Patients with pleurisy tend to lie on the affected side mainly to relieve chest pain; patients with massive pleural effusion tend to lie on the affected side mainly to relieve respiratory distress. So, what are the differential diagnostic methods for forced lateral recumbency? The following is the differential diagnosis of forced lateral recumbency. Examination: 1.Conventional examination: routine blood, blood sedimentation, liver function, blood sugar, five TB-AB of hepatitis B. 2.Ultrasound examination: thoracic A-ultrasound or B-ultrasound examination, which can measure the amount and localization of fluid. 3.X-ray: chest frontal and lateral films, high KV, tomography or CT examination if necessary. 4.Pleural fluid: routine, biochemistry, LDH and protein ratio of pleural fluid and blood, ADA. 5.Bacteriology: sputum smear, pleural fluid collection, culture or TB-DNA of pleural fluid to check TB bacilli. Differential diagnosis of forced lateral position: 1, forced squatting position: short distance walking or other activities due to the feeling of breathing out of difficulty and palpitations and take the squatting distance position or knee-chest position to relieve symptoms, seen in cyanotic congenital heart disease. 2, forced sitting position (sitting breathing): sitting position, hands on the knees or support the side of the bed, in order to make the diaphragm fall to increase the lung volume and lower limbs to reduce the return blood volume, to reduce the burden on the heart, seen in cardiac and pulmonary insufficiency. 3.Forced standing position: sudden onset of pain in the precordial region during walking and forced to stand immediately, and the right hand to caress the precordial region, seen in angina pectoris. 4.Forced prone position: prone position can make the muscles of the spine relaxed, seen in spinal diseases. 5, forced supine position: the patient lies on his back, legs flexed to reduce the tension of the abdominal muscles, seen in acute peritonitis.