Characterization of anorectal pressure and the anorectal inhibitory reflexin healthy preterm and term infants

Objectives: To evaluate anorectal motor function in healthy premature and t erm infants with the use of micromanometric techniques. Study design: Anorectal manometry vas performed in 22 healthy neonates (9 f emale) with a mean postmenstrual age of 32 weeks (range, 30 to 38 weeks) wi th a micromanometric anorectal assembly (od 2.0 mm). The assembly incorpora ted a 2-cm-long sleeve sensor for measurement of resting anal sphincter pre ssures and relaxation, and 4 sideholes recorded anal and rectal pressures. Rectal distension was performed with a latex balloon or direct air insuffla tion to elicit the anorectal inhibitory reflex (AR). Results: The mean anal sphincter pressure, rectal pressure, and rhythmic wa ve frequency were 40 mm fig (range, 7 to 65 mm Hg), 11 mm Hg (range, 1 to 2 7 mm Hg), and 10/min (range, 8 to 14/min), respectively. A normal AR could be elicited in 21 of the 22 infants studied. Conclusion: An anorectal micromanometric sleeve catheter is suitable for us e in evaluating anorectal pressures in preterm and term neonates. Insufflat ion of air without the use of a balloon to elicit the AR is reliable and su itable for use in infants <34 weeks. Premature infants older than 30 weeks' postmenstrual age have normal anorectal pressures and a normal AR.