These three cases describe instances of false positive diagnoses of infantile hypertrophic pyloric stenosis (IHPS) based on abdominal ultrasonography findings. In Case 1, upper GI series found no pyloric stenosis. In Cases 2 and 3, upper GI series also did not confirm the diagnosis of IHPS suggested by ultrasonography. Reliance solely on ultrasonography without considering other clinical evidence can increase the risk of false positive diagnoses of IHPS and unnecessary surgery. A palpable pyloric mass on examination under anesthesia is important for confirming the diagnosis before proceeding with pyloromyotomy.

2. Infantile Hypertrophic Pyloric Stenosis
a report of 3 cases of
false positives in the sonographic diagnoses
高雄市立聯合醫院 小兒外科 李振豐

3. Case 1
 Age : 2m10d/o Sex: female
 B.H. : G2P2, NSD, full-term, BBW 2600 grams
 PH : Hyperbilirubinemia and phototherapy at our
pediatric ward at age of 7days
 P.I. : Easy postprandial vomiting (non-bilious)
since 20 d/o, persistent postprandial
vomiting in spite of medical treatment,
ultrasonographic diagnosis of infantile
hypertrophic pyloric stenosis (twice) at
OPD, and pediatric surgical consultation
was requested after admission.

4. Plain Abdomen

5. Abdominal ultrasonography (1st)(34d/o)
Pylorus - longitudinal axis : 20.4 mm
short axis : 9.6 mm
muscle thickness : 4.3 mm

6. Abdominal ultrasonography (2nd)(40d/o)
Pylorus – longitudinal axis : 21.0 mm
muscle thickness : 4.3 mm

8. Laboratory tests
CBC & DC
Biochemistry
Blood gas

9. P.E. on Consultation
MD and MN
Consc : alert
Conj : not anemic
Sclera : not icteric
Neck : supple, no LAP
Chest : symmetric
H.S.: no murmur
B.S.: no rale
Abdomen : soft and flat
bowel sound: present
*visible gastric peristaltic wave : negative
*palpable olive mass : negative

10. Upper GI series (by the pediatric surgeon)
no Pyloric Stenosis, Gastroesophageal reflux

12. Case 2
 Age : 1m5d/o Sex : male
 B.H. : G1P1, C/S, GA 36 weeks, BBW 2640 g
 P.H. : n.p.
 PI : progressive postprandial vomiting for 3-4
days, suspected infantile hypertrophic
pyloric stenosis by abdominal
ultrasonography at OPD, pediatric surgical
consultation was requested after admission

13. Abdominal ultrasonography
Pylorus - longitudinal axis : 21.9 mm
short axis : 15.2 mm
muscle thickness : 5.13 - 5.53 mm

14. Laboratory tests
CBC & DC
Biochemistry
Blood gas

15. Plain Abdomen

16. P.E. on Consultation
MD and MN, BW 3514 grams
Consc: alert
Conj: not anemic
Sclera: not icteric
Conj: not icteric
Neck: supple, no LAP
Chest: symmetric
H.S.: no murmur
B.S.: no rale
Abd: soft, slightly distended
hyperactive bowel sound
*no visible gastric peristaltic wave
*no palpable olive mass

17. Upper GI series
gastroesophageal reflux

19. Case 3
 Age : 29 d/o Sex : male
 B.H. : NSD, full-term, BBW 2635 g (Pojen H.)
 P.H. : admission at KCGMH for frequent
postprandial vomiting (9 d/o – 29 d/o)
 P.I. : 1. for 自費托嬰
2. still easy postprandial vomiting
3. BW 2965 grams

20. Abdominal ultrasonography (1st)(45d/o)
Pylorus – longitudinal axis : 2.13 cm
muscle thickness : 0.37 cm
Sonographic diagnosis : IHPS can not be ruled out
Suggestion : upper GI if symptom persists

21. Abdominal ultrasonography (2nd)(56d/o)
Pylorus – muscle thickness : 0.408 cm
Sonographic diagnosis: IHPS can not ruled out
Suggestion : UGI series if symptom persists

22. Abdominal ultrasonography (3rd)(66d/o)
Pylorus – longitudinal axis : 1.78 cm
muscle thickness : 0.388cm
Sonographic diagnosis : IHPS can not be ruled out

23. Pediatric surgery consultation (70d/o)
 C.C. : postprandial vomiting
watery diarrhea with diaper dermatitis and perineal
skin erosion
 B.W. : formula feeding, 150ml / 5hrs
B.W.- 2635 g  5.5 kg
 P.E.: distended abdomen with hyperactive bowel sound
anorectal digital examination – anal stenosis
 DX : 1. GER
2. anal stenosis
 RX : 1. daily anal dilatation for 4-6 weeks
2. conservative treatment, i.e. small frequent feedings,
position change, and medication as necessary

24. Abdominal ultrasonography (4th)(84d/o)
Pylorus – longitudinal axis : 1.54 cm
muscle thickness : 0.349 cm
Sonographic diagnosis : IHPS cannot be ruled out

25. Upper GI series (86d/o)

27. Infantile Hypertrophic Pyloric Stenosis
 Incidence
- 2-4 in 1000 Caucasian
- fewer than 1 in 1000 Asian and African
 Male preponderance
- between 4:1 and 10:1
- firstborn males are accounting for 40-60%
 Age of presentation
- most commonly 3-6th week of age
- (as early as 1st week, and as late as 5th month)
 Family history
- 15-20 folds increase in risk

