View source for Pyloric stenosis

{{Infobox medical condition (new)
| name            = Pyloric stenosis
| image           = Pyloric stenosis.svg
| caption         = Pylorus stenosis condition
| field           = [[General surgery]]
| symptoms        = Projectile vomiting after feeding<ref name=Ran2011/>
| complications   = [[Dehydration]], [[electrolyte problems]]<ref name=Ran2011/>
| onset           = 2 to 12 weeks old<ref name=Ran2011/>
| duration        =
| causes          = Unknown<ref name=Ge2012/>
| risks           = [[Cesarean section]], [[preterm birth]], [[bottle feeding]], first born<ref name=Zh2017/>
| diagnosis       = physical examination,<ref name=Ran2011/> [[ultrasound]]<ref name=Pan2012/>
| differential    = [[Gastroesophageal reflux]],<ref name=Ran2011/> [[intussusception (medical disorder)|intussusception]]<ref name=Mar2017>{{cite journal | vauthors = Marsicovetere P, Ivatury SJ, White B, Holubar SD | title = Intestinal Intussusception: Etiology, Diagnosis, and Treatment | journal = Clinics in Colon and Rectal Surgery | volume = 30 | issue = 1 | pages = 30–39 | date = February 2017 | pmid = 28144210 | pmc = 5179276 | doi = 10.1055/s-0036-1593429 }}</ref>
| prevention      =
| treatment       = Surgery<ref name=Ran2011/>
| medication      =
| prognosis       = Excellent<ref name=Ran2011/>
| frequency       = 1.5 per 1,000 babies<ref name=Ran2011/>
| deaths          =
}}
<!-- Definition and symptoms -->
'''Pyloric stenosis''' is a [[stenosis|narrowing]] of the opening from the [[stomach]] to the first part of the [[small intestine]] (the [[pylorus]]).<ref name=Ran2011/> Symptoms include projectile [[vomiting]] without the presence of [[bile]].<ref name=Ran2011/> This most often occurs after the baby is fed.<ref name=Ran2011/> The typical age that symptoms become obvious is two to twelve weeks old.<ref name=Ran2011/>

<!-- Cause and diagnosis -->
The cause of pyloric stenosis is unclear.<ref name=Ge2012>{{cite journal | vauthors = Georgoula C, Gardiner M | s2cid = 2780184 | title = Pyloric stenosis a 100 years after Ramstedt | journal = Archives of Disease in Childhood | volume = 97 | issue = 8 | pages = 741–5 | date = August 2012 | pmid = 22685043 | doi = 10.1136/archdischild-2011-301526 }}</ref> Risk factors in babies include birth by [[cesarean section]], [[preterm birth]], [[bottle feeding]], and being firstborn.<ref name=Zh2017>{{cite journal | vauthors = Zhu J, Zhu T, Lin Z, Qu Y, Mu D | title = Perinatal risk factors for infantile hypertrophic pyloric stenosis: A meta-analysis | journal = Journal of Pediatric Surgery | volume = 52 | issue = 9 | pages = 1389–1397 | date = September 2017 | pmid = 28318599 | doi = 10.1016/j.jpedsurg.2017.02.017 | doi-access = free }}</ref> The diagnosis may be made by feeling an olive-shaped mass in the baby's abdomen.<ref name=Ran2011/> This is often confirmed with [[ultrasound]].<ref name=Pan2012>{{cite journal | vauthors = Pandya S, Heiss K | title = Pyloric stenosis in pediatric surgery: an evidence-based review | journal = The Surgical Clinics of North America | volume = 92 | issue = 3 | pages = 527–39, vii-viii | date = June 2012 | pmid = 22595707 | doi = 10.1016/j.suc.2012.03.006 }}</ref>

