What Is Kerley B Lines

Let’s break that down. The lungs are divided into tiny lobules, like a honeycomb. Each lobule is surrounded by connective tissue called the . Inside these septa run small veins and lymphatic channels. When the pressure in the left side of the heart rises (e.g., due to CHF or mitral valve disease), that pressure backs up into the pulmonary veins. This increases capillary hydrostatic pressure, forcing fluid out of the capillaries and into the interstitial space. The interlobular septa become fluid-logged—swollen, thickened, and more opaque to X-rays. When you see a Kerley B line, you are literally seeing a cross-section of a waterlogged "wall" between lung lobules.

Short, fine lines that create a "reticular" or spider-web appearance throughout the lungs. These are rarely seen and often considered a radiographic artifact. Clinical Significance what is kerley b lines

"Think of the anatomy," he said, sketching quickly. "The lung is divided into lobules, like little hexagons or squares. The walls of those squares are the . They contain veins and lymphatics. When the pressure in the veins goes up—like in left-sided heart failure—fluid gets forced out of the vessels and into these septa." Let’s break that down

"Okay," Leo muttered. "I see the wall."

To truly appreciate Kerley B lines, we must credit Dr. Peter Kerley, an Irish radiologist working at Westminster Hospital in London. In the 1930s, before CT scans, echocardiograms, or even widespread use of diuretics, Kerley was meticulously analyzing chest X-rays of patients with mitral stenosis (a then-common consequence of rheumatic fever). He noticed three distinct types of interstitial markings. In a 1933 paper, he described "A," "B," and "C" lines. While A and C lines have largely faded into historical obscurity, became a cornerstone of thoracic radiology. It’s a testament to his observational genius that a finding from 90 years ago remains clinically vital today. Inside these septa run small veins and lymphatic channels