Meckel's Diverticulum - Clinical Presentation and Pitfalls in Diagnosis in the Pediatric Age Group in Singapore.

Purpose: The purpose of this study was to study the presentation of patients who underwent Meckel's diverticulectomy (MD) and utility of pertechnetate Meckel's scan in the diagnosis of MD.
Methods: The clinical presentation of a retrospective cohort of patients who underwent MD from January 2007 to December 2019 was studied. The modes of presentation, treatment, and the diagnostic utility of pertechnetate Meckel's scans were evaluated. False-positive and false-negative scans were reviewed. The presence of gastric mucosa on histology of Meckel's was correlated with presentation as gastrointestinal bleeding and positive scan results.
Results: Ninety-nine patients underwent MD. Thirty-five out of 263 (13.3%) Meckel's scans done were positive. There was a male preponderance (86.9%). The peak age of presentation was 0-4 years (rectal bleeding or intestinal obstruction). Only a third of the patients with Meckel's diverticulum Meckel's had a preoperative diagnosis of Meckel's. The sensitivity/specificity of Meckel's scan was higher in patients presenting with painless rectal bleeding. Seven patients were false positive (weak tracer uptake or ectopic uptake) and five were false negative. Two patients with false-negative Meckel's scan, having gastrointestinal bleeding had gastric mucosa on histology of Meckel's.
Conclusion: Meckel's diverticulum has a male predominance. Meckel's scan has a high sensitivity in the children presenting with fresh painless rectal bleeding but is of limited use in the diagnosis of Meckel's diverticulum in other forms of presentations. False-positive scans can be anticipated in the presence of weak or ectopic uptake. False-negative scans can occur even in the presence of bleeding and in spite of the presence of gastric mucosa in the Meckel's diverticulum. Laparoscopy is a useful tool in diagnosis and treatment. Copyright:

INTRODUCTION

The incidence of Meckel's diverticulum is between 1% and 3%.[12] Clinical symptoms and complications can arise from small bowel obstruction, bleeding, inflammation, or umbilical abnormalities. Meckel's diverticulum being the cause of the clinical problem may not be diagnosed preoperatively when the child presents with intestinal obstruction or inflammation. Majority of the Meckel's remain silent and are diagnosed incidentally during small bowel contrast studies, laparoscopy, or laparotomy done for unrelated conditions, or when complications arise from the diverticulum.[34] Meckel's scan is commonly used for the diagnosis of Meckel's diverticulum. Sensitivity and specificity of Meckel's scan in published literature are around 85% and 95%, respectively.[567] The current study looked at the various presentations of Meckel's diverticulum in our multiracial Asian population. We also analyzed the limitations of using Meckel's scan in diagnosing Meckel's diverticulum in our setup.

METHODS

Study design

This was a retrospective observational study from January 2007 to December 2019 conducted in a tertiary children's hospital in Singapore. Institutional review board (IRB) approval was obtained before the commencement of this study (IRB 2016/2557). All patient admissions during the period of study were captured on the hospital electronic medical record system. The duration of follow-up was 1 year – 13 years with a median of 6.5 years.

Subjects and study group

The clinical presentation of all patients who underwent Meckel's diverticulectomy (MD) was studied (age, sex, mode of presentation, and scan results if done). The detailed records of the patients who underwent both the Meckel's scan and surgery were analyzed. The sensitivity, specificity, positive predictive values, and negative predictive value of Meckel's scan were calculated. The histology of the Meckel's diverticulum of all scan positive and negative patients was reviewed. All the patients who had positive Meckel's scans but did not have a Meckel's diverticulum at operation or improved without surgery were followed up (false positive). Patients with a negative Meckel's scan but had Meckel's diverticulum at operation were reviewed (false negative).

Protocol for obtaining Meckel's scan

All patients who underwent a Meckel's scan had a standardized scanning protocol. Patients were kept nil by mouth for 4–6 h before the Technetium-99m pertechnetate scintigraphy. Ranitidine was administered by intravenous infusion over a period of 10–20 min at a dose of 1 mg/kg to a maximum dose of 50 mg 1 h before imaging. Five dynamic images were acquired over a period of 30–40 min.

Statistical analysis

Categorical and continuous data were summarized as frequency with percentage and mean ± standard deviation, respectively. Diagnostic accuracy of Meckel's scan was calculated using sensitivity, specificity, positive predictive values, and negative predictive values with corresponding 95% confidence interval (CI). P < 0.05 is considered to be statistically significant, and all statistical analyses were done using the IBM SPSS Statistics for Windows, Version 19 (New York, USA).

