Ans. b. Intussusception (Ref; Ghai 8/e p287; Sabiston 19/e p1851; Schwartz 9/e p1433-I434; Bailey 26/e 1184. 1187, 1193. 25/e p1191, 1196. 1198; Shackelford 7/e p1059-106)Most likely diagnosis in a 6 months old child, who woke up in night, crying with abdominal pain, which got relieved on passing red stool, is intussusception.'Intussusception refers to the telescoping of a proximal segment of intestine (intussusceptum) into a distal segment (intussuscipiens). This is a common cause of intestinal obstruction in children between 3 months and 6 years. Most cases occur in infants during the weaning period following introduction of a new food, vaccination or upper respiratory tract infection. The classic triad of abdominal pain, red current jelly stools (blood and mucus) and palpable mass is seen only in a small percentage of children. Ultrasound is the investigation of choice that confirms the diagnosis ('dough nut' sign) and provides information about presence of a mass as lead point. Early reduction either with saline (under ultrasound guidance), barium contrast (both diagnostic and therapeutic) or with air insufflation is advisable. Reduction with air is safer with lower recurrence rates. Failure of radiological reduction or suspected intestinal gangrene may necessitate surgery and resection.'- Ghai 8/e p287IntussusceptionTelescoping of one portion of the intestine into the other.Middle layer is isolated between two sharp bends and first to become gangrenousQ.Highest incidence between 4 and 10 monthsQ of ageApprox. 80-90% of cases occurs between 3 and 36 monthsQ.Mostly idiopathic in infants and toddlersQ (no clear etiology).MC type: IleocolicQEtiology and Predisposing Factors:Upper respiratory tract infections or gastroenteritisQ (adenovirus and rotavirus have been implicated) have been thought to be contributory to the development of 'idiopathic' intussusception. Hypertrophy of Peyer's patchesQ can be seen at surgery, but no single etiologic factor predominates.Approximately 5-10% of cases have a true pathologic lead point. The older the toddler, the more likely there will be a lead pointQ.MC lead point is Meckel's diverticulumQ.Other lead points include polyps, the appendix, intestinal duplication, foreign bodies, and tumors such as hamartomas associated with Peutz-Jeghers syndrome.Henoch-Schonlein purpura: Submucosal hemorrhage acts as a lead pointQ.Cystic fibrosis: Risk for recurrent intussusceptionQClinical Features:Typical history: Sudden, short-duration, cyclic crampy abdominal painQ.During these episodes the infant cries inconsolably with the knees drawn upQ.Between episodes the infant is asymptomaticQ.Vomiting is almost universalQ.Initially the passage of stools may be normal while later on blood mixed with mucus is evacuated- red currant jelly stool.An abdominal mass may be palpated- a sausage shaped abdominal massQ (increase in size and firmness during the paroxysm of pain)There may be an associated feeling of emptiness in the right iliac fossa (Sign of Dance)QOccult or gross blood in 60-90% of cases on rectal examinationQApex may be palpable or even protrude from anus in extensive ileocolic or colocoiic intussusceptionQDiagnosis:USG: Kidney-shaped mass in the longitudinal view or a target sign in the transverse viewHydrostatic reduction by contrast agent or air enema (preferred) is the diagnostic and therapeutic procedure of choiceQ.Successful reduction is confirmed by reflux of airQ (or barium) into the small bowel.Treatment:Hydrostatic reduction by contrast agent or air enema is the diagnostic and therapeutic procedure of choiceQ.The success rate with air or barium reduction should exceed 70%Q.Failure of reduction or the presence of peritonitis mandates operative interventionQ, which can be performed laparoscopically or by a standard approach.Definitive surgical procedure: Ileocolectomy with primary anastomosisQRecurrence:Recurrence after successful hydrostatic reduction is 5-10%, recurrence rate after operative reduction is 1-4%.Recurrence is usually managed by hydrostatic reductionQ.Third recurrenceQ is an indication for operative intervention to look for a lead point.