図１３〜図１６は省略．図１で左横隔膜下に遊離ガス（▲）を認め，図２〜図４の↑も遊離ガスである．消化管穿孔の可能性はあるが，腹水を認めず，腹部所見も心窩部に圧痛を認めるだけで腹膜刺激症状を呈していなかったので保存的に経過観察した．次第に腹痛は軽減し，5日間で退院した．退院前日の上部内視鏡検査で胃と十二指腸には異常所見を認めない．性行為による腹腔内遊離ガスと思われる．

参考症例（Nonsurgical free air）：53歳女性．3日前から食後の上腹部痛があり，当日になって腹痛が増強したので来院した．体温：37.5℃，腹部はsoft and flat で，右下腹部に軽度の圧痛がある．図１は腹部立位単純写真． WBC：9400，CRP：1.0mmg/dl．
図１〜図４で大量の遊離ガス（G）があり，図１５と図１６で腹水（※）を認めたので手術となった．骨盤腔にわずかに混濁した腹水を認めるだけで，腹膜炎の所見はなく，腸管や他臓器に全く異常を認めなかった．術後は順調に経過し，腹痛も消失した．腹水培養：陰性． 1週間目の上部内視鏡検査で異常なし．原因不明の遊離ガスであった．

文献考察１）：婦人科的（非外科的）腹腔内遊離ガス（ pneumoperitoneum：PP）
Am Surg. 1998 Apr;64(4):313-22.
Nonsurgical pneumoperitoneum: a case report and a review.（表１，２，３）
Rowe NM, Kahn FB, Acinapura AJ, Cunningham JN Jr.

The finding of extraluminal gas on plain radiographs is usually associated with a perforated viscus. But, as this case shows, the finding of pneumoperitoneum（PP） is not pathogenic of a perforated viscus or even of a surgical emergency, because there are many benign explanations for a pneumoperitoneum. Perhaps the most important maneuver for differentiating between the two is by performing a through history and physical examination. This in conjunction with either a diagnostic peritoneal lavage, contrast studies, or endoscopic evaluation can help prevent a patient from having needless surgery. The causes of a nonsurgical pneumoperitoneum are described as well as a treatment plan for patients presenting with a nonsurgical pneumoperitoneum.ID: 9544141
要旨：Rubin testでも証明されているように，不妊症検査で卵管の開存を検査する際，正常なら子宮内腔から腹腔内への交通が認められる．または，腹腔内陰圧状態で空気が子宮，卵管から腹腔内へ吸引されることが知られている．従って，性交で腹腔内遊離ガスが発生することは容易に推測できる．

文献考察２）：性交後腹腔内遊離ガス．
Am Surg. 2002 May;68(5):430-3.
Pneumoperitoneum after rough sexual intercourse.
Johnson EK, Choi YU, Jarrard SW, Rivera D.

Our objective is to report on a case of nonsurgical pneumoperitoneum and review the mechanism/gynecologic causes of such. We present a case report and review of the literature based on a MEDLINE search using the keywords pneumoperitoneum and nonsurgical. Radiographic evidence of free intraperitoneal air suggests hollow viscus rupture and usually warrants urgent surgical management. Findings of diffuse rebound tenderness and guarding solidify the decision for urgent surgical exploration. We present a case of a patient who presented with all of the above findings that subsequently underwent a negative laparotomy. On the day after surgery she admitted to having had rough sexual intercourse 3 days before presentation. Nonsurgical pneumoperitoneum has a number of unusual causes. Intra-abdominal, thoracic, gynecologic, iatrogenic, and miscellaneous etiologies are encountered. It was determined that the pneumoperitoneum in this case was secondary to rough sexual intercourse. We concluded that pneumoperitoneum secondary to nonsurgical causes represents a diagnostic dilemma. In the patient with free intraperitoneal air on plain X-ray one should be suspicious of less common nonsurgical etiologies. The majority of patients will require laparotomy. Thorough sexual and gynecologic/obstetrical history is a valuable adjunct in identifying the patient who does not.PMID: 12013285