What is the normal length of small bowel in a preemie?

After informing a dad that his preemie baby has only 45 cm of small bowel left after surgery for NEC, he asked me a question that caught me off guard.
“So how much should he have at 27 weeks gestation?”
Knowing that the small bowel almost doubles in length at the last trimester, I estimated 100 cm’s but then headed back to the books/PDF files to figure out a more exact answer.

Fortunately, there had been some back and forth emails between two of my attendings about papers that looked into expected bowel lengths for preemies.
Went home, pulled the emails out of my ‘Educational’ folder in ‘Mail’, transferred the PDF’s to my ‘Papers’ software, synced my MBP with my iPad (go paperless!), then read the articles during my 45 post-call spin session.

In the first article (via Dr Philip Glick), by Touloukian et al, the authors measured the length of small bowel obtained from autopsy specimens of 30 babies of various gestational ages. The authors documented the bowel length over three age ranges and noted that the small bowel more than doubled its length during the third trimester. As attractive as this article is in its simplicity, several confounding factors, including the fact that post mortem changes may affect the measured length of bowel, limit the accuracy of these bowel measurements.

In the second article, published more than 30 years later (via Dr Doruk Ozgediz), by Strujis et al, the authors obtained intraoperative measurements of small bowel in 108 patients whose post conceptual age ranged from 24 weeks to 5 years. The authors linked the bowel length to gestational age, weight, and patient length at time of surgery. They noted that all three variables predicted the length of bowel with similar accuracy, and suggested that patient height be used since it is more consistent and easier to measure.

Why is this important? Knowing the expected normal length of bowel in a preemie baby makes estimations of the potential risk of short gut syndrome and other outcomes, after intestinal resection, easier; this helps better council parents. It also helps answer the question: "Well, how much bowel should my baby normally have?”

References:
1. Touloukian RJ, et al. Normal intestinal length in preterm infants. Journal of Pediatric Surgery (1983) 18(6):720
2. Strujis M, et al. Establishing norms for intestinal length in children. Journal of Pediatric Surgery (2009) 44:933