In HSCR, the lack of ganglion cells seen in microscopic level is always followed by morphological changes seen macroscopically, mainly differentiated after the third month of life in narrowed AGS, funnel shape hypo ganglionic segment (TZ) and dilated NGS. Surgical management of HSCR consists of resection of the AGS and TZ determined from contrast enema preoperatively (11). However, significant differences have been described between TZ determined in contrast enema and that found intraoperatively by FSB (12). Frongia et al. reported 94.4% concordance of contrast enema with the histologically assessed TZ in those with rectosigmoid HSCR, but only 50% in those with long-segment HSCR (3). Also, contrast enema can be challenging, especially in newborns, in ultra-short HSCR and in those with TCA, in whom the colon can appear normal in caliber (13)(14). Thus, intraoperative confirmation by FSB of the presence of ganglion cells and non-hypertrophied nerve fibers is needed for determining of the level of resection (5)(15). Many pediatric surgeons resect also dilated segment in order to avoid difficulties in performing the anastomosis and problems related to the dysmotility of the dilated segment. Examination of samples from FSB has potential for technical errors (tissue handling and freezing artifacts mainly) and increased cost and time. Also, it is not always available particularly in resource-limited settings. Most studies had confirmed that the length of TZ varies but is most frequently ≤ to 5 cm in the recto-sigmoid HSCR (16)(17), in rare cases it can be longer than 15 cm showing hypoganglionosis in longitudinal antimesenteric aspect due to an irregular distribution of ganglion cells in transition zone (18). In our study, level of resection in the NGS was determined only by macroscopic assessment intraoperatively. Accuracy of this evaluation was confirmed postoperatively by confirming the presence of ganglion cells and non-hypertrophied nerve fibers in all resections in at least 5 cm distally from the resection margins respectively 5 cm above the TZ, a conclusion that was announced from previous researches also (4)(19). However, how safe is predicting the level of resection without HP confirmation from the FSB. Thakkar H. et all, stated that not all surgeons await a frozen section review of the proximal donut prior to completing the pull-through (20). In 10 of 123 cases resection was done in TZ in study of Beltman L. et all, in which surgeon’s intraoperative judgement was used for the determination of the correct level of resection considering dilated segment above TZ the level where healthy bowel was expected to do the first FSB (21). Also, in a study of Saad S. et all, resection was made 5–10 cm above the TZ without intraoperative determination of level of resection with FSB (22). In our study, in cases with AGS located until distal half of sigmoid colon, the resection was done 5–10 cm above the visualized TZ while in those with proximal half of rectosigmoid colon and distal part of descending colon resection was done 10–15 cm above the TZ. Postoperative microscopic examination of the resections showed that the macroscopic assessment determined the level of resection in the NGS. Some hospitals still rely on contrast enema for determination of AGS and TZ preoperatively due to unavailability of frozen section facilities (9)(10). Contrast enema in our study was used besides for preoperative planning also to exclude cases with long segment and TCA in which cases two-staged procedure with intraoperative FTB was done. None of the cases was ultra-short HSCR in our study and only three cases were excluded due to TCA. Some pediatric surgeons in cases where the clinical and imaging signs are quite characteristic for HSCR start the operative procedure without prior HP confirmation of HSCR by performing the first HP confirmation from the trans rectal biopsy performed as FSB (20)(22) and then proceed with operation planed based on contrast enema till at least 5 cm above the last confirmation of ganglion cells and no-hypertrophied nerve fibers confirmed from FSB where they then perform the bowel resection (8). The main intraoperative challenge is determining the level of resection above the TZ in order to avoid complications related to retained TZ. Recommendations changed widely regarding the resection over the transitional zone from 2 cm to 15 cm (4). Schäppi et al. recommend that the proximal resection margin be at least 2-3cm of colon proximal to the first biopsy showing normal ganglion density (14). White and Langer recommended excising > 2cm while Kapur and Coyle > 5cm of proximal to the most distant ganglionic biopsy in order to avoid a transition zone pulled through (TZPT) (23)(24)(25). Also, Smith C, Kapur RP et al, proposed that the level of resection should be performed at least 5 cm proximal to the TZ (4). In an article from Jeffry A. and Marc L. TZ have been described to measure between 1 to 10 cm recommending to perform an anastomosis 3–10 cm above the biopsy site with normal