominal viscera outside of their abdominal cavity or stable with findings ranging from a generalized decrease of abdominal muscle tone to a localized inguinal or umbilical mass.

Now, if a pediatric patient presents with an abdominal wall defect, perform an ABCDE assessment to determine if they are stable or unstable. If unstable, stabilize the airway, breathing, and circulation. Next, obtain IV access and consider starting IV fluids and antibiotics. Then, place your patient on continuous vital sign monitoring, and provide supplemental oxygen if needed.

Consider placing a nasogastric or orogastric tube to empty the stomach. Finally, cover any protruding abdominal viscera with a warm moist sterile gauze or bowel bag to decrease the risk of necrosis, infection, and evaporative fluid losses.

Once you have initiated acute management, obtain a focused history and physical examination. History might include prenatal testing showing an elevated alpha-fetoprotein level and a prenatal ultrasound revealing an abdominal wall defect with viscera outside of the abdominal cavity. As far as the newborn physical exam goes, you’ll notice visceral herniation through a skin defect in the abdomen. These findings should make you consider gastroschisis and omphalocele. Proceed with your evaluation by assessing the viscera for a membrane covering.

If a membrane is absent, consider gastroschisis. In this case, history might include risk factors such as a teenage birthing parent or antenatal use of tobacco; drugs, like opioids and cocaine; or decongestants. The physical exam will reveal that the defect is to the right of the midline and umbilicus and that the herniation contains bowel, usually small intestine. Intestinal atresia may also be present. At this point, diagnose gastroschisis.

Here’s a clinical pearl! The most common complication of gastroschisis is gastrointestinal dysmotility. This occurs because without a protective membrane, the bowel is exposed to amniotic fluid during pregnancy.

On the other hand, if you identify that the viscera are covered by a membrane consisting of peritoneum, Wharton’s jelly, and amnion, consider omphalocele. In this case, history may reveal other congenital defects, including cardiac, genitourinary, or neural tube defects. There is often an associated genetic disorder, such as Trisomy 13, 18, or 21; or Beckwith-Wiedeman syndrome. Meanwhile, the physical exam will reveal that the defect is midline, and that the hernia sac contains small bowel and possibly stomach, colon, bladder, or liver. At this point, you can diagnose omphalocele.

Here’s a high yield-fact! Other, much less common, full thickness defects of the abdominal wall include bladder exstrophy, cloacal exstrophy, and limb body wall syndrome, which is fatal and involves multiple organ systems.

Okay, now that we’ve considered unstable patients, let’s return to the ABCDE assessment and discuss stable patients. Begin with a focused history and physical examination. History might reveal a mass or bulge that changes with valsalva. The physical exam might include a skin, fascial, or muscle defect; an abdominal or inguinal mass; or umbilical discharge. With these findings, consider an abdominal wall defect and assess the abdominal muscle tone and skin.

If you find decreased muscle tone and wrinkled skin, consider prune belly syndrome. Here, most patients are biological males. If a prenatal ultrasound was performed, you’ll see a history of oligohydramnios, bladder distension, and ureteral or kidney dilatation. Renal dysplasia and bladder outlet obstruction can cause varying degrees of prenatal oligohydramnios that may result in pulmonary hypoplasia. There might also be a history of cardiac and skeletal anomalies. On physical exam, you’ll appreciate absent or lax abdominal musculature, a distended palpable bladder, and undescended testes.

Your next step is to obtain a chest and abdominal X-ray, voiding cystourethrogram, and echocardiogram. The X-ray will demonstrate a bell-shaped thorax and abdomen, while the voiding cystourethrogram will show ureteral reflux and dilatation, a distended bladder, and renal dysplasia or dilation. The echocardiogram might reveal an atrial or ventricular septal defect, or evidence of Tetralogy of Fallot. At this point, you can diagnose prune belly syndrome, also known as Eagle-Barrett syndrome or triad syndrome.

Here’s another clinical pearl! The characteristic triad for prune belly syndrome consists of the absent abdominal muscles, urinary tract malformation, and undescended testes you appreciated on physical exam and imaging.