Bochdalek hernia, a less common type of diaphragmatic hernia, involves an opening in the diaphragm, the muscle separating the chest and abdominal cavities. While primarily identified in newborns, this condition can, in rare instances, manifest or become symptomatic in adults. Understanding why this congenital anomaly can remain unnoticed for decades before causing issues involves examining its developmental roots and the physiological changes that can eventually trigger symptoms.
A Developmental Origin
Bochdalek hernia is fundamentally a congenital diaphragmatic hernia (CDH), meaning it is present from birth. This condition arises from an incomplete formation or fusion of the diaphragm during fetal development, typically occurring between the eighth and tenth weeks of gestation. During this critical period, various components of the diaphragm, including the pleuroperitoneal membranes, fail to fully close, leaving a defect, most commonly in the posterolateral (back and side) region of the diaphragm. This opening creates an abnormal connection between the abdominal cavity and the chest cavity.
The size and specific location of this opening can vary significantly among individuals. In many cases, the defect is small, or the presence of other abdominal organs, such as the liver or spleen, might initially block the opening, preventing organs from migrating into the chest cavity.
Why it Emerges Later in Life
Many Bochdalek hernias remain asymptomatic for years, sometimes even decades, despite being present since birth. One significant reason for this delayed emergence is the size of the diaphragmatic defect. Smaller openings may not allow immediate or substantial herniation of abdominal contents into the chest cavity, thus causing no noticeable symptoms in infancy or childhood. The defect might be too narrow for organs to pass through easily, or it could be intermittently obstructed by surrounding tissues.
Another contributing factor is the presence of a hernia sac, a peritoneal lining that can encapsulate the herniated organs. This sac acts as a protective barrier, preventing direct contact between abdominal contents and the lungs and potentially reducing the severity of symptoms or delaying their onset. Over time, sustained or repeated pressure from the abdomen can gradually stretch or weaken this sac, or the organs themselves can slowly migrate through the defect. This gradual displacement of abdominal contents, such as the stomach, intestines, or spleen, into the chest cavity can eventually lead to symptoms as they begin to compress the lungs or heart, or interfere with their function.
Factors That Trigger Symptoms
The manifestation of symptoms from a previously asymptomatic Bochdalek hernia in adults is often precipitated by specific events or physiological changes that increase pressure within the abdomen. Activities that significantly elevate intra-abdominal pressure can force abdominal organs through the existing diaphragmatic defect. Examples include heavy lifting, which acutely strains the abdominal muscles, or chronic conditions like persistent coughing, straining during bowel movements, or difficulty urinating due to prostate enlargement.
Pregnancy is another notable factor, as the growing uterus exerts considerable pressure on abdominal organs, potentially pushing them into the chest cavity through the hernia. Similarly, obesity contributes to chronically elevated intra-abdominal pressure, increasing the likelihood of herniation and symptom development over time. Blunt abdominal or chest trauma, such as from a car accident or a significant fall, can also trigger symptoms by acutely enlarging the defect or forcefully displacing organs into the chest.
Age-related changes can also play a role, as the weakening of connective tissues that occurs with aging might make the diaphragmatic defect more prone to herniation. The diaphragm itself, like other muscles and tissues, can lose some of its elasticity and strength over decades. Specific medical conditions that lead to increased abdominal volume or pressure, such as ascites (fluid accumulation in the abdomen) or the presence of large abdominal tumors, can also contribute to the emergence of symptoms by providing additional force to push organs through the pre-existing diaphragmatic opening.