<!-- Treatment -->
Treatment initially begins by correcting [[dehydration]] and [[electrolyte problems]].<ref name=Ran2011/> This is then typically followed by surgery, although some treat the condition without surgery by using [[atropine]].<ref name=Ran2011/> Results are generally good in both the short term and the long term.<ref name=Ran2011/>

<!-- Epidemiology and history -->
About one to two per 1,000 babies are affected, and males are affected about four times more often than females.<ref name=Ran2011/> The condition is very rare in adults.<ref>{{cite journal | vauthors = Hellan M, Lee T, Lerner T | s2cid = 25249604 | title = Diagnosis and therapy of primary hypertrophic pyloric stenosis in adults: case report and review of literature | journal = Journal of Gastrointestinal Surgery | volume = 10 | issue = 2 | pages = 265–9 | date = February 2006 | pmid = 16455460 | doi = 10.1016/j.gassur.2005.06.003 }}</ref> The first description of pyloric stenosis was in 1888, with surgical management first carried out in 1912 by [[Conrad Ramstedt]].<ref name=Ran2011>{{cite journal | vauthors = Ranells JD, Carver JD, Kirby RS | title = Infantile hypertrophic pyloric stenosis: epidemiology, genetics, and clinical update | journal = Advances in Pediatrics | volume = 58 | issue = 1 | pages = 195–206 | date = 2011 | pmid = 21736982 | doi = 10.1016/j.yapd.2011.03.005 }}</ref><ref name=Ge2012/> Before surgical treatment, most babies with pyloric stenosis died.<ref name=Ran2011/>

==Signs and symptoms==
Babies with this condition usually present any time in the first weeks to 6 months of life with progressively worsening [[vomiting]]. It is more likely to affect the first-born with males more commonly than females at a ratio of 4 to 1.<ref name="Naffaa 2019">{{cite journal | vauthors = Naffaa L, Barakat A, Baassiri A, Atweh LA | title = Imaging Acute Non-Traumatic Abdominal Pathologies in Pediatric Patients: A Pictorial Review | journal = Journal of Radiology Case Reports | volume = 13 | issue = 7 | pages = 29–43 | date = July 2019 | pmid = 31558965 | pmc = 6738493 | doi = 10.3941/jrcr.v13i7.3443 }}</ref> The vomiting is often described as non-bile stained ("non bilious") and "projectile vomiting", because it is more forceful than the usual spitting up ([[gastroesophageal reflux]]) seen at this age.  Some infants present with poor feeding and weight loss but others demonstrate normal weight gain. Dehydration may occur which causes a baby to cry without having tears and to produce less wet or dirty diapers due to not urinating for hours or for a few days. Symptoms usually begin between 3 and 12 weeks of age. Findings include epigastric fullness with visible peristalsis in the upper abdomen from the infant's left to right.<ref>{{cite web |url=http://www.mayoclinic.com/health/pyloric-stenosis/DS00815/DSECTION=symptoms |title=Pyloric stenosis: Symptoms |publisher=MayoClinic.com |date=2010-08-21 |access-date=2012-02-21 |url-status=live |archive-url=https://web.archive.org/web/20120225151016/http://www.mayoclinic.com/health/pyloric-stenosis/DS00815/DSECTION=symptoms |archive-date=2012-02-25 }}</ref> Constant hunger, belching, and [[Baby colic|colic]] are other possible signs that the baby is unable to eat properly.

==Causes==
Rarely, infantile pyloric stenosis can occur as an [[Dominance (genetics)|autosomal dominant]] condition.<ref name="pmid7333028">{{cite journal | vauthors = Fried K, Aviv S, Nisenbaum C | title = Probable autosomal dominant infantile pyloric stenosis in a large kindred | journal = Clinical Genetics | volume = 20 | issue = 5 | pages = 328–30 | date = November 1981 | pmid = 7333028 | doi = 10.1111/j.1399-0004.1981.tb01043.x | s2cid = 40464656 }}</ref> It is uncertain whether it is a [[congenital]] anatomic narrowing or a functional hypertrophy of the pyloric sphincter muscle.{{citation needed|date=August 2020}}