ganglion cells (18). Tomuschat C. et suggest performing the coloanal anastomosis 5–10 cm proximal to the most distant ganglionic biopsy is safe (17). Georgeson recommended that a 10-15cm margin of ganglionic colon should be resected prior to completing the anastomosis (26). The presence of TZ in the anastomosis is associated with constipation and a higher incidence of HAEC (27). Conversely, despite undergoing complete resection of the AGS and TZ, some patients still suffer from severe constipation or episodes of HAEC, while patients with a TZPT have a higher risk for constipation and HAEC (28). However, De la Torre et all stated that there was no difference in these complications between those with and without TZPT (29). In 13 patients out of 60 cases in our research operated from HSCR, signs of constipation were identified after the operation due to colon hypo motility, which were treated with conservative therapy. In the two-decade follow-up of these cases, HAEC was cause of one hospitalization in 17 and in two cases they were repeated within two years for three and four times respectively, indicating the repetition of contrast enema and trans rectal biopsy in one case even though the presence of NGS was confirmed from his resection. From the FTHB performed 2 and 4 cm above the dentate line, it was found that from the sample taken at the 2nd centimeter above the dentate line, rare ganglion cells were found (hypoganglionosis), while in the fourth centimeter normally ganglionated segment was confirmed. It was reconfirmed also by IHC re-examination that the normally ganglionated segment was present up to the seventh centimeter distally to the resected margin. The hypoganglionosis found at this level may have been due to possible partial ischemia at the level of the anastomosis, a phenomenon reported in the literature as the cause of hypoganglionosis and aganglionosis (30)(31). The same patient was treated with dilations for 3 months after the operation due to the development of post-operative stenosis that may also have been a consequence of the ischemia of the anastomosis. Determining the normoganglionic "safe zone" through FSB is safer than the surgeon’s intraoperative judgement, but it is also necessary to take into account the considerable degree of subjectivity in the correct identification of the hypo ganglionic zone from the normoganglionic one and the length of stay in the anesthesia until receiving the result from the FSB. In the 60 cases operated without FSB in our research, in no case was FSB performed, reducing the time of stay in anesthesia, avoiding the involvement of the Pathologist with additional expenses, making it less expensive and much more effective in reducing number of FSB. In our research, comparison of macroscopic and microscopic results showed significant correlation and suggest that macroscopic assessment can reliably predict the presence of NGS in cases with short segment HSCR. However, macroscopic evaluation has been shown to be much higher in experienced hands (9)(10)(21). It also has been shown to be challenging in identifying TZ in neonatal age and in some cases also under the age of three months even from experienced pediatric surgeon as it has been shown from contrast enema studies (1)(32)(33). We reviewed the literature and no research so far had used comparison between microscopic and macroscopic evaluation for decision making for the level of resection during definitive operation in HSCR. The sensitivity of macroscopic evaluation in our study was 100% but we believe that this resulted since all cases in our study were above 9 months of age and in all cases AGS was between sixth centimeter above dentate line and lower third of descending colon. The third possible reason could have been that resection was done 5–10 cm above TZ in cases with AGS located until lower half of sigmoid colon and had less dilated segment and 10–15 cm in cases from proximal half of sigmoid colon until lower third of descending colon accompanied with more pronounced dilated segment. TZ may be difficult to identify intraoperatively in ultra-short segment as well as in neonatal age since TZ is not well differentiated. Our study’s focus was on accuracy of intraoperative prediction of resection level in normaly ganglionate segment using morfologic changes in te bowel segments in ss-HSCR. We believe that this method is less accurate in long segment HSCR since TZ is much longer and it has been found to have less concordance with contrast enema also. In addition, further multicenter studies with a larger sample size is necessary to clarify and confirm our findings.
Limitations
Surgeons experience in assessing of TZ and NGS, subgroups of patients such as age under 3 months and ultra-short HSCR are considered possible limitations for macroscopic assessment in predicting the level of resection in NGS. It should be tested by other centers in order to strengthen the validity of this method that will lower cost expenses and additional time during operations in Hirschsprung's disease