PEDIATRIC SURGERY UPDATE ©
VOLUME 02, 1994

VOL 02 NO 01 JANUARY 1994

Fetal Neuroblastoma

Routine use of prenatal sonography will increase the incidental diagnosis of fetal neuroblastoma. Most are detected during the third trimester of pregnancy as cystic/solid suprarenal mass. The tumor does not cross the placenta but can metastize in utero to the fetal liver or placenta. After birth 50% of babies have elevated HMA/VMA levels. Most enjoy improved survival due to: lower stage of disease, cystic variety (in -situ), and higher stage IV-S (which has been associated with spontaneous inmuno-regression. Adverse biologic features are: diploid tumor karyotype (cytometry) and amplify N-myc oncogene. They can be very difficult to differentiate from neonatal adrenal hemorrhage; T2 of MRI can be of help. Are they neuroblastoma in-situ, and will they regress spontaneously without treatment are question waiting answer in the near future.

Prenatal CCAM

Congenital cystic adenomatoid malformation is a lung bud lesion characterize by dysplasia of respiratory epithelium caused by overgrowth of distal bronchiolar tissue. Prenatally diagnosed CCAM prognosis depends on the size of the lung lesion and can cause: mediastinal shift, hypoplasia of normal lung tissue, polyhydramnios, and fetal hydrops (cardiovascular shunt). Classified in two types based on ultrasound findings: macrocystic (lobar, > 5 mm cysts, anechoic, favorable prognosis) and microcystic (diffuse, more solid, echogenic, lethal). Occurs as an isolated (sporadic) event with a low rate of recurrence. Survival depends on histology. Hydrops is caused by vena caval obstruction, heart compression and mediastinal shift. The natural history is that some will decrease in size, while others disappear. Should be follow with serial sonograms. Prenatal management for impending fetal hydrops has consisted of thoraco-amniotic shunts (dislodge, migrate and occlude), and intra-uterine fetal resection (technically feasible, reverses hydrops, allows lung growth). Post- natal management consist of lobectomy.

Fetal Intestinal Obstruction

The fetal gastrointestinal tract (foregut, midgut and hindgut) undergoes ventral folding between 24-28 days' gestation. By the 5- 6th wk the stomach rotates to the right and the duodenum occludes by cell proliferation. Recanalization of the duodenum occurs around the 8th wk. The midgut rotation takes place during the 6-11th wk and the final peritoneal closure by 10th wk. The fetal GI tract begins ingestion and absorption of amniotic fluid by the 14th wk. This fluid contributes to 17% effective nutrition; proximally obstructed gut can cause growth retardation. Fetal intestinal obstruction is caused by: failure of recanalization (duodenal atresia), vascular accidents (intestinal atresias), intrauterine volvulus, intussusception, or intraluminal obstruction (meconium ileus). Esophageal obstruction causes polyhydramnios, absent visible stomach and is related to tracheo-esophageal anomalies. Duodenal obstruction seen as two anechoic cystic masses is associated to aneuploidy (trisomy 21) and polyhydramnios. Jejuno- ileal obstruction produces dilated anechoic (fluid-filled) serpentine masses and bowel diameter of 1-2 cm. Large bowel obstruction is most often caused by meconium ileus, Hirschsprung's disease or imperforate anus. The colon assumes a large diameter and the meconium is seen echogenic during sonography. In general the method of delivery is not changed by the intrauterine diagnosis of intestinal obstruction. Timing can be affected if there is evidence of worsening intestinal ischemia (early delivery recommended after fetal lung maturity).

