DELAYED STOOLING IN NEONATES Shruti Patel, MSIII UNSOM
DELAYED STOOLING IN NEONATES Shruti Patel, MSIII UNSOM Normal Passage Healthy full term infants 99% pass meconium within 24 hours of birth 100% pass meconium within 48 hours of birth Preterm infants 37% pass within 24 hours 99% pass within the 9th day after birth Clinical Presentation Failure to pass meconium in a timely fashion Abdominal distention Refusal to feed Bilious vomitting Palpable distended loops of bowel Case A 3,480 g (7 lb, 7 oz) male infant was born after 40 weeks' gestation to a 27 yo G2P1 mother via NSVD . There were no complications during the pregnancy and delivery. He did not pass meconium in the first 24 hours and had the onset of vomiting on the first day. His abdomen became mildly distended. The infant was not able to feed, and abdominal distention increased by day 2. Case Rectal examination revealed a tight anus. On the second day, flat and upright abdominal films demonstrated numerous loops of dilated bowel. Barium enema radiographic examination showed that most of the dilated bowel was colon. Differential Hirschsprung's disease Meconium plug syndrome Meconium ileus Anorectal malformation Small left colon syndrome Iatrogenic Hypoganglionosis Neuronal intestinal dysplasia type A Neuronal intestinal dysplasia type B Megacystis-microcolon-intestinal hypoperistalsis syndrome Hirschsprung's Disease Congenital aganglionic megacolon Incidence : 1 out of 4000 live births; 20-25% cases of neonatal bowel obstruction Males: Female = 4:1 8% also have Down Syndrome Eight genetic mutations identified: most common – RET proto-oncogene Also associated with MEN2, anomalies of kidneys and urinary tract, congenital heart disease and other genetic disorders Pathophysiology Defect in craniocaudal migration of neural crest cells to innervate the large intestine during first 12 weeks of gestation Distal portion of the colon lacks network of nerves: Auerbach’s and Meissner’s plexus Affected segment cannot relax and pass stool through Most often involves the rectosigmoid and internal anal sphincter Clinical Presentation Failure to pass meconium in first few days of life Abdominal distention, refusal to feed, vomitting Passage of meconium plug followed by sparse BM Anus and rectum narrow and empty of stool explosive expulsion of gas and stool after the digital rectal examination (squirt sign or blast sign) Complications Enterocolitis Potentially life threatening Due to proliferation of bacteria due to stasis Sepsis like presentation Fever, vomitting, diarrhea, GI bleeding Can progress to toxic megacolon fluid resuscitation, intravenous antibiotic therapy, rectal irrigations, emergency colostomy. Volvulus Rare complication Sigmoid colon ; less common involvement of transverse colon Diagnosis Rectal Biopsy Gold standard Diagnosis established if ganglion cells absent Abdominal Radiographs Distal intestinal obstruction Dilated bowel loops proximal to aganglionic region Contrast Enema: Cone shaped transition zone Anorectal Manometry Useful when segment involved is ultrashort Relaxation of int. anal sphincter w/ distention of rectum excludes HD. - rectosphinteric reflex Treatment/Outcome Surgical resection of affected segment Bring normal ganglionic bowel down to anus Anal dilatations Long term Complications: Constipation Fecal incontinence Enterocolitis Occurs within 1st year post-op Major cause of morbidity and mortality Increased risk in long-segment disease Meconium Plug Syndrome Mild and transient functional distal obstruction Inspissated immobile meconium Unclear etiology Incidence : 1/500-1000 live births Delayed passage of meconium > 24-48 hrs Intestinal dilation Diagnosis/Treatment Plain abd. radiograph: Gaseous distention of intestinal loops without fluid levels Contrast Enema: Both diagnostic and therapeutic Rectal Stimulation: Thermometer or digital rectal exam Normal BM after the plug is passed. All symptoms resolve* Meconium Ileus Obstruction at the level of terminal ileum with inspissated meconium 30% of intestinal obstruction cases 50% of ML patients with undamaged gut 50% associated with volvulus, atresia, perforation 15% of CF present with MI 80-90% with FT infants with MI have Cystic Fibrosis Clinical Presentation Within first three days Failure to pass meconium Abdominal distention present at birth As air swallowed, within hours, increases distention bile stained vomit Massive distention, abdominal tenderness or abdominal erythema complications Complex: perforation, peritonitis, atresia, volvulus; 40% of CF is complex Simple: If no associated GI pathology Diagnosis Stabilized w/ nastograstric decompression and correction of fluid and electrolyte abnormalities Radiography w/ contrast enema: Diagnostic Reveals microcolon and meconium pellets in the terminal ileum “Ground-glass” appearance Calcifications, large air-fluid