General Pathogenesis of Digestive System Involvement
In intrauterine infections (IUI) of viral, parasitic, or bacterial etiology, the pathological process in the digestive organs is frequently triggered hematogenously. The pathogen (e.g., herpes viruses, cytomegalovirus, parvovirus, Toxoplasma, Treponema pallidum) travels through the umbilical vein directly into the fetal liver. Subsequently, the infection is disseminated via the bloodstream to other organs.
General morphological features of hepatobiliary and abdominal cavity involvement include:
- Early stromal fibrosis of the organs.
- Extramedullary hematopoiesis (intensive formation of hematopoietic foci in the liver and splenic tissue).
- Delayed tissue maturation.
- Development of hemorrhagic syndrome.
Macroscopically, these processes manifest as pronounced hepatosplenomegaly (enlargement of the liver and spleen) and jaundice, which accompany intrauterine growth restriction.
Viral Infections: Hepatitis and Sialadenitis
Viruses transmitted transplacentally play a crucial role in the pathology of the neonatal digestive system.
Congenital Rubella Infection occurs during maternal viremia. The virus causes multiple congenital malformations and inflammatory processes. Macroscopically, hepatosplenomegaly is observed in the hepatobiliary system, while microscopic examination reveals giant cell hepatitis and multiple foci of extramedullary hematopoiesis.
Congenital Cytomegalovirus (CMV) Infection The risk of fetal infection in seronegative mothers reaches 50%. The pathomorphological picture is characterized by specific involvement of the salivary glands and liver. Epithelial cells predominantly undergo cytomegaloviral transformation:
- Cells significantly increase in size (cytomegalic cells).
- The nucleus is displaced eccentrically.
- A clear halo forms around the nucleus (the «owl-eye» phenomenon).
- Eosinophilic inclusions are found within the nucleus (less commonly in the cytoplasm).
Lymphomakrophagic infiltration develops in the organ stroma. Clinically, the process manifests as jaundice and hepatosplenomegaly.
Bacterial and Parasitic Gastrointestinal Infections
Various pathogens establish a specific morphological pattern within the abdominal cavity organs.
- Congenital Listeriosis: The pathogen Listeria monocytogenes penetrates transplacentally. The most frequent form is granulomatous sepsis. Granulomas (gray-white foci 1–10 mm in size) are localized in the liver, spleen, and intestinal wall. Microscopically, these are necrotic foci containing gram-positive microbes, surrounded by macrophages, lymphocytes, and leukocytes. In extremely premature infants, the cellular response is absent—only necrotic foci with an abundance of listeriae are visible in the liver.
- Congenital Tuberculosis: Characterized by involvement of the liver and spleen with the formation of large foci of caseous necrosis. Fibrinous peritonitis frequently develops in the abdominal cavity. A distinctive histological feature in fetuses is the extremely rare formation of epithelioid and Langhans giant cells.
- Congenital Syphilis: Vasculitis followed by fibrosis develops in the liver and spleen, accompanied by the formation of infiltrates composed of plasma cells and lymphoid follicles (early congenital syphilis).
- Toxoplasmosis: In addition to classic CNS involvement, microscopy may reveal hepatitis in the liver with specific pseudocysts (spherical structures 20–60 µm in size filled with parasites).
Fetal and Neonatal Sepsis
Intrauterine sepsis also severely impacts the digestive organs. Characteristic signs of fetal sepsis include marked jaundice, persistent hepatosplenomegaly, and splenic myelosis (along with thymic involvement). When the disease progresses as septicopyemia, purulent peritonitis becomes one of the most frequent manifestations alongside purulent meningitis.