# Detecting edema **URL:** \ **Category:** Factual Questions\ **Created:** [October 6, 2016, 12:22pm UTC](https://boards.straightdope.com/t/detecting-edema/767761 "2016-10-06T12:22:08Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Cardigan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardigan/32/187_2.png) [@Cardigan](https://boards.straightdope.com/u/Cardigan)\ **Post date:** [October 6, 2016, 12:22pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/1 "2016-10-06T12:22:08Z")
How do doctors test for the presence of edema? Do they just jab the patient with a needle and see if fluid starts gushing out, or is the methodology perhaps a little more sophisticated than that? ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [October 6, 2016, 12:45pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/2 "2016-10-06T12:45:37Z")
IME they just push on the area and look for pitting (tissue response). Many people have some degree of edema in their ankles after prolonged time on their feet, for example. Try pushing the tissue there and comparing what happens to the same test done on your wrist. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [October 6, 2016, 12:46pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/3 "2016-10-06T12:46:31Z")
Edema generally shows up in the feet and ankles first, due to gravity. A visual inspection accompanied by a gentle squeeze of the tissues will quickly show if edema is present there. If the edema is due to heart failure then it’s also often detectable in the lungs by listening with a stethoscope. That’s the simplified version for how 99+% edema is diagnosed. ---
**Author:** ![Cardigan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardigan/32/187_2.png) [@Cardigan](https://boards.straightdope.com/u/Cardigan)\ **Post date:** [October 6, 2016, 1:21pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/4 "2016-10-06T13:21:53Z")
> [@Qadgop\_the\_Mercotan](#): > > Edema generally shows up in the feet and ankles first, due to gravity. A visual inspection accompanied by a gentle squeeze of the tissues will quickly show if edema is present there. > > If the edema is due to heart failure then it’s also often detectable in the lungs by listening with a stethoscope. > > That’s the simplified version for how 99+% edema is diagnosed. If the patient is morbidly obese - would that complicate diagnosis? ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [October 6, 2016, 2:17pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/5 "2016-10-06T14:17:03Z")
> [@Cardigan](#): > > If the patient is morbidly obese - would that complicate diagnosis? One can still generally tell the difference between fat ankles and fat, edematous ankles. ---
**Author:** ![Cardigan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardigan/32/187_2.png) [@Cardigan](https://boards.straightdope.com/u/Cardigan)\ **Post date:** [October 6, 2016, 4:38pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/6 "2016-10-06T16:38:21Z")
> [@Qadgop\_the\_Mercotan](#): > > One can still generally tell the difference between fat ankles and fat, edematous ankles. Good to get that kind of confirmation from an MD. Thanks. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [October 6, 2016, 9:37pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/7 "2016-10-06T21:37:21Z")
Push your thumb into the suspected part, depress and hold down for 5 seconds. Release instantly. How long until the depression regains original shape? ---
**Author:** ![Cardigan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardigan/32/187_2.png) [@Cardigan](https://boards.straightdope.com/u/Cardigan)\ **Post date:** [October 7, 2016, 12:18pm UTC](https://boards.straightdope.com/t/detecting-edema/767761/8 "2016-10-07T12:18:17Z")
Postscript - Patient got taken to the doc. Yep, edema. Thanks all for the responses. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [October 9, 2016, 7:33am UTC](https://boards.straightdope.com/t/detecting-edema/767761/9 "2016-10-09T07:33:05Z")
Edema is caused by fluid that leaves blood vessels to enter tissue. This depends on a balance of osmotic pressures from proteins and hydrostatic pressures. Fluid collects in areas due to gravity - if you lie down all the time it collects in the back, for most folks it collects in the ankles. If you push on the area for a second, pitting edema will leave an indentation. Edema can also be caused by heat and immobility. Lymphedema due to cancer, etc. does not pit. Edema is often caused by heart failure, but can also be due to liver and kidney problems. Pulmonary edema is an important cause of difficulty breathing, and is diagnosed by hearing crackles, ultrasound or X-Ray (or seeing bad leg edema, heart sound changes, asterixes, caput medusae, etc.)