RESULTS

Patient demographics

A total of 99 patients underwent MD [Figure 1]. All the preoperatively suspected patients with Meckel's diverticulum underwent laparoscopic transumbilical MD (LATUM). Eighty-six patients were males (87%). Four patients were found to have incidental MD at surgery for other conditions. Table 1 gives a breakdown of the mode of presentation in relation to age. The common mode of presentation was rectal bleeding (35%), intestinal obstruction (30%), and incidental MD with appendicitis (25%), as shown in Figure 1. It was observed that MD has the highest incidence in the first 4 years of life. Lower gastrointestinal bleeding was the most common mode of presentation, followed by intestinal obstruction in the first 4 years of life. The rarer forms of presentation included incidental findings during surgery for an unrelated cause or perforated Meckel's with peritonitis or in association with childhood intussusception as a lead point.

Figure 1

Presentation of Meckel's diverticulum between 2007 and 2019

Table 1

Age distribution of Meckel’s diverticulum and breakdown of patients with Meckel’s diverticulum

Age	Total number of patients (n=99)	Patient with bleeding (n=35) All scan positive	Patient with IO (n=30)	Patient with appendicitis (n=25)	Others e.g.,: Incidental Meckel’s diverticulitis (n=9)
0-4	38	16	14	3	5
5-8	16	5	6	4	1
9-12	25	6	6	11	2
13-16	20	8	4	7	1

IO: Intestinal Obstruction

A total of 263 patients (170 males) underwent a Meckel's scan (192 patients had bleeding per rectum). Other indications for Meckel's scan included recurrent abdominal pain, with a clinical suspicion of the presence of a Meckel's diverticulum. Only 37 patients were scanned positive [Figure 2]. Thirty out of 35 patients who were confirmed to have a MD intraoperatively were scanned positive for Meckel's diverticulum. Five of the 226 Meckel's scan negative patients underwent surgery for lower gastrointestinal bleeding, and were subsequently found to have MD intraoperatively. Only 11.4% (30/263) were true positives on Meckel's scan. Another 68 patients who did not undergo a Meckel's scan had Meckel's diverticulum intraoperatively. Of these, 64 patients underwent MD. The reasons for nonoperation in the rest were because of the absence of any associated pathology and a narrow base. MD was done by LATUM and diagnostic laparoscopy always preceded endoscopy as this avoided bowel distension with gas.

Figure 2

Flow chart of patient identified with Meckel's diverticulum

Sensitivity and specificity of the Meckel's scan

The overall sensitivity and specificity of Meckel's scan are shown in Table 2. The sensitivity and specificity for Meckel's scan were 86% and 97%, respectively, when applied for all patients with symptomatic Meckel's diverticulum. The sensitivity and specificity of the Meckel's scan in patients with per rectal bleeding were higher than when used for patients with all symptomatology (sensitivity 94% [95% CI: 75.58–99.21] and specificity 96% [95% CI 92.07–98.62]).

Table 2

Sensitivity and specificity of the total Meckel’s scan and patient’s presenting with gastrointestinal bleeding only

	Meckel’s scan (n=263)		With bleeding (n=192)
	Percentage	95% CI	Percentage	95% CI
Sensitivity	85.7	69.74-95.19	93.6	78.58-99.21
Specificity	96.9	93.78-98.76	96.3	92.07-98.62
Positive likelihood ratio	27.9	13.30-58.62	25.1	11.39-55.34
Negative likelihood ratio	0.15	0.07-0.33	0.1	0.02-0.26
Positive predictive value	81.1	67.12-90.00	82.9	68.68-91.42
Negative predictive value	97.8	95.15-99.01	98.7	95.30-99.66
Prevalence	13.3	9.45-18.02	-

CI: Confidence interval

Histology and Meckel's scan

The histology of the excised MD of 35 patients were reviewed. Seventeen scan-positive patients (49%) demonstrated only gastric mucosa on histology. Two patients (9%) with MD presenting with lower gastrointestinal bleeding were Meckel's scan negative despite having gastric mucosa on histology. Others excised specimens had gastric mucosa, and in addition, ileal mucosa (eight scans positive and two scans negative), pancreatic tissue (two and both scan positive), and two patients had additional colonic mucosa (both scan positive). One patient had isolated pancreatic tissue and was scan negative.

False-positive and false-negative scans

Seven patients had a false-positive scan. Four of these patients underwent surgery and were proven to have no Meckel's diverticulum at operation. While three of them were detected with a strong positive scan. The other three patients settled down and are well. Out of the five false-negative scans, two patients presented with gastrointestinal bleeding, two patients presented with chronic abdominal pain, and one patient had surgery for adhesive obstruction. All the false-negative patients underwent surgery and the removal of Meckel's diverticulum.