VOL 02 NO 02 FEBRUARY 1994

Meconium Ileus

Meconium Ileus (MI) is a neonatal intraluminal intestinal obstruction associated with Cystic Fibrosis (10-20%). The distal ileum is packed with an abnormally thick, viscous, inspissated meconium. The meconium has a reduced water content the result of decreased pancreatic enzyme activity and a prolonged small bowel intestinal transit time. MI can be classified as simple or complicated. Simple MI appears in the first 48 hrs of life with abdominal distension and bilious vomiting. Complicated MI is more severe (< 24 hrs) with progressive abdominal distension, respiratory distress, and peritonitis. X-Ray findings are: dilated bowel loops, absent air-fluid levels, "soap-bubble" granular appearance of distal ileum due to a mixture of air with the tenacious meconium. Therapy consists of Gastrografin enema for simple cases: hyperosmolar solution draws fluid to the bowel lumen causing an osmotic diarrhea. Operative therapy is reserved for failed gastrografin attempts and complicated cases (associated to volvulus, atresias, gangrene, perforation or peritonitis). Surgical procedures has included: ileostomy with irrigation, resection with anastomosis, and resection with ileostomy (Mikulicz and Bishop- Koop). Post-operative management includes: 10% acetylcysteine p.o., oral feedings (pregestimil), pancreatic enzyme replacement, and prophylactic pulmonary therapy. Long-term prognosis depends on the degree of severity and progression of cystic fibrosis pulmonary disease.

Alarming Hemangiomas

Hemangioma is the most common tumor of infancy characterized by proliferation of capillary endothelium. Natural history is of rapid post-natal proliferative growth (8-18 mo) to a slow but inevitable regression during the next 5-8 years (involutive phase). Most are small and harmless. Alarming hemangiomas are associated with heart failure and thrombocytopenic coagulopathy (Kasabach-Merritt syndrome). Management consist of: (1) high dose steroids (rate response 30-60%), (2) radiation therapy, (3) surgery, and recently (4) alpha-interferon. Alpha-interferon inhibits the proliferation of endothelial cells, smooth muscle cells and fibroblast. Minimal side effects such as fever, elevation of liver function tests and flu-like syndrome has been reported. It is given subcutaneously, early withdrawal can cause re-growth of the lesion and has been found successful for severe complicating hemangiomas.

CIPO

Chronic Intestinal Pseudo-Obstruction (CIPO) is a rare disorder of intestinal motility in infants and children characterized by recurrent attacks of abdominal pain, distension, vomiting, constipation and weight loss in the absence of obvious mechanical lesions. The disease can be familial or sporadic. Suggested etiology is degeneration of enteric nervous or smooth muscle cells. The diagnosis is based an history, physical exam, radiographies and motility studies. X-Ray hallmarks are: absent strictures, absent, decreased or disorganized intestinal motility, and dilated small/large bowel loops. Associated conditions identified in 10-30% of patients are bladder dysfunction (megacystis) and neurological problems. Histologic pattern portrayed: myenteric plexus hyperplasia, glial cell hyperplasia, and small ganglion cells (hypoganglionosis). Management is primary supportive: intestinal decompression (NG), long-term TPN and antibiotic prophylaxis. Motility agents are unsuccessful. Venting gastrostomy with home parenteral nutrition has shortened the high hospitalization rate associated to this disease process. A similar condition can be seen in early fed prematures due to immaturity of intestinal motility.

VOL 02 NO 03 MARCH 1994

IH in Prematures

The incidence of inguinal hernia(IH) in premature babies (9-11%) is higher than full-term (3-5%), with a dramatic risk of incarceration (30%). Associated to these episodes of incarceration are chances of: gonadal infarction (the undescended testes complicated by a hernia are more vulnerable to vascular compromise and atrophy), bowel obstruction and strangulation. Symptomatic hernia can complicate the clinical course of babies at NICU ill with hyaline membrane, sepsis, NEC and other conditions needing ventilatory support. Repair should be undertaken before hospital discharge to avoid complications. Prematures have: poorly developed respiratory control center, collapsible rib cage, deficient fatigue-resistant muscular fibers in the diaphragm that predispose then to potential life-threatening post-op respiratory complications such as: need of assisted ventilation (most common), apnea and bradycardia, emesis, cyanosis and re-intubation (due to laryngospasm). Independent risk factors associated to this complications are (1) history of RDS/bronchopulmonary dysplasia, (2) history of patent ductus arteriosus, (3) low absolute weight (< 1.5 Kg), and (4) anemia (Hgb < 10 gm- is associated to a higher incidence of post-op apnea). Postconceptual age (sum of intra- and extrauterine life) has been cited as the factor having greatest impact on post-op complications. These observation makes imperative that preemies (with post conceptual age of less than 45 weeks) be carefully monitored in-hospital for at least 24 hours after surgical repair of their hernias. Outpatient repair is safer for those prematures above the 60 wk. of postconceptual age. The very low birth weight infant with symptomatic hernia can benefit from epidural anesthesia.

