Meconium-related obstruction in preterm infants

There are no RCTs of oral or rectal acetylcysteine for meconium-related obstruction in preterm infants. Several case series [4, 5] and controlled studies [6, 7] have reported variable efficacy of acetylcysteine orally or rectally in preterm infants.

In a retrospective controlled study [6], 132 preterm infants <1250 g with meconium obstruction were given first-line saline rectal irrigations 5–10 mL/kg every 6 hours and metoclopramide 0.1 mg/kg/dose PO or IV every 6 hours. Infants received either oral acetylcysteine 100 mg/kg (10% solution = 1 mL) every 6 hours (n = 34) or rectal enema (1 mL of acetylcysteine 10% [100 mg] added to 9 mL sodium chloride 0.9% ) 5–10 mL/kg every 6 hours (n = 52) or no additional treatment (n = 35). There was a reduction in mean time to resolution of obstruction (12 days oral NAC group; 10 days rectal NAC group; 15 days control group) and full enteral feeding. None of the infants was given a contrast enema. Hospital stay and mortality rate did not differ between groups.

A before and after study [7] reported 6 of 99 infants born <1500 g in the before period had a meconium-associated bowel obstruction with 4 perforated and 6 surgically managed, compared to 18 of 42 (43%) diagnosed with meconium-related bowel obstruction in the after period. Twelve of 18 resolved with sodium chloride 0.9% enemas, whilst the other 6 resolved with acetylcysteine 100 mg/mL (dose not reported) through an orogastric tube and ultrasound guided diatrizoic acid (Gastrografin) enemas. None required surgery. No complications arose relating to the conservative treatment nor were there any bowel perforations.

There are case reports [8-10] of use of acetylcysteine for both gastric and intestinal obstruction with milk curds (lactobezoar) [11]. Successful treatment of gastric lactobezoar was reported using 10 mg/kg/dose of acetylcysteine 10% diluted with 50 mL of sodium chloride 0.9% administered via nasogastric tube over 30 minutes followed by clamping of the nasogastric tube for two hours and repeated 6 hourly up to 7 doses in total [8-10]. A case series reported two extremely preterm infants with intestinal obstruction secondary to human-milk-fortifier-associated curds treated with nasogastrically instilled acetylcysteine and elimination of human milk fortifier [11]. One resolved without surgery whilst the other infant required operative treatment despite nasogastric acetylcysteine and repeated enemas.