A newborn infant with abdominal mass

Prepared by......... Nuthapong Ukarapol, M.D., Somporn Chotinaruemol, M.D.

CC : A term newborn baby with abdominal mass
PI : A female term AGA newborn was referred for evaluating of abdominal mass. She is now 10 days old. Since birth, an abdominal mass was detected. The patient passed meconium once within 24 hours, since then, there has been no record of passing stools. However, there was no problem with urination. She later on, developed feeding problems with billous vomiting. A nasogastric tube was placed into the stomach and she was kept "NPO" since then. Parenteral nutrition has been introduced for the past 5 days. Four days before the referal, while on parenteral nutrition, she developed fever an episode of fever which later subsied with ampicillin and gentamicin. She was then referred to CMU hospital for investigating of the abdominal mass. ( the result of Hemoculture: Klebsiella pneumoniae )

Physical examination
A female newborn, looks alert, BW 2700 g, Length 48 cm., Head circumference 43 cm.
Vital signs: Temp 37, HR 150/min, RR 55/min, BP 68/44 mmHg
Abdomen: normal bowel sound, distension, an ill-defined cystic mass (approximately 10 cm in diameter)is palpated at right side abdomen. The surface is smooth. There is no tenderness. The mass is fixed. Bimanual palpation is questionable. Otherwise: normal
Problems:

Abdominal mass
Clinical manifestations of bowel obstruction
A history of Klebsiella pneumoniae bacteremia (possibly complication from parenteral nutrition v.s. intraperitoneal infection)

Laboratory investigations:

CBC: Hb 10.5 gm/dl Hct 32.8% WBC13,900/cumm (N59, L38, Mono3) Platelet 14,000/cumm
UA: normal, BUN 30 mg/dl, Cr 0.4 mg/dl, Na 135 mEq/L, K 2.8 mEq/L, Cl 102 mEq/L, TCO2 17 mEq/L
LFTs: albumin/globulin 2.6/2 gm/dl, alkaline phosphatase 191 IU/L, cholesterol 102 mg/dl, AST/ALT 23/15 IU/L, TB/DB 18.95/12.54 mg/dl, PT13.9 (10.5 sec), PTT 57.1 (32.9 sec)

Fig1: There is a soft tissue mass occupying right side abdomen with evidence of dilated small bowel, consistent with mechanical obstruction. Fig 2: A chest film reveals an air density over the liver, consistent with pneumoperitoneum. Lung parenchyma appears normal. Fig 3: An abdominal ultrasonography demonstrate a cystic mass containing thick fibrin contents in the right side abdomen.
Discussion 1:
What are the differential diagnoses, regarding abdominal mass in the newborn infant?
Abdominal masses in the newborn:
1. Renal masses (55%): hydronephrosis, multicystic dysplastic kidney, polycystic kidney, Mesoblastic nephroma/Wilm's tumor, renal vein thrombosis, renal ectopia
2. Genital masses (15%): hydrometrocolpos, ovarian cyst
3. GI masses (15%): duplications, obstruction, mesenteric/omental cyst, splenic hematoma/cyst, meconium peritonitis
4. Hepatobiliary (5%): liver cyst, liver tumor, choledochal cyst, hydrops of gall bladder, neuroblastoma (metastasis)
5. Retroperitoneal masses (5%): lymphangioma, extra-adrenal neuroblastoma, anterior meningocele, teratoma, rhabdomyosarcoma
6. Adrenal masses (5%): neuroblastoma, adrenal hemorrhage
Progression:

Due to there was evidence of bowel perforation and peritonitis, exploratory laparotomy was performed. The operative findings showed evidence of small bowel obstruction from ileal atresia and meconium peritonitis. Peritoneal decontamination and ileostomy were done.

Discussion 2:
What is the cause of meconium peritonitis?
How to manage a newborn with meconium peritonitis?
The most common cause of meconium peritonitis is underlying GI obstrunction, particularly ileal atresia. However, in Caucasians, 10-20% of this condition may be an early manifestation of cystic fibrosis, in which thick viscous meconium obstructs in the terminal ileum. The clinical spectrum of meconium ileus can present as simple or complicated (e.g. bowel perforation and sepsis). Physical examination will reveal a large cystic abdominal mass if bowel perforation has occurred prenatally. Sometimes, an abdominal radiograph may show the calcified extraluminal meconium, which implies antenatal bowel perforation.
To differentiate between anatomical obstruction and meconium ileus, barium enema might be helpful. In uncomplicated case, this measure, using hyperosmolar water-soluble contrast, can also a therapeutic option. However, complication rate (perforation) is also as high as 11%.
Surgical management is an option for the patients with bowel perforation and obstruction. Before operation, the patient should be stabilized with fluids, electrolytes, antibiotics, and bowel decompression. The goals of operation are debridement of nonviable tissue, relief of obstruction, and reconstitution of intestinal continuity if possible. Bowel and peritoneal surface will be very inflamed and friable, and acute blood loss and ongoing bleeding are important considerations.
Discussion 3:
Meconium ileus vs. meconium plug syndrome?
 
Meconium plug syndrome
Meconium ileus
Location distal colon distal small bowel
Pathophysiology decreased colonic motility increased viscosity of meconium/anatomical obstruction
Predisposting factors preterm, magnesium intoxication, hypoglycemia, infants of diabetic mothers, Hirschsprung's disease, cystic fibrosis Anatomical obstruction e.g. ileal atresia, cystic fibrosis
Outcome better worse
Suggested reading:
1. Kays DW. Surgical conditions of neonatal intestinal tract. Clinics in Perinatology 1996;23:353-77.
2. Schwartz MZ, Shaul DB. Abdominal masses in the newborn. Pediatr Rev 1989;11:172-9.

Final Diagnosis :Meconium peritonitis

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