259.Free air beneath the diaphragm（膈下游离气体）

‍and left (dotted white arrow) hemidiaphragms representing free intraperitoneal air. The patient had undergone abdominal surgery 3 days earlier. Free air can remain for up to 7 days after surgery in an adult, but serial studies should demonstrate a progressively decreasing amount of air. ‍ ‍

Notes

1. crescent   /'krɛsnt/ adj. 新月形的

2. intraperitoneal   /'intrə,peritəu'ni:əl/ adj. 腹腔内的

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Extensive Reading

Recognizing Extraluminal Air in the Abdomen

Recognition of extraluminal air is an important finding that can have an immediate effect on the course of treatment.

Air is normally not present in the peritoneal or extraperitoneal spaces, bowel wall, or biliary system.

• Air outside of the bowel is called extraluminal air.

The four most common locations of extraluminal air:

• Intraperitoneal (pneumoperitoneum) (frequently called free air)

• Retroperitoneal air

• Air in the bowel wall (pneumatosis intestinalis)

• Air in the biliary system (pneumobilia)

来源：每天朗读一段医学影像学英语文章