Pyloric Stenosis: Sensitivity and Specificity

Introduction: Congenital hypertrophy of the pyloris, i.e. the gastric outlet. Onset on average 3-5 weeks of life. Corrected surgically.

Note that the diagnostic accuracies have changed over time:

" Over the 25-year period, 901 infants underwent PM. Patients presented at a younger age, weighed more, and had a shorter length of illness in the most recent time period. Hypochloremic alkalosis was found half as frequently in the most recent time period compared to the earliest group. A palpable pyloric tumor was present in 79% of patients in the earliest time period compared with 23% in the most recent time period. Sixty-one percent of patients in the earliest group and 96% in the latest group underwent an imaging study, reflecting the referring physician's evaluation before referral to the surgeon." [PMID 9233980]

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Prevalence

The sensitivity and specificity of findings for Pyloric Stenosis are listed below. See the left navigation bar to change the display.

Sensitive and Specific Findings

Finding	Sensitivity	Specificity	Comments, Study
Upper GI Series	100%	100%	The decision analysis concluded that UGI should be the first test ordered, rather than US. Study: J Pediatr Surg. 1998 May;33(5):676-81. PMID: 9607467
Abdominal US	90%	100%	Study: J Pediatr Surg. 1998 May;33(5):676-81. PMID: 9607467

Specific Findings

Finding	Sensitivity	Specificity	Comments, Study
Abdominal Mass	73%	100%	pyloric stenosis vs GERD Most pediatricians find that feeling pyloric mass is very insensitive. Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693
Abnormal Serum Chloride	50%	99%	<= 98 mmol/l pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693
Abnormal Serum Bicarbonate	36%	99%	>= 29 mmol/l pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693

Sensitive Findings

Finding	Sensitivity	Specificity	Comments, Study
Projectile Vomiting	93%	39%	pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693

Poorly Diagnostic Findings

Finding	Sensitivity	Specificity	Comments, Study
Weight loss	81%	68%	pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693