Warning!

The FDA has recommended labeling changes for the use of anectine (succinylcholine chloride- depolarizing muscle relaxant). Anectine should not be used for routine, elective pediatric surgery. A series of cardiac arrests and deaths (36 cases reported in the last three years) after the use of anectine in children with a previously undiagnosed myopathy has prompted this issue. Children with myopathies have increase sensitivity to succinylcholine developing rhabdomyolysis, hyperkalemia and cardiac arrest (mortality 55%). Healthy children undergoing surgery can have occult forms of myopathy that cannot be known beforehand. Otherwise, anectine is indicated in instances of rapidly securing the airway: emergency intubation, laryngospasm and full stomach.

Splenic Cysts

Splenic cysts in children are either considered true epidermal (congenital), pseudocysts (post-traumatic), or infectious (echinococcus) in etiology. They are rare, benign, solitary cysts often producing few symptoms. They may present as a palpable mass in the left side of the abdomen or during evaluation for another abdominal problem. Ultrasound (large unilocular sonolucent cyst) is the most important diagnostic method, and can be supplemented by CT-Scan. The lining of the cyst is a flattened endothelium surrounded by fibrous tissue. This mesothelium can produced carcinoembryonic antigen (CEA). Indications for surgery are: (1) risk of complications (rupture, bleeding), (2) size greater than 5 cm., (3) infectious etiology, and a (4) symptomatic child (pain, mass or splenomegaly). Their management formerly total splenectomy has changed to: interventional sonography with fluid aspiration (catheter placement), or partial splenic decapsulation (cystectomy); the result of recognition of the physiologic importance (hematologic and immunologic) of the spleen, together with the development of radiological imaging and operative surgery. Long term follow-up with radionuclide scans is recommended.

VOL 02 NO 04 APRIL 1994

Bilateral Cryptorchidism

The undescended testis is the most frequent disorder of male sexual differentiation affecting 0.8% of boys by age one year. The etiology is varied but many cases represent disturbances of the hypothalamic-pituitary-gonadal axis and may represent a forme fruste of hypogonadotrophic hypogonadism. Bilateral cryptorchidism occurs in 10-30% of cases. Management consists of hormonal therapy a/o surgical orchiopexy. Human Chorionic Gonadotropin (HCG) is superior to Gonadotropin Releasing Hormone (GnRH) and placebo in the treatment of bilateral cases, with success rates of 23%. Regression analysis showed treatment is more successful the younger the child; after six months of age medical treatment with LHRH and HCG has produced descent in half managed cases. A recent study in young male rat revealed that the fertility defect is partially prevented by early orchiopexy and adjunctive hormonal therapy is probable of little additional benefit. Infertility is common in patients with history of bilateral cryptorchidism even after successful prepubertal orchiopexies, and azoospermia is present in 18% of bilateral cases pexed as children. Although the undescended testis experience a substantial increase of developing later malignancy, the absolute risk is so small that does not appear to justify special surveillance after surgery. Laparoscopy for the impalpable and bilateral undescended testis is of value to diagnosed testicular absence, identify intra-abdominal testis, and transect vessels for later Stephen-Fowler approach.

