Situs ambiguus is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen. Clinically heterotaxy spectrum generally refers to any defect of Left-right asymmetry and arrangement of the visceral organs; however, classical heterotaxy requires multiple organs to be affected. This does not include the congenital defect situs inversus, which results when arrangement of all the organs in the abdomen and chest are mirrored, so the positions are opposite the normal placement. Situs inversus is the mirror image of situs solitus, which is normal asymmetric distribution of the abdominothoracic visceral organs. Situs ambiguus can also be subdivided into left-isomerism and right isomerism based on the defects observed in the spleen, lungs and atria of the heart. Individuals with situs inversus or situs solitus do not experience fatal dysfunction of their organ systems, as general anatomy and morphology of the abdominothoracic organ-vessel systems are conserved. Due to abnormal arrangement of organs in situs ambiguus, orientation across the left-right axis of the body is disrupted early in fetal development, resulting in severely flawed cardiac development and function in 50–80% of cases. They also experience complications with systemic and pulmonary blood vessels, significant morbidity, and sometimes death. All patients with situs ambiguus lack lateralization and symmetry of organs in the abdominal and thoracic cavities and are clinically considered to have a form of heterotaxy syndrome. Heterotaxy syndrome with atrial isomerism occurs in 1 out of every 10,000 live births and is associated with approximately 3% of congenital heart disease cases.
Pulmonary-renal syndrome (PRS) is a rare medical syndrome in which respiratory failure involving bleeding in the lungs and kidney failure (glomerulonephritis) occur. PRS is associated with a high rate of morbidity and death. The term was first used by Goodpasture in 1919 to describe the association of respiratory and kidney failure. Causes
Pulmonary-renal syndromes are most commonly caused by an underlying autoimmune disease. PRS is most commonly due to ANCA-associated vasculitides (e.g., granulomatosis with polyangiitis) or due to anti-basement membrane diseases (e.g., Goodpastures syndrome). Granulomatosis with polyangiitis usually presents with nasopharyngeal involvement as well, whereas Goodpastures will not. Microscopic polyangiitis is the most common cause of pulmonary-renal syndrome.Other causes include systemic lupus erythematosus, eosinophilic granulomatosis with polyangiitis, microscopic polyangiitis, dermatomyositis, polymyositis, mixed connective tissue disease, poststreptococcal glomerulonephritis, rheumatoid arthritis, and systemic sclerosis. Less common causes also include IgA vasculitis and cryoglobulinemic vasculitis. Other etiologies include toxic injury such as paraquat poisoning, infection with hantavirus, leptospirosis, or legionella, or vascular, as seen in nephrotic syndrome when a renal vein thrombosis embolizes to the lungs. Diagnosis
Differential diagnosis
Cardiogenic shock can mimic a pulmonary renal syndrome and lead to coughing up blood due to pulmonary edema and kidney failure from inadequate blood flow. Treatment
Treatment is primarily by corticosteroids and immunosuppressive medications like cyclophosphamide, methotrexate, and azathioprine. Plasmapheresis can be used in some circumstances. == References ==