Division of Body Imaging, Department of Radiology, Stony Brook University Medical Center, Stony Brook, NY.
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HistoryA 6-week-old male presents with a history of vomiting for 4 days. The mother reports the vomiting had increased over the past day and "would shoot half way across the room." The vomitus was without frank blood or bile. An ultrasound (US) was requested (Figs. 1-4).IMAGING FINDINGSThere is an elongated and thickened pylorus as shown in Figure 5 (the annotated version of Fig. 1), which suggests hypertrophic pyloric stenosis (HPS). Figures 6 and 7 (the annotated versions of Figs. 2 and 3) show that the pyloric canal has opened, and both the antrum and pylorus are filled with fluid, which is atypical for HPS. The pyloric length is now much shorter, and there is no evidence of HPS. Changeability of image measurements from those typical of HPS to those that appear normal suggests pylorospasm (PS). Two arrows onFigure 8 (the annotated version of Fig. 4) point to a wide fluid-filled distal esophagus seen just below the diaphragm. Fluid was observed on real time passing from stomach to distal esophagus suggesting concurrent gastroesophageal reflux (GER).DIFFERENTIAL DIAGNOSTIC CONSIDERATIONSProper assessment of the vomiting neonate is challenging. Vomiting is the forceful extrusion of gastric contents and is never normal in the neonate.1 A correct diagnosis is important for decisions on appropriate treatment, including possible pyloromyotomy in case of HPS. Differential diagnostic considerations vary with age, history, and type of vomitus. Vomiting must also be differentiated from GER, a common occurrence in the first 3 months of life.The patient had nonbilious vomiting at several weeks of age with no history of vomiting from birth. Bowel malrotation and duodenal obstruction are unlikely possibilities. Major differential diagnostic considerations for vomiting in a nonseptic neonate that first develops only after several weeks of normalcy include HPS, PS, and GER, which can simulate vomiting. Regurgitation is often not easily differentiated from true vomiting and may even be described as "projectile" in nature, particularly after overfeeding. Gastroesophageal reflux may be diagnosed by a pH probe. Such workups are not typical in the first 3 months of life. Gastroesophageal reflux diagnosis by fluoroscopy involves radiation. Ultrasound can show echoless water refluxing from stomach into the esophagus (Fig. 4). McCauley et al2 showed that a more dilated distal esophagus on upper gastrointestinal (UGI) series suggested a greater degree of reflux. This is also seen in US assessment. Ultrasound neither can assess the more proximal esophagus nor evaluate esophageal mucosa for ulcerations.The key entity to exclude when assessing projectile vomiting is HPS. Not all parents of patients with HPS will complain of projectile vomiting. In addition, complaints of projectile vomiting definitively occur in cases that prove not to be HPS, including refluxing children who are overfed and children who have PS.Patients with PS, the diagnosis of the subject, have spasmodic contraction of the pylorus and a lack of coordinated gastric emptying. Normal gastric emptying involves a contraction of the gastric antrum followed by sequential contractions of the pyloric region and the duodenum. Overly rapid emptying is prevented by pyloric muscle contraction that inhibits excessively fast gastric emptying.