Human peritoneal adhesions are highly cellular, innervated, and vascularized

Peritoneal adhesions are a major complication of healing following surgery or infection and can lead to conditions such as intestinal obstruction, inf ertility, and chronic pain. Mature adhesions are the result of aberrant per itoneal healing and historically have been thought to consist of non-functi onal scar tissue. The aim of the present study was to analyse the cellular composition, vascularity, and extracellular matrix distribution of human pe ritoneal adhesions, to determine whether adhesions represent redundant scar tissue or are dynamic regenerating structures. Furthermore, the histologic al appearance of each adhesion was correlated with the clinical history of the patient, to determine whether maturity or intraperitoneal pathology inf luences adhesion structure. Human peritoneal adhesions were collected from 29 patients undergoing laparotomy for various conditions and were prepared for histology, immunocytochemistry, and transmission electron microscopy. A ll adhesions were highly vascularized, containing well-developed arterioles , venules, and capillaries. Nerve fibres, with both myelinated and non-myel inated axons, were present in adhesions from nearly two-thirds of the patie nts, with increased incidence in those with a malignancy. Approximately one -third of the adhesions contained conspicuous smooth muscle cell clusters l ined by collagen fibres of heterogeneous size. Adipose tissue was a consist ent feature of all the adhesions, with some areas displaying fibrosis, Ther e appeared to be no correlation between the estimated maturity or site of e ach adhesion and its histological appearance. However, intraperitoneal path ology at the time of surgery did influence the incidence of some histologic al features, such as the presence of nerve fibres, clusters of smooth muscl e cells, and inflammation. This study challenges previous concepts that adh esions represent non-functional scar tissue and clearly demonstrates that e stablished adhesions are highly cellular, vascularized, and innervated, fea tures more consistent with dynamic, regenerating structures. Copyright (C) 2000 John Wiley & Sons, Ltd.