Abdominal masses are a common clinical sign and a common reason for patients to seek medical attention. The abdominal masses that appear in the neonatal period are very different from those in adults, and are mostly related to congenital and embryonic factors. Diagnosis】 The diagnosis of abdominal masses is mainly the determination of the nature and source, and attention should be paid to the site, size, shape, texture, pressure pain, mobility, and pulsation. If a mass is palpated in the upper middle abdomen, it is often a stomach or pancreatic tumor, cyst, etc.; a mass under the right costal margin is often considered to have liver and biliary tract diseases; in children, a mass in the lumbar abdomen should be excluded from nephroblastoma, and if there is a deep, hard, irregular mass, it may be a retroperitoneal tumor such as neuroblastoma or teratoma; a mass above the inguinal ligament may be from ovarian cyst, inguinal hernia, spermatic cord sheath The mass above the inguinal ligament may be from ovarian cyst, inguinal hernia, spermatic sphincter, etc. 2. Pay attention to the size of masses Huge masses mostly occur in the ovaries, kidneys, liver, pancreas and uterus, and cysts predominate, for example: mucinous cystadenoma of ovary, which can occupy the whole abdominal cavity, and the ultrasound shows a huge echogenic area with multiple light bands separating it; patients with severe hydronephrosis have a significant sense of mass on one side; mesenteric cysts and large omental cysts also show huge cysts. 3.Mass shape and texture Regular and smooth surface masses are mostly benign, mostly cysts or lymph nodes, which are easily distinguished under ultrasound; irregular, uneven and hard surface, malignant tumors are considered first, followed by inflammatory masses or tuberculosis masses. In the differentiation of benign and malignant tumors, color Doppler ultrasound can be used to judge from the blood flow situation. If a pediatric patient has a tubular mass with bloody stool, the focus should be on investigating whether there is intussusception, and the ultrasound image shows the “target ring” sign in transverse section or “sleeve” sign in longitudinal section, which can basically diagnose intussusception. 4, the presence of pulsatile The pulsation of arteries can be seen or palpated in the abdomen in lean patients, such as: palpable dilated pulsation near the abdominal midline, then the abdominal aorta or branch aneurysms should be considered. Ultrasound is very clear and rapid in the diagnosis of vascular disease. 5, pressure pain Inflammatory masses have obvious pressure pain, such as adhesion masses due to inflammation of the digestive tract, Merkel’s diverticulitis or intestinal duplication malformation, etc. In addition, neonatal appendicitis is also a rare cause. 6.Concomitant symptoms The mass combined with anemia, malnutrition and other wasting symptoms are mostly malignant tumors, and the presence of pelvic and presacral tumors is noted in those with combined low intestinal obstruction. Differential diagnosis】 The common diseases of neonatal abdominal masses are as follows. 1, hepatoblastoma The tumor is usually larger in neonatal onset, showing asymmetric enlargement of the liver, and sometimes a clear mass can be palpated. Ultrasonography shows that the liver is enlarged, there is a limited elevation of the hepatic peritoneum, round or oval shaped echogenic masses with clear borders are seen in the liver, single or multiple fused masses of different sizes, liquid dark areas are seen if there is necrosis and bleeding, strong echogenic masses with acoustic shadow are seen if there are calcified foci in the tumor, rich blood flow bundles are seen in the periphery of the mass and inside the tumor by color Doppler, and arterial blood flow is predominant by pulsed Doppler. CT and enhancement scans can clarify the extent and nature of the lesion. Serum AFP is abnormally elevated. However, it should be distinguished from hemangioendothelial cell tumor of liver. Nephroblastoma (renal embryonal tumor) is the first malignant tumor in the pediatric urological tract, unilateral and can occur in any part of the kidney. Abdominal mass is the most common symptom, mostly found by chance. About 30% of children have hematuria, occasional low fever and abdominal pain. Ultrasound: Nephroblastoma is located in the kidney, the kidney is morphologically abnormal, only the upper pole of the kidney or lower pole of the kidney remains in the shape of a cup, or in the shape of a moon bud, the tumor is mostly round, the peritoneum is smooth and intact, the border is clear, the echogenicity in the tumor is diverse, homogeneous, solid, strong echogenicity and irregular echogenicity, etc. CT, MRI, IVP can determine the source, the adjacent relationship, the degree of destruction and the size of the tumor, etc. 3.Neuroblastoma originates from sympathetic ganglion cells, most of the tumors are in the adrenal medulla, the rest are in the retroperitoneum or posterior mediastinal paraspinal sympathetic chain. The clinical manifestation is often an incidentally discovered abdominal mass that increases rapidly but without obvious pain, with a fixed location, hard texture and multiple nodules on the surface. Ultrasound presentation: retroperitoneal or paraspinal masses with non-homogeneous or largely homogeneous strong echogenic internal echoes and nudged but structurally normal kidneys. Urinary hypervanillic acid and vanillic mandelic acid tests and serum neuron-specific enolase tests are also of great significance, and CT, MRI, PET and other tests can achieve a clear preoperative diagnosis. 4.Congenital common bile duct cyst is one of the common pediatric biliary anomalies, due to congenital abnormal pancreaticobiliary cohesion, congenital weakness of the bile duct wall or abnormal nerve structure at the end of the common bile duct, which affects the bile excretion and causes the pressure in the common bile duct to rise and then expand and hypertrophy to form a cyst. The clinical manifestations often include vomiting, abdominal pain, right upper abdominal mass, jaundice in case of acute obstruction, fever and peritonitis in case of inflammation or even perforation. The cystic mass in the common bile duct, proximal to the hepatic duct, is thickened and unsmooth when combined with infection, with poor intracapsular acoustic transmission, and hyper-echoic dots and flocculent drift in the cyst, and strong echogenic clusters with acoustic shadowing when combined with stones. 5.Severe hydronephrosis is mostly caused by congenital ureteral malformation, stenosis, atresia and other reasons. The imaging examination shows that the kidney is extremely enlarged and loses its normal shape, the renal peritoneum is intact and smooth, the renal cortex is 1~3mm thin, and the kidney is a huge echoless dark area with regular strips of separation. 6.Teratoma is a tumor formed by the development of three kinds of germ layers, mostly benign, located in retroperitoneum, presacral or originated from the germ line, manifested as an abdominal mass, and intestinal obstruction may occur with rectal compression. Ultrasonography, CT, MRI and other imaging examinations show masses of polyembryonic origin with mixed structures such as fat, hair masses or even skeletal structures. 7.Other rare causes include inflammatory mass formation in meconium peritonitis, and calcified spots in the abdominal cavity seen on X-ray is a specific manifestation; the intestinal mass formed by intestinal tube overlapping in intussusception, and the ultrasound image shows the “target ring” sign in transverse section or “sleeve” sign in longitudinal section can The diagnosis can be made. In addition, intestinal duplication malformation, yolk duct malformation, congenital mesenteric cyst, large omental cyst, ovarian cyst, etc. can also form abdominal masses and need to be noted.