Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review

00:00 / 00:00



Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review

Respiratory system


Pleural effusion, pneumothorax, hemothorax and atelectasis: Pathology review

USMLE® Step 1 questions

0 / 9 complete


USMLE® Step 1 style questions USMLE

of complete

A 60-year-old man comes to the emergency department because of progressive shortness of breath and chest pain for the past three weeks. Medical history includes type II diabetes mellitus, hyperlipidemia, and a myocardial infarction six years ago. Temperature is 37.1°C (98.9°F), pulse is 80/min, blood pressure is 135/87 mmHg, and respirations are 20/min. Physical examination reveals 2+ pitting edema in the bilateral lower extremities. Respiratory examination is notable for dullness to percussion and decreased breath sounds at the bilateral lung bases. Cardiac auscultation reveals a heart sound occurring immediately after the S2 sound. A chest x-ray is obtained and shows blunting of the costophrenic angles bilaterally. The patient’s serum protein level is 7 g/dL, and serum lactate dehydrogenase is 280 U/L. If a thoracentesis were performed, which of the following laboratory findings would most likely be present in this patient’s pleural fluid?  


During a night shift in the Emergency Department, you see George, a 21 year old, who complains of sharp, stabbing left-sided chest pain and shortness of breath, both of which appeared suddenly while he was playing video games. He is a smoker and mentions his younger brother suffered a pneumothorax last year. On examination, the left side of his chest is slightly more expanded than the right side and his breathing is very shallow. The affected side is also hyperresonant on percussion and there’s diminished breath sounds on auscultation. Then there’s Anna, a 58-year-old with progressively worsening dyspnea, pleuritic chest pain, and fever. She has a history of diabetes and cirrhosis. On examination, her blood pressure and heart rate are both increased, and jugular venous pressure is elevated. Also, the base of her left lung field is dull to percussion with decreased breath sounds. Her lower extremities have pitting edema up to the knee. X-rays were performed in both individuals. In George’s case it showed a retracted visceral pleural edge with a decrease in the left lung volume. In Anna, it showed left sided costophrenic angle blurring. Now, they both seem to present with conditions affecting the pleura. But to understand the pathophysiology, it’s a good idea to review the anatomy and physiology first. Ok, so the pleura covers the lungs and consists of the parietal pleura, which is stuck to the chest wall, and the visceral pleura, which is stuck to the lungs. It extends all the way up to the clavicle and first rib, which is something that will help you understand why neck injuries can cause tension pneumothorax. Also know the inferior limit of the pleura is the 7th rib on the midclavicular line, the 10th rib on the mid axillary line, and the 12th rib on the paravertebral line. Between the layers of the pleura is the pleural space, containing 10 to 20 milliliters of a lubricating fluid that helps reduce friction as the lungs expand and contract. There’s also pressure within the pleural space, established by two main opposing forces. One is the muscle tension of the diaphragm and chest wall, which contract and expand the thoracic cavity outwards. The other is the elastic recoil of the lungs, which is the lungs’ tendency to collapse inward. The two forces pulling in opposite directions creates a slight vacuum in the pleural space with a pressure of -5 centimeters of water, relative to 0 centimeters of water in both the thoracic cavity and the lungs. The difference in pressure aids air exchange during inspiration and expiration to help the lungs keep their shape and not collapse.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Fishman's Pulmonary Diseases and Disorders, 2-Volume Set, 5th edition" McGraw-Hill Education / Medical (2015)
  6. "Dyspnea" CRC Press (2014)
  7. "Management of spontaneous pneumothorax: state of the art" European Respiratory Journal (2006)
  8. "Pneumothorax" Respiration (2008)
  9. "Lack of Association Between Atelectasis and Fever" Chest (1995)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.