==Pathophysiology==
The [[gastric outlet obstruction]] due to the [[hypertrophic]] pylorus impairs emptying of gastric contents into the [[duodenum]]. As a consequence, all ingested food and gastric secretions can only exit via vomiting, which can be of a projectile nature. While the exact cause of the hypertrophy remains unknown, one study suggested that neonatal [[hyperchlorhydria|hyperacidity]] may be involved in the pathogenesis.<ref>{{cite book|last1=Rogers|first1=Ian|last2=Vanderbom|first2=Frederick|title=The Consequence and Cause of Pyloric Stenosis of Infancy|date=2014-02-26|publisher=More Books Lembert Academic Publishers|isbn=978-3-659-52125-6}}</ref> This physiological explanation for the development of clinical pyloric stenosis at around 4 weeks and its spontaneous long term cure without surgery if treated conservatively, has recently been further reviewed.<ref>{{cite journal | vauthors = Rogers IM | title = Pyloric stenosis of infancy and primary hyperacidity--the missing link | journal = Acta Paediatrica | volume = 103 | issue = 12 | pages = e558-60 | date = December 2014 | pmid = 25178682 | doi = 10.1111/apa.12795 | s2cid = 38564423 }}</ref>

Persistent vomiting results in loss of stomach acid ([[hydrochloric acid]]). The vomited material does not contain [[bile]] because the pyloric obstruction prevents entry of duodenal contents (containing bile) into the stomach. The [[chloride]] loss results in a [[hypochloremia|low blood chloride level]] which impairs the kidney's ability to excrete bicarbonate. This is the factor that prevents correction of the [[alkalosis]] leading to metabolic alkalosis.<ref name="Acidbase">Kerry Brandis, [http://www.anaesthesiamcq.com/AcidBaseBook/ab7_3.php Acid-Base Physiology] {{webarchive|url=https://web.archive.org/web/20051210041619/http://www.anaesthesiamcq.com/AcidBaseBook/ab7_3.php |date=2005-12-10 }}. Retrieved December 31, 2006.</ref>

A secondary [[hyperaldosteronism]] develops due to the [[hypovolemia|decreased blood volume]]. The high [[aldosterone]] levels causes the kidneys to avidly retain [[Sodium|Na<sup>+</sup>]] (to correct the intravascular [[volume depletion]]), and excrete increased amounts of [[Potassium|K<sup>+</sup>]] into the urine (resulting in a [[hypokalemia|low blood level of potassium]]).{{citation needed|date=August 2020}}The body's compensatory response to the metabolic alkalosis is hypoventilation resulting in an elevated arterial pCO<sub>2</sub>.

==Diagnosis==
[[File:Pyloric-stenosisLocal.jpg|thumb|upright=1.3|Pyloric stenosis as seen on ultrasound in a 6-week-old<ref>{{cite web|last1=Dawes|first1=Laughlin|title=Pyloric stenosis {{!}} Radiology Case {{!}} Radiopaedia.org|url=https://radiopaedia.org/cases/pyloric-stenosis|website=radiopaedia.org|access-date=20 April 2017|language=en|url-status=live|archive-url=https://web.archive.org/web/20170420171421/https://radiopaedia.org/cases/pyloric-stenosis|archive-date=20 April 2017}}</ref>]]
Diagnosis is via a careful history and physical examination, often supplemented by radiographic imaging studies. Pyloric stenosis should be suspected in any infant with severe vomiting. On physical exam, [[palpation]] of the abdomen may reveal a mass in the [[epigastrium]]. This mass, which consists of the enlarged pylorus, is referred to as the 'olive',<ref name=Shaoul>{{cite journal | vauthors = Shaoul R, Enav B, Steiner Z, Mogilner J, Jaffe M | title = Clinical presentation of pyloric stenosis: the change is in our hands | journal = The Israel Medical Association Journal | volume = 6 | issue = 3 | pages = 134–7 | date = March 2004 | pmid = 15055266 | url = http://www.ima.org.il/FilesUpload/IMAJ/0/51/25944.pdf }}</ref> and is sometimes evident after the infant is given formula to drink. Rarely, there are [[peristalsis|peristaltic]] waves that may be felt or seen ([http://www.nejm.org/doi/full/10.1056/NEJMicm1214572 video on NEJM]) due to the stomach trying to force its contents past the narrowed pyloric outlet.{{citation needed|date=August 2020}}

