Asplenia (the congenital or acquired absence of the spleen) and hyposplenism (defective spleen function) are common causes of morbidity and mortality. The spleen is a secondary lymphoid organ that is responsible for the regulation of immune responses and blood filtration. Hence, asplenia or hyposplenism increases susceptibility to severe and invasive infections, especially those sustained by encapsulated bacteria (namely, Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type b). Asplenia is predominantly due to splenectomy for either traumatic events or oncohaematological conditions. Hyposplenism can be caused by several conditions, including haematological, infectious, autoimmune and gastrointestinal disorders. Anatomical disruption of the spleen and depletion of immune cells, especially IgM memory B cells, seem to be predominantly responsible for the clinical manifestations. Early recognition of hyposplenism and proper management of asplenia are warranted to prevent overwhelming post-splenectomy infections through vaccination and antibiotic prophylaxis. Although recommendations are available, the implementation of vaccination strategies, including more effective and immunogenic vaccines, is needed. Additionally, screening programmes for early detection of hyposplenism in high-risk patients and improvement of patient education are warranted.

无脾症（先天性或后天性脾脏缺失）和脾功能减退症（脾脏功能缺陷）是发病率和死亡率的常见原因。脾脏是次级淋巴器官，负责调节免疫反应和血液过滤。因此，无脾或脾功能减退会增加对严重和侵袭性感染的易感性，尤其是那些由有荚膜细菌（即脑膜炎奈瑟菌、肺炎链球菌、流感嗜血杆菌）引起的感染类型 b)。无脾主要是由于外伤事件或肿瘤血液病症的脾切除术所致。脾功能减退症可由多种情况引起，包括血液学、感染、自身免疫和胃肠道疾病。脾脏的解剖学破坏和免疫细胞（尤其是 IgM 记忆 B 细胞）的耗竭似乎是导致临床表现的主要原因。早期识别脾功能减退和适当管理无脾是必要的，以通过疫苗接种和抗生素预防来防止压倒性的脾切除术后感染。尽管有可用的建议，但仍需要实施疫苗接种策略，包括更有效和免疫原性的疫苗。此外，