IS Case 565: Bat wing pattern of pulmonary edema

Sirisha Jasti, MD

Imaging Sciences URMC

Imaging Sciences URMC 2010
Publication Date: 2011-11-16


Patient is a 29-year-old female with history of preeclampsia and status post-Cesarean section with cough and shortness of breath.


PA view of the chest showed increased airspace opacities centrally with relative sparing of the lateral chest, consistent with "bat wing" pattern of pulmonary edema.


Bat wing pattern of pulmonary edema


Pulmonary edema is the accumulation of fluid in the interstitium and alveoli of the lungs. Increased hydrostatic pressure in the capillaries, decreased oncotic pressure or impaired permeability can all cause pulmonary edema. The most common cause of pulmonary edema is cardiogenic. It is a gradual process and usually starts with the transfer of fluid into the interstitium. When the fluid transfer exceeds the capacity of the lymphatics, fluid starts to accumulate in the interstitium. The buildup of fluid eventually causes fluid to fill up the alveoli and affect gas exchange.

The accumulation of fluid initially starts at the bases due to gravity. The fluid at the bases causes vascular flow to be redistributed to the apices and this causes the increased interstitial markings at the apices of the lungs.

“Bat wing” pattern of pulmonary edema refers to centralization of alveolar and interstitial infiltrates with relative sparing of the lateral regions of the lungs, unlike the edema which starts with initial fluid accumulation in the gravity influenced areas. This type of pattern is seen more commonly in edema due to left heart failure or renal disease and the cause for this type of pattern of edema is unknown.


  1. Fleischner FG. The butterfly pattern of acute pulmonary edema. Am J Cardiol. 1967 Jul;20(1):39-46. PMID: 6026923
  2. de Araújo MCM, Coelho JR. Acute pulmonary edema.
  3. Robin ED, Cross CE, Zelis R. Pulmonary edema. 1. N Engl J Med. 1973 Feb 1;288(5):239-246. PMID: 4565760
  4. Robin ED, Cross CE, Zelis R. Pulmonary edema. 2. N Engl J Med. 1973 Feb 8;288(6):292-304. PMID: 4566344

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