levels indicated complications Contraindicated if evidence of perforation Treatment Simple Meconium Ileus Administration of diatrizoate meglumine (Gastrografin) enema Hyperosmolar enema breaks up meconium plug: 16-50% success rate Intravenous fluids Surgical evacuation of meconium if enema unsuccessful Complex Meconium Ileus Perforation, peritonitis, atresia require immediate surgery Resection, intestinal anastomosis, and ileostomy Anorectal Malformations Incidence: 1/4000-8000 Failure of the complex embryological development involving intestinal tract and geritourinary structures Anal Stenosis 20% of anorectal malformations Anus is very small and tight Central black dot of meconium present Ribbon-like stools passed after intense straining Treatment: Anal Dilatation Repeated for several months Anal Atresia Imperforate or absent anus with or without fistulas Equal incidence in males and females High: Rectum ends above the levator muscle Often presents with fistula ending in prostatic urethra or vagina Low: Rectum partially descends through the levator muscle Well formed sacrum and prominent anal dimple Cutaneous fistula anterior to external anal sphincter near scrotum or vulva - mistaken for anus Associated Anomalies 50-70% have urologic or other anomalies present Verterbral defects Anal atresia Cardiac defects Transesophageal fistula Esophageal atresia Renal defects Radial upper Limb hypoplasia Diagnosis Easy to detect on physical exam Radiograph w/ Barium enema X-ray: anatomical location of the malformations, also detect spine and sacrum abnormalities Ultrasound: abnormal anchoring of spinal cord Echocardiogram: screen for heart defects MRI: Definite diagnosis of spinal and pelvic abnormalities Treatment Surgical correction To preserve bowel, urinary, and sexual function High anal atresia Fistulas: gently dilated to allow gas and meconium to pass Colostomy Low anal atresia Corrected electively when condition stable Small Left Colon Syndrome Functional distal bowel obstruction Transient dysmotility in the descending colon >50% - born to diabetic mothers Resolves spontaneously Not related to meconium inspissation or aganglionosis Abdominal distention, bilious vomitting, failure to pass meconium within 24 hrs Diagnosis & Treatment Abdominal radiograph: Contrast Enema: Normal caliber rectum Small caliber sigmoid and descending colon Abrupt transition zone at the splenic flexure Distended loops of bowel with air-fluid levels Diagnostic and therapeutic Spontaenous passage of meconium with symptom resolution Suction rectal biopsy and CF workup Always done to r/o other diagnosis Other Causes Maternal medications/drugs Illicit drugs Magnesium sulfate Ganglionic blocking agents Neonatal medical conditions Hypothyroidism Hypercalcemia Hypokalemia Sepsis CHF Other Causes Hypoganglionosis Symptoms and radiologic findings similar to Hirschsprung’s disease – often co-exist Reduced number of ganglion cells Neuronal Intestinal Dysplasia hypoplasia of the sympathetic innervation of the myenteric plexus and mucosa mucosal inflammation. Megacystis-microcolon-intestinal hypoperistalsis syndrome (rare) Small bowel shortened and dilated; colon is microcolon Megaureters and megacystis Case The surgeon performed an anal dilatation, and the infant subsequently passed gas and meconium, which was followed by resolution of all symptoms. After discharge from the hospital, the infant's mother continued performing periodic anal dilatation because he had difficulties moving his bowel. Digital rectal examination by the physician when the infant was five weeks of age revealed a tight anus and liquid stool but no impaction. One week later, the mother noticed a bloody ring around his bowel movements. Barium enema radiographic examination at this time showed a transition zone in the distal portion of the sigmoid colon, with marked dilatation of the descending colon and left side of the transverse colon . Anorectal manometry showed an absent rectosphincteric reflex. No ganglion cells were seen in the rectal biopsy. These findings were consistent with Hirschsprung's disease. References Loening-Baucke V, Kimura K. Failure to Pass Meconium: Diagnosing Neonatal Intestinal Obstruction. Am Fam Physician. 1999 Nov 1;60(7):2043-2050. Parisi MA. Hirschsprung disease overview. GeneReviews [Internet] 2002 (revised 2011). Available at: http://www.ncbi.nlm.nih.gov/books/NBK1439/ Eggermont E, De Boeck K. Small-intestinal abnormalities in cystic fibrosis patients. Eur J Pediatr 1991; 150:824. Yang J, Cummings EA, O'connell C, Jangaard K. Fetal and neonatal outcomes of diabetic pregnancies. Obstet Gynecol 2006; 108:644. Ellis H, Kumar R, Kostyrka B. Neonatal small left colon syndrome in the offspring of diabetic mothers-an analysis of 105 children. J Pediatr Surg. 2009;44(12):2343
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