Intraabdominal calcifications in children

Causes of intra-abdominal calcifications

The presence of calcifications in the abdominal cavity in children requires a detailed analysis of their anatomical localization. There are several main groups of causes:

• Adrenal: can result from prior hemorrhage, neuroblastoma development, or a rare genetic disorder — Wolman disease (Wolman disease).
• Hepatobiliary: accompany structural liver lesions (hepatoblastoma, hemangioendothelioma) and serve as markers of congenital TORCH infections.
• Intraluminal: form in the setting of low intestinal obstruction or complex anorectal malformations (when a fistula into the urinary tract is present).

Additionally, calcifications may be detected in complicated meconium ileus, nephrocalcinosis, teratomas, intravascular thrombi, as well as in intestinal duplications and mesenteric cysts.

Pneumatosis intestinalis: differential diagnosis

Pneumatosis intestinalis (Pneumatosis intestinalis), characterized by the accumulation of gas bubbles in the bowel wall, is most commonly associated with necrotizing enterocolitis (NEC) in newborns. However, this symptom is nonspecific and can accompany a spectrum of pathologies:

1. Ischemic and inflammatory processes: Hirschsprung's disease, inflammatory bowel disease (IBD), and clostridial infection.
2. Congenital anomalies: cyanotic ("blue") congenital heart defects, gastroschisis, anorectal atresia.
3. Infectious lesions: cytomegalovirus or rotavirus gastroenteritis.
4. Iatrogenic and systemic factors: sequelae of colonoscopy, corrosive ingestion, short bowel syndrome, prolonged steroid therapy, post-organ transplantation states (liver, bone marrow, kidney), and graft-versus-host disease.
5. Severe underlying conditions: immunodeficiencies, AIDS (AIDS), collagenoses, chronic granulomatous disease, and oncohematology (leukemias, lymphomas).

Necrotizing enterocolitis (NEC): pathophysiology

NEC is a multifactorial pathological process. The TLR4 receptor in the mucosa plays a key role in its pathogenesis: its hyper-response to pathogenic microflora sharply exacerbates local ischemia.

Risk factors have a cumulative (additive) effect. These include prematurity (the lower the birth weight and gestational age, the higher the risk), hypoxia (the main cause of "term" NEC in congenital heart defects), delayed initiation of enteral feeding, and cow's milk protein allergy. Prolonged antibiotic therapy promotes colonization by atypical pathogens, sometimes leading to nosocomial outbreaks — "cluster" NEC. Multiple blood transfusions also serve as a factor aggravating the process.

Clinically, the disease predominantly manifests in the second week of life after the initiation of enteral feeding. The terminal ileum and colon are primarily affected. Early nonspecific signs include lethargy, feeding intolerance, temperature instability, bradycardia, increased gastric aspirate volume, and abdominal distension. With transmural spread of inflammation, bloody-mucoid diarrhea, vomiting, and shock appear.

Imaging diagnostics of NEC and perforations

Radiography and ultrasound are used for visualization. There are four classic radiographic patterns in NEC:

• Generalized loop dilation: the earliest symptom. A "fixed loop" — persistent dilation of a specific bowel segment on serial imaging — is considered an alarming sign.
• Pneumatosis intestinalis: the volume of gas in the wall directly correlates with the severity of the lesion.
• Portal venous gas: visualized as branching bright lines over the liver shadow, radiating from the portal vein to the periphery. It occurs in a third of patients and is a poor prognostic sign.
• Free gas (pneumoperitoneum): a marker of occurred perforation.

If perforation is not obvious on a standard anteroposterior (AP) radiograph, a horizontal beam view in the supine position is used. This method allows detecting gas between loops or over the liver without changing the infant's body position in a dangerous way. A left lateral decubitus radiograph is used as an alternative.

Ultrasound examination is a valuable adjunct. It allows detecting signs of NEC earlier than radiography and assessing peristalsis in real time. Prognostically unfavorable ultrasound findings (often indicating the need for surgical intervention) include: the appearance of free gas, cessation of peristalsis, echogenic ascites, and focal fluid collections. The bowel wall is also evaluated — thickening greater than 2.6 mm, thinning less than 1 mm, and the absence of normal perfusion are considered dangerous.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Wolman disease: pathogenesis and role in adrenal calcification.
• The role of the TLR4 receptor in the pathophysiology of mucosal ischemia.
• Ultrasound criteria for impaired bowel wall perfusion (Doppler imaging pattern).
• Management tactics: when peritoneal drainage is sufficient versus when resection is required.
• Meconium ileus: radiological patterns and formation of intraluminal calcifications.

Other Topics in "Pediatric Diagnostic Radiology"

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