カーネットサイン：Carnett sign

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Carnett’s sign / Carnett sign / カーネット徴候（101104）
percussion tenderness 陽性、カーネット徴候陰性の持続性腹痛患者。最終診断は帯状疱疹（L1）
とその関連痛となった・・・。普通に考えれば腹腔内の病気、特に腹膜炎を起こすような疾患を第
一に考えて、精査を行うと思う。それでも必ずしも腹腔内病変とは言えないケースもあるわけで、
ここが臨床診断の難しいところだ。まあ、手技が下手なことは否定できないし、患者からの情報を
医学用語に変換するところで既に躓いていたりするわけで、判断に困ることは多い・・・。
これを機会に、カーネット徴候の基本、検査特性について勉強してみることにした。
□方法/評価
方法には大きく分けて、両脚を挙げてもらう方法と、肩/頭部を挙げてもらう方法があるが、腹壁
を緊張させることで増悪する疼痛/圧痛は筋骨格由来と判断する原理は変わらない。

palpation is repeated with the muscles tensed by straight leg raising. 1)

If the pain is the same or worse with tensed muscles, then the sign is positive and the pain is
likely to be coming from the muscles or other superficial structures and not from within the
abdomen. 1)

腹痛の原因が、腹壁（筋肉、骨、神経）にあるか腹腔内にあるかを判断するための身体診察
手技である。4)
【方法】
1 患者は仰臥位で、両腕をクロスさせて胸に置く。
2 最強圧痛点を確認し、検者はその場所に手を置いたまま。
3 患者の頭部と両肩がベッドからわずかに浮く程度に挙上させ、腹部の筋肉を緊張させる。
【判定】
陰性：圧痛減弱一腹腔内臓器の疼痛を示唆。
陽性：圧痛不変一腹壁性の疼痛を示唆。
強陽性：圧痛増強一腹壁性の疼痛を強く示唆。（【参考】我々（著者ら）は圧迫せずに、
頭部と両肩の挙上のみで患部の疼痛が惹起された場合も強陽性（腹壁性）と判定してい
る。）
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（参考文献 3 より引用）
（参考文献 4 より引用）
□検査特性
はっきりと感度、特異度を示した論文を発見できなかったが、海外のインターネット上の質問コー
ナーらしいサイトには感度 78％、特異度 88％と記載があった（情報源不明なので注意）。これをも
とに計算すると、陽性尤度比 6.5、陰性尤度比 0.25 となり、単独での判断は難しいが、まずまずの
検査といえるかもしれない。

As always, a physical sign does not stand alone. 1)

One surgical paper showed that only 6% of patients with significant intra-abdominal disease
had abdominal wall tenderness (Carnett positive) but 28% of patients with nonspecific
abdominal pain (NSAP) were Carnett positive. 1)
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Investigators in one study found that of 120 emergency department admissions for acute
abdominal pain, 23 of 24 patients with a positive Carnett's sign had a normal laparotomy. 2)

In another study of 72 patients with obscure, chronic abdominal pain and a positive Carnett's
sign, two patients were found to have pain related to spinal metastases from recurrence of
known gynecologic malignancies; otherwise, when combined with other information from the
history and physical examination, a positive Carnett's sign was found to be a reliable predictor
of abdominal wall pain. 2)

Investigators in yet another study prospectively evaluated patients with chronic abdominal
pain who met minimal criteria for abdominal wall pain. Criteria included a positive Carnett's
sign or very superficial tenderness combined with pain that was constant or highly localized
to an area no larger than a fingertip. Four patients proved to have visceral disease
(esophagitis, bile duct stricture, diverticular disease and visceral neuropathy); these patients
did not respond to the injection of a local anesthetic. Of the 79 patients in the study, 72 (91
percent) experienced at least 50 percent pain relief with one injection of local anesthetic, and
at least 56 patients (78 percent) had permanent relief with one or two injections. Thus, when
combined with other clinical criteria, a positive Carnett's sign is valuable as a sign of
abdominal wall pain. 2)
The sensitivity and specificity of the Carnett's sign have not been well established. One of the
largest studies to address the issue (published only as an abstract) focused on 33 patients with
chronic abdominal wall pain who were compared with 62 patients considered to have visceral
pain. The sensitivity and specificity of the Carnett's sign was 78 and 88 percent, respectively.
However, two observers agreed on a positive Carnett's sign in only 76 percent of cases.
Carnett's sign may not be interpretable in patients who cannot comply adequately with leg or
head-raising maneuvers. False positive results may occur from visceral causes of pain that
involve the local parietal peritoneum.
( http://www.medicalgeek.com/disease-syndromes-procedures/5400-carnetts-sign.html )
参考文献
1.
Dugdale A. Carnett sign. Aust Fam Physician. 2008 Jan-Feb;37(1-2):8.
2.
Suleiman S, Johnston DE. The abdominal wall: an overlooked source of pain. Am Fam
Physician. 2001 Aug 1;64(3):431-8.
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3.
Ortiz DD. Chronic pelvic pain in women. Am Fam Physician. 2008 Jun 1;77(11):1535-42.
4.
生坂政臣.めざせ！外来診療の達人.東京,日本医事新報社,2006.
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