Achalasia

Achalasia in children is an uncommon esophageal motor disorder distinguished by clinical, radiological and manometrics features. Incidence is estimated in 0.1 cases/year per 100,000 population under 14 years of age. Clinical presentation is characterized by progressive dysphagia, regurgitation, weight loss, chest pain and nocturnal cough. Infants exhibit failure to thrive. Diagnosis is established by barium swallow and confirmed by manometry and motility studies. Ba swallow shows' esophageal dilatation, motility alteration and a small caliber (bird-beak) cardio-esophageal junction. Manometry reveals elevated E-G sphincter pressure, non- peristaltic esophageal contraction and failed relaxation of lower esophageal sphincter upon swallowing. Videoflouroscopy can be of help in the screening of esophageal motors disorders. Esophageal pneumatic balloon dilatation is not an effective method of treatment in children due to the high rate of recurrence of symptoms. Primary therapy is surgical (Heller's modified esophagomyotomy), and results are similar after a transabdominal or thoracic approach. Many authors favor a concomitant antireflux procedures in these patients. Nifedipine can be of help as a short management in preparation for surgery. Long-term result presents' a connection between achalasia and malignant disease of the esophagus.

Christmas Tree Deformity

This anomaly consists of a proximal high jejunal atresia with the blood supply of the distal jejunum and ileum supplied by the ileocolic and marginal vessels. The small intestine distal to the atresia is coiled in a spiral-like fashion around a rudimentary mesentery similar to an apple-peel or Christmas tree. The etiology is a intrauterine vascular accident (block) after the take off of the first branch of the superior mesenteric artery. Most are premature infants with associated malrotation. Management consist of tapering the proximal jejunum and anastomosing it to the distal bowel peel. Malabsorption can be a post-op problem until the blood supply and intestinal length improves. Parenteral nutrition has improved survival rates of this patients.

VOL 02 NO 05 MAY 1994

IA: Males Decisions

The most important decision in the initial management of Imperforate Anus (IA) male patient during the neonatal period is whether the baby needs a colostomy and/or another kind of urinary diversion procedure to prevent sepsis or metabolic derangements. Male patients will benefit from perineal inspection to check for the presence of a fistula (wait 16-24 hours of life before deciding). During this time start antibiotherapy, decompress the GI tract, do a urinalysis to check for meconium cells, and an ultrasound of abdomen to identify urological associated anomalies. Perineal signs in low malformations that will NOT need a colostomy are: meconium in perineum, bucket-handle defect, anal membrane and anal stenosis. These infants can be managed with a perineal anoplasty during the neonatal period with an excellent prognosis. Meconium in urine shows the pt has a fistula between the rectum and the urinary tract. Flat "bottom" or perineum (lack of intergluteal fold), and absence of anal dimple indicates poor muscles and a rather high malformation needing a colostomy. Patients with no clinical signs at 24 hours of birth will need a invertogram or cross-table lateral film in prone position to decide rectal pouch position. Bowel > 1 cm from skin level will need a colostomy, and bowel < 1 cm from skin can be approach perineally. Those cases with high defect are initially managed with a totally diverting colostomy. Diverting the fecal stream reduces the chances of genito-urinary tract contamination and future damage.

Pyloric Stenosis Revisited

Reviewing 137 consecutive cases of Pyloric Stenosis during a 6.5 year period managed by the author at the region of Bayamon, and dividing the patients into the three most commonly encountered metabolic disturbances: hypochloremia, alkalosis and hypochloremic alkalosis, we found that the most important factor (p< 0.001) determining the probability of developing a metabolic disturbance was age at diagnosis; the older the child the higher the probability of developing hypochloremic alkalosis. Neither age, sex, race, birth weight, gestational age, firstborn, the presence of a palpable pyloric muscle (olive), or the hospital stay showed any association to the metabolic derangements characteristics of this condition. Post-op vomiting(22%) was a self-limiting event which resolved during the first 48 hrs after surgery upon resuming the oral feeding schedule. Persistent vomiting (4%) after myotomy is caused by an associated allergic gastropathy.

