Cavagna E, Carubia G, Schiavon F
Unità Operativa Autonoma di Radiologia, Ospedale S. Martino, Viale Europa, 22, 32100 Belluno BL.
Radiol Med. 2000 Jun;99(6):432-7.
Rectus sheath hematomas are a frequent but sometimes misdiagnosed disease in patients under anti-coagulative drugs, hemodialysis, or simply in the elderly. The most frequent localization is in the lower part of the abdomen: the explanation lies in the anatomy of the abdominal wall, especially in the arcuate line of the rectus sheath. Aim of this work is to explain the reason of the almost constant location correlating the anatomy with the CT features.
The rectus abdominis muscle lies between the aponeuroses of the transverse and oblique muscles which form the so called rectus sheath. This arrangement is found from the costal arch to a level approximately between the umbilicus and the pubic symphisis, where the rear layer of the rectus sheath ends with a curved edge, called the arcuate or semicircular line of Douglas. Beneath this line the aponeuroses of the three muscles pass in front of the rectus which is separated from the peritoneum only by the fascia trasversalis, a thin connective layer between the rectus and the preperitoneal fat. In this lower aspect of the muscle the perforating branches of the inferior epigastric artery running in the preperitoneal fat may rupture causing a large hematoma widely spreading in this loose space.
11 cases of rectus sheath hematoma diagnosed over 5 years were reviewed. They were referred to US because of a rapidly growing palpable mass or painful swelling of the abdominal wall with acute anemia. Sonography was performed in 11 patients and CT in 7.
10 hematomas were located in the lower third of the rectus muscle below the arcuate line in the pelvis, 1 was in the upper third of the muscle: the vast majority of pelvic hematomas is easily accounted for by the peculiar anatomy of the region.
The diagnosis of hematoma of the rectus abdominis, sometimes misleading, should be included as a differential in all the patients who present with acute abdominal pain and blood loss. The anatomy of abdominal wall correlates well with CT findings and explains the reason why most hematomas are found in the lower third of the muscle.
The diagnosis, whether clinical or based on imaging findings, needs accurate pathoanatomic knowledge of the anterior abdominal wall. Once the diagnosis has been confirmed (by US or CT) patients should be treated conservatively as those that are operated are at risk of developing complications, mainly hemorrhagic.
腹直肌鞘血肿在接受抗凝药物治疗、血液透析的患者中较为常见，但有时也会被误诊，在老年人中也时有发生。最常见的部位是腹部下部：原因在于腹壁的解剖结构，尤其是腹直肌鞘的弓状线。本研究的目的是通过将解剖结构与CT特征相关联来解释几乎恒定的血肿部位的原因。
腹直肌位于构成所谓腹直肌鞘的横肌和斜肌腱膜之间。从肋弓到大约脐部与耻骨联合之间的水平都存在这种结构，在该水平处，腹直肌鞘的后层以弯曲边缘结束，称为道格拉斯弓状线或半环线。在这条线以下，三块肌肉的腱膜在腹直肌前方通过，腹直肌仅通过腹横筋膜与腹膜分隔开，腹横筋膜是腹直肌与腹膜前脂肪之间的一层薄结缔组织层。在肌肉的这个下部区域，走行于腹膜前脂肪中的腹壁下动脉穿支可能破裂，导致大血肿在这个疏松间隙广泛扩散。
回顾了5年间诊断的11例腹直肌鞘血肿病例。这些患者因可触及的肿块迅速增大或腹壁疼痛性肿胀伴急性贫血而接受超声检查。11例患者进行了超声检查，7例进行了CT检查。
10例血肿位于盆腔内弓状线以下腹直肌的下三分之一处，1例位于肌肉的上三分之一处：盆腔内绝大多数血肿很容易用该区域独特的解剖结构来解释。
腹直肌血肿的诊断有时具有误导性，对于所有出现急性腹痛和失血的患者，都应将其作为鉴别诊断之一。腹壁的解剖结构与CT表现密切相关，解释了为什么大多数血肿位于肌肉的下三分之一处。
无论是临床诊断还是基于影像学检查结果的诊断，都需要对前腹壁有准确的病理解剖学知识。一旦确诊（通过超声或CT），患者应接受保守治疗，因为接受手术的患者有发生并发症的风险，主要是出血性并发症。
