Signs of pneumoperitoneum U should be familiar with!

Diagnosing pneumoperitoneum is a piece of cake when you see the classic sign " Air under the diaphragm".

Air under diaphragm

But this sign is present in an erect x-ray. Suppose your patient is too sick to get an erect x-ray done ( might be incubated), and instead you get a supine film done, then these are the signs you should look out for.



These include signs like:
1. Falciform ligament sign: Outline of falciform ligament = long vertical line to the right of midline extending from ligamentum teres notch to umbilicus; most common structure outlined
2. Ligamentum teres sign:  air outlining fissure of ligamentum teres hepatis
3. Morison’s pouch-doge’s cap sign :  triangular collection of gas in Morison pouch
4. Cupola sign / moustache sign: gas trapped below central tendon of diaphragm
5. Rigler’s sign : air on both sides of bowel as intraluminal gas and free air outside 
6. Football sign: large pneumoperitoneum outlining entire abdominal cavity
7. Telltale triangle sign : triangular air pocket between 3 loops of bowel
8. Inverted “V” sign:  outline of both lateral umbilical ligaments

This article from the ThaiGastro journal " Pneumoperitoneum: Signs on Supine Abdominal Radiograph" provides detailed look of these signs and images.