Pyloric Stenosis: Likelihood Ratios

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 likelihood ratios of findings for Pyloric Stenosis are listed below. See the left navigation bar to change the display.

Good Positive and Negative Likelihood Ratios

Finding	+LR	-LR	Comments, Study
Upper GI Series	inf	0	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	inf	0.1	Study: J Pediatr Surg. 1998 May;33(5):676-81. PMID: 9607467
Abdominal Mass	inf	0.3	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
Weight loss	2.5	0.3	pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693
Abnormal Serum Chloride	50	0.5	<= 98 mmol/l pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693

Good Negative Likelihood Ratio

Finding	+LR	-LR	Comments, Study
Projectile Vomiting	1.5	0.2	pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693

Good Positive Likelihood Ratio

Finding	+LR	-LR	Comments, Study
Abnormal Serum Bicarbonate	36	0.6	>= 29 mmol/l pyloric stenosis vs GERD Study: Am J Emerg Med. 1999 Jan;17(1):28-31. PMID: 9928693