DISCUSSION

Earlier studies on Meckel's diverticulum reported from Singapore and Malaysia are mainly case reports.[89101112] Bleeding and other complication of Meckel's are much more common in the younger population in literature which is similar in our population. Several studies from Asia and Turkey have not looked at the efficacy of Meckel's scan in diagnosis.[131415] Hence, the current study of MD among our multiethnic population in Singapore was undertaken to know if the mode of presentation of MD and diagnostic accuracy of the Meckel's scan was similar to that reported in the Western literature. We found an extreme male preponderance in our population, unlike the 2:1 ratio reported in the literature. Only around 11% of the clinically suspected 263 patients (bleeding PR or chronic abdominal pain) had a positive scan in our population. Moreover, only a third of our Meckel's diverticulum patients were preoperatively suspected as Meckel's and others were picked up incidentally during laparotomies.

Recent article by Chen et al.[16] found that preoperative diagnosis is difficult, and a suspicion of Meckel's diverticulum must be investigated if patient is presented with abdominal pain, bleeding per rectum, or intestinal obstruction. The authors performed 78 Meckel's scans and 55 were positive (70.51%).[16] In our current study, only 30 out of 263 Meckel's scans (11.4%) were true positive. Hence, it is futile to order Meckel's scan in the absence of typical rectal bleeding. The target population in which the test is ordered must be young and presenting with a typical painless fresh rectal bleeding. In the rest of the patients, other diagnostic modalities including diagnostic laparoscopy must be considered.

Ueberrueck et al.[17] found 230 cases of incidental Meckel's diverticulum in 7927 patients with acute appendicitis, out of which, only 188 (80.7%) Meckel's diverticulum were removed. No significant complication was found in patients without removal of Meckel's diverticulum (follow-up duration of 14.5 ± 5.8 years). The authors recommended that Meckel's diverticulum with obvious pathology should always be removed. In cases of perforated appendicitis, incidental Meckel's diverticulum should be left in place.[17] In our present study, 25 patients with acute appendicitis had incidental Meckel's diverticulum. Only had Meckel's diverticulum removed at a later date.

The incidence of gastric mucosa in MD is estimated to be between 17% and 50%.[518] Ectopic tissue such as of gastric, duodenal, colonic, or pancreatic origin may be present in MD. Rutherford and Akers[19] studied 148 pediatric patients with special reference to patterns of bleeding and found ectopic gastric mucosa in 57% of the patient. In our own series, 48.6% of the MD which were examined had gastric mucosa on histopathology.

Despite the availability of modern imaging techniques, the diagnosis of MD remains challenging. Kong et al. reported that the sensitivity of a Meckel's scan was 81%, whereas specificity was 97%.[6] The present study suggests that sensitivity and specificity of Meckel's scan can be improved if it is only used for patients who were presented with rectal bleeding. Meckel's scan has a several limitations that may lead to false-negative tests result such as insufficient gastric mucosa, dilution of the radioisotope, runoff due to ongoing bleeding, suboptimal techniques, and loss of function of the gastric mucosa. Other conditions such as gastrogenic cysts, enteric duplications, Barrett's esophagus, obstructed bowel loops, inflammatory bowel lesions, arteriovenous malformations, and some bowel tumors may lead to false-positive Meckel's scan. Some urinary tract abnormalities may also affect the uptake of pertechnetate and influence the sensitivity of Meckel's scan.[2021222324] Several technical points should also be given attention, including fasting and emptying the bowel and bladder before the procedure. Lateral films are acquired in addition at 30 min to record the renal activity. There are certain specific characteristics on the scan that may be more supportive of a diagnosis of MD that contains ectopic gastric mucosa; in these cases, the hyperactivity is as follows: (i) prominent, (ii) rounded, (iii) small in size, (iv) appearing 10–20 min after injection, (v) parallel to the intensity of uptake in the stomach, (vi) usually located in the right lower quadrant, and (vii) may change in position on moving the child.

The diagnosis of MD can also be enhanced using single-photon emission CT/CT imaging.[2526] It has been found that the fused images facilitate the precise anatomic location of a focused uptake. This can help to reduce the incidence of false-positive Meckel's scans that occur due to activity in the genitourinary tract or vascular malformations present near bowel loops. In addition, in the case of negative examinations, it can potentially reveal other causes for abdominal pain and bleeding. However, this involves a higher radiation dose than conventional Meckel's scintigraphy.

CONCLUSION

In our local, multiethnic population, MD has a higher preponderance in males than reflected in literature. Symptomatic patients are most commonly present with rectal bleeding or bowel obstruction. Two-thirds of our patients with MD did not have a preoperative diagnosis. The sensitivity and specificity of Meckel's scan with concomitant administration of ranitidine in an Asian population are excellent and are comparable to the reports in published literature. It has a higher diagnostic yield when performed in patients presenting with rectal bleeding.

Patients who continue to have significant gastrointestinal bleeding after a negative scan may benefit a diagnostic laparoscopy as there are patients who have a false-negative Meckel's scan.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.