Neonatal Appendicitis: A Case for Early Diagnosis?
Neonatal appendicitis is extremely uncommon with scant case reports. Preoperative clinical diagnosis is difficult in newborns where peritonitis is consequent to a variety of aetiologies. Localising signs like wall oedema, tenderness and a lump could possibly be thought of as appendicitis if there is high index of suspicion. One such case is presented here and literature reviewed.
Acute appendicitis is extremely rare in occurrence in the newborn period with less than 141 cases collected over a century. Subsequent literature review has infrequent case reports given the fact that certain peculiar features in the neonate make the appendix less prone for inflammation. The clinical features are elusive, common to any peritonitis in newborn period whereas failure to consider this in the differential diagnosis carries a very high morbidity and mortality.[2-4] High index of suspicion can lead to early surgical exploration coupled with advances in neonatal care with excellent outcome.
A 14-day-old male neonate born preterm at 34 weeks gestation by lower segment caesarean section (LSCS) presented with bilious vomiting of one day duration. He was admitted for observation and developed persistent vomiting and abdominal distension within 24 hours. He refused feeds, became tachypneic, hypothermic, and showed signs of shock. He was on formula feeds and had passed pellet-like stools. He had right lower quadrant swelling, and abdominal wall erythema noted on inspection and, tenderness and a tender lump on palpation.
Lab investigations revealed a white blood cell count of 18,000 per cubic mm with 80% neutrophils and normal platelet counts. Serum bilirubin was 10.4 mg/dl and electrolytes were normal. The c-reactive protein (CRP) was more than 120 mg/L. Plain x-ray showed haziness in the right lower quadrant with distended small bowel loops with few fluid levels (Figure 1). Faecal pellets were also seen in the colon. The abdominal ultrasound showed dilated small bowel loops with free echogenic peritoneal fluid suggesting perforative peritonitis.
Provisionally diagnosed as appendicitis due to abdominal wall oedema in the right lower quadrant with an underlying lump, the neonate required haemodynamic stabilisation and initial treatment. Exploratory laparotomy was performed through a supraumbilical transverse incision to ascertain the cause of peritonitis. Peritoneum had free thick, yellow exudate without any perforation and the ileal loops were adherent to each other with flimsy fibrinopurulent flakes which were separated (Figures 2 and 3). The appendix was retrocaecal, kinked, inflamed, and with retroperitoneal oedema. The appendix was dissected and appendicectomy performed.
The culture came back positive for coagulase-positive methicillin resistant staphylococcus (MRSA) strains which were sensitive to clindamycin. The patient had an uneventful recovery and is thriving well at the one year follow up. The histopathology confirmed peri appendicitis with transmural infiltration of neutrophils with an intraluminal faecal pellet. Ganglion cells were normal.
Acute appendicitis features amongst the rarest causes of acute intra-abdominal sepsis in the neonates carrying a very high mortality in undiagnosed cases ranging between 20% and 25%. Less than 141 cases collected over a century, and only 52 cases reported between 1990 and 2014, with an overall incidence of neonatal appendicitis (NA) reported as 0.04-0.2%. Deiss described the first case of neonatal appendicitis in 1908 however, the first survivor of abdominal disease was reported 45 years later by Meigher and Lucas in 1952. Most often the diagnosis was established retrospectively after surgical exploration.[5-11]
Low incidence of neonatal appendicitis is because many of the risk factors operating in grown-ups are absent in newborns. Though obstruction of the base of appendix is the prime precursor in the cascade of events, recumbence of the newborn, funnel shape of foetal appendix, lack of pellet-like residue in breast-fed infants, and uncommon lymphoid hyperplasia secondary to viral infections, make the appendix least likely to be infected in neonates.
Abdominal distension, vomiting, abdominal tenderness, restlessness or lethargy, and fever were the most common symptoms in the published reports. Being non-specific they may not give any clue to the clinical diagnosis. Alternately, a thin appendicular wall and a small omentum is not enough to wall off infection, as well as a small abdominal cavity makes inflammation prone for perforation and peritonitis with high mortality. Localized oedema and erythema and tenderness point to appendicular abscess or a walled off perforation, however of the 35% neonates with one or more of these signs only 3 of them were correctly diagnosed prior to laparotomy.
A high index of suspicion is needed for prompt diagnosis of this rare cause of acute abdomen in neonates. In the reviewed literature, clinical signs and symptoms like refusal of feeds, irritability, lethargy, along with leucocytosis coupled with radiological evidence of pneumatosis and free intra-abdominal gas may provide a clue to the diagnosis.[6-11]
Incidentally NA may occur secondary to other complex causes like Hirschsprung’s disease, cystic fibrosis and necrotizing enterocolitits (NEC). Isolated NA is still rare and more perturbing as the clinical features are indistinguishable. Admittedly these signs occurring exclusively indicate appendicitis rather than peritonitis due to NEC.
Martin and Perrin suggested that obstruction caused by Hirschsprung’s disease could play a role in the pathogenesis however only 4 cases of Hirschsprung’s disease co-existing with inflamed appendix in 52 cases reported from 2000 to 2014. Peri appendicitis without transmural infiltration of neutrophils is said to be characteristic of appendicular perforation due to congenital megacolon. Majority of published reports do not carry the histology to substantiate the significance. Neonatal appendicitis could be a limited form of necrotizing enterocolitis as more than 50% of infants with appendicitis were preterm. Signs of perforated appendix such as flank erythema or oedema, palpable mass and tenderness are also seen in necrotising enterocolitis but when present in term infants indicate appendicitis rather than necrotising enterocolitis.
Etiological role of obstruction due to pellet-like stool of cystic fibrosis and meconium ileus has been contemplated but is yet to be proved. Since the present case was on formula feeds and had pellet-like stools, it could have caused luminal obstruction causing inflammation.
Mortality of neonatal appendicitis has reduced considerably owing to rapid advances in antibiotic therapy, neonatal intensive care, and diagnostic modalities but ranges between 20% and 25%.[6,9] The main cause for the high incidence of perforation and consequently the high mortality rate was the difficulty in establishing the diagnosis in a neonate presenting with nonspecific symptoms such as vomiting, irritability, refusal to feed and abdominal distension. Ancillary investigations, apart from identifying the organism responsible for septicaemia when present are of little value in establishing the precise preoperative diagnosis. The diagnosis is usually made at laparotomy and with histopathology.
The rarity of neonatal appendicitis together with a lack of specific signs and low index of suspicion has led to a delay in diagnosis leading to a high mortality. Early perforation due to fragility of neonatal appendix which is poorly walled off from infection due to an underdeveloped omentum along with the immature immune system in neonates could be the contributing factors to high mortality. A high index of suspicion and early exploration is the only treatment in the current era of advanced neonatal care.
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