Vascular Access: Neonates

Vascular access is indicated to administer fluid, drugs, and nutrients in sick neonates. Peripheral venous cannulation is the initial preferred method. Complications associated to peripheral teflon catheter use are: extravasation with skin loss, phlebitis, and bacterial colonization. Within the first two weeks of life, umbilical vessel cannulation should be considered. Central venous catheter placement should be considered for long term delivery of TPN, antibiotics or venous sampling. Routes of access are: the external jugular veins, facial veins, internal jugular veins, the saphenous veins and the subclavian veins. Catheters are of silastic material (Broviac) or polyurethane. Complications associated to central vein catheters are:(1)sepsis- most common and serious, no other source of infection and positive blood culture. They are associated to fibrin sheath formation and thrombosis within the catheter. Most are managed with antibiotics, for fungi- catheter must be removed. (2) Mechanical- dislocation, occlusion, and breakage. (3) thrombosis- the result of hypercoagulability.

VOL 02 NO 06 JUNE 1994

IPBD

Idiopathic Perforation of the Bile Ducts (IPBD) is the second most common cause of surgical jaundice restricted to the first three months of life (biliary atresia is first). The pathogenesis is unknown, most attractive theory is faulty embryogenic malformation of common bile duct associated to distal mechanical obstruction (sludge, stenosis, etc.). Most perforations occur at the junction of the cystic duct with the common bile duct. The infant presents an indolent course of jaundice, acholic stools, choluria, failure to thrive, and progressive abdominal distension most commonly. Less frequently the clinical course is acute with peritonitis and systemic signs of sepsis. Bilious ascites (localized) is the hallmark finding and is pathognomonic of IPBD in this age group. Ultrasound shows loculated ascitic fluid in porta hepatis and can help to guide diagnostic paracentesis (bile fluid). DISIDA scan confirms the diagnosis showing extravasation of isotope to the peritoneum. Management is surgical (medical tx is fatal), consist of intraoperative diagnostic cholangiography, tube cholecystostomy for follow-up, penrose drainage of porta hepatis, systemic antibiotics and TPN. Most perforations seal by 2-3 wk., the drains can be removed when tube cholangiogram shows a patent biliary tree. Prognosis is excellent with absent hepato-biliary long-term sequelae.

Hypothermia

Human beings are homeothermic organisms because of thermoregulation. This equilibrium is maintained by a delicate balance between heat produced and heal lost. Heat production mechanisms are: voluntary muscle activity increasing metabolic demands, involuntary muscle activity (shivering) and non-shivering (metabolizing brown fat). Heat loss occurs from heat flow from center of the body to the surface and from the surface to the environment by evaporation, conduction, convection and radiation. There is an association between hypothermia and mortality in the NICU's. The surgical neonate is prone to hypothermia. Below the 35 degrees centigrade the newborn experiences lassitude, depressed respiration, bradycardia, metabolic acidosis, hypoglycemia, hyperkalemia, elevated BUN and oliguria (neonatal cold injury syndrome). Factors that precipitate further these problems are: prematurity, prolonged surgery, and eviscerated bowel (gastroschisis).

IA: Female Concepts

The most frequent defect in females patient with imperforate anus (IA) is vestibular fistula, followed by vaginal fistulas. In more than 90% of females cases perineal inspection will confirm the diagnosis. These infants require a colostomy before final corrective surgery. The colostomy can be done electively before discharge from the nursery while the GI tract is decompressed by dilatation of the fistulous tract. A single orifice is diagnostic of a persistent cloacal defect usually accompany with a small- looking genitalia. Cloacas are associated to distended vaginas (hydrocolpos) and urologic malformations. This makes a sonogram of abdomen very important in the initial management of these babies for screening of obstructive uropathy (hydronephrosis and hydroureter). Hydrocolpos can cause compressive obstruction of the bladder trigone and interfere with ureteral drainage. Failure to gain weight and frequents episodes of urinary tract infections shows a poorly drained urologic system. A colostomy in cloacas is indicated. 10% of babies will not pass meconium and will develop progressive abdominal distension. Radiological evaluation will be of help along with a diverting colostomy in this cases. Perineal fistulas can be managed with cutback without colostomy during the neonatal period.