SRB has proven to be a valuable diagnosing technique of HD since its recording in 1965, especially for its high accuracy and minimal invasion. It has been proved that the sensitivity and specificity of SRB are 96.8% and 99.4% in some systematic reviews in recent years . Most clinicians will suggest preterm patients who are suspected of HD to not perform SRB until reaching term-corrected age or gain more weight. The sensitivity and specificity of SRB on term-corrected infants ranged from 46–100% and 97–100% [10–12]. It has been confirmed that the intestinal wall muscle layer will increase with age, and the intestinal wall of preterm infants were thinner than term infants. Therefore, in theory, the risk of bowel perforation in preterm infants undergoing rectal biopsy is greater than that of full-term or older children. But D.R.Halleran et. review the RSB of PHD in their institute believed that suction rectal biopsy can be performed safely in preterm infants as small as 1590–2000 g with high accuracy. Clinicians should not hesitate to perform a biopsy for a premature infant when clinically appropriate . In our cases, there were 10 patients who were less than 37 gestational weeks at the time of biopsy. The biopsy results suggested HD in 4 of them and was confirmed after the surgery. Among the rest, 5 were cured with appropriate treatment in each case and well developed till now. There were 35 patients who were older than 37 gestational weeks at the time of biopsy. Eleven of them had HD that were verified in surgery. The rest 24 cases were cured with appropriate treatment and well developed till now. Then the sensitivity of SRB was 93.7–100%, and specificity was 100% in our cohort.
We have 16 preterm infants whose biopsy weights were less than 2500 g, while 5 cases less than 2000 g. The youngest baby was 31.5 weeks whose biopsy age was 33.5 weeks while biopsy weight was 1580 g. The biopsy result of him was normal. All of the cases had no complications after RSB. This study demonstrates that the diagnosis of PHD can be made reliably. Because most premature infants have delayed feces which is similar symptom to the manifestations of HD, it’s difficult to distinguish them. The accuracy of contrast was lower in younger HD while the risk of NEC maybe rose. From our case, the safety and accuracy of RSB in late preterm infants are high. Early diagnosis can provide the best treatment for children in a targeted manner.
But it is worth noting that the premature infants may have poor clinical conditions because of its hypoplasia. In this research, we focus on the gastrointestinal symptoms and RSB and omit other conditions, especially those affecting the time of the performing. This may be one of the reasons why we have a small cohort. But from this study we consider that RSB is safe and accurate on premature babies their biopsy age were more than 37 weeks. Of course, more cases are needed draw a correct conclusion. The performer needs to evaluate the conditions of the preterm. Bedside rectal suction biopsy is not recommended worldwide for premature infants less than 32 weeks old, especially with a body weight of < 1500 g.
In addition, an experienced pathologist is very important. Immature ganglion cells may not be perceived since the biopsy result depends on the entire process from material extraction, sectioning, staining, etc. Even if our clinicians obtain satisfied specimens (at least 3 mm diameter and a minimum of one-third of the sample should include the submucosa according to the International Working Group of the 2009 World Congress of Gastroenterology), biopsies do not have ganglion cells on every slide. The experience from our hospital’s pathologists was that about 13–15 slides were made from each tissue while some needs to be continuously sliced or continuously sliced repeatedly according to the specimens. At the same time, calretinin immunohistochemical stain was performed. When the nucleus and cytoplasm were positive, it was identified as ganglion cells. However, the dysplastic ganglion cells are less typical than normal ganglion cells in staining effect, while there is no uniform definition of development stages of ganglion cell in the world, such as cell size and nucleoplasm morphology. An experienced pathologist has higher accuracy in identifying those cells. According to the follow-ups of our cases, the pathological results are consistent with the clinical outcomes.
These results suggest that RSB is safe and accurate for late preterm infants. As for the premature infants’ various clinical symptoms, the timing of biopsy still needs to be decided by clinicians.