Most cases of pyloric stenosis are diagnosed/confirmed with [[Medical ultrasonography|ultrasound]], if available, showing the thickened pylorus and non-passage of gastric contents into the proximal duodenum. Muscle wall thickness 3 millimeters (mm) or greater and pyloric channel length of 15&nbsp;mm or greater are considered abnormal in infants younger than 30 days. Gastric contents should not be seen passing through the pylorus because if it does, pyloric stenosis should be excluded and other differential diagnoses such as pylorospasm should be considered. The positions of [[superior mesenteric artery]] and [[superior mesenteric vein]] should be noted because altered positions of these two vessels would be suggestive of intestinal malrotation instead of pyloric stenosis.<ref name="Naffaa 2019"/>

Although the baby is exposed to radiation, an [[upper GI series]] (X-rays taken after the baby drinks a special [[contrast agent]]) can be diagnostic by showing the pylorus with elongated, narrow lumen and a dent in the [[duodenal bulb]].<ref name="Naffaa 2019"/> This phenomenon caused "[[string sign]]" or the "railroad track/double track sign" on X-rays after contrast is given. Plain x-rays of the abdomen sometimes shows a dilated stomach.<ref>{{Cite journal |last1=Riggs |first1=Webster |last2=Long |first2=Larry |title=The Value of the Plain Film Roentgenogram in Pyloric Stenosis |date=May 1971 |url=http://www.ajronline.org/doi/10.2214/ajr.112.1.77 |journal=American Journal of Roentgenology |language=en |volume=112 |issue=1 |pages=77–82 |doi=10.2214/ajr.112.1.77 |pmid=5582036 |issn=0361-803X|url-access=subscription }}</ref>

Although upper gastrointestinal endoscopy would demonstrate pyloric obstruction, physicians would find it difficult to differentiate accurately between hypertrophic pyloric stenosis and pylorospasm.{{citation needed|date=August 2020}}

Blood tests will reveal low blood levels of [[hypokalemia|potassium]] and [[hypochloremia|chloride]] in association with an [[metabolic alkalosis|increased blood pH and high blood bicarbonate level]] due to loss of [[gastric acid|stomach acid]] (which contains [[hydrochloric acid]]) from persistent vomiting.<ref>{{cite web |title=Pyloric Stenosis - Clinical Practice Guidelines |url=https://www.rch.org.au/clinicalguide/guideline_index/Pyloric_stenosis/ |website=The Royal Children's Hospital Melbourne |access-date=17 March 2022 |archive-url=https://web.archive.org/web/20220131111314/https://www.rch.org.au/clinicalguide/guideline_index/Pyloric_stenosis/ |archive-date=31 January 2022}}</ref><ref>{{cite web |last1=Bhatt |first1=Binoy |last2=Reddy |first2=Srijaya K. |title=Chapter 140: Pyloric Stenosis |url=https://accessanesthesiology.mhmedical.com/content.aspx?bookId=1750&sectionId=117322493 |publisher=Access Anesthesiology |access-date=17 March 2022 |archive-url=https://web.archive.org/web/20220317094622/https://accessanesthesiology.mhmedical.com/content.aspx?bookId=1750&sectionId=117322493 |archive-date=17 March 2022}}</ref> There will be exchange of extracellular potassium with intracellular hydrogen ions in an attempt to correct the pH imbalance. These findings can be seen with severe vomiting from any cause.{{citation needed|date=August 2020}}