28. Clinical Presentation
 Clinical triad
- Projectile vomiting (non-bilious)
- Visible gastric peristaltic wave
- Palpable pyloric (olive) tumor (50-90%)
 Hypochloremic hypokalemic metabolic alkalosis
(serum pH >7.45, chloride <98, and base excess >+3)
 Dehydration
 Constipation
 Coffee-ground flecks if 2° gastritis (15-20%)
 Jaundice (3-5%)(↓ hepatic glucuronyl transferase)

31. Diagonosis of IHPS
 Clinical diagnosis: 60-90%
History, Lab, S/S,
palpable olive mass (pathognomonic)
 Plain film & barium upper GI series
 Ultrasonography - the gold standard imaging
 Over the past 30 years, increased reliance on
imaging has decreased clinical diagnosis from
up to 90% of cases to as little as 23%.
(J. Paediatric and Child Health 49 (2013) 33–37)

32. Plain Abdomen in IHPS

33. Gastric Peristaltic Wave
Note : On NG tube and empty the stomach of content
and then Inflation of air into stomach

34. Palpable pyloric tumor (olive mass)
Note: On NG tube and empty the stomach of content
and left NG open
and bottle feeding of water
https://survivinginfantsurgery.wordpress.com
test feed

35. www.diagnostic imaging.com

36. Upper GI series
string sign
double track sign
shoulder sign
mushroom sign

37. Diagnostic Criteria
of Ultrasonography
 Pyloric muscle
thickness > 3-4mm
 pyloric muscle
length > 15-20mm
 pyloric diameter
> 10-14mm
Both a high sensitivity (90-99%)
and high specificity (97-100%).
 False positive:
pyloric spasm
 False negative:
prematurity or early disease
ATOTW 276 – Infantile Hypertrophic Pyloric Stenosis,
26th November 2012

39. Diagnostic ultrasound Fifth Edition Copyright © 2018 by Elsevier, Inc.
Pitfalls in Sonographic Diagnosis

40. Pitfalls in Sonographic Diagnosis
Diagnostic ultrasound Fifth Edition Copyright © 2018 by Elsevier, Inc.

43. Treatment of IHPS
 Definitive treatment : Surgery (both safe and effective)
- Ramstedt pyloromyotomy (since 1911 ~)
open vs laparoscopic
 Other approaches (not recommended)
- Atropine, iv or oral (relaxation of pyloric muscle)
- Conservative treatment
(including a trial of continuous nasoduodenal tube feedings)
- Balloon dilatation (endoscopically guided)
https://survivinginfantsurgery.wordpress.com

44. Preoperative preparation
Preoperative treatment → correcting fluid deficit (dehydration),
acid-base and electrolyte imbalances.
 Normal electrolytes with mild or no dehydration
- as usual
 Moderate or severe dehydration
-*surgery delayed and intensive electrolyte and fluid therapy
**• pH ≤7.45 and/or base excess ≤3.5
• Bicarbonate <26 mEq/L
***• Sodium ≥132 mEq/L
***• Potassium ≥3.5 mEq/L
• Chloride ≥100 mEq/L
• Glucose ≥72 mg/dL (4.0 mmol/L)
* : IHPS is a medical emergency, not a surgical emergency
** : correction of alkalosis is essentially to prevent postoperative apnea
*** : severe hypokalemia (serum potassium <2.5 mEq/L) or hyponatremia (serum
sodium <120 mEq/L) are at high risk of postoperative complications.

45. Ramstedt pyloromyotomy (open)

46. Incisions for pyloromyotomy
Minimally invasive surgery
Circumumbilical incision
(supraumbilical)

47. Surgery 136:827-32, 2004
Laparoscpic pyloromyotomy

48. Complications
 Mucosal perforation
- incidence : 2%, ususally duodenal end.
(<1% unrecognized intraoperatively)
- treatment : close mucosa and reinforced with omental patch
NG tube decompression & NPO for 48 hrs
 Incomplete pyloromyotomy
- rare (0-7%) → re-operation
 Others
- SSI : 4%
- postoperative emesis (44%): transient mucosal edema, GER,
gastric atony.
(incomplete pyloromyotomy).

50. Misdiagnosis and Negative Laparotomy
 The rate of negative laparotomy was rarely reported (1~4%).
 Reliance upon the ultrasound appearance of the pylorus
without taking into account other important diagnostic
evidence will increase the risk of false-positive diagnoses
and unnecessary laparotomy. (Pyloric Stenosis: Is Over-Reliance on
Ultrasound Scans Leading to Negative Explorations? Eur J Pediatr Surg 1997, 7(6):328-30.)
 If there is no palpable ‘tumor’ on a test feed, criteria for
surgery should include a palpable pyloric mass on
examination under anesthesia (EUA). In the absence of
palpable mass on EUA, upper GI endoscopy may be used
to demonstrate features of IHPS before proceeding with
pyloromyotomy. (Negative exploration for pyloric stenosis – Is it preventable?
BMC Pediatrics 2008, 8:37)

51. Thank You