==Treatment==
[[Image:Pyloromyotomie.jpg|thumb|Vertical pyloromyotomy scar (large) 30 hrs post-op in a one-month-old baby]]
[[Image:PyloricStenosisHorizontal.jpg|thumb|Horizontal pyloromyotomy scar 10 days post-op in a one-month-old baby]]
[[Image:Pylorusstenose.jpg|thumb|Horizontal pyloromyotomy scar 35 years post-op in a three-month-old baby]]
<!-- [[File:Laparoscopic Pyloromyotomy scar, 6hrs post-op.jpg|thumb|Laparoscopic Pyloromyotomy scar, 6hrs post-op]] -->
Infantile pyloric stenosis is typically managed with surgery;<ref name=AskewOverview>{{cite journal | vauthors = Askew N | title = An overview of infantile hypertrophic pyloric stenosis | journal = Paediatric Nursing | volume = 22 | issue = 8 | pages = 27–30 | date = October 2010 | pmid = 21066945 | doi = 10.7748/paed.22.8.27.s27 }}</ref> very few cases are mild enough to be treated medically.

The danger of pyloric stenosis comes from the dehydration and electrolyte disturbance rather than the underlying problem itself. Therefore, the baby must be initially stabilized by correcting the dehydration and the abnormally high blood pH seen in combination with low chloride levels with IV fluids. This can usually be accomplished in about 24–48 hours.{{citation needed|date=August 2020}}

Intravenous and oral [[atropine]] may be used to treat pyloric stenosis. It has a success rate of 85–89% compared to nearly 100% for pyloromyotomy, however it requires prolonged hospitalization, skilled nursing and careful follow up during treatment.<ref name="pmid17210480">{{cite journal | vauthors = Aspelund G, Langer JC | title = Current management of hypertrophic pyloric stenosis | journal = Seminars in Pediatric Surgery | volume = 16 | issue = 1 | pages = 27–33 | date = February 2007 | pmid = 17210480 | doi = 10.1053/j.sempedsurg.2006.10.004 }}</ref> It might be an alternative to surgery in children who have contraindications for anesthesia or surgery, or in children whose parents do not want surgery.{{cn|date=May 2022}}

===Surgery===
The definitive treatment of pyloric stenosis is with surgical '''[[pyloromyotomy]]''' known as '''Ramstedt's''' procedure (dividing the [[muscle]] of the [[pylorus]] to open up the gastric outlet).  This surgery can be done through a single incision (usually 3–4&nbsp;cm long) or [[Laparoscopic surgery|laparoscopically]] (through several tiny incisions), depending on the surgeon's experience and preference.<ref>{{cite web |url=http://www.medpagetoday.com/Surgery/ThoracicSurgery/12497 |title=Medical News:Laparoscopic Repair of Pediatric Pyloric Stenosis May Speed Recovery – in Surgery, Thoracic Surgery from |publisher=MedPage Today |date=2009-01-16 |access-date=2012-02-21 |url-status=live |archive-url=https://web.archive.org/web/20120223065448/http://www.medpagetoday.com/Surgery/ThoracicSurgery/12497 |archive-date=2012-02-23 }}</ref>

Today, the laparoscopic technique has largely supplanted the traditional open repairs which involved either a tiny circular incision around the navel or the Ramstedt procedure.  Compared to the older open techniques, the complication rate is equivalent, except for a markedly lower risk of wound infection.<ref name="pmid19635317">{{cite journal | vauthors = Sola JE, Neville HL | title = Laparoscopic vs open pyloromyotomy: a systematic review and meta-analysis | journal = Journal of Pediatric Surgery | volume = 44 | issue = 8 | pages = 1631–7 | date = August 2009 | pmid = 19635317 | doi = 10.1016/j.jpedsurg.2009.04.001 }}</ref>  This is now considered the standard of care at the majority of children's hospitals across the US, although some surgeons still perform the open technique. Following repair, the small 3mm incisions are difficult to see.

The vertical incision, pictured and listed above, is no longer usually required, though many incisions have been horizontal in the past years. Once the stomach can empty into the [[duodenum]], feeding can begin again. Some vomiting may be expected during the first days after surgery as the gastrointestinal tract settles. Rarely, the [[myotomy]] procedure performed is incomplete and projectile vomiting continues, requiring repeat surgery. Pyloric stenosis generally has no long term side-effects or impact on the child's future.{{citation needed|date=August 2020}}

==Epidemiology==
Males are more commonly affected than females, with firstborn males affected about four times as often, and there is a [[genetic predisposition]] for the disease.<ref name="kh">{{cite web |url= http://www.kidshealth.org/parent/medical/digestive/pyloric_stenosis.html |title= Pyloric Stenosis |publisher= The Nemours Foundation |date= November 2007 |last= Dowshen |first= Steven |access-date= 2007-12-30 |url-status= live |archive-url= https://web.archive.org/web/20080112102237/http://www.kidshealth.org/parent/medical/digestive/pyloric_stenosis.html |archive-date= 2008-01-12 }}</ref> It is commonly associated with people of Scandinavian ancestry, and has multifactorial inheritance patterns.<ref name="pmid7333028" /> Pyloric stenosis is more common in Caucasians than Hispanics, Blacks, or Asians. The incidence is 2.4 per 1000 live births in Caucasians, 1.8 in Hispanics, 0.7 in Blacks, and 0.6 in Asians. It is also less common amongst children of mixed race parents.<ref>{{EMedicine|EMERG|397|Pediatrics, Pyloric Stenosis}}</ref>  Caucasian male babies with [[blood type]] B or O are more likely than other types to be affected.<ref name="kh"/>

Infants exposed to [[erythromycin]] are at increased risk for developing hypertrophic pyloric stenosis, especially when the drug is taken around two weeks of life<ref name=Erythromycin>{{cite journal | vauthors = Maheshwai N | title = Are young infants treated with erythromycin at risk for developing hypertrophic pyloric stenosis? | journal = Archives of Disease in Childhood | volume = 92 | issue = 3 | pages = 271–3 | date = March 2007 | pmid = 17337692 | pmc = 2083424 | doi = 10.1136/adc.2006.110007 }}</ref> and possibly in late pregnancy and through breastmilk in the first two weeks of life.<ref name="Kong2013">{{cite journal | vauthors = Kong YL, Tey HL | s2cid = 45531743 | title = Treatment of acne vulgaris during pregnancy and lactation | journal = Drugs | volume = 73 | issue = 8 | pages = 779–87 | date = June 2013 | pmid = 23657872 | doi = 10.1007/s40265-013-0060-0 }}</ref>
{{clear}}

== References ==
{{Reflist}}

== External links ==
* [http://www.nejm.org/doi/full/10.1056/NEJMicm1214572 Peristaltic waves video on NEJM]

{{Medical condition classification and resources
 | DiseasesDB      = 11060
 | DiseasesDB_mult = {{DiseasesDB2|29488}} 
 | ICD10           = {{ICD10|Q|40|0|q|38}}
 | ICD9            = {{ICD9|537.0}}, {{ICD9|750.5}}
 | ICDO            =
 | OMIM            =
 | MedlinePlus     = 000970
 | eMedicineSubj   = emerg
 | eMedicineTopic  = 397
 | eMedicine_mult  = {{eMedicine2|radio|358}}, {{eMedicine2|article|929829}} 
 | MeshID          = D046248
}}
{{Gastroenterology}}
{{Congenital malformations and deformations of digestive system}}

[[Category:Congenital disorders of digestive system]